Smad6信号干扰对MSCs骨向分化中Smad5及Smurf1基因表达的影响

目的研究在骨形态发生蛋白2(BMP-2)诱导的骨髓间充质干细胞(MSCs)骨向分化中Smad6信号干扰对Smad5、Smurf1基因表达的影响。方法培养小鼠骨髓MSCs,并分为3组:A组为对照细胞;B组细胞用携带绿色荧光蛋白(GFP)的空白载体病毒转染+BMP-2骨向诱导;C组细胞用Smad6重组RNA干扰载体转染+BMP-2诱导。结果病毒转染后GFP在MSCs中有效表达,病毒转染效率接近100%。与A组比较,BMP-2诱导24h显著提高了B组Smurf1 mRNA水平(P<0.01);而Smad6信号干扰在两个时间点则进一步提高了C组Smurf1 mRNA水平,并显著高于B组(P<0.01)。C组磷酸化的Smad5(pSmad5)和Smurf1水平在两个时间点也显著高于B组(P<0.01),而Smad5蛋白水平则未受影响。结论在BMP-2诱导的MSCs骨向分化中,Smad6 RNA干扰可促进Smad5磷酸化,并引起Smurf1基因表达代偿性增高。     

蛋白激酶CK2β siRNA对肺腺癌细胞A549生长的抑制作用

目的：探讨蛋白激酶CK213特异性干扰RNA对肺腺癌细胞系A549增殖的影响。方法：构建蛋白激酶CK2psiRNA表达质粒pGPU6-CSNK2B，以与人编码序列无同源性的通用阴性对照表达质粒pGPU6一NC作对照，分别用脂质体转染法转染A549细胞。采用RT-PCR、Western Blot、免疫细胞化学技术检测转染后（K2pmRNA和蛋白表达，同位素参入法检测CK2活性，细胞计数法检测转染后A549的细胞生长曲线和倍增时间，流式细胞术检测转染后对A549细胞周期的影响。结果：重组质粒稳定转染A549细胞后，转染pGPU6一CSNK2B组CK213mRNA、细胞胞浆蛋白表达和CK2激酶活性均较转染pGPU6一NC组和未转染组细胞明显下降（P〈0．05），各组间细胞胞核蛋白CK213表达无明显差异（P〉0．05）；CK2活性的抑制率与CK213蛋白表达抑制率大致平行；转染pGPU6一CSNK2B组细胞生长相对缓慢，细胞的倍增时间为56h，而未转染组细胞的倍增时间为39h；流式细胞结果显示转染pGPU6-CSNK2B组A549细胞增殖指数明显降低（P〈0．05），细胞阻滞于G0／G1期。结论：蛋白激酶CK2B特异性siRNA表达质粒可以阻抑A549细胞CK2t3的表达，抑制细胞增殖和CK2激酶活性，为CK2 siRNA作为抗肿瘤药物的开发和CK2药靶的研究奠定了基础。     

Toll样受体2基因小干扰RNA对高氧所致氧化应激状态下肺泡上皮细胞功能的影响

目的探讨Toll样受体2（TLR2）基因小干扰RNA（siRNA）对体外高氧暴露条件下A549细胞TLR2基因、蛋白表达及其下游信号通路功能的影响。方法肺泡上皮细胞株A549置于6孔培养板培养,完全随机分为4组：N组（正常培养组）、H组（高氧组）、T组（高氧±TLR2-siRNA转染组,转染化学合成TLR2-siRNA）和C组（高氧±阴性对照siRNA转染组,转染化学合成含对照序列的阴性对照-siRNA）。运用脂质体转染技术介导化学合成siRNA转染,其中H组、T组和C组细胞高氧培养6h后,流式细胞术检测转染后A549细胞5．羧基荧光素双醋酸盐的表达率,实时定量荧光聚合酶链反应方法检测各组A549细胞TLR2mRNA的表达水平,流式细胞术方法检测各组A549细胞TLR2蛋白表达变化,凝胶电泳迁移率实验检测各组细胞核因子KB核转录水平,酶联免疫吸附测定方法检测各组上清液中白细胞介素6（IL-6）和IL-8含量。结果转染后A549细胞5-羧基荧光素双醋酸盐的表达率为（92．3±9．6）％;经高氧处理后,H组和C组的TLR2mRNA、TLR2蛋白水平、核因子KB核转录水平较N组均明显上调[（1．68±0．02）、（1．52±0．06）比（1．26±0．02）,（9．1±0．8）、（7．8±1．4）比（5．9±2．8）,（484±64）、（378±38）比（46±3）]（P〈0．05）,各组上清液IL-6、IL-8含量较N组也明显升高（P〈0．05）;而T组TLR2mRNA表达（0．87±0．06）、TLR2蛋白表达（2．8±0．4）、核因子KB核转录水平（228±29）和上清液IL-6、IL-8含量较H组和C组均明显下调[IL-6：（48．5±6．3）ng／L比（66．7±7．8）、（59．6±6．5）ng／L,IL-8：（125±19）ng／L比（773±96）、（971±149）ng／L]（均P〈0．05）;T组与N组相比,各项检测指标表达差异也有统计学意义（P〈0．05）。结论针对TLR2mRNA的小干扰RNA可以部分抑制高氧诱导的A549细胞的炎症反应,但是并不能完全阻断核因子KB-炎症因子信号通路。     

咯利普兰在骨髓间充质干细胞向成骨细胞分化中的作用

目的 研究咯利普兰在体外骨髓间充质干细胞向成骨细胞诱导分化过程中的作用.方法 体外分离培养小鼠股骨骨髓间充质干细胞,随机分为咯利普兰10 μmol/L组(A组)和对照组(B组).骨髓间充质干细胞向成骨诱导分化后,检测碱性磷酸酶(ALP)活性;Western blot检测Runx2和骨钙素表达;茜素红染色观察钙结节形成情况.结果 与B组相比,A组ALP活性及Runx2、骨钙素表达均增加(P＜0.01或P＜0.05),钙结节形成更加明显.结论 咯利普兰能提高体外骨髓间充质干细胞向成骨细胞诱导分化的能力.     

BMP-2 通过BMP/Smad/ID3 通路调控非小细胞肺癌 A549细胞的凋亡

目的探讨BMP-2通过BMP通路调控非小细胞肺癌A549细胞凋亡的作用机制。方法通过双酶切/连接克隆的方法,构建BMP-2 siRNA慢病毒载体及BMP-2慢病毒载体并进行包装;转染慢病毒后,采用荧光显微镜对转染效率进行定性分析,流式细胞术对转染率进行定量分析,RT-qPCR和Western blotting检测BMP-2基因的表达,CCK-8检测细胞增殖,流式细胞术检测细胞凋亡,Western blotting检测凋亡蛋白的表达水平以及A549细胞中Smad1/5/8、磷酸化Smad1/5/8(p-Smad1/5/8)和ID3蛋白的表达水平。结果转染后第3、4 d,BMP-2 siRNA可显著抑制A549细胞的增殖(P<0.05);转染后24 h,BMP-2 siRNA可显著诱导A549细胞的凋亡(P<0.05),且活化的凋亡蛋白Caspase-9和Caspase-3的表达水平显著升高(P<0.05),而过表达ID3可抑制BMP-2 siRNA对细胞凋亡的诱导作用。与未处理组和阴性对照组相比,BMP-2过表达组细胞中p-Smad1/5/8表达水平显著上调(P<0.05),而Smad1/5/8总蛋白表达水平无明显变化(P>0.05),ID3蛋白的表达显著上调(P<0.05)。结论BMP-2可通过BMP/Smad/ID3通路参与调控A549细胞的增殖和凋亡。     

降脂壮骨方剂含药血清对大鼠骨髓基质细胞骨形态发生蛋白-2表达的影响

目的研究高胆固醇血清以及降脂壮骨方剂含药血清干预下大鼠骨髓基质细胞骨形态发生蛋白-2（BMP-2）表达的变化。方法取成年大鼠股骨,用密度梯度离心方法分离大鼠骨髓基质细胞,原代培养细胞至第三代,并用流式细胞仪进行细胞鉴定。选取第三代细胞,随机分为三组。A组正常血清对照组：2％空白血清（体积比）;B组高胆固醇血清损伤组：终浓度为4mmol／L高胆固醇血清;C组中药血清预处理＋高胆固醇血清损伤组：2％中药血清（体积比）预处理2h后＋终浓度为4mmol／L高胆固醇血清。回收细胞提取总RNA,检测BMP-2表达变化,并进行统计学分析。结果与空白血清对照组相比,高胆固醇血清损伤组骨髓基质细胞增殖受抑制;BMP-2的mRNA表达水平降低（P〈0．01）。与高胆固醇血清损伤组相比,中药血清预处理＋高胆固醇血清损伤组骨髓基质细胞生长状态明显改善,BMP-2的mRNA表达水平增高（P〈0．01）。结论降脂壮骨方剂含药血清可以增强高胆固醇血清环境下骨髓基质细胞BMP-2、雌激素受体（ER）,明显改善骨髓基质细胞生长状态,有利于骨质疏松症的治疗。     

环氧酶-2在骨形态蛋白9诱导间充质干细胞骨向分化中的作用研究

目的研究环氧酶-2(COX-2)在骨形态蛋白9(BMP9)诱导间充质干细胞(MSCs)成骨分化过程中的作用,以及COX-2影响BMP9功能的可能机制。方法采用定量PCR、蛋白印迹和免疫细胞化学染色分析BMP9对COX-2表达的影响。采用化学发光法检测碱性磷酸酶(ALP)的活性,用RT-PCR法检测Smad6、Smad7 mRNA表达水平,用蛋白印迹检测Runx2、Dlx-5、Smad1/5/8及磷酸化Smad1/5/8蛋白水平。通过体内异位成骨实验检测COX-2对BMP9诱导MSCs成骨分化的影响。利用萤光素酶报告质粒检测BMPs/Smads信号活化程度。结果 BMP9明显诱导COX-2表达,抑制COX-2酶活性或沉默COX-2均抑制BMP9诱导C3H10T1/2细胞ALP活性增加。沉默COX-2明显抑制BMP9诱导C3H10T1/2细胞表达Runx2和Dlx-5,以及BMP9诱导的C3H10T1/2细胞异位成骨。沉默COX-2抑制BMPR-Smad报告质粒萤光素酶活性,降低Smad1/5/8的磷酸化水平,以及抑制Smad6和Smad7的mRNA表达。结论 COX-2对BMP9诱导MSCs成骨分化具有重要调节作用,其机制可能与COX-2调节BMPs/Smads信号转导有关。     

胞外pH值通过BMP-2信号通路影响高磷诱导的血管平滑肌细胞钙化

目的 探讨骨形态发生蛋白2（bone morphogenetic protein 2,BMP-2）信号通路在不同pH值环境影响高磷诱导的大鼠血管平滑肌细胞（vascular smooth muscle cells, VSMCs）钙化中的作用。方法 选取5～8周龄健康雄性SD大鼠,体外分离培养大鼠胸主动脉VSMCs,采用免疫细胞化学方法鉴定。将VSMCs用随机抽样法分为正常对照组(pH7.4)、pH7.4+高磷组、pH7.1+高磷组及pH7.7+高磷组。采用茜素红染色及邻甲酚酞络合酮比色法检测细胞钙化情况,酶联免疫吸附法检测细胞碱性磷酸酶(ALP)活性,用反转录聚合酶链反应（RT-PCR）法检测BMP-2、Smad1及 Runt 相关转录因子2（Runx2） mRNA的表达。结果 与正常对照组相比,pH7.4+高磷组大鼠VSMCs的钙含量增加（P<0.05）、茜素红染色钙化结节增多,Runx2 mRNA表达及ALP活性均增高（P<0.05）;与pH7.4+高磷组相比,pH7.1+高磷组大鼠VSMCs的钙含量减低（P<0.05）、茜素红染色钙化结节减少,Runx2 mRNA表达及ALP活性均降低（P<0.05）,BMP-2、Smad1mRNA表达均降低（P<0.05）,pH7.7+高磷组大鼠VSMCs的钙含量增加（P<0.05）、茜素红染色钙化结节增多,Runx2 mRNA表达及ALP活性均增高（P<0.05）,BMP-2、Smad1mRNA表达均增高（P<0.05）。结论 胞外酸性环境（pH7.1）抑制高磷诱导的大鼠VSMCs钙化,胞外碱性环境（pH7.7）促进高磷诱导的大鼠VSMCs钙化,其机制可能是通过BMP-2信号通路介导了VSMCs的表型转化。     

PC12细胞SLC6A4基因沉默稳转细胞系的建立及SLC6A4基因沉默对缺氧PC12细胞凋亡的影响

目的 构建SLC6A4基因RNA干扰（RNAi）-短发夹RNA（shRNA）慢病毒表达载体,建立慢病毒介导沉默SLC6A4基因的PC12细胞稳转细胞系,检测SLC6A4基因沉默对缺氧诱导的细胞凋亡的影响。方法 设计合成3条针对SLC6A4基因的shRNA干扰序列,构建于慢病毒载体质粒GV248中,在293T细胞中共转染进行慢病毒包装。转染大鼠肾上腺髓质嗜铬细胞瘤PC12细胞,荧光显微镜观察GFP荧光,筛选最佳shRNA干扰序列,应用嘌呤霉素筛选出稳定转染的细胞株。应用RT-PCR方法检测SLC6A4基因的表达,Western blot方法检测蛋白5-HTT的表达变化,流式细胞术检测沉默SLC6A4基因对缺氧诱导的PC12细胞凋亡的影响。结果 成功构建SLC6A4-shRNA慢病毒载体并转染PC12细胞,与正常对照组及干扰对照组比较,干扰组细胞内SLC6A4基因和蛋白表达明显降低（P<0.01）,证实慢病毒载体能够有效沉默SLC6A4基因,沉默SLC6A4基因可以逆转缺氧诱导的细胞凋亡。结论 通过shRNA慢病毒载体途径可有效沉默PC12细胞SLC6A4基因,沉默SLC6A4基因可以逆转缺氧诱导的细胞凋亡。     

表皮生长因子受体通路基因干扰与放线菌素D联合对胶质瘤生长抑制作用的研究

目的探讨靶向性表皮生长因子受体（EGFR）信号转导通路关键基因丝氨酸苏氨酸激酶（AKT）小分子干扰RNA构建体与化疗药放线菌素D（ACTD）联合对胶质瘤生长的抑制作用。方法选择AKT的siRNA靶序列构建靶向AKT的siRNA表达质粒,并以空载siRNA表达质粒为对照进行脂质体介导的小分子干扰siRNA表达质粒单独及分别与化疗药物ACTD对胶质瘤细胞C6系生长抑制作用的研究。TUNEL法分析细胞凋亡;流式细胞术分析细胞周期变化,^3H-TdR掺人法分析细胞增殖。结果与c6细胞和转染空载体的C6细胞比较,转染siRNA表达质粒组AKT表达下调72％。TUNEL法发现C6组和空载转染组几乎没有凋亡细胞,而siRNA表达质粒组的凋亡率明显增加（Χ^2=35．26,P〈0．01）;流式细胞分析发现siRNA表达载体转染后S期指数较对照细胞减少,而加入化疗药物ACTD后S期指数较对照细胞明显减少^3H-TdR掺人法发现与C6组和空载转染组比较,转染组细胞自第2天起存活率均明显下降（P〈0．01）,且加入ACTD后治疗各组之间存活率也有明显差异（均P〈0．01）;以siRNA表达载体转染组联合ACTD组减低最显著。结论靶向AKT的siRNA表达质粒联合化疗药ACTD显著抑制肿瘤细胞增殖并诱导细胞凋亡。因此,质粒介导的siRNA表达载体为胶质瘤靶向性基因治疗与化疗药物联合可以成为胶质瘤治疗的一种新策略。     

Icariin regulates miR-23a-3p-mediated osteogenic differentiation of BMSCs via BMP-2/Smad5/Runx2 and WNT/β-catenin pathways in osteonecrosis of the femoral head

Icariin is commonly used for the clinical treatment of osteonecrosis of the femoral head (ONFH). miR-23a-3p plays a vital role in regulating the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). The present study aimed to investigate the roles of icariin and miR-23a-3p in the osteogenic differentiation of BMSCs and an ONFH model. BMSCs were isolated and cultured in vitro using icariin-containing serum at various concentrations, and BMSCs were also transfected with a miR-23a inhibitor. The alkaline phosphatase (ALP) activity and cell viability as well as BMP-2/Smad5/Runx2 and WNT/β-catenin pathway-related mRNA and protein expression were measured in BMSCs. Additionally, a dual-luciferase reporter assay and pathway inhibitors were used to verify the relationship of icariin treatment/miR-23a and the above pathways. An ONFH rat model was established in vivo, and a 28-day gavage treatment and lentivirus transfection of miR-23a-3p inhibitor were performed. Then, bone biochemical markers (ELISA kits) in serum, femoral head (HE staining and Digital Radiography, DR) and the above pathway-related proteins were detected. Our results revealed that icariin treatment/miR-23a knockdown promoted BMSC viability and osteogenic differentiation as well as increased the mRNA and protein expression of BMP-2, BMP-4, Runx2, p-Smad5, Wnt1 and β-catenin in BMSCs and ONFH model rats. In addition, icariin treatment/miR-23a knockdown increased bone biochemical markers (ACP-5, BAP, NTXI, CTXI and OC) and improved ONFH in ONFH model rats. In addition, a dual-luciferase reporter assay verified that Runx2 was a direct target of miR-23a-3p. These data indicated that icariin promotes BMSC viability and osteogenic differentiation as well as improves ONFH by decreasing miR-23a-3p levels and regulating the BMP-2/Smad5/Runx2 and WNT/β-catenin pathways.     

诱导人骨髓间充质干细胞向成骨细胞分化

目的探讨人骨髓间充质干细胞(mesenchymal stem cells，MSCs)向成骨细胞诱导分化的能力。方法选用不同代次的MSCs，使用条件培养基，观察细胞的形态变化，采用细胞化学和免疫组化的方法检测碱性磷酸酶、钙盐沉积及Ⅰ型胶原的表达。结果MSCs在条件培养基中，15d后可见细胞变为多边形，碱性磷酸酶和Ⅰ型胶原染色阳性，形成钙结节，表现成骨细胞分化特点。结论在一定培养条件下成功诱导人MSCs向成骨细胞分化。在骨组织工程学方面MSCs作为种子细胞具有潜在的应用价值。     

Icariin regulates miR-23a-3p-mediated osteogenic differentiation of BMSCs via BMP-2/Smad5/Runx2 and WNT/β-catenin pathways in osteonecrosis of the femoral head

Icariin is commonly used for the clinical treatment of osteonecrosis of the femoral head (ONFH). miR-23a-3p plays a vital role in regulating the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). The present study aimed to investigate the roles of icariin and miR-23a-3p in the osteogenic differentiation of BMSCs and an ONFH model. BMSCs were isolated and cultured in vitro using icariin-containing serum at various concentrations, and BMSCs were also transfected with a miR-23a inhibitor. The alkaline phosphatase (ALP) activity and cell viability as well as BMP-2/Smad5/Runx2 and WNT/β-catenin pathway-related mRNA and protein expression were measured in BMSCs. Additionally, a dual-luciferase reporter assay and pathway inhibitors were used to verify the relationship of icariin treatment/miR-23a and the above pathways. An ONFH rat model was established in vivo, and a 28-day gavage treatment and lentivirus transfection of miR-23a-3p inhibitor were performed. Then, bone biochemical markers (ELISA kits) in serum, femoral head (HE staining and Digital Radiography, DR) and the above pathway-related proteins were detected. Our results revealed that icariin treatment/miR-23a knockdown promoted BMSC viability and osteogenic differentiation as well as increased the mRNA and protein expression of BMP-2, BMP-4, Runx2, p-Smad5, Wnt1 and β-catenin in BMSCs and ONFH model rats. In addition, icariin treatment/miR-23a knockdown increased bone biochemical markers (ACP-5, BAP, NTXI, CTXI and OC) and improved ONFH in ONFH model rats. In addition, a dual-luciferase reporter assay verified that Runx2 was a direct target of miR-23a-3p. These data indicated that icariin promotes BMSC viability and osteogenic differentiation as well as improves ONFH by decreasing miR-23a-3p levels and regulating the BMP-2/Smad5/Runx2 and WNT/β-catenin pathways.     

Fabrication of hybrid scaffold based on hydroxyapatite-biodegradable nanofibers incorporated with liposomal formulation of BMP-2 peptide for bone tissue engineering

In the present study, we fabricated an efficient, simple biomimetic scaffold to stimulate osteogenic differentiation of mesenchymal stem cells (MSCs). Electrospun poly L-lactic acid nanofibers were employed to mimic the nanofibrillar structure of bone proteins and coated with hydroxyapatite nanoparticles to simulate bone minerals. Thereafter, we regulated the release pattern of BMP-2 peptide through covalent attachment of an optimized liposomal formulation to the scaffold. The fabricated platform provided a sustained release profile of BMP-2 peptide up to 21?days while supporting cellular attachment and proliferation without cytotoxicity. In-vitro results confirmed the superiority of the scaffold containing liposomes through enhancement of growth and differentiation of MSCs. Ectopic bone formation model exhibited significant localized initiation of bone formation of liposome incorporated scaffold. Consequently, these findings demonstrated that our designed platform with modified release properties of BMP-2 peptide considerably promoted osteogenic differentiation of MSCs making it a unique candidate for bone regeneration therapeutics.     

Dual effects of heparin on BMP-2-induced osteogenic activity in MC3T3-E1 cells

Heparin displays several types of biological activities by binding to various extracellular molecules, including pivotal roles in bone metabolism. We have previously reported that heparin competitively inhibits the binding activity of bone morphogenic protein-2 (BMP-2) to BMP and the BMP receptor (BMPR) and suppresses BMP-2 osteogenic activity. In the present study, we examined whether heparin affects osteoblast differentiation induced by BMP-2 at various time points in vitro. We found that 72 h of treatment with heparin inhibited alkaline phosphatase (ALP) activity. However, 144 h of treatment enhanced the ALP activity in BMP-2-stimulated MC3T3-E1 cells. Although heparin decreased the phosphorylation of Smad1/5/8 after 0.5 h of culture, prolonged periods of culture with heparin enhanced the Smad phosphorylation. In addition, 72 h of treatment with heparin enhanced the mRNA expression of runx2 and osterix in BMP-2-stimulated MC3T3-E1 cells. Furthermore, the mRNA expression of BMP antagonists and inhibitory Smads induced by BMP-2 was preferentially blocked by heparin at the 24 and 48 h time points. These findings indicate biphasic effects of heparin on BMP-2 activity and suggest that heparin has complex effects on the BMP-2 osteogenic bioactivities. Prolonged culture with heparin stimulated BMP-2-induced osteogenic activity via down-regulation of BMP-2 antagonists and inhibitory Smads.     

Mollugin enhances the osteogenic action of BMP-2 via the p38–Smad signaling pathway

Bone morphogenetic protein 2 (BMP-2) has been used clinically to encourage bone regeneration; although, there can be major side effects with larger doses. Therefore, there is a need to identify new small molecules to potentiate the osteogenic action of BMP-2. In this study, we investigated the effect of mollugin on bone formation in murine bi-potential mesenchymal progenitor C2C12 cells by combination with BMP-2. We found mollugin could enhance the BMP-2-mediated osteoblast differentiation of C2C12 cells. This was accompanied by the induction of other osteogenic BMPs. We also found the enhancing potential of mollugin may involve activation of the p38–Smad1/5/8 signaling axis. Furthermore, mollugin promoted skeletal development in zebrafish. The combination of BMP-2 with small molecules, including mollugin, could minimize its clinical limitations, and these molecules might lead to the development of effective stem cell stimulants for bone regeneration and fracture healing.     

Nectandrin A Enhances the BMP-Induced Osteoblastic Differentiation and Mineralization by Activation of p38 MAPK-Smad Signaling Pathway

Osteoblastic activity of nectandrin A was examined in C2C12 cells. Nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization, manifested by the up-regulation of differentiation markers (alkaline phosphatase and osteogenic genes) and increased calcium contents. In C2C12 cells co-transfected with expression vector encoding Smad4 and Id1-Luc reporter, nectandrin A increased Id1 luciferase activity in a concentration-dependent manner, when compared to that in BMP-2 treated cells, indicating that Smad signaling pathway is associated with nectandrin A-enhanced osteoblastic differentiation in C2C12 cells. In addition, nectandrin A activated p38 mitogen-activated protein kinase (MAPK) in time- and concentration-dependent manners, and phosphorylated form of pSmad1/5/8 and alkaline phosphatase activity were both decreased when the cells were pretreated with SB203580, a p38 MAPK inhibitor, suggesting that p38 MAPK might be an upstream kinase for Smad signaling pathway. Taken together, nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization of C2C12 cells via activation of p38 MAPK-Smad signaling pathway, and it has a therapeutic potential for osteoporosis by promoting bone formation.