吉林大学学报(医学版)  2020, Vol. 46 Issue (05): 963-971     DOI: 10.13481/j.1671-587x.20200511

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郭玮玮, 秦悦, 杨海波, 米占虎
GUO Weiwei, QIN Yue, YANG Haibo, MI Zhanhu
LncRNA MALAT1通过miR-34c/SATB2轴对脂肪间充质干细胞成骨分化的促进作用
Promotion effect of LncRNA MALAT1 on osteogenic differentiation of adipose-derived mesenchymal stem cells through miR-34c/SATB2 axis
吉林大学学报(医学版), 2020, 46(05): 963-971
Journal of Jilin University (Medicine Edition), 2020, 46(05): 963-971
10.13481/j.1671-587x.20200511

文章历史

收稿日期: 2020-02-10
LncRNA MALAT1通过miR-34c/SATB2轴对脂肪间充质干细胞成骨分化的促进作用
郭玮玮 , 秦悦 , 杨海波 , 米占虎     
宁夏医科大学总医院创伤骨科, 宁夏银川 750001
[摘要]: 目的 :探讨长非编码RNA肺癌转移相关转录本1(LncRNA MALAT1)通过微小RNA(miR)-34c/特异AT序列结合蛋白2(SATB2)轴对脂肪来源的间充质干细胞(ADSCs)成骨分化的影响,并阐明其作用机制。方法 :人ADSCs转染Lenti-NC、Lenti-MALAT1、sh-NC、sh-MALAT1、miR-NC和miR-34c,RT-PCR法检测ADSCs中LncRNA MALAT1、miR-34c和SATB2 mRNA表达水平;miRcode和TargetScan 7.1网站预测并通过荧光素酶报告基因实验验证miR-34c与LncRNA MALAT1、miR-34c与SATB2之间的靶向结合作用;Western blotting法检测ADSCs中成骨标志物Runt相关转录因子2(Runx2)、骨桥蛋白(OPN)和骨钙蛋白(OCN)表达水平;碱性磷酸酶(ALP)染色和茜素红S(ARS)染色检测ADSCs中ALP和ARS水平及钙盐沉积。结果 :与第0天比较,ADSCs成骨诱导第3、7、14和21天后,细胞中LncRNA MALAT1、SATB2、Runx2、OPN和OCN蛋白表达水平明显升高(P < 0.05),miR-34c表达水平明显降低(P < 0.05)。与Lenti-NC组和sh-NC组比较,Lenti-MALAT1组ADSCs中LncRNA MALAT1表达水平,Runx2、OPN和OCN蛋白表达水平,ALP和ARS水平明显升高(P < 0.01),sh-MALAT1组上述指标明显降低(P < 0.01)。与miR-NC+Lenti-NC组比较,miR-34c+Lenti-NC组ADSCs中Runx2、OPN和OCN蛋白表达水平明显降低(P < 0.01),ALP和ARS水平明显降低(P < 0.01),miR-34c+Lenti-MALAT1组ADSCs中上述各项指标比较差异无统计学意义(P>0.05)。与Lenti-NC+miR-NC组比较,Lenti-SATB2+miR-NC组ADSCs中Runx2、OPN和OCN蛋白表达水平及ALP和ARS水平明显升高(P < 0.01),Lenti-SATB2+miR-34c组上述各项指标差异无统计学意义(P>0.05)。结论 :LncRNA MALAT1通过miRNA-34c/SATB2轴促进ADSCs的成骨分化。
关键词: 长链非编码RNA    肺癌转移相关转录本1    脂肪间充质干细胞    成骨分化    微小RNA-34c    特异AT序列结合蛋白2    
Promotion effect of LncRNA MALAT1 on osteogenic differentiation of adipose-derived mesenchymal stem cells through miR-34c/SATB2 axis
GUO Weiwei , QIN Yue , YANG Haibo , MI Zhanhu     
Department of Orthopedic Trauma, General Hospital, Ningxia Medical University, Yinchuan 750001, China
[ABSTRACT]: Objective: To explore the effect of LncRNA MALAT1 on the osteogenic differentiation of adipose-derived mesenchymal stem cells(ADSCs) through the microRNA-34c/SATB2 axis, and to clarify its mechanism. Methods: The human ADSCs were transfected with Lenti-NC, Lenti-MALAT1, sh-NC, sh-MALAT1, miR-NC and miR-34c. RT-PCR method was used to detect the expression levels of LncRNA MALAT1, miR-34c and SATB2 mRNA in the ADSCs. MiRcode and TargetScan 7.1 website were used to predicte and the targeted binding effect between miR-34c and LncRNA MALAT1, miR-34c and SATB2 were verified through luciferase reporter gene experiment; Western blotting method was used to detect the expression levels of osteogenic markers Runx2, OPN and OCN proteins in the ADSCs; ALP staining and Alizarin red S(ARS) staining were used to detect the levels of ALP and ARS and calcium salt deposition in the ADSCs. Results: Compared with day 0, the expression levels of LncRNA MALAT1, SATB2, Runx2, OPN, and OCN proteins in the cells were significantly increased on the 3rd, 7th, 14th, and 21st days after osteogenic induction of ADSCs (P < 0.05); the expression levels were significantly reduced (P < 0.05). Compared with Lenti-NC group or sh-NC group, the expression level of LncRNA MALAT1, the expression levels of Runx2, OPN and OCN proteins, and the levels of ALP and ARS in the ADSCs in Lenti-MALAT1 group were significantly increased (P < 0.01), and the indexes mentioned obove in sh-MALAT1 group were significantly decreased (P < 0.01). Compared with miR-NC+Lenti-NC group, the expression levels of Runx2, OPN and OCN proteins in the ADSCs in miR-34c+Lenti-NC group were significantly reduced (P < 0.01), and the levels of ALP and ARS were decreased(P < 0.01), but the indexes mentioned obove in miR-34c+Lenti-MALAT1 group had no statistically significant differences (P>0.05). Compared with Lenti-NC+miR-NC group, the expression levels of Runx2, OPN and OCN proteins in the ADSCs in Lenti-SATB2+miR-NC group were significantly increased (P < 0.01), and the levels of ALP and ARS were significantly increased (P < 0.01);but the indexes mentioned above in Lenti-SATB2+miR-34c group had no statistically significant differences(P>0.05). Conclusion: LncRNA MALAT1 promotes the osteogenic differentiation of ADSCs through the miRNA-34c/SATB2 axis.
KEYWORDS: long non-coding RNA    metastasis-associated lung adenocarcinoma transcript 1    adipose-derived mesenchymal stem cells    osteogenic differentiation    microRNA-34c    special AT-rich sequence binding protein 2    

脂肪间充质干细胞(adipose-derived stem cells,ADSCs)具有自我更新和多向分化潜能,可用于再生或修复骨组织[1]。与骨髓来源的间充质干细胞比较,ADSCs组织来源更丰富,细胞增殖速度更快[2]。然而,尽管有大量研究ADSCs可分化为多种谱系,但ADSCs分化的分子机制仍不明了。长链非编码RNA(long non-coding RNA,LncRNA)和微小RNA(miRNA)在成骨细胞分化中起关键作用[3-4]。研究[5]表明:LncRNA-KCNQ1OT1通过激活Wnt/β-catenin通路促进成骨分化以减弱骨溶解。LncRNA H19的异常表达与成骨分化有关[6]。细胞实验[7]表明:LncRNA肺癌转移相关转录本1(metastasis-associated lung ademocarcinoma transcript 1,MALAT1)通过抑制miR-204的表达,促进成骨细胞特异性标志物碱性磷酸酶(ALP)、骨钙蛋白(OCN)和矿化的骨基质形成。研究[8]表明:miRNA参与调节成骨细胞和破骨细胞分化过程。miR-34c通过调节成骨细胞中特异AT序列结合蛋白2(special AT-rich sequence binding protein 2,SATB2)和Runt相关转录因子2(Runx2)等多个靶点,影响成骨细胞和破骨细胞在体内的骨稳态[9]。过表达SATB2可以促进乙醇诱导的骨坏死患者骨髓间充质干细胞(bone marrow mesenchyml stem cells,BMSCs)的成骨分化[10]。目前,LncRNA MALAT1在ADSCs成骨分化中的作用尚不清楚。本研究旨在探讨LncRNA MALAT1通过miR-34c/SATB2轴在ADSCs成骨分化中的作用,以期为明确LncRNA MALAT1调控ADSCs成骨分化的机制和骨损伤的治疗提供科学指导。

1 材料与方法 1.1 细胞、主要试剂和仪器

原代人ADSCs购自美国ScienCell公司,HEK-293T细胞购自中国典型培养物保藏中心。DMEM培养基购自美国Hyclone公司,胎牛血清(FBS)购自美国Gibco公司,青链霉素混合液(100×)购自北京索莱宝科技有限公司,Lipofectamine 3000转染试剂购自美国Invitrogen公司,SYBRPremix Ex TaqTMⅡ试剂盒购自日本TaKaTa公司,BCA蛋白定量试剂盒购自北京全式金公司,lentiviral-pEF-1a/Puro-NC(Lenti-NC)、lentiviral-pEF-1a/Puro-MALAT1(Lenti-MALAT1)、lentiviral-pEF-1a/Puro- SATB2(Lenti-SATB2)、lentiviralpGLVU6/Puro-sh-NC(sh-NC)、lentiviralpGLVU6/Puro-sh-MALAT1(sh-MALAT1)、miR-NC和miR-34c mimic(miR-34c)均购自上海GenePharma公司,油红O和茜素红购自美国Sigma公司,FITC-CD44抗体、FITC-CD29抗体、PE-CD90抗体、PE-CD105抗体和PE-vWF抗体购自美国BD公司,Runx2抗体、OPN抗体和OCN抗体购自英国Abcam公司。倒置相差显微镜购自日本Nikon公司,实时荧光定量PCR仪购自瑞士Roche公司,微量分光光度计购自美国Thermo Scientific公司。

1.2 细胞培养

ADSCs和HEK-293T细胞用含10% FBS、100 IU·mL-1青霉素和100 mg·L-1链霉素的DMEM培养基中,于37℃、5% CO2条件下培养。

1.3 成骨细胞分化诱导

诱导ADSCs成骨分化:当ADSCs长至80%~90%密度时,将培养基替换为成骨细胞特异性诱导培养基(含10%FBS,10 mmol·L-1 β-甘油磷酸钠,0.1 μmol·L-1地塞米松和0.2 mmol·L-1抗坏血酸磷酸的低糖DMEM),每2 d更换1次培养基,于37℃、5%CO2条件下培养0、3、7、14和21 d。诱导ADSCs成脂分化:当ADSCs长至80%~90%密度时,将培养基替换为成脂细胞特异性诱导培养基(含10%FBS,10 mmol·L-1 β-甘油磷酸钠,1 μmol·L-1地塞米松,0.5 mmol·L-1 3-异丁基-1-甲基黄嘌呤,10 μmol·L-1胰岛素和200 μmol·L-1吲哚美辛的低糖DMEM),每2 d更换1次培养基,于37℃、5%CO2条件下培养14 d。

1.4 免疫荧光染色检测ADSCs中CD44、CD29、CD90、CD105和vWF表达

ADSCs成骨诱导培养基培养21 d后,弃去细胞培养基,PBS缓冲液清洗后,4%多聚甲醛固定,0.1% Triton X-100穿透,10%脱脂奶粉封闭,FITC-CD44抗体(1︰200)、FITC-CD29抗体(1︰200)、PE-CD90抗体(1︰200)、PE-CD105抗体(1︰200)和PE-vWF抗体(1︰200)避光孵育2 h,DAPI染色,荧光显微镜下观察细胞发光情况。

1.5 油红O染色法检测细胞脂滴形成

ADSCs弃去成脂诱导培养基,PBS缓冲液清洗后,4%多聚甲醛固定。PBS缓冲液清洗细胞后,0.3%油红O室温染色20 min。弃去染液,蒸馏水洗涤后,显微镜观察并拍照。

1.6 ADSCs中ALP水平检测

ADSCs弃去成骨诱导培养基,根据BCIP/NBT碱性磷酸酯酶显色试剂盒说明书检测细胞中ALP水平,酶标仪405 nm处检测各组细胞吸光度(A)值,对ALP水平进行定量。计算公式:ALP水平=[(样品组A值-空白组A值)-(对照组A值-空白组A值)]/(对照组A值-空白组A值)。

1.7 RT-PCR法检测ADSCs中miR-34c表达和LncRNA MALAT1、SATB2、Runx2、OPN及OCN mRNA表达水平

收集转染后的ADSCs,TRIzol法提取样品中的总RNA,分光光度计测定RNA浓度,逆转录合成cDNA。按照SYBRPremix Ex TaqTMⅡ试剂盒说明书进行RT-PCR法检测。反应条件:95℃、30 s;95℃、5 s,58℃、30 s,40个循环;95℃、15 s,58℃、30 s,95℃、15 s。以U6和GAPDH为内参,采用2-ΔΔCt法计算miR-34c表达水平和LncRNA MALAT1、SATB2、Runx2、OPN及OCN mRNA表达水平。引物序列见表 1

表 1 RT-PCR法引物序列 Tab. 1 Primer sequences of RT-PCR method
Primer Primer sequence (5'-3')
miR-34c F:ACACTCCAGCTGGGAGGCAGTGTAGTT-
AGCT
R:TGGTGTCGTGGAGTCG
LncRNA
MALAT1
F:GGTAACGATGGTGTCGAGGTC
R:CCAGCATTACAGTTCTTGAACATG
SATB2 F:GCAGTTGGACGGCTCTCTT
R:CACCTTCCCAGCTTGATTATTCC
Runx2 F:GACGAGGCAAGAGTTTCACC
R:GGTTCCCGAGGTCCATCTAC
OPN F:ATCTCCTAGCCCCACAGAAT
R:CATCAGACTGGTGAGAATCATC
OCN F:AGGGCAGCGAGGTAGTGA
R:CCTGAAAGCCGATGTGGT
GAPDH F:AGACAGCCGCATCTTCTTGT
R:TGATGGCAACAATGTCCACT
U6 F:CGCTTCGGCAGCACATATACTAAAATT⁃
GGAAC
R:GCTTCACGAATTTGCGTGTCATCCTTGC
1.8 细胞转染

成骨诱导后的ADSCs或293T细胞接种于6孔细胞培养板,每孔4×105个细胞,待细胞密度达到60%~70%时,按照Lipofectamine 3000说明书进行miR-34c和miR-NC的转染,终浓度均为60 nmol·L-1。37℃、5%CO2条件下培养48 h。ADSCs转染慢病毒时,将细胞培养液更换为含6 mg·L-1聚凝胺和感染复数(MOI)=20的lentiviral-pEF-1a/Puro-NC(Lenti-NC)、lentiviral-pEF-1a/Puro-MALAT1(Lenti-MALAT1)、lentiviral-pEF-1a/Puro-SATB2(Lenti- SATB2)、lentiviralpGLVU6/Puro-sh-NC(sh-NC)和lentiviralpGLVU6/Puro-sh-MALAT1(sh-MALAT1)慢病毒的新鲜培养基,37℃、5%CO2条件下培养48 h。

1.9 荧光素酶报告实验检测LncRNA MALAT1与miR-34c和miR-34c与SATB2之间的靶向结合作用

miRcode(http://www.miRcode.org/)预测MALAT1与miR-34c的靶向结合位点,TargetScan 7.1(http://www.TargetScan.org/vert_/)预测miR-34c和SATB2之间的靶向结合位点。针对LncRNA MALAT1 3'-UTR端和SATB2 3'-UTR端序列构建野生型(WT)和突变型(MUT)报告基因质粒。参照“1.8”步骤,将MALAT1-WT和MALAT1-MUT(或SATB2-WT和SATB2-MUT)分别与miR-NC和miR-34c共同转染至HEK-293T细胞中,48 h后检测荧光素酶活性。

1.10 茜素红S(ARS)染色检测细胞钙盐沉积

弃去ADSCs成骨诱导培养基,PBS缓冲液清洗后,4%多聚甲醛固定。PBS缓冲液清洗细胞后,0.1%ARS染色液室温孵育20 min。弃去染液,蒸馏水洗涤。为了定量钙盐沉积,向细胞中加入含有10 mmol·L-1磷酸钠的10%氯化十六烷基吡啶,并用酶标仪检测各样品在562 nm处的A值。ARS水平=[(样品组A值-空白组A值)-(对照组A值-空白组A值)]/(对照组值-空白组A值)。

1.11 Western blotting法检测细胞中Runx2、OPN和OCN蛋白表达水平

收集转染后的ADSCs或293T细胞,BCA法测定蛋白浓度,取30 μg蛋白进行SDS-PAGE凝胶电泳分离蛋白,并将其转至PVDF膜上。10%脱脂奶粉室温封闭3 h,加入Runx2(1︰1 500)、OPN(1︰1 000)、OCN(1︰2 000)和GAPDH(1︰2 000),4℃孵育过夜。HRP标记二抗(1︰2 500)室温孵育1 h后,ECL发光、曝光。Image J分析条带灰度值,以目的蛋白条带灰度值与GAPDH条带灰度值比值表示目的蛋白表达水平。

1.12 统计学分析

采用SPSS 21.0统计软件进行统计学分析。各组细胞中荧光素酶活性,LncRNA MALAT1、miR-34、SATB2、Runx2、OPN和OCN表达水平,ALP和ARS水平均以x±s表示,2组间样本均数比较采用两独立样本t检验,多组间样本均数比较采用单因素方差分析。以P < 0.05为差异有统计学意义。

2 结果 2.1 ADSCs的特征和多能分化潜能的鉴定

ADSCs中间充质干细胞标记物CD29、CD90、CD44和CD105呈阳性表达,而内皮细胞标记物vWF呈阴性表达(图 1A~F,见插页二);同时细胞具有长丝状结构(图 2A,见插页三),表明该细胞是ADSCs。油红O染色法和ALP染色检测结果显示:在成脂或成骨诱导条件下,ADSCs中有红色脂滴形成(图 2B,见插页三)和橘红色钙盐沉积(图 2C,见插页三)。

A: CD29; B: CD90; C: CD44; D: CD105; E: vWF [labeled with FITC (green color) or PE (red color)]; F: Negative control. 图 1 免疫荧光染色检测ADSCs中CD29.CD90、CD44.CD105和vWF的表达(× 400) Fig. 1 Expressions of CD29, CD90, CD44, CD105 and vWF in ADSCs detected by immunofluorescence staining(× 400)
A: Typical cobblestone-like morphology of ADSCs; B: Oil red Ostaining; C: Alizarin red staining. 图 2 ADSCs多向分化潜能的鉴定(× 200) Fig. 2 Identification of multi- differentiation potential of ADSCs(× 200)
2.2 ADSCs成骨分化过程中LncRNA MALAT1、miR-34c、SATB2、Runx2、OPN及OCN mRNA表达水平

与第0天比较,ADSCs成骨诱导第3、7、14和21天后细胞中LncRNA MALAT1和SATB2及成骨标记物Runx2、OPN和OCN mRNA表达水平均明显升高(P < 0.05),miR-34c mRNA表达水平明显降低(P < 0.05)。见图 3

*P < 0.05, **P < 0.01 vs day 0. 图 3 成骨分化过程中ADSCs中LncRNA MALAT1(A)、miR-34c(B)、SATB2(C)、OPN(D)、OCN(E)和Runx2(F)mRNA表达水平 Fig. 3 Expression levels of LncRNA MALAT1 (A), miR-34c (B), SATB2 (C), OPN (D), OCN(E), and Runx2(F) mRNA in ADSCs during osteogenie differentiation
2.3 各组细胞中LncRNA MALAT1、Runx2、OPN和OCN蛋白表达水平及ALP和ARS水平

与Lenti-NC组比较,Lenti-MALAT1组ADSCs中Runx2、OPN和OCN蛋白表达水平明显升高(P < 0.01),见图 4A,LncRNA MALAT1蛋白表达水平明显升高(P < 0.01),见图 4B,ALP和ARS活水平明显升高(P < 0.01),见图 5插页三)和图 6;与sh-NC组比较,sh-MALAT1组ADSCs中Runx2、OPN和OCN蛋白表达水平明显降低(P < 0.01),见图 4A,MALAT1蛋白表达水平明显降低(P < 0.01),见图 4B,ALP和ARS水平明显降低(P < 0.01),见图 5插页三)和图 6

Lane 1: Lenti-NC group; Lane 2: Lenti-MALAT1 group; Lane 3: sh-NC group; Lane 4: sh-MALAT1 group. *P < 0.05, **P < 0.01 vs Lenti-NC group; P < 0.01 vs sh-NC group. 图 4 各组ADSCs中LncRNA MALAT1、Runx2、OPN和OCN蛋白表达电泳图(A)和直条图(B, C) Fig. 4 Electrophoregram (A) and histogram (B, C) of expressions of MALAT1, Runx2, OPN and OCN proteins in ADSCs in various groups
图 5 ALP和ARS染色检测ADSCs中ALP活性和钙盐沉积 Fig. 5 ALP activities and calcium salt deposition in ADSCs detected by ALP and ARS staining
*P < 0.01 vs Lenti-NC group; P < 0.05, △△P < 0.01 vs sh-NC group. 图 6 各组ADSCs中ALP和ARS水平 Fig. 6 Levels of ALP and ARS in ADSCs in various groups
2.4 荧光素酶报告实验中各组ADSCs中miR-34c、Runx2、OPN和OCN表达水平及ALP和ARS水平

LncrRNA MALAT1与miR-34c结合位点见图 7A。荧光素酶报告实验结果显示:与miR-NC组比较,miR-34c转染后MALAT1-WT组荧光素酶活性明显降低(P < 0.01),MALAT1-MUT组荧光素酶活性差异无统计学意义(P > 0.05,见图 7B)。与miR-NC+Lenti-NC组比较,miR-34c+Lenti-NC组ADSCs中miR-34c表达水平明显升高(P < 0.01,见图 7C),LncRNA MALAT1表达水平明显降低(P < 0.05,见图 7C),Runx2、OPN和OCN蛋白表达水平明显降低(P < 0.01),见图 8,ALP和ARS水平明显降低(P < 0.01,见图 9插页三)和图 10,miR-34c+Lenti-MALAT1组ADSCs中miR-34c、MALAT1表达水平及Runx2、OPN和OCN表达水平,ALP和ARS水平差异无统计学意义(P > 0.05)。

B:*P < 0.05, **P < 0.01 vs miR-NC group; C:*P < 0.05, **P < 0.01vs miR-NC+Lenti-NC group; P < 0.05, △△P < 0.01 vs miR-34c+Lenti-NC group. 图 7 miRcode、荧光素酶报告实验和RT-PCR法检测各组细胞中miR-34c和LncRNA MALAT1的靶向结合(A)及各组细胞中荧光素酶活性、miR-34c和MALAT1 mRNA表达水平(B,C) Fig. 7 Targeted binding of miR-34c and MALAT1 (A) and activities of luciferase expression levels of miR-34c and LncRNA MALAT1 in cells in various groups(B, C) detected by miRcode, luciferase report experiment and RT-PCR methods
Lane 1: miR-NC+Lenti-NC; Lane 2: miR-34c +Lenti-NC group; Lane 3: miR-34c+Lenti-MALAT1 group. *P < 0.01 vs miR-NC+Lenti-NC group. 图 8 Western blotting法检测共转染组ADSCs中Runx2、OPN和OCN蛋白表达电泳图(A)和直条图(B) Fig. 8 Electrophoregram(A) and histogram(B) of expressions of Runx2, OPN and OCN proteins in ADSCs in co-transfection groups detected by Western blotting method
图 9 ALP和ARS染色检测共转染组ADSCs中ALP活性和钙盐沉积 Fig. 9 ALP activities and calcium salt deposition in ADSCs in co-transfection groups detected by ALP and ARS staining
*P < 0.05, **P < 0.01 vs miR-NC+Lenti-NC group. 图 10 共转染组ADSCs中ALP和ARS水平 Fig. 10 Levels of ALP and ARS in ADSCs in co-transfection groups
2.5 miR-34c与SATB2结合位点和靶向结合及LncRNA MALAT1、miR-34c和SATB2表达水平

miR-34c与SATB2结合位点见图 11A。荧光素酶报告实验结果显示:与miR-NC组比较,miR-34c转染后SATB2-WT组荧光素酶活性明显降低(P < 0.01),SATB2-MUT组荧光素酶活性差异无统计学意义(P > 0.05),见图 11B;与miR-NC+Lenti-NC组比较,miR-NC+Lenti-SATB2组ADSCs中SATB2 mRNA表达水平明显升高(P < 0.01),见图 11C;Runx2、OPN和OCN蛋白表达水平明显升高(P < 0.01),见图 12;ALP和ARS水平明显升高(P < 0.01),见图 13插页三)和图 14;miR-34c+Lenti-SATB2组LncRNA MALAT1表达水平明显降低(P < 0.05),miR-34c表达水平明显升高(P < 0.01),见图 11C;SATB2、Runx2、OPN和OCN蛋白表达水平及ALP和ARS水平差异无统计学意义(P > 0.05)。

*P < 0.01 vs miR-NC group; P < 0.05, △△P < 0.01 vs Lenti-NC + miR-NC group. 图 11 miR-34c与SATB2结合位点和靶向结合(A)及各组细胞中LncRNA MALAT1、miR-34c和SATB2 mRNA表达水平(B, C) Fig. 11 Binding sites of miR-34c and SATB2 and targeted binding (A) and expression levels of LncRNA MALAT1, miR-34c and SATB2 mRNA in cells in various groups(B, C)
Lane 1: miR-NC+Lenti-NC group; Lane 2: miR-NC+ Lenti-SATB2 group; Lane 3: miR-34c+ Lenti-SATB2 group.*P < 0.01 vs miR-NC+Lenti-NC group. 图 12 Western blotting法检测各组ADSCs中Runx2、OPN和OCN蛋白表达电泳图(A)和直条图(B) Fig. 12 Electrophoregram (A) and histogram (B) of expressions of Runx2, OPN and OCN proteins in ADSCs in various groups detected by Western blotting method
图 13 ALP和ARS染色检测ADSCs中ALP活性和钙盐沉积 Fig. 13 ALP activities and calcium salt deposition in ADSCs detected by ALP and ARS staining
*P < 0.01 vs miR-NC+Lenti-NC group. 图 14 各组ADSCs中ALP和ARS水平 Fig. 14 Levels of ALP and ARS in ADSCs in various groups
3 讨论

ADSCs是位于脂肪组织中的再生细胞,具有多向分化潜能[11]。ADSCs可通过脂肪细胞置换促进组织新陈代谢和血管生成[12]。BMSCs是骨再生的细胞来源,最近研究[13]表明:BMSCs的增殖能力和成骨分化能力随年龄和骨质疏松程度的增加而降低,而ADSCs在老年和骨质疏松情况下成骨分化能力不变。因此,ADSCs成骨分化机制受到越来越多的关注。LncRNAs是一种转录本长度超过200nt的非编码RNA,参与多种生物学过程,包括表观遗传调控、RNA衰变、细胞分化和转录[14]。研究[15]表明:LncRNA在调节骨骼系统相关的生物学活性方面(骨质疏松症和骨关节炎)具有重要作用。LncRNA MALAT1通过调节miR-214/ATF4轴促进成骨分化[16]

研究[17]表明:LncRNA在成骨-成脂谱系中起表观遗传调控作用。LncRNA MIAT1促进ADSCs的成骨分化并逆转炎症的不良反应[18]。本研究结果显示:在ADSCs成骨分化过程中,MALAT1的表达水平升高,MALAT1正向调控ADSCs成骨分化,这与之前的研究结果一致。研究[19]表明:miRNA参与调节成骨细胞和破骨细胞分化过程,如miR-221-5p通过靶向smad3抑制BMSCs成骨分化;miRNA-429通过靶向SCD-1抑制氧化应激下人BMSCs的成骨分化[20]。lncRNA和miRNA间的相互作用参与成骨分化过程,GAO等[21]研究表明:骨质疏松患者的BMSCs中MALAT1表达水平明显降低,成骨诱导BMSCs后MALAT1表达水平升高。敲除MALAT1则抑制BMSCs的成骨分化,MALAT1通过靶向miR-143促进BMSCs的成骨分化;lncRNA TUG1通过使miR-204-5p海绵化而促进成骨细胞的分化,从而导致Runx2表达上调[22]。LncRNA MEG3通过靶向miR-133a-3p抑制BMSCs的成骨分化[23]。本研究结果显示:在ADSCs成骨分化过程中,miR-34c与MALAT1间存在相互调控作用,MALAT1通过靶向抑制miR-34c的表达促进ADSCs成骨分化。

SATB2是成骨细胞分化的特异性免疫组织化学生物标记物,对骨和软组织肿瘤发挥重要作用[24]。研究[25]表明:许多特异性miRNAs通过转化生长因子β(TGF-β)/骨形态发生蛋白(BMP)信号途径参与SATB2诱导的早期成骨分化。miR-34b/c靶向调控SATB2[26-27]。miR-383通过靶向SATB2负调控大鼠BMSCs的成骨细胞分化[28]。本研究结果显示:SATB2可促进ADSCs成骨分化,miR-34c通过靶向SATB2负调控ADSCs成骨分化。

综上所述,LncRNA MALAT1通过microRNA-34c/SATB2轴促进ADSCs的成骨分化。本研究结果为探究lncRNA调控ADSCs成骨分化的机制和骨损伤的治疗提供了新的科学依据。

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