运动性骨骼肌适应的炎症诱导机制研究现状

运动人体科学界、运动医学界普遍认为炎症诱导肌卫星细胞激活的机制是运动性骨骼肌适应的最重要机制。运动肌会因机械损伤、缺血／再灌注、钙离子升高尤其牵拉激活型Ca^2＋通道激活导致的Ca^2＋升高,产生肿瘤坏死因子-α（tumornec rosisfactor,TNF-α）、白细胞介素-1β（interleukin-1β,IL-1β）、白细胞介素-8（interleukin-8,IL-8）等各种促炎症因子。这些细胞因子以内皮细胞为媒介将白细胞尤其是中性粒细胞由血液引向骨骼肌组织导致炎症发生。一定范围内或一定程度的炎症反应过程中,炎症造成的缺氧及炎症募集的ED^2＋巨噬细胞产生的成纤生长因子、胰岛素样生长因子-1会激活卫星,随着卫星细胞内各种肌源性调节因子的程序性合成,卫星细胞并从G0期重返细胞周期,进行细胞的增殖,既实现卫星细胞的自我更新、维持,又有序地进行细胞分化、同损伤肌细胞融合,最终完成骨骼肌的正常生长、损伤肌肉的修复及再生。     

细胞膜去极化通过激活MAPK信号通路促进原代肌母细胞增殖

细胞膜去极化可促进某些细胞包括肌卫星细胞的增殖,但去极化对于肌母细胞的作用还不清楚.本文通过培养基中高浓度的钾离子(K~+)引发小鼠原代肌母细胞膜的去极化,采用直接计数法评估细胞的增殖能力.结果显示,在K~+浓度为25 mmol/L的培养基中培养24 h后,肌母细胞数量较常规培养基(5 mmol/L K~+)明显增加,但K~+高至50 mmol/L和100 mmol/L时对细胞增殖没有促进作用.通过流式细胞技术进行细胞周期分析显示,25 mmol/L K~+处理使G1期的细胞数量减少,S期的细胞数量增加.免疫荧光染色和Western blot研究发现,25 mmol/L K~+处理后,对肌母细胞的肌分化能力没有影响.进一步研究发现,25 mmol/L K~+明显促进了肌母细胞MAPK信号通路(ERK1/2)的激活,并与其促进细胞增殖的效应相关. MEK1/ERK1/2的两种抑制剂U0126和PD98059均可减弱细胞膜去极化引起的细胞增殖促进效应.综上,研究结果表明细胞膜去极化通过激活MAPK通路促进小鼠原代肌母细胞的增殖.     

MTMR14基因缺失促进小鼠成肌细胞增殖和分化

为研究磷酸肌醇磷酸酶肌管相关蛋白14(MTMR14)在骨骼肌发生中的作用,通过组织切片和细胞培养技术研究了MTMR14敲除对骨骼肌的组织结构、成肌细胞分化和增殖的影响.结果表明:MTMR14敲除小鼠的腓肠肌和比目鱼肌的结构较同窝野生型小鼠产生了明显变化,MTMR14敲除小鼠的成肌细胞的分化和增殖成肌小管过程较野生型显著加快.MTMR14基因敲除后小鼠肌管细胞中平均细胞核数显著增加.故MTMR14基因缺失/敲除导致骨骼肌组织结构异常,干扰了骨骼肌肌肉发生过程中的成肌细胞的增殖和分化.     

新型雌激素受体GPR30抑制子宫肌瘤平滑肌细胞的增殖

子宫肌瘤是女性生殖器最常见的一种良性肿瘤,是由子宫平滑肌细胞异常增殖形成的,故又称为子宫平滑肌瘤.GPR30是新型雌激素偶联G蛋白受体,在乳腺癌的发生发展中起到重要作用,但是在子宫肌瘤疾病中的作用未见报道.对取自临床病人样本的子宫肌瘤和周边正常子宫肌组织,分离其平滑肌细胞,通过应用Western blot、real-time PCR(RT-qPCR)、免疫荧光等技术,验证GPR30对其增殖的影响.结果表明,在子宫肌瘤组织和子宫肌瘤平滑肌细胞中,GPR30的mRNA和蛋白的表达水平显著高于周边的正常子宫肌组织和子宫肌平滑肌细胞.在子宫肌瘤平滑肌细胞中,GPR30的特异性激动剂G-1,可以激活表皮生长因子受体EGFR,抑制细胞的增殖.这为子宫肌瘤的研究与治疗提供了新视角,具有重要的理论和实际意义.     

人E-钙粘素融合蛋白基质激活脐带间充质干细胞EGF受体及其功能的研究

上皮细胞钙粘素(E-cadherin)介导细胞间粘附连接,通过多级信号转导调控细胞粘附、增殖、迁移等多种细胞行为.本实验室前期研究中成功构建了基于E-cadherin胞外域的E-cad-Fc融合蛋白作为人间充质干细胞(hMSCs)的培养基质,其能够激活上皮细胞生长因子受体(Epidermal growth factor receptor,EGFR)信号通路,促进hMSCs增殖,但目前为止尚不明确E-cad-Fc基质能否替代EGF在hMSCs培养过程中发挥特异性功能.因此,本研究首先利用基因芯片技术分析了E-cad-Fc对EGF相关信号通路的影响,并筛选出显著差异表达的基因.利用western blot评价了E-cad-Fc和EGF在短时间内对hMSCs中EGFR的激活,并初步评价了两者对hMSCs定向诱导分化的影响.研究结果表明,E-cad-Fc基质可替代EGF持续性激活EGFR的磷酸化,并在定向诱导分化过程中促进hMSCs的转胚层进程.该研究为探讨钙粘素基质对hMSCs细胞行为的调控作用及其信号转导机制奠定了基础.     

La3+通过重组细胞骨架影响大鼠成骨细胞增殖、分化

研究了稀土离子La3 对体外培养的成骨细胞增殖、分化及细胞骨架的影响,并初步探讨了相关机理.用细胞计数法检测了成骨细胞的增殖.用RT-PCR技术测定了碱性磷酸酶(ALP)、骨钙素(OC)、骨桥蛋白(OPN),骨涎蛋白(BSP)以及cbfa-1 mRNA水平.采用激光扫描共聚焦显微镜观察了细胞中F肌动蛋白(F-actin)的变化.结果显示:La3 在48h促进了成骨细胞增殖;在4 d促进了早期分化指标ALP,BSP和cbfa-1 mRNA的表达;在21d促进了晚期分化指标OC和OPN mRNA的表达.与此同时,La3 使成骨细胞骨架发生重组.另外,Western Blot分析证实La3 作用于成骨细胞短时间即可激活粘着斑激酶(FAK)酪氨酸磷酸化.结果提示,La3 通过提高FAK酪氨酸的磷酸化水平,改变细胞骨架的分布和聚合,从而促进成骨细胞的增殖和分化.     

STAT3信号转导通路及肿瘤治疗的方法

STAT3是一类由750～800个氨基酸组成的DNA结合蛋白,有αβγ三种亚型,它因可介导细胞的恶性转化而被确认为癌基因,STAT3在早期胚胎发育和骨髓细胞的分化中发挥着不可缺少的重要作用,此外它还参与了肿瘤的增殖、分化、血管生成、侵袭转移和免疫逃避等生理功能的调控.与STAT3相关的几条信号转导通路特别是Jak-STAT3信号转导通路在多种肿瘤细胞中均有激活,体内外阻断或抑制肿瘤细胞中STAT3的信号通路可抑制细胞恶性增殖和存活,并诱导细胞凋亡,而对正常细胞却无影响.     

磷脂酰肌醇-3激酶结构与功能研究进展

磷脂酰肌醇-3激酶家族成员在生长因子等因素激活后可产生磷脂类物质,作为第二信使绑定和激活不同的靶细胞,形成复杂的信号级联反应,最终在细胞增殖、分化、趋化、存活、蛋白交通、糖代谢等活动中发挥核心作用.在详细介绍磷脂酰肌醇-3激酶家族成员分类、结构特征的基础上,对磷脂酰肌醇-3激酶依赖性的信号通路及其相关功能进行了介绍.     

L-肉碱及耐力运动对过氧化物酶体增殖物激活受体影响的研究

过氧化物增殖物激活受体(PPARs)是一类能被脂肪酸以及外源性过氧化物酶体增殖剂(PP)等激活的核内受体，它与脂肪代谢以及脂肪分化、沉积密切相关。L-肉碱、适度的运动可改善脂质代谢，而脂质代谢的中间以及最终代谢产物是PPARs的配体，PPARs被其激活又进一步影响脂质代谢。     

肾脏纤维化的细胞和分子机制研究进展

肾脏纤维化是所有慢性肾脏病进展至终末期肾病的共同病理过程.其特征是炎症细胞浸润、肌成纤维细胞激活和大量细胞外基质沉积,最终导致肾脏正常结构破坏,形成疤痕组织.肾脏纤维化包括4个相互重叠的过程:持续的炎症,肌成纤维细胞的活化与增殖,细胞外基质的合成、组装和沉积,肾小管萎缩和毛细血管丢失.肾脏纤维化通常呈局灶性分布,提示局部组织微环境在其发生发展过程中发挥着重要的作用.活化的肌成纤维细胞产生大量的胶原蛋白、纤连蛋白和蛋白聚糖,它们通过相互化学交联,从而抵抗基质金属蛋白酶的降解.肾小管萎缩和毛细血管丢失显著加速肾脏疤痕组织的形成.笔者将简要讨论在肾脏纤维化发生发展过程中组织微环境的改变,肌成纤维细胞的来源和激活,细胞外基质的产生、组装和调控,以及肾小管与毛细血管损伤对肾脏纤维化进程的影响.     

Imbalance between pSmad3 and Notch induces CDK inhibitors in old muscle stem cells

Adult skeletal muscle robustly regenerates throughout an organism's life, but as the muscle ages, its ability to repair diminishes and eventually fails. Previous work suggests that the regenerative potential of muscle stem cells (satellite cells) is not triggered in the old muscle because of a decline in Notch activation, and that it can be rejuvenated by forced local activation of Notch. Here we report that, in addition to the loss of Notch activation, old muscle produces excessive transforming growth factor (TGF)-beta (but not myostatin), which induces unusually high levels of TGF-beta pSmad3 in resident satellite cells and interferes with their regenerative capacity. Importantly, endogenous Notch and pSmad3 antagonize each other in the control of satellite-cell proliferation, such that activation of Notch blocks the TGF-beta-dependent upregulation of the cyclin-dependent kinase (CDK) inhibitors p15, p16, p21 and p27, whereas inhibition of Notch induces them. Furthermore, in muscle stem cells, Notch activity determines the binding of pSmad3 to the promoters of these negative regulators of cell-cycle progression. Attenuation of TGF-beta/pSmad3 in old, injured muscle restores regeneration to satellite cells in vivo. Thus a balance between endogenous pSmad3 and active Notch controls the regenerative competence of muscle stem cells, and deregulation of this balance in the old muscle microniche interferes with regeneration.     

Rejuvenation of aged progenitor cells by exposure to a young systemic environment

The decline of tissue regenerative potential is a hallmark of ageing and may be due to age-related changes in tissue-specific stem cells. A decline in skeletal muscle stem cell (satellite cell) activity due to a loss of Notch signalling results in impaired regeneration of aged muscle. The decline in hepatic progenitor cell proliferation owing to the formation of a complex involving cEBP-alpha and the chromatin remodelling factor brahma (Brm) inhibits the regenerative capacity of aged liver. To examine the influence of systemic factors on aged progenitor cells from these tissues, we established parabiotic pairings (that is, a shared circulatory system) between young and old mice (heterochronic parabioses), exposing old mice to factors present in young serum. Notably, heterochronic parabiosis restored the activation of Notch signalling as well as the proliferation and regenerative capacity of aged satellite cells. The exposure of satellite cells from old mice to young serum enhanced the expression of the Notch ligand (Delta), increased Notch activation, and enhanced proliferation in vitro. Furthermore, heterochronic parabiosis increased aged hepatocyte proliferation and restored the cEBP-alpha complex to levels seen in young animals. These results suggest that the age-related decline of progenitor cell activity can be modulated by systemic factors that change with age.     

A common somitic origin for embryonic muscle progenitors and satellite cells

In the embryo and in the adult, skeletal muscle growth is dependent on the proliferation and the differentiation of muscle progenitors present within muscle masses. Despite the importance of these progenitors, their embryonic origin is unclear. Here we use electroporation of green fluorescent protein in chick somites, video confocal microscopy analysis of cell movements, and quail-chick grafting experiments to show that the dorsal compartment of the somite, the dermomyotome, is the origin of a population of muscle progenitors that contribute to the growth of trunk muscles during embryonic and fetal life. Furthermore, long-term lineage analyses indicate that satellite cells, which are known progenitors of adult skeletal muscles, derive from the same dermomyotome cell population. We conclude that embryonic muscle progenitors and satellite cells share a common origin that can be traced back to the dermomyotome.     

Self-renewal and expansion of single transplanted muscle stem cells

Adult muscle satellite cells have a principal role in postnatal skeletal muscle growth and regeneration. Satellite cells reside as quiescent cells underneath the basal lamina that surrounds muscle fibres and respond to damage by giving rise to transient amplifying cells (progenitors) and myoblasts that fuse with myofibres. Recent experiments showed that, in contrast to cultured myoblasts, satellite cells freshly isolated or satellite cells derived from the transplantation of one intact myofibre contribute robustly to muscle repair. However, because satellite cells are known to be heterogeneous, clonal analysis is required to demonstrate stem cell function. Here we show that when a single luciferase-expressing muscle stem cell is transplanted into the muscle of mice it is capable of extensive proliferation, contributes to muscle fibres, and Pax7(+)luciferase(+) mononucleated cells can be readily re-isolated, providing evidence of muscle stem cell self-renewal. In addition, we show using in vivo bioluminescence imaging that the dynamics of muscle stem cell behaviour during muscle repair can be followed in a manner not possible using traditional retrospective histological analyses. By imaging luciferase activity, real-time quantitative and kinetic analyses show that donor-derived muscle stem cells proliferate and engraft rapidly after injection until homeostasis is reached. On injury, donor-derived mononucleated cells generate massive waves of cell proliferation. Together, these results show that the progeny of a single luciferase-expressing muscle stem cell can both self-renew and differentiate after transplantation in mice, providing new evidence at the clonal level that self-renewal is an autonomous property of a single adult muscle stem cell.     

热敏灸对运动大鼠运动能力和心肌、骨骼肌细胞线粒体过氧化损伤的影响

目的研究热敏灸对运动大鼠运动能力和心肌、骨骼肌细胞线粒体过氧化损伤的影响。方法将40只大鼠随机分为正常对照组、单纯运动组、运动+普通悬灸组和运动+热敏灸组,采用14 d递增大强度跑台运动训练和生物化学的方法,观察热敏灸对运动大鼠运动能力和心肌、骨骼肌细胞线粒体过氧化损伤的影响。结果运动+热敏灸组大鼠疲劳相关症状显著改善,跑台力竭时间显著高于运动+普通悬灸组和单纯运动组。运动+热敏灸组大鼠心肌、骨骼肌细胞线粒体SOD酶活性高于单纯运动组、运动+普通悬灸组,心肌细胞线粒体SOD酶活性低于正常对照组,但骨骼肌细胞线粒体SOD酶活性与正常对照组比较,差异无显著性;MDA含量低于单纯运动组和运动+普通悬灸组,但高于正常对照组。结论热敏灸足三里穴具有明显的抗运动性疲劳作用,机理与热敏灸降低过度运动大鼠心肌和骨骼肌细胞线粒体过氧化损伤有关。     

穿戴髌腱加压带对跳跃动作影响的生物力学研究

为探讨髌腱加压带对股四头肌肌力、活化程度和跳跃力学的影响,招募16位自愿参与本实验的健康受试者,运用等速肌力仪及表面肌电测试系统,监测穿戴髌腱加压带前后股四头肌肌力及肌肉活化程度,并利用三维测力台分析3种不同跳模式的地面反作用力.结果显示:①穿戴髌腱加压带对股四头肌肌力及肌肉活化程度无显著影响,但可有效提升股内侧肌活化程度并可降低股外侧肌活化程度;②穿戴髌腱加压带可显著增加蹲踞跳起跳时地面反作用力,但对下蹲跳和着地反弹跳起跳时的地面反作用力无影响作用;③穿戴髌腱加压带虽不影响下蹲跳及着地反弹跳的地面反作用力,但却在负荷率及着地反弹跳第1次及第2次着地时地面反作用力方面存在下降趋势.认为穿戴髌腱加压带对于股四头肌肌力输出与肌肉活化程度没有负面效益,不会影响股四头肌在运动过程中的伸张-收缩循环机制,能降低着地时的冲击负荷.     

下肢运动方式对COPD有创机械通气患者肌力的影响

为了比较运动方式对COPD有创机械通气患者肌力的影响，对入住ICU的112例COPD有创机械通气患者进行分组对照实验.按预设的早期运动方案，两组患者下肢运动方式不一样，干预组采用床上脚踏车进行下肢运动，对照组采用手动下肢运动.结果表明，脱离ICU监护时下肢主、客观肌力指标、ICU活动水平和Barthel指数评分以及出院时Barthel指数评分，两组患者之间差异有统计学意义(P<0.05)， 脱离ICU监护时上肢主、客观肌力指标和出院6个月Barthel指数，两组患者之间差异无统计学意义(P>0.05)，说明COPD有创机械通气患者实施床上脚踏车运动安全可行，且可以改善下肢肌力和运动水平，促进日常生活功能的恢复.     

下肢运动方式对COPD有创机械通气患者肌力的影响

为了比较运动方式对COPD有创机械通气患者肌力的影响，对入住ICU的112例COPD有创机械通气患者进行分组对照实验.按预设的早期运动方案，两组患者下肢运动方式不一样，干预组采用床上脚踏车进行下肢运动，对照组采用手动下肢运动.结果表明，脱离ICU监护时下肢主、客观肌力指标、ICU活动水平和Barthel指数评分以及出院时Barthel指数评分，两组患者之间差异有统计学意义(P<0.05)， 脱离ICU监护时上肢主、客观肌力指标和出院6个月Barthel指数，两组患者之间差异无统计学意义(P>0.05)，说明COPD有创机械通气患者实施床上脚踏车运动安全可行，且可以改善下肢肌力和运动水平，促进日常生活功能的恢复.     

有氧运动对青少年骨骼肌细胞葡萄糖氧化代谢的影响

研究有氧运动对青少年骨骼肌細胞葡萄糖代谢的影响,因为青少年骨骼肌細胞葡萄糖氧化代谢规律和青年小鼠是相同的。为了便于采集骨骼肌细胞將青年小鼠作为研究対象,选用3月龄健康雄性Sprague-Dawley小鼠30只,随机将其划分成安静组、中等强度有氧运动组和过度有氧运动组,每组10只洧氧运动方式为游泳。经7周有氧运动后,中等强度有氧运动组体重、体重变化和体重变化率均显著低于对照组(P0.05);过度有氧运动组各体重指标均低于对照组,差异具有非常显著性(P0.01)。经7周有氧运动后,中等强度有氧运动组血糖显著低于对照组(P0.05),血清胰岛素显著高于对照组(P0.05)过度有氧运动组血糖低于对照组血清胰岛素高于对照组差异均具有非常显著性(P0.01)。经7周有氧运动后,中等强度有氧运动组和过度有氧运动组GT4含量均显著高于对照组(P0.05)。经7周有氧运动后,中等强度有氧运动组和过度有氧运动组MEF2mRNA表达均高于对照组差异具有非常显著性(P0.01)。说明适宜有氧运动能够促进青少年骨骼肌細胞葡萄糖代谢,但过度有氧运动会使机体在一定程度上受到损伤。