CN113018440B - Application of miR-7977 as drug target for inhibiting high-sugar-induced apoptosis of Ad-MSCs - Google Patents

Abstract

The invention discloses application of miR-7977 as a drug target for inhibiting high-sugar-induced apoptosis of Ad-MSCs, and belongs to the technical field of biomedicine. Specifically, the invention discovers that promoting miR-7977 expression has stronger anti-apoptosis effect on Ad-MSCs. In addition, the research of the invention proves that the inhibition of the apoptosis of Ad-MSCs can promote the healing of the diabetic wound, so the invention provides an effective treatment strategy for the repair of the diabetic wound.

Description

Application of miR-7977 as drug target for inhibiting high-sugar-induced apoptosis of Ad-MSCs

Technical Field

The invention belongs to the technical field of biological medicines, and particularly relates to application of miR-7977 as a drug target for inhibiting high-sugar-induced apoptosis of Ad-MSCs.

Background

The chronic wound surface of diabetes is one of the common diseases in clinic and is the main cause of diabetes disability. Because of metabolic disorder, impaired immune function, slow nerve response and other reasons of a diabetic patient, the diabetic wound is difficult to heal by self and has a long course of disease, so that the pain of the patient is brought, and heavy economic burden and nursing pressure are brought to families of the patient, and therefore, the occurrence and treatment of the diabetic wound are increasingly serious social problems. Currently, a variety of stem cells including Ad-MSC (adipose mesenchymal stem cells) have been used to treat diabetic wounds.

miRNA is endogenous non-coding small molecular RNA for regulating gene expression, regulates gene expression at the level after transcription, and participates in physiological processes such as cell cycle, apoptosis, development, differentiation, metabolism and the like. The typical mode of action of mirnas with target mrnas is mainly two. In most cases, the single-stranded miRNA in the complex is not perfectly complementary paired with the 3' UTR of the target mRNA, blocking translation of the target gene, thereby regulating gene expression. This approach mainly affects the protein expression level, but not the stability of the mRNA. Another mode of action is similar to siRNA, when miRNA is completely complementary paired to mRNA, Ago2 protein directly causes its degradation by cleaving mRNA, thereby effecting gene silencing.

In conclusion, the studies suggest that the binding effect of miRNA and the target gene is related to the degree of pairing between miRNA and the target gene. When the miRNA is incompletely paired with the target gene, the miRNA plays a role in inhibiting the expression of the target gene; when the miRNA is completely paired with a certain sequence of the target gene, the target gene may be disrupted in the complementary region, thereby silencing the gene. In addition, miRNAs sometimes also cause histidine modifications and DNA methylation in the promoter region, thereby affecting the expression of target genes.

The application aims to research the regulation and control effect of miRNA and target genes on the apoptosis of adipose-derived mesenchymal stem cells, so as to find a drug target for promoting the repair of diabetic wounds.

Disclosure of Invention

The invention aims to provide application of miR-7977 or target genes thereof in inhibiting high-sugar-induced apoptosis of Ad-MSCs.

The invention also aims to provide application of the miR-7977 or the target gene thereof in preparation of a medicament for promoting diabetic wound repair.

The third purpose of the invention is to provide the application of miR-7977 or a target gene thereof in screening of drugs for inhibiting high-sugar-induced apoptosis of Ad-MSCs.

The fourth purpose of the invention is to provide the application of the miR-7977 or the target gene thereof in screening of medicines for promoting the diabetic wound repair.

The fifth purpose of the invention is to provide a medicine for promoting the repair of the diabetic wound.

The invention also aims to provide a medicament for inhibiting the apoptosis of the Ad-MSCs induced by high sugar.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides application of miR-7977 or a target gene thereof in preparation of a medicine for inhibiting apoptosis of Ad-MSCs induced by high sugar.

Preferably, the high sugar refers to that the concentration of glucose in a culture medium or the concentration of blood sugar in an experimental animal is more than or equal to 16.7 mmol/L.

Preferably, the target gene of miR-7977 comprises STK 4.

The invention also provides application of the miR-7977 or the target gene thereof in preparation of a medicament for promoting diabetic wound repair. In a specific embodiment of the invention, the target gene of miR-7977 is STK 4.

The invention also provides a pharmaceutical composition for inhibiting the apoptosis of the Ad-MSCs induced by high sugar or promoting the repair of diabetic wounds.

Further, the pharmaceutical composition comprises an agent for promoting miR-7977 expression and/or an agent for inhibiting miR-7977 target gene expression.

Still further, agents that inhibit the expression of the miR-7977 target gene include agents that inhibit the expression of the STK4 gene.

The reagent for promoting miR-7977 expression comprises an RNA-based microRNA functional acquisition technology, a reagent for up-regulating miR-7977 expression by using a gene-specific miR mimics technology, and a compound promoter.

The agent for inhibiting the expression of STK4 gene of the present invention includes an agent for inhibiting the expression of mRNA of STK4 gene or an agent for inhibiting the expression of STK4 protein.

The agent for inhibiting STK4 gene expression comprises STK4 antibody, STK4 ligand antibody, modified STK4, partial peptide of STK4, siRNAs targeting STK4 gene sequence, shRNAs, antisense molecules, DNA enzyme, and expression vector containing the siRNAs, the shRNAs and the antisense molecules.

Further, the pharmaceutical composition also comprises a pharmaceutically acceptable carrier and/or an auxiliary material.

Further, the carrier and/or adjuvant includes pharmaceutically acceptable carriers, diluents, fillers, binders and other excipients, depending on the mode of administration and the designed dosage form. Therapeutically inert inorganic or organic carriers known to those skilled in the art include, but are not limited to, lactose, corn starch or derivatives thereof, talc, vegetable oils, waxes, fats, polyols (e.g., polyethylene glycol, water, sucrose, ethanol, glycerol), and the like, various preservatives, lubricants, dispersants, flavoring agents, wetting agents, sweeteners, fragrances, emulsifiers, suspending agents, preservatives, antioxidants, colorants, stabilizers, salts, buffers, and the like, to which suitable pharmaceutically acceptable carriers and formulations are also added, as well as those described in detail in Remington's Pharmaceutical Sciences (19th ed.,1995) for aiding the stability of the formulation or for improving the activity or its bioavailability or for producing an acceptable mouthfeel or odor in the case of oral administration, and those that can be used in such Pharmaceutical compositions can be in the form of their original compounds per se, or optionally in the form of a pharmaceutically acceptable salt thereof. The pharmaceutical composition thus formulated may be administered by any suitable means known to those skilled in the art, as desired, by administering a safe and effective amount of the drug of the present invention to a human.

The appropriate dose of the pharmaceutical composition of the present invention can be prescribed in various ways depending on factors such as the method of preparation, the mode of administration, the age, body weight, sex, disease state, diet, time of administration, route of administration, excretion rate and reaction sensitivity of the patient, and usually, a skilled physician can easily determine the prescription and the dose of administration effective for the desired treatment or prevention.

Further, the pharmaceutical composition can be prepared into various clinical pharmaceutical dosage forms as antitumor drugs according to needs, including but not limited to oral preparations or parenteral dosage forms, wherein the oral preparations include tablets, capsules, pills, granules, microcapsule tablets, suspensions, dripping pills and oral liquid preparations; the parenteral administration dosage form comprises an injection, an aerosol, a suppository or a subcutaneous administration dosage form.

Further, the route of administration of the pharmaceutical composition is not limited as long as it can exert the desired therapeutic or prophylactic effect, and includes, but is not limited to, intravenous, intraperitoneal, intraocular, intraarterial, intrapulmonary, oral, intravesicular, intramuscular, intratracheal, subcutaneous, topical, inhalation, through the skin, through the pleura, through the mucosa, skin, gastrointestinal, intraarticular, intraventricular, rectal, vaginal, intracranial, intraurethral, intrahepatic. In some cases, the administration may be systemic. In some cases topical administration.

Further, the dosage of the pharmaceutical composition is not limited as long as the desired therapeutic effect or prophylactic effect is obtained, and may be appropriately determined depending on the symptoms, sex, age, and the like. The dose of the therapeutic or prophylactic pharmaceutical composition of the present invention can be determined using, for example, the therapeutic effect or prophylactic effect on a disease as an index.

The invention also provides a method for inhibiting high-sugar induced apoptosis of Ad-MSCs in vitro, which comprises promoting miR-7977 expression and/or inhibiting miR-7977 target gene expression.

Further, the miR-7977 target gene includes the STK4 gene.

The invention also provides application of the miR-7977 or the target gene thereof in screening of a medicine for inhibiting high-sugar-induced apoptosis of Ad-MSCs or a medicine for promoting diabetic wound repair.

The invention also provides a method for screening a medicine for inhibiting the apoptosis of the Ad-MSCs induced by high sugar or a medicine for promoting the wound repair of diabetes, which comprises the following steps:

(1) treating a system expressing or containing miR-7977 or a target gene thereof with a test substance;

(2) detecting the expression of miR-7977 or a target gene thereof in the system;

(3) selecting a test agent that can promote expression of miR-7977 or inhibit a miR-7977 target gene;

preferably, the miR-7977 target gene comprises an STK4 gene.

Further, the system is selected from: a cell system, a subcellular system, a solution system, a tissue system, an organ system, or an animal system.

Further, the test substances include, but are not limited to: interfering molecules, nucleic acid inhibitors, small molecule compounds and the like designed aiming at miR-7977 or target genes thereof or upstream or downstream genes thereof.

Further, the selected test agent described in step (3) is one that promotes the expression level of miR-7977 or inhibits the expression level of a miR-7977 target gene as compared to the expression level detected in the absence of the test agent.

The term "expression level" refers to the amount of a gene product present in vivo or in a sample at a particular time point. The expression level can be measured/quantified/detected, for example, by protein or mRNA expressed by the gene. The expression level can be quantified, for example, as follows: normalizing the amount of the gene product of interest present in the sample with the total amount (total protein or mRNA) of the same type of gene product in the same sample or reference sample (e.g., a sample obtained from the same individual at the same time or a fraction of the same size (weight, volume) of the same sample), or determining the amount of the gene product of interest/defined sample size (weight, volume, etc.). The expression level can be measured or detected by any method known in the art, such as a method for direct detection and quantification of a gene product of interest (e.g., mass spectrometry), or a method for indirect detection and measurement of a gene product of interest that generally works by binding the gene product of interest to one or more different molecules or detection devices (e.g., primers, probes, antibodies, protein scaffolds) specific for the gene product of interest. Also known to the skilled person is the determination of the level of gene copy, which also includes the determination of the absence or presence of one or more fragments (e.g. by nucleic acid probes or primers, such as quantitative PCR, Multiplex ligation-dependent probe amplification (MLPA) PCR).

The miR-7977 is selected from at least one of pri-miRNA, pre-miRNA, mature miRNA and dsmiRNA.

Drawings

FIG. 1 shows a graph of the results of GO on the high sugar induced apoptosis of Ad-MSCs, where A: a streaming graph; b: a stream result statistical chart; c: TUNEL results plot; d: TUNEL results statistical plots;

FIG. 2 shows a graph of the results of GO effect on apoptosis-related factor expression during hyperglycemia-induced apoptosis of Ad-MSCs, where A: a western blot; b: a statistical map of western blot results;

fig. 3 shows a graph of the results of GO on Linc00324 expression, where a: gene sequencing result graph; b: a qPCR histogram; c: a result graph of the effect of different GO concentrations on Linc00324 expression under high-sugar conditions; d: a result graph of the effect of different GO concentrations on Linc00324 expression under non-high sugar conditions;

FIG. 4 shows graphs showing the results of Linc00324 expression assays in Linc00324 expression downregulated cell lines and overexpressed cell lines, where A: an immunofluorescence profile; b: a qPCR histogram;

fig. 5 shows a graph of the results of the effect of Linc00324 expression on apoptosis, where a: TUNEL results plot; b: TUNEL results statistical plots; c: a streaming graph; d: a stream result statistical chart; e: immunoblot patterns of apoptosis-related factor expression;

fig. 6 shows a graph of the effect of co-culture of a cell line highly expressing Linc00324 with GO on apoptosis, where a: TUNEL results plot; b: TUNEL results statistical plots; c: a streaming graph; d: a stream result statistical chart;

fig. 7 shows a graph of the results of the Linc00324 localization, where a: (ii) a nucleic acid electropherogram; b: a qPCR histogram;

FIG. 8 shows a graph of the results of Linc00324 expression on miR-7977 expression regulation;

FIG. 9 shows a graph of the results of detecting miR-7977 localization using FISH assay;

FIG. 10 shows a graph of results predicting the site of action of Linc00324 in miR-7977, wherein A: schematic diagram of experimental scheme; b: a result graph;

fig. 11 shows a graph of the results of detecting binding between miR-7977 and Linc00324, where a: RIP experiment; b: in vitro affinity experiments;

FIG. 12 is a graph showing the results of the effect of miR-7977 inhibitors on the expression level of Linc 00324;

FIG. 13 shows a graph of the results of flow cytometry analysis of the effect of miR-7977 mimetics on apoptosis of Ad-MSCs in a high sugar environment, wherein A: a streaming graph; b, flow type statistical chart;

FIG. 14 shows a graph of the results of the TUNEL method for analyzing the effect of miR-7977 mimetics on apoptosis of Ad-MSCs in a high sugar environment, wherein A: TUNEL results plot; b: TUNEL results statistical plots;

figure 15 shows a graph of the results of miR-7977 mimetics on the expression of apoptosis-related factors, where a: a western blot; b: a western blot statistical map;

fig. 16 shows a graph of the results of detecting the effect of miR7977 on STK4 expression using a luciferase reporter, where a: a scheme of an experiment; b: a result graph;

fig. 17 shows a graph of the results of detecting the effect of miR7977 on STK4 expression using qPCR and Western blot experiments, wherein a: a western blot; b: a western blot result chart; c: a qPCR histogram;

FIG. 18 shows a graph of the results of flow cytometry analysis of the effect of XMU-MP-1 on apoptosis, where A: a streaming graph; b: a stream type statistical graph;

FIG. 19 is a graph showing the results of analysis of the effect of XMU-MP-1 on apoptosis using the TUNEL method, wherein A: TUNEL results plot; b: TUNEL results statistical plots;

FIG. 20 is a graph showing the results of analyzing the effect of XMU-MP-1 on apoptosis using Western blot;

figure 21 shows a graph of the results of flow cytometry analysis of the effect of miR-7977 mimetics on apoptosis, where a: a streaming graph; b: a stream type statistical graph;

figure 22 shows a graph of the results of analyzing the effect of miR-7977 mimetics on apoptosis using the TUNEL method, where a: TUNEL results plot; b: TUNEL results statistical plots;

FIG. 23 shows a graph of the results of analyzing the effect of miR-7977 mimetics on apoptosis using Western blot, A: a western blot; b: a western blot result chart;

figure 24 shows a graph of results of flow cytometry analysis of the effect of miR-7977 inhibitors on apoptosis, where a: a streaming graph; b: a stream type statistical graph;

fig. 25 shows a graph of the results of analyzing the effect of miR-7977 inhibitors on apoptosis using the TUNEL method, wherein a: TUNEL results plot; b: TUNEL results statistical plots;

FIG. 26 shows a graph of the results of analyzing the effect of miR-7977 inhibitor on apoptosis using Western blot, A: a western blot; b: a western blot result chart;

fig. 27 shows a result graph of GO detection on wound repair impact using fluorescent staining method, where a: a fluorescent substance picture; b: a statistical chart;

fig. 28 shows a graph of results characterizing wound healing effects using a wound healing index, where a: a real object diagram; b: a statistical chart;

FIG. 29 is a graph showing the results of HE staining of a tissue section;

FIG. 30 is a graph showing Masson staining results;

FIG. 31 shows a fluorescence plot of tissue immunofluorescence detecting CD31 and TNF-. alpha.expression;

FIG. 32 shows a histogram of tissue immunofluorescence assay CD31 and TNF-. alpha.expression, where A: TNF-alpha; b: CD 31;

FIG. 33 is a graph showing the results of ELISA detection of wound-healing-associated cell secretion.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention only and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples, generally following conventional conditions, such as Sambrook et al, molecular cloning: the conditions described in the laboratory Manual (New York: Cold Spring harbor laboratory Press,1989), or according to the manufacturer's recommendations.

Examples

Method and device

1. Cell co-culture

The final concentration is 0.1mg/ml (+),0.2mg/ml (++) and 0.4mg/ml (+++) graphene oxide (GO (graphene oxide)) (Xianfeng, Nanjing) solution were added to Ad-MSCs medium at 37 deg.C with 5% CO₂While adding glucose to a final concentration of 16.7 mmol/L. After 48 hours of incubation, further experiments were performed.

2. CM-Dil staining

CM-Dil (Invitrogen, USA) labels cells by binding to lipid molecules of the membrane structure with strong and stable red fluorescence (excitation 420 nm/emission 488nm) detected by xenogenisis ivis200 imaging system (xenogenin Corp).

3. Western blotting

Cell extracts were separated on SDS-polyacrylamide gels, and the proteins were then transferred to nitrocellulose membranes and incubated with rabbit polyclonal antibodies against STK4, anti-BIM, anti-Bax, anti-BCL-2, anti-AGO 2(1:500, Cell Signaling Technology) and monoclonal antibodies against beta-actin (1:1000, Cell Signaling Technology). Immunoreactive protein bands were detected using the Tanon scanning system (Tanon Science & Technology co., ltd., beijing, china).

4. Flow cytometry

Following experimental treatment, Ad-MSCs were stained with annexin V-Fluorescein Isothiocyanate (FITC)/PE (Roche, USA) for 1h at 37 deg.C, then detected by flow cytometry, and analyzed for apoptosis using FlowJo _ V10 software.

5. TUNEL assay

Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay (in situ cell death detection kit; roche diagnostics) was used to determine apoptosis of Ad-MSCs. Ad-MSCs were incubated with TdT and fluorescein-labeled dUTP for 45 min at 37 ℃. The percentage of apoptotic cells was then assessed.

6. RNA-pull down experiment

Pierce^TMMagnetic RNA protein pull down kit (Thermo Fisher Scientific, Massachusetts, USA) was used for RNA-pull down assay. High-yield in vitro transcription kit (Thermo Fisher Scientific) and Pierce RNA3' end desulfurization biotinylation kit (Thermo Fis) using biotin-labeled RNAtrancript Aid T7her Scientific) and then treated with RNase-free dnase i (thermo Scientific). Recovered protein was detected by western blot. The procedure is based on the Western blot protocol previously described according to the manufacturer's instructions and standards.

7. Establishment of diabetic nude mouse wound model

All procedures were approved by the Xuzhou university of medical care and use Committee (project No.: XYFY2016-KL 033). After 12 hours of fasting (free drinking water), the body weight was weighed and injected intraperitoneally with 2% STZ at a dose of 150 mg/kg. After one week, the blood glucose concentration of the rats was measured from the tail vein with a glucometer, the blood glucose concentration being greater than 16.7 mmol/L.

8. RNA binding protein immunoprecipitation (RIP)

Using Magna RIP^TMRIP analysis was performed using RNA binding protein immunopurification kit (Millipore). A positive control anti-SNRNP 70 antibody was used in the RIP procedure. The sample was incubated with proteinase K and the non-precipitated RNA was isolated.

9. Fluorescence In Situ Hybridization (FISH)

Genephrma synthesized FITC-labeled probes for detecting Linc00324 and Cy 3-labeled probes for detecting miR-7977. The signal of the probe was detected by fluorescence in situ hybridization kit (Genephrma, Shanghai, China) according to the manufacturer's instructions. Images were recorded digitally using a Lei TCS SP8 laser scanning confocal microscope (Leica Microsystems, Mannheim, Germany).

10、qRT-PCR

RNA was extracted and prepared for RT-qPCR. The total RNA was reverse transcribed to cDNA using Prime Script reverse transcriptase kit (chinese grand union, Takara) according to the manufacturer's protocol. Quantitative RT-PCR was performed by a Roche-Light Cycler 96 sequence detector (Roche, Germany) using SYBR Green chemistry. Specific primers are shown in table 1.

TABLE 1 primer sequences

11. Establishment of cell line with Linc00324 expression down-regulation and over-expression

The method comprises the following steps: the downregulated plasmid of Linc00324 (vector name pLKD-CMV-EGFP-2A-Puro-U6-shRNA) and the overexpression plasmid (vector name GL109pSLenti-EF1a-EGFP-F2A-Puro-CMV-MCS) were co-transfected with the viral packaging helper plasmids pMD2.G and pSPAX2 into 293T cells for viral packaging. After 48 hours of transfection, concentration and purification, the viral supernatant from the infected supernatant was collected. Mu.l of the collected viral supernatant was added to Ad-MSCs cells with 3. mu.l of polybrene reagent (1. mu.g/ml). Transfection efficiency was observed using a fluorescence microscope 72 hours after virus infection of cells. At this time, cells were collected and dispersed in a single cell suspension, and the expression or overexpression level of the target gene was detected using qPCR and Western blotting. Cell lines that stably express or overexpress the target gene are tested for more than three consecutive generations.

Interference sequence:

shLinc00324-F：CCGGCCACTTCCTTGACGCTATTCTCAAGAGAAATAGCGTCAAGGAAGTGGTTTTTTG(SEQ ID NO.13)；shLinc00324-R：AATTCAAAAAACCACTTCCTTGACGCTATTTCTCTTGAGAATAGCGTCAAGGAAGTGG(SEQ ID NO.14)；

an overexpression sequence:

CMV-F：CGCAAATGGGCGGTAGGCGTG(SEQ ID NO.15)；H101-Kpn I-R：CGTTGGGAGTGAATTAGCC(SEQ ID NO.16)。

12. construction of wild-type (WT) and mutant (Mut) luciferase reporter genes

The method comprises the following steps: one day prior to transfection, Ad-MSCs cells were plated in 24-well plates and inoculated with 5X 104 cells/well Ad-MSCs cells. And the cell fusion degree reaches 80-90% on the third day. The medium was removed, washed carefully with PBS and replaced with serum-free medium, 250. mu.l per well, 5% CO at 37 ℃₂Culturing in a cell culture box. According to the amount of 20pmol of Linc00324 plasmid/NC per well, it was added to 100. mu.l of Opti-MEM. At the same time, another EP tube was changed. Mu.l Lipofectamine2000 was taken and added to 100. mu.l Opti-MEM. After mixing, it was allowed to stand at room temperature for 5 minutes(ii) a Addition of RNA in the previous step&Reporter gene and Lipofectamine 2000. Mix well and incubate at room temperature for 20 minutes. This was added to a 24-well plate, and four replicate wells were made. At 37 ℃ 5% CO₂Incubate in cell incubator for 4-6 hours and replace with complete medium. After 24 to 48 hours of culture, the medium was discarded, washed 2-3 times with PBS, and the protein was collected with 1X Passive lysine Buffer.

13. Affinity detection of Linc00324 and miR-7977

The method comprises the following steps: generally, each antibody can be labeled with 3-5 biotin, when labeling is carried out, the ratio of biotin to antibody is influenced by the concentration of the antibody, biotin should exceed protein by 12 times (mole) for a 10mg/ml antibody solution, and should exceed 20 times for a 2mg/ml antibody solution, and biotin can also be directly added into a protein solution in the form of powder. The protein sample must not contain sodium azide, BSA, glycine, Tris or any other additive with free amino groups.

13.1 pretreatment of antibody/protein:

13.1.1 mu.l of the labeled reaction solution (0.1M PBS pH7.2) was added to an ultrafiltration column of appropriate cut-off, 1mg of the antibody was added thereto, and the mixture was mixed well.

13.1.24 deg.C, 6,000rpm, centrifuging for 2min, and discarding the filtrate; add 200. mu.l of labeled reaction solution to the ultrafiltration column and mix well. Centrifuging at 6,000rpm at 4 deg.C for 2min,

13.1.3 repeating the steps 1.26-7 times.

13.1.4 mixing the residual liquid in the ultrafiltration column, and standing at room temperature for 1 min; the ultrafiltration column was inverted and placed in a new ultrafiltration tube at 4 ℃ and 6,000rpm for 2min and the liquid was collected.

13.1.5 mu.l PBS was mixed in the ultrafiltration column and left to stand for 1 min. The column was inverted, filtered at 4 ℃ and 6,000rpm for 2min, and the liquid was collected.

13.1.6 step 1.4 was combined with the collected filtrate of step 1.5, the antibody concentration was adjusted to 2mg/ml with the labeled reaction solution, and the mixture was left at 4 ℃ until use.

13.2 labeling of Biotin:

13.2.1 biotin was dissolved in a suitable solvent (see the specification of biotin purchased, different biotin and different solvents) at a concentration of 20mg/ml, and the mixture was added to the antibody solution at a molar ratio of biotin to antibody molecules of 1:20 and reacted at room temperature for 1 hour.

13.2.2 Sephadex separation purification/dialysis bags or ultrafiltration tubes to remove free biotin and other reagents.

13.2.3 the antibodies are preserved in a suitable antibody preservation solution.

14. Transfection of miR-7977 mimic group and inhibitor group

The method comprises the following steps:

1) inoculating the recovered conventionally cultured cells into a 6-well plate according to 105, adding 2-4mL of complete culture medium, uniformly mixing, and placing in a carbon dioxide incubator at 37 ℃ overnight;

2) preparing the following solution in a sterile state: mu.g of the miR-7977 plasmid to be transfected (purchased in Kayji organism) was diluted with 100. mu.l of serum-free medium, b: diluting 25. mu.l of Lipofectamine transfection reagent with 100. mu.l of serum-free medium;

3) mixing the solutions a and b, shaking up, and standing at room temperature for about 30 min;

4) culturing the cells to about 80% of a monolayer, washing the cells for 2 times by using a serum-free culture medium, adding 1mL of the serum-free culture medium into each hole, dropwise adding the mixed solution a and b into each hole, shaking gently and uniformly in the cross direction, and culturing for 24 hours in a carbon dioxide incubator at 37 ℃;

5) and pouring out the transfection solution, replacing the transfection solution with a complete culture medium for continuous culture, and detecting the protein expression amount after culturing for 3-4 days.

15. Construction of STK4 mutant 3' -UTR reporter gene without binding site of miR-7977

The method comprises the following steps: the miR-7977 and STK4 are interchanged to construct a chimeric mutant variant which can be obtained by the method of overlapping PCR. The principle is as follows: for example, two genes, one designated as A and one designated as B.

The sequence of A is 5'-atgcatgctagctagaacgctacgctgactaccccctgatc-3' (SEQ ID NO.17),

the sequence of B is 5'-atgctagtagctagccccccccaggggataattttttaaaacg-3' (SEQ ID NO. 18).

First we will design a primer, assuming that the sequence of the primer is:

A1:5’-atgcatgctagctagaacgct-3’(SEQ ID NO.19)

A2:5’-ggggggctagctactagcatgatcagggggtagtcagcgt-3’(SEQ ID NO.20)

B1:5’-acgctgactaccccctgatcatgctagtagctagcccccc-3’(SEQ ID NO.21)

B2:5’-cgttttaaaaaattatcccct-3’(SEQ ID NO.22)

(in designing primers, 20 sequences of the 5 'end of the B gene were added to the 3' end of A2, and 20 sequences of the 3'end of the A gene were added to the 5' end of B1.)

The method comprises the following steps:

1) amplifying A gene by A1 and A2, and amplifying B gene by B1 and B2;

2) recovering the A and B genes;

3) a + B is amplified by taking A and B as a common template and A1 and B2 as primers, so that the A + B is spliced by using a recombinant PCR method.

16. MiR-7977 mimetics and overexpressed Linc00324 co-transfected Ad-MSCs

1) pCDNA3.1 vector double digestion

2) Connecting the processed target fragment with the vector

The above ligation solution was incubated overnight at 16 ℃. Transformation (competent cells: DH5 a). Resistance: amp, 37 ℃, cultured overnight. After transformation, the Linc00324 genes are respectively subjected to plate selection, bacteria shaking at 37 ℃ at 250 rpm for 14 hours, and PCR identification. Stable cell lines were established as described in (1) and cotransfection was carried out as described in (14).

17. MiR-7977 inhibitor and expression-down-regulated Linc00324 co-transfected Ad-MSCs

The method comprises the following steps: 3 to 4 siRNA targets are designed according to the transcript of the Human Linc00324 gene, and primer synthesis is arranged. Annealing the single-stranded primer into a double-stranded oligo sequence, connecting the double-stranded oligo sequence with a double-enzyme digestion linearized RNA interference vector, and replacing the original ccdB toxic gene. Transformants are screened by colony PCR, and sequencing verification is carried out on the screened positive clones. And (5) sequencing to verify correct clone, and performing high-purity plasmid extraction. Stable cell lines were established as described in (1) and cotransfection was carried out as described in (14).

18. Statistical analysis

The results shown represent at least three replicates. All quantitative data are expressed as mean + SEM. Statistical analysis was performed using SPSS version 22.0 (SPSS Inc, Chicago, Il). Differences in multiple groups were compared by one-way analysis of variance (ANOVA) followed by post-test. The difference between the two groups was determined by t-test. P values <0.05 were considered statistically significant (./P < 0.05).

Second, result in

(1) GO can reduce the apoptosis of Ad-MSCs induced by high sugar.

And after co-culturing GO and Ad-MSCs, detecting the apoptosis condition of the Ad-MSCs by using a flow cytometer. A significant decrease in the apoptosis rate of Ad-MSCs after co-culture was found in the same high-sugar environment (FIG. 1A, B). Apoptosis was then detected with TUNEL kit with similar results (fig. 1C, D). Furthermore, the reduction of apoptotic cells was more pronounced with increasing GO concentration. Western blot and QPCR experimental results show that the expression of pro-apoptotic molecules Bax, BIM and STK4 is reduced along with the increase of GO, and the expression of anti-apoptotic molecules bcl-2 is increased along with the increase of GO (figure 2), which indicates that GO has an inhibiting effect on the apoptosis of adipose mesenchymal stem cells in a high-sugar environment.

(2) GO (graphene oxide) inhibition expression of Linc00324 in Ad-MSCs (Ad-MSCs)

And (3) carrying out gene sequencing on the cells after the GO and the Ad-MSCs are co-cultured. Sequencing showed that multiple LncRNA expression was changed after co-culture (fig. 3A). The expression of Linc00324 was significantly different as verified by qPCR (FIG. 3B). It was found that Linc00324 expression in Ad-MSCs decreased with increasing GO concentration during co-culture (FIG. 3C, D).

Establishing a Linc00324 expression down-regulation and over-expression cell line (figure 4), and verifying the cell line, wherein the apoptosis of a Linc00324 expression down-regulation group is obviously reduced under the high-sugar condition, and the apoptosis rate of a Linc00324 over-expression group is opposite; linc00324 expression down-regulated expression of the pro-apoptotic molecules Bax, BIM, STK4 decreased, expression of the anti-apoptotic molecule bcl-2 increased, whereas Linc00324 over-expressed the set trended in the opposite direction (FIG. 5). To further verify whether GO regulates apoptosis via Linc00324, co-culture of GO with a cell line highly expressing Linc00324 revealed no reduction in apoptosis (fig. 6). Thus, Linc00324 is one of the factors by GO that regulates apoptosis.

(3) Linc00324 as molecular sponge of miR-7977

To determine the mechanism by which Linc00324 regulates apoptosis in Ad-MSCs, the localization of Linc00324 was examined. The results show that Linc00324 is predominantly localized to the cytoplasm (fig. 7), suggesting that it may have a function to compete for endogenous RNA, and may act as a molecular sponge for mirnas.

A search of the miRDB database showed the 5 miRNAs with the highest binding scores. qPCR primers were designed against these 5 miRNAs to determine if they were regulated by Linc 00324. Notably, miR-7977 levels were significantly reduced in the Linc00324 overexpressing group, while miR-7977 levels were increased in the Linc00324 knockout group (fig. 8).

The localization of miR-7977 using FISH assay revealed that miR-7977 is mainly localized in the cytoplasm (FIG. 9). In addition, to predict the likely sites of Linc00324 in miR-7977, wild-type (WT) and mutant (Mut) luciferase reporter genes were constructed, including firefly and Renila luciferase sequences (FIG. 10A). Luciferase assay results showed that the miR-7977 mimetic reduced the fluorescence intensity of Linc00324WT, but had no effect on Linc00324MUT (fig. 10B).

Endogenous binding between miR-7977 and Linc00324 was studied using RIP. The results show that compared with miR-7977 point mutation (Linc00324-mut), an empty vector (MS2) and another lncRNA-ATB without miR-7977 targeting site vector, the wild type (Linc00324-wt) with miR-7977 targeting site has obvious enrichment effect on miR-7977. (FIG. 11A).

Biotin-labeled Linc00324 down-regulated the affinity of miR-7977 in vitro, further confirming endogenous binding between miR-7977 and Linc00324 (FIG. 11B).

In addition, the expression levels of the miR-7977 mimetic group and the inhibitor group Linc00324 were also examined, and it was found that the expression level of the Linc00324 was decreased in the miR-7977 mimetic group, while the expression level of the Linc00324 was increased in the miR-7977 inhibitor group (FIG. 12). Therefore, Linc00324 acts as a sponge for miR-7977.

(4) MiR-7977 targeting STK4 to inhibit apoptosis of Ad-MSCs

Flow cytometry analysis (FIG. 13) and TUNEL method (FIG. 14) showed that the miR-7977 mimetic group reduced apoptosis in high sugar environments, while the miR-7977 inhibitor group increased apoptosis rate. WB experimental results showed that after transfection of miR-7977 mimic, bax, BIM and STK4 expression decreased, while bcl-2 expression increased (FIG. 15). Therefore, miR-7977 can reduce apoptosis of Ad-MSCs.

Predicting a downstream target of miR-7977 through MiRDB microRNA target prediction, and selecting STK4 closely related to apoptosis. To determine whether miR-7977 is directed against STK4, the STK 43' -UTR sequence was cloned into psiCHECK^TM-2 in a carrier. And a mutant 3' -UTR reporter gene without a binding site with miR-7977 is constructed (FIG. 16A). The data indicate that the introduction of miR-7977 reduced the luciferase activity of the reporter gene, while the activity of the mutated 3' -UTR reporter gene remained unchanged (fig. 16B). Meanwhile, qPCR and Western blot experiments prove that miR-7977 has an inhibition effect on STK4 on the levels of mRNA and protein (FIG. 17). The STK4 inhibitor XMU-MP-1 is added into the miR-7977 inhibitor group. Flow cytometry analysis showed that XMU-MP-1 inhibited miR-7977 inhibitor and induced apoptosis (FIG. 18), which is consistent with the results of TUNEL analysis (FIG. 19) and Western blot analysis (FIG. 20). Therefore, the miR-7977 can directly target the 3' -UTR of the STK4, can reduce the expression of the STK4 and can inhibit the apoptosis of the adipose-derived mesenchymal stem cells.

(5) Linc00324 regulates and controls high-sugar-induced apoptosis of Ad-MSCs by miR-7977/STK4

The miR-7977 mimic and the over-expressed Linc00324 are co-transfected into Ad-MSCs, and flow cytometry analysis shows that the miR-7977 mimic can remarkably inhibit apoptosis caused by the over-expressed Linc00324 (figure 21). TUNEL experiments (figure 22) and Western blot experiments (figure 23) also gave consistent results. In addition, Ad-MSCs were co-transfected with miR-7977 inhibitors and Linc00324, which downregulates expression. The results show that the miR-7977 inhibitor group reversed the decrease in apoptosis caused by the down-regulation of Linc00324 (fig. 24). TUNEL experiments (figure 25) and Western blot experiments (figure 26) also gave consistent results. Based on the data, Linc00324 regulates the apoptosis of high-sugar-induced Ad-MSCs by miR-7977/STK 4.

(6) GO inhibits apoptosis of diabetic nude mice and promotes wound healing

In order to further confirm the influence of GO on wound repair of diabetic nude mice mediated by Ad-MSCs, a skin wound repair model of diabetic nude mice is simulated and established. A wound surface with the diameter of 1.5CM is established, a fluorescent dye CM-Dil is injected into the wound margin skin of each group of nude mice intradermally, the cell survival rate is calculated according to the attenuation degree of the fluorescent dye intensity after 7 days, and the highest cell survival rate of a Linc00324 and GO mixed culture group (the concentration of 0.4mg/mL and 24 hours of co-culture) with the expression reduced is found (figure 27). The wound healing effect of nude mice was then evaluated for 14 days. Wound healing rate was calculated as the 14 day wound area divided by the original wound area. The results show that the GO group is superior to the blank control group, and the wound healing effect of the down-regulated Linc00324 and GO mixed culture group is the best (figure 28). HE staining of the tissue sections showed that the thickness of the neogenetic epidermis of the Linc00324 down-regulated group and the GO mixed culture group was significantly higher than that of the other groups (fig. 29), and Masson staining showed that the fibrous tissues of the Linc00324 down-regulated group and the GO mixed culture group were aligned, indicating that the post-healing was better (fig. 30). Further, tissue immunofluorescence was used to detect angiogenesis (CD31) and inflammatory response (TNF- α) of the wound tissue, and CD31 was highly expressed in the down-regulated and GO groups, while TNF- α was low expressed, indicating that the wound was well healed (fig. 31, 32). ELISA assays were performed on wound tissue to detect cytokines associated with wound healing and similar results were obtained (fig. 33). In vivo experiment results show that GO can inhibit apoptosis of stem cells in diabetic nude mice, thereby promoting wound healing.

The above-described embodiments are only for illustrating the present invention and are not to be construed as limiting the present invention. As will be understood by those of ordinary skill in the art: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

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Application of miR-7977 as drug target for inhibiting high-sugar-induced apoptosis of Ad-MSCs

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Claims (9)

1. The application of the reagent for promoting miR-7977 expression and/or the reagent for inhibiting STK4 gene expression in the preparation of the medicines for inhibiting the apoptosis of Ad-MSCs induced by high sugar.

2. The use of claim 1, wherein the high sugar is glucose concentration in culture medium or blood sugar concentration in experimental animal greater than or equal to 16.7 mmol/L.

3. The application of the reagent for promoting miR-7977 expression and/or the reagent for inhibiting STK4 gene expression in the preparation of medicines for promoting diabetic wound repair.

4. The use according to any one of claims 1 to 3, wherein the medicament further comprises a pharmaceutically acceptable carrier.

5. The use of any one of claims 1 to 3, wherein the agent for promoting miR-7977 expression comprises an RNA-based microRNA functional acquisition technology, a gene-specific miR mimics technology up-regulation miR-7977 expression reagent, and a compound promoter.

6. The use according to any one of claims 1 to 3, wherein the agent that inhibits the expression of STK4 gene comprises an agent that inhibits the expression of STK4 gene mRNA or an agent that inhibits the expression of STK4 protein.

7. A method for inhibiting high sugar-induced apoptosis of Ad-MSCs in vitro, comprising promoting miR-7977 expression, and/or inhibiting STK4 gene expression.

The application of miR-7977 or a target gene thereof in screening of a drug for inhibiting high-sugar-induced apoptosis of Ad-MSCs or a drug for promoting diabetic wound repair, wherein the target gene of miR-7977 is an STK4 gene.

9. A method for screening a medicine for inhibiting the apoptosis of Ad-MSCs induced by high sugar or a medicine for promoting the wound repair of diabetes, which is characterized by comprising the following steps:

(1) treating a system expressing or containing miR-7977 or a target gene thereof with a test substance;

(2) detecting the expression of miR-7977 or a target gene thereof in the system;

(3) selecting a test agent that can promote expression of miR-7977 or inhibit a miR-7977 target gene;

the miR-7977 target gene is STK4 gene.

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