中国生物工程杂志  2017, Vol. 37 Issue (5): 9-18

文章信息

刘红霞, 施琼, 周一青, 安利钦, 严树涓, 张汝益, 翁亚光.
LIU Hong-xia, SHI Qiong, ZHOU Yi-qing, AN Li-qin, YAN Shu-juan, ZHANG Ru-yi, WENG Ya-guang.
过表达miR-155抑制BMP9诱导间充质干细胞C3H10T1/2成骨分化
Overexpression of miR-155 Inhibits the Osteogenic Differentiation of Mesenchymal Stem Cells C3H10T1/2 Induced by BMP9
中国生物工程杂志, 2017, 37(5): 9-18
China Biotechnology, 2017, 37(5): 9-18
http://dx.doi.org/DOI:10.13523/j.cb.20170502

文章历史

收稿日期: 2016-11-08
修回日期: 2017-01-23
过表达miR-155抑制BMP9诱导间充质干细胞C3H10T1/2成骨分化
刘红霞, 施琼, 周一青, 安利钦, 严树涓, 张汝益, 翁亚光     
重庆医科大学检验医学院 临床检验诊断学教育部重点实验室 重庆 400016
摘要: 目的 研究过表达miR-155对BMP9诱导间充质干细胞C3H10T1/2成骨分化的影响。 方法 ① 用重组腺病毒Ad-BMP9(BMP9)诱导C3H10T1/2细胞成骨分化,定量PCR(qPCR)检测miR-155的表达,RT-PCR检测Runx2和ALP的表达。② miR-155和BMP9共同处理C3H10T1/2细胞,qPCR检测miR-155的表达,ALP活性和染色检测早期成骨能力。③ miR-155和BMP9共同处理C3H10T1/2细胞,诱导分化14d茜素红S染色检测晚期成骨能力。④ miR-155和BMP9共同处理C3H10T1/2细胞,qPCR检测成骨分化相关基因Runx2OSXCOL1A1ALPOCNOPN的表达。⑤ miR-155和BMP9共同处理C3H10T1/2细胞,Western blot检测p-Smad1/5/8、OCN和OPN蛋白水平的表达。⑥ qPCR和Western blot分别检测HIF1α和VEGF的mRNA表达水平和蛋白质表达水平。⑦ 应用荧光素酶报告基因对miR-155的靶基因进行筛选和验证。 结果 在BMP9诱导C3H10T1/2细胞成骨分化过程中,过表达miR-155降低ALP活性及染色;减少钙盐沉积;成骨分化相关基因Runx2OSXCOL1A1ALPOCNOPN表达降低;抑制p-Smad1/5/8、OCN和OPN蛋白水平的表达;HIF1α和VEGF的mRNA和蛋白表达水平减少。在对靶基因的检测中,过表达miR-155可以抑制HIF1α蛋白水平的表达,但对其mRNA水平无明显影响。 结论 miR-155过表达减弱BMP9诱导间充质干细胞C3H10T1/2成骨分化,可能是通过抑制Smad/BMP信号通路发挥作用,也有可能是通过抑制靶基因HIF1α的表达来发挥作用。
关键词: miR-155     骨形态发生蛋白9     C3H10T1/2     成骨分化     HIF1α    
Overexpression of miR-155 Inhibits the Osteogenic Differentiation of Mesenchymal Stem Cells C3H10T1/2 Induced by BMP9
LIU Hong-xia, SHI Qiong, ZHOU Yi-qing, AN Li-qin, YAN Shu-juan, ZHANG Ru-yi, WENG Ya-guang     
Key Laboratory of Clinical Laboratory Diagnostics of Ministry Education, Faculty of Laboratory Medicine, Chongqing Medicine University, Chongqing 400016, China
Abstract: Purpose To investigate the effect of overexpressed miR-155 on the osteogenic differentiation of mesenchymal stem cells C3H10T1/2 cells induced by BMP9, and the related mechanisms contained in this process. Methods ① Used adenovirus BMP9 (BMP9) to induced the osteogenic differentiation of C3H10T1/2 cells, tested the expression of miR-155 by quantitative PCR (qPCR), detected the expression of Runx2 and ALP use RT-PCR. ② Cotransfected BMP9 and miR-155 into C3H10T1/2 cells, measured the expression of miR-155 by qPCR, ALP activity and ALP staining evaluated the early osteogenesis ability of C3H10T1/2 cells. ③ Cotransfected BMP9 and miR-155 into C3H10T1/2 cells, used Alizarin red S staining to estimate the osteogenesis ability in the later stage of differentiation in 14d. ④ Treated C3H10T1/2 cells with BMP9 and miR-155, tested osteogenesis-related genes by qPCR, include Runx2, OSX, COL1A1, ALP, OCN and OPN. ⑤ Treated C3H10T1/2 cells with BMP9 and miR-155, detected the expression of p-Smad1/5/8, OCN and OPN on protein levels used Western blot. ⑥ qPCR and Western blot examined the expression of HIF1α and VEGF on mRNA and protein levels respectively. ⑦ Confirmed the target gene of miR-155 by luciferase reporter assay. Results During the process of osteogenic differentiation of C3H10T1/2 cells induced by BMP9, overexpressed miR-155 decreased ALP activity, ALP staining and Alizarin red S staining. Repressed the expression of bone-related genes, such as Runx2, OSX, COL1A1, ALP, OCN and OPN, also. On the protein levels, overexpressed miR-155 inhibited the expression of p-Smad1/5/8, OCN and OPN, the expression of HIF1α and VEGF were decreased on mRNA and protein levels, too. Through luciferase reporter assay, confirmed that HIF1α is one of the target genes of miR-155, miR-155 decreased the expression of HIF1α on protein level, not on mRNA level, yet. Conclusion Overexpressed miR-155 could inhibit the osteogenic differentiation induced by BMP9 in mesenchymal stem cells C3H10T1/2 cells, it may through Smad/BMP signaling pathway and its target gene HIF1α to play the inhibitory effect in this process.
Key words: miR-155     Bone morphogenetic protein 9     C3H10T1/2     Osteogenic differentiation     HIF1α    

间充质干细胞(mesenchymal stem cell, MSC)是一种具有自我复制能力和多向分化潜能的成体干细胞,可以分化为成骨细胞、软骨细胞、脂肪细胞和成肌细胞等多种结缔组织细胞,已成为骨应用组织工程学研究中成骨细胞的重要来源。BMP9属于TGF-β超家族成员,已有研究证实其可以诱导间充质干细胞成骨分化[1]。但目前BMP9尚未进入临床使用,对成骨诱导的调控机制仍然研究的不够完整,这就需要我们对其中包含的具体机制进行深入的研究。microRNA(miRNA)是一类长度约为22个核苷酸的非编码单链小分子RNA,通过抑制靶基因mRNA的翻译过程或降解靶基因的mRNA分子,介导转录后基因表达的调控,其在细胞的增值、分化以及很多疾病的发生发展过程中发挥巨大作用[2-8]

miR-155是一个多功能miRNA[9],目前对它的研究主要集中在炎症[10]、免疫性疾病[11-13]、血液肿瘤[14-16]、实体肿瘤及心血管疾病[17-21]中,但对成骨分化的作用了解的并不多。有研究表明,在人类肺表皮细胞系A549中,miR-155可以通过抑制Smad1和Smad5来抑制BMP信号通路[17]。但miR-155在BMP9诱导间充质干细胞C3H10T1/2成骨分化中的作用尚未见报道,文章旨在研究BMP9诱导成骨分化过程中miR-155的作用,并对其相关的作用机制进行初步探究。

1 材料与方法 1.1 材料

1.1.1 细胞和重组腺病毒来源

小鼠间充质干细胞系C3H10T1/2细胞购于ATCC公司;重组腺病毒BMP9由本实验室前期构建保存。本实验所保存的BMP9携带绿色荧光标签GFP,因此可用荧光显微镜来观察其感染效率。

1.1.2 试剂来源

DMEM高糖培养基购于Hyclone公司;胎牛血清购于美国Gibco公司,链霉素、青霉素、茜素红S染料、维生素C和β-磷酸甘油购于Sigma公司;转染试剂EntransterTM-R4000购于北京英格恩生物科技有限公司;碱性磷酸酶(ALP)染色试剂盒购于碧云天生物科技有限公司;碱性磷酸酶(ALP)活性检测试剂盒购于BD公司;RNA提取试剂Trizol及Lipofectamine 2000购于Invitrogen公司;M-MLV逆转录酶、RT-PCR试剂盒购于TaKaRa公司;内切酶和T4连接酶、qRCR试剂SYBR Green购于TaKaRa公司;pMIR-REPORT microRNA(miRNA)expression reporter购于Ambion公司;荧光素酶检测试剂盒购自Promega公司;PCR引物由南京金斯瑞生物科技有限公司合成。p-Smad1/5/8、Smad1/5/8抗体购于Santa Cruz公司,HIF1α和VEGF抗体购于沈阳万类生物科技有限公司。β-actin抗体和二抗购于北京中杉金桥生物技术有限公司,其他试剂均为进口分装或国产分析纯。

1.1.3 转染所用寡核苷酸序列

miR-155模拟物(miR-155) 及miR-155抑制剂(anti-miR-155) 阴性对照物(NC)由上海吉玛制药技术有限公司合成。与miR-155结合的靶基因的野生和突变序列由南京金斯瑞生物科技有限公司按照表 1序列信息合成。

表 1 寡核苷酸序列信息 Table 1 Oligoribonucleotide sequences information
Name Sequence(5′→3′)
mmu-miR-155 mimic (F)UUAAUGCUAAUUGUGAUAGGGGU
(R)CCCUAUCACAAUUAGCAUUAAUU
mmu-miR-155 inhibitor (F)ACCCCUAUCACAAUUAGCAUUAA
Negative control (NC) (F)UUCUCCGAACGUGUCACGUTT
(R)ACGUGACACGUUCGGAGAATT
WT-HIF1α (F)CTAGGAGTAATTTTAGAAGCATTATTTTAGGAATATATAGTTGTCACAG
(R)CTGTGACAACTATATATTCCTAAAATAATGCTTCTAAAATTACTC
MT-HIF1α (F)CTAGGAGTAATTTTAGAACGTAAATTTTAGGAATATATAGTTGTCACAG
(R)AGCTCTGTGACAACTATATATTCCTAAAATTTACGTTCTAAAATTACTC
Note: WT-HIF1α, HIF1α-3′-UTR wild type; MT-HIF1α, HIF1α-3′-UTR mutant type; F. Forward; R. Reverse

1.2 方法

1.2.1 细胞培养

C3H10T1/2细胞系和HEK 293细胞系均培养于含有10%胎牛血清的DMEM高糖培养基中,其中含有100U/ml青霉素和100μg/ml链霉素,在37℃、5% CO2的饱和湿度培养箱中培养。

1.2.2 细胞转染

用胰酶消化处于对数生长期的细胞,接种于6孔板中,待细胞密度长至70%左右时,按照EntransterTM-R4000试剂说明书进行操作,把miR-155、anti-miR-155或NC转染到C3H10T1/2细胞中,6h后换液,再转染BMP9诱导其成骨分化,6h后换液。

1.2.3 ALP染色及活性测定

将C3H10T1/2细胞接种于24孔板后,待细胞密度达到70%时进行不同的处理,6h后换液,培养7d后,弃去培养基用PBS冲洗2次,4℃ 100%乙醇固定1h,每孔加入NBT/BCIP溶液200μl进行ALP染色,避光30min后观察染色结果。根据试剂盒说明书进行ALP活性测定。

1.2.4 茜素红S染色

C3H10T1/2细胞接种于24孔板,细胞融合度达到70%时给予不同的处理,6h后换液,同时加入工作浓度50μg/ml的维生素C、10mmol/L的β-磷酸甘油,继续培养14d进行茜素红S染色:弃去孔板中的培养基,PBS冲洗3次后用4℃ 0.05%戊二醛固定10min,去离子水洗3次后加入0.4%茜素红S染液,染色5min,弃去染液,去离子水终止反应并洗涤,显微镜下观察并成像。

1.2.5 PCR

6孔板培养C3H10T1/2细胞,细胞覆盖达到70%时给予不同处理,分别在适当时间点提取RNA,根据试剂盒说明书逆转录成cDNA进行RT-PCR或qPCR(miRNA检测以U6为内参,一般基因检测以β-actin为内参)。qPCR数据分析采用比较CT法(ΔΔCT),目的基因相对表达量=2-[(CT处理-CT内参)-(CT对照-CT内参)],所有数值取三次重复的平均值。实验所用引物序列见表 2

表 2 引物序列(小鼠) Table 2 The sequence of Primers for PCR (mouse)
Genes Sequence(5′→3′)
mmu-miR-155 (RT) GTCGTATCCAGTGCAGGGTCCGAGGTATTCGCACTGGATACGACACCCCT
U6 (RT) AAAATATGGAACGCTTCACGAATTTG
mmu-miR-155 (F) GGCGTTAATGCTAATTGTGAT (R) GTGCAGGGTCCGAGGT
U6 (F) CTCGCTTCGGCAGCACATATACT (R) ACGCTTCACGAATTTGCGTGTC
Runx2 (F) TCTGACAAAGCCTTCATGTCC (R) AAATAGTGATACCGTAGATGCG
OSX (F) GAAGTCCAATGGGGATCTGA (R) GAATCCCTTTCCCTCTCCAG
COL1A1 (F) CGGCTCCTGCTCCTCTTA (R) TTCATTGCATTGCACGTCAT
ALP (F) TGACCTTCTCTCCTCCATCC (R) CTTCCTGGGAGTCTCATCCT
OCN (F) CTGCTTGTGACGAGCTATCAG (R) TGATACCGTAGATGCGTTTGT
OPN (F) GAGGAAACCAGCCAAGGTAAG (R) AAAGCAAATCACTGCCAATCTC
β-actin (F) ATGAAGGCGTGGCAACAT (R) GCCATTGGCTCTGTCCTG
HIF1α (F) TCAGCATACAGTGGCACTCA (R) GGTTAAGGCTCCTTGGATGA
VEGF (F) AGCACAGCAGATGTGAATGC (R) AATGCTTTCTCCGCTCTGAA
Note: RT. Reverse transcription; F. Forward; R. Reverse

1.2.6 Western blot

C3H10T1/2细胞经不同处理因素处理至需要的天数后,用RIPA裂解液于冰上裂解细胞,离心取上清液,BCA法检测上清液总蛋白浓度,加入适量load buffer煮沸10min,取总量50μg的蛋白质经过SDS-PAGE电泳、转膜、封闭、孵一抗、洗膜、孵二抗、洗膜显影后,最后成像保存。

1.2.7 荧光素酶报告基因实验

TargetScan和PicTar靶基因预测软件预测到的miR-155靶基因位点加上HindⅢ和SpeⅠ酶切位点后用T4连接酶连接到报告载体上。用Lipofectamine 2000将阳性质粒和对照质粒转染到HEK 293细胞中,48h后根据试剂盒说明书检测荧光素酶活性。

1.3 统计学分析

数据采用均数±标准差(x±s)表示,组间比较采用单因素方差分析,两组间比较采用t检验,统计所用软件为SPSS17.0,P < 0.05认为差异有统计学意义。

2 结果 2.1 在BMP9诱导间充质干细胞C3H10T1/2细胞成骨分化过程中miR-155的表达变化

用腺病毒BMP9诱导C3H10T1/2细胞成骨分化的不同天数里,miR-155的表达先升高,3d时降低,5d升到最高(P < 0.01),7d又下降[图 1(a)]。荧光显微镜下观察BMP9成功感染细胞[图 1(b)]。在BMP9成骨分化的不同天数里,Runx2和ALP的表达也升高,说明BMP9诱导成骨分化成功[图 1(c)]。

图 1 miR-155在BMP9诱导C3H10T1/2细胞成骨分化不同天数中的表达 Figure 1 The expression of miR-155 in different osteogenic differentiation days of C3H10T1/2 cells induced by BMP9 (a) Tested the expression of miR-155 in different differentiation days of C3H10T1/2 cells induced by BMP9 used qPCR **P < 0.01 compared with 0d (b) BMP9 infected C3H10T1/2 cells successful (×100) (c) RT-PCR detected the expression of Runx2 and ALP in different differentiation days of C3H10T1/2 cells that induced by BMP9
2.2 过表达miR-155减弱BMP9诱导的C3H10T1/2细胞早期成骨分化

在BMP9诱导C3H10T1/2细胞成骨分化过程中,转染miR-155后7d, qPCR检测miR-155表达明显升高(P < 0.001);而anti-miR-155转染则可有效抑制内源性miR-155的表达(P < 0.001)[图 2(a)]。与阴性对照组BMP9+NC组相比,过表达miR-155可显著减少细胞的ALP活性(P < 0.01),减弱ALP染色;而抑制miR-155则能逆转其对ALP活性以及ALP染色的抑制作用[图 2(b)(c)]。

图 2 过表达miR-155抑制BMP9诱导的C3H10T1/2细胞早期成骨分化 Figure 2 Overexpressed miR-155 inhibits the osteogenic differentiation of C3H10T1/2 cells induced by BMP9 in early stage (a) Tested the expression of miR-155 after overexpressing or inhibiting miR-155 in C3H10T1/2 cells osteogenic differentiation induced by BMP9 used qPCR **P < 0.001 compared with control group (b) Detected ALP activity of C3H10T1/2 cells in 7d **P < 0.01 (c) ALP staining of C3H10T1/2 cells in the 7d of differentiation (×100)
2.3 过表达miR-155减弱BMP9诱导的C3H10T1/2细胞晚期成骨分化

过表达miR-155并用BMP9诱导C3H10T1/2细胞成骨分化14d,茜素红S染色检测发现与对照组相比,过表达miR-155明显减少了细胞的钙盐沉积,而抑制miR-155则促进了细胞的钙盐沉积(图 3)。

图 3 过表达miR-155抑制BMP9诱导的C3H10T1/2细胞晚期成骨分化 Figure 3 Overexpressed miR-155 inhibits the later stage of osteogenic differentiation of C3H10T1/2 cells induced by BMP9
2.4 过表达miR-155降低BMP9诱导的成骨相关因子的表达

在用BMP9诱导C3H10T1/2细胞成骨分化过程中,过表达miR-155抑制成骨分化相关因子的表达。利用qPCR检测转染miR-155并成骨诱导3d的细胞,发现与对照组相比Runx2OSXCOL1A1的表达受到明显的抑制(P < 0.001、P < 0.05、P < 0.01)[图 4(a)~(c)]。在成骨分化7d时检测ALPOCNOPN的表达,结果与前面的三个基因一致,过表达miR-155显著降低了它们的表达(P < 0.05、P < 0.001、P < 0.01),而降低内源性miR-155的表达后,miR-155对以上成骨分化相关基因的抑制作用消失[图 4(d)~(f)]。

图 4 过表达miR-155抑制BMP9诱导的成骨分化相关因子的表达 Figure 4 Overexpressed miR-155 decreased the expression of osteogenesis related genes induced by BMP9 Tested the expression of Runx2(a), OSX(b) and COL1A1(c) used qPCR *P < 0.05, **P < 0.01, ***P < 0.001 compared with BMP9+NC group. Tested the expression of ALP(d), OCN(e) and OPN(f) by qPCR *P < 0.05, **P < 0.01, ***P < 0.001 compared with BMP9 +NC group
2.5 过表达miR-155抑制BMP信号通路

在BMP9诱导C3H10T1/2细胞成骨分化3d时,Western blot检测蛋白的表达水平,结果显示,与对照组BMP9+NC相比,过表达miR-155显著抑制Runx2和p-Smad1/5/8蛋白的表达水平(P < 0.01、P < 0.001);相反,抑制miR-155的表达则能促进Runx2的表达(P < 0.001),而对p-Smad1/5/8的表达无影响[图 5(a)]。在成骨诱导的7d时检测OCN和OPN的表达,结果显示,过表达miR-155减少了OCN和OPN蛋白的表达水平(P < 0.05、P < 0.001);而抑制miR-155的表达则增加了OCN和OPN蛋白的表达水平(P < 0.001、P < 0.05)[图 5(b)]。

图 5 过表达miR-155抑制p-Smad1/5/8以及OCN和OPN的表达 Figure 5 Overexpressed miR-155 decreased the expression of p-Smad1/5/8, OCN and OPN
2.6 过表达miR-155抑制HIF1α和VEGF的表达

qPCR检测HIF1α mRNA水平的表达,结果显示,在成骨分化过程中,过表达miR-155明显抑制了HIF1α的表达(P < 0.01),而下调miR-155的表达则能逆转其抑制作用[图 6(a)]。qPCR检测HIF1α下游靶基因VEGF mRNA的表达水平,结果同HIF1α的结果一致(P < 0.001)[图 6(b)]。Western blot检测结果与qPCR结果一致,过表达miR-155能够显著下调HIF1α和VEGF蛋白的表达水平(P < 0.001),同时,抑制内源性miR-155的表达则可以使其抑制作用消失[图 6(c)]。

图 6 过表达miR-155抑制HIF1α和VEGF mRNA蛋白的表达水平 Figure 6 Overexpressed miR-155 repressed the expression of HIF1α and VEGF on mRNA and protein level
2.7 miR-155直接靶向HIF1α

转染miR-155进入C3H10T1/2细胞,qPCR检测其转染效率,miR-155表达显著升高(P < 0.001),证明转染成功[图 7(a)]。qPCR检测HIF1α mRNA的表达水平,结果显示与对照组NC相比,过表达miR-155组和抑制miR-155组HIF1α的表达均无明显差异[图 7(b)]。Western blot检测其蛋白质表达水平,结果显示与对照组相比,miR-155抑制了HIF1α蛋白的表达水平(P < 0.001),而抑制miR-155的表达则对HIF1α蛋白的表达水平无影响[图 7(c)]。靶基因预测软件找到miR-155与HIF1α的结合位点,并对其位点进行突变[图 7(d)],得到野生型和突变型结合序列。荧光素酶活性检测结果显示,miR-155显著抑制HIF1α 3′-UTR荧光素酶活性(P < 0.001),而突变了结合位点后,其抑制作用消失[图 7(e)]。

图 7 miR-155直接靶向HIF1α Figure 7 miR-155 targets HIF1α directly
3 讨论

骨骼的重塑是伴随个体一生的连续的过程,这个重塑过程需要骨的重吸收和骨生成相互协调,从而取代损伤的骨或者满足机体代谢的需要[22]。骨重建,或者骨转换是由成骨细胞和破骨细胞在数量和活性上保持微妙的平衡来调控的。很多重要的信号分子参与调控间充质干细胞分化为成骨细胞,BMP信号通路在促进成骨细胞分化以及骨生成中有很显著的作用[23]。研究发现,除了传统的BMP2、BMP7之外,BMP9诱导MSC成骨分化能力最强,但其具体的调控机制还不是特别清楚,仍需要对其进行深入研究以促进其临床使用。目前,一些研究集中在BMP信号通路能够调控miRNA,并以此作为研究miRNA在成骨细胞中的作用方式[24-25]。从这些研究中可以看出,这类BMP调控的miRNA在调节成骨细胞的分化中有很重要的作用。

前期课题组用BMP9诱导小鼠间充质干细胞C3H10T1/2细胞成骨分化过程中,用micro芯片筛选出三个差异表达的miRNA,又用qPCR对芯片结果进行验证,其中就包括miR-155这个差异表达的miRNA。在本实验前期结果显示,过表达miR-155抑制BMP9诱导的C3H10T1/2细胞的ALP活性、ALP染色及钙盐沉积,且过表达miR-155降低了成骨分化相关基因如Runx2OSXCOL1A1ALPOCNOPN mRNA水平的表达,并且从蛋白质表达水平检测到其对早期成骨标志物Runx2有显著的抑制作用,对晚期成骨标志物OCN和OPN也有明显的抑制作用。为进一步探讨miR-155抑制BMP9所诱导的成骨分化的作用机制,我们通过实验发现过表达miR-155能够抑制p-Smad1/5/8蛋白的表达,表明miR-155能抑制Smad/BMP信号的活化。已有研究证明HIF1α能够增强BMP9诱导间充质干细胞成骨分化的能力,结合生物信息学分析,我们进一步探讨在BMP9诱导C3H10T1/2细胞成骨分化过程中,miR-155是否对HIF1α的表达有影响。本实验研究证明,在BMP9诱导C3H10T1/2细胞成骨分化过程中,过表达miR-155明显抑制HIF1α和其下游靶基因VEGF mRNA和蛋白质水平的表达,并通过荧光素酶报告基因实验证实了HIF1α是miR-155的一个靶基因。结合此部分实验与相关文献显示,miR-155也可能是通过抑制了HIF1α的表达而减弱了BMP9诱导间充质干细胞成骨分化的能力来发挥其在整个过程中的抑制作用。总而言之,在BMP9所诱导的C3H10T1/2细胞成骨分化过程中,miR-155作为一个负调节因子,可能是通过抑制Smad/BMP信号通路发挥作用,也可能是通过直接抑制其靶基因HIF1α的表达,而使HIF1α促进BMP9诱导成骨分化的能力减弱来发挥作用。而在后期的研究中,我们可以研究miR-155这两个抑制间充质干细胞成骨分化机制的相互关系,它们是简单的相加关系还是具有协同作用。本课题研究将为探讨BMP调控的miRNA在调节成骨细胞的分化中的重要作用提供基础,并为BMP9诱导的间充质干细胞向成骨分化的全面调控机制研究提供理论和实验依据。

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