骨骼肌钝挫伤恢复过程中HIF-1α、AMPKα2表达的改变

目的：观测大鼠骨骼肌钝挫伤（SMBI）恢复进程中腺苷酸活化蛋白激酶α2（AMPKα2）、缺氧诱导因子-1α（HIF-1α）的表达变化,探讨SMBI恢复可能生物学机制。方法：雄性Wistar大鼠48只,随机选取6只作为正常对照组;另42只大鼠重物砸伤后肢小腿建立钝挫伤模型后分7组（n=6）,造模后各组分别在伤后12 h、2 d、5 d、7 d、10 d、15 d、30 d取材,检测小腿三头肌HIF-1α、AMPKα2表达的变化。结果：损伤后12 h HIF-1α、AMPKα2表达均明显升高,在伤后15 d开始回落接近正常;HIF-1α、AMPKα2表达的峰值出现在伤后2 d内,伤后5 d后表达量开始下降;除HIF-1α mRNA在伤后2 d组表达出现峰值外,其余时间点二者mRNA与蛋白表达时程变化基本一致。结论：SMBI后,HIF-1α、AMPKα2可能通过参与调解缺氧适应、肌细胞再生、能量代偿起到促进伤后恢复的作用。     

自噬在急性心肌梗死发病中作用的研究进展

自噬是生物细胞内普遍存在且高度保守的一种生理过程,其通过溶酶体融合降解细胞内的大分子组分、受损的细胞器以及侵入胞内的病原菌,以达到维持细胞稳态的目的。自噬在多种疾病的发生发展中也发挥十分重要的作用,尤其是心血管疾病。自噬对其病程的发展可以发挥两种截然不同的作用。适当的自噬作用可以降低炎症反应和氧化应激促进细胞的存活,以及通过减少泡沫细胞的形成而对维持心血管的正常功能起一个保护作用;但过度的自噬作用会对细胞造成不可逆的损伤,诱导细胞发生不依赖于caspase的自噬性细胞死亡,增加局部的炎症反应,从而促进动脉粥样硬化病变的发展。本文就自噬在急性心肌梗死发生发展中作用的研究进展进行了综述,探讨自噬成为预防及治疗心血管疾病新靶标的可能性。     

鳞翅目昆虫中自噬相关分子Atg8的研究进展

自噬是细胞通过溶酶体自主降解以实现细胞内物质循环利用的过程,在昆虫细胞分化和个体发育中起着重要作用。鳞翅目昆虫属于完全变态昆虫,会通过自噬和凋亡完成蜕变重建过程,是研究自噬机制的模式生物。自噬相关蛋白Atg8是哺乳动物微管相关蛋白1轻链3的同系物,是自噬相关蛋白的核心蛋白家族,对自噬小体形成、膜的延伸、特定物质识别等具有重要意义。文中就鳞翅目昆虫Atg8在自噬信号通路中的作用、Atg8结构特点、Atg8表达分布及Atg8-PE/Atg8水平与自噬活性关系进行了综述。Atg8-PE是自噬信号通路中两个类泛素结合系统之一,在自噬中起着关键作用。序列分析表明,鳞翅目昆虫Atg8与其他真核生物同源蛋白的整体结构相似,尤其与其他昆虫同源蛋白的氨基酸序列高度一致,体现了Atg8的高度保守性。鳞翅目昆虫发育不同阶段,Atg8在中肠、唾液腺、卵巢、脂肪体、丝腺等器官中的表达分布各不相同。并且,Atg8在核质中分布也存在差异,Atg8在细胞核与细胞质之间的穿梭可能存在蛹化前阶段的某些细胞中。通过检测Atg8-PE在细胞内的表达水平或Atg8含量的变化,可以评价细胞自噬的发生程度。     

间歇性禁食与运动对骨骼肌自噬的激活及减脂效果的比较

目的:以运动作为对比,观察不同时长(14 d、28 d)间歇性禁食的体重控制效果,探究其对骨骼肌质量及自噬的影响。方法:选取60只SD大鼠(雄)随机分为3组(n=20):安静对照组(Sed组)、间歇性禁食组(InF组)、有氧运动组(Exe组),设实验周期分别为14 d和28 d。InF组采用间歇性禁食(隔日禁食),Exe组施加跑台运动干预,每周记录体重。DEXA检测体脂并计算体脂指数,天平称量比目鱼肌湿重(双侧)并计算湿重指数,免疫荧光检测细胞外基质蛋白laminin反映肌纤维横截面积、检测LC3标记自噬体,透射电镜观察自噬体数量及形态,Western blot检测自噬相关蛋白ULK1、LC3、p62及调控蛋白AMPKα、p-AMPKα(Thr172)的表达情况。结果:①干预7 d开始,InF、Exe组大鼠体重显著低于Sed组,且InF组体重显著低于Exe组(P<0.01),28 d干预后InF、Exe组体脂指数显著低于Sed组,且InF组体脂指数显著低于Exe组(P<0.05)。②干预28 d时Exe组单根肌纤维面积较Sed、InF组明显增大(P<0.01)。③在各...     

运动时长和强度对大鼠骨骼肌线粒体自噬的影响及其机制

本文旨在探讨不同时长、不同强度运动对大鼠骨骼肌线粒体功能和自噬的影响及FUNDC1的作用.选取60只雄性SD大鼠随机分为2周、4周的安静对照组(Con组)、中等强度运动组(M-ex组,跑台运动16 m/min,1 h/d,6 d/week)和大强度运动组(Hi-ex组,跑台运动35 m/min,20 min/d,6 d...     

运动训练及饮食限制对小鼠骨骼肌线粒体自噬Bnip3/Nix表达的影响*

目的:探讨运动训练和饮食限制对小鼠骨骼肌线粒体自噬蛋白Bnip3/Nix表达的影响。方法:C57雄性小鼠按体重随机分为对照组(C),不做干预;饮食限制组(D),饮食控制在C组的60%;运动训练组(E),10周递增负荷耐力训练;饮食限制加运动训练组(DE),进行饮食限制和耐力训练。8只/组,干预10周后,麻醉处死提取腓肠肌,Western blot技术检测Bnip3、Nix蛋白表达。结果:与C组比较,干预后D、E及DE组的体重和体重增长值均显著降低(P＜0.01),腓肠肌Bnip3、Nix蛋白表达升高,其中仅DE组Nix蛋白表达升高具有统计学意义(P＜0.05)。结论:运动训练加饮食限制能有效促进小鼠骨骼肌Nix蛋白表达,有利于骨骼肌线粒体自噬发生。     

自噬的相关分子机制

细胞自噬是真核生物中高度保守的一类生物学途径,它通过降解细胞浆内不同组分,维持细胞自身平衡并帮助细胞在应激情况下生存。自噬在生物体生长发育、免疫防御、肿瘤抑制及神经退行性疾病中都有重大的意义。哺乳动物细胞中,自噬过程主要由自噬相关蛋白（Atg）所形成的一系列复合物所调控,这些蛋白质分别在自噬的启动、自噬泡的形成、延伸及成熟和降解过程中发挥重要的作用。在此,本文针对一些重要的自噬相关蛋白质对近年来自噬分子机制的研究进展做一总结。     

线粒体自噬的研究进展

由于线粒体在生物氧化和能量转换过程中会产生活性氧,线粒体DNA又比核DNA更容易发生突变,因此线粒体是一种比较容易受到损伤的细胞器.及时清除细胞内受损的线粒体对细胞维持正常的状态具有重要的作用.细胞主要通过自噬来清除损伤线粒体,维持细胞稳态.越来越多的研究表明,线粒体自噬是一种特异性的过程,线粒体通透性孔道通透性的改变在这个过程中起着重要的作用.线粒体自噬在维持细胞内线粒体的正常功能和基因组稳定性上起着重要作用,但是线粒体发生自噬的信号通路及其调控机制还有待进一步深入研究.     

Wnt信号通路在骨骼肌损伤修复过程中的作用及机制研究CSCD

Wnt信号通路分为经典Wnt信号通路和非经典Wnt信号通路,而非经典Wnt信号通路又可分为Wnt/Ca^(2+)信号通路、Wnt/PCP信号通路和Wnt/PI3K信号通路。经典Wnt信号通路的恰当激活可有效抑制Notch信号通路,促进成肌分化和肌管融合。但经典Wnt信号通路过早或持续性激活,可通过调节多种细胞因子的表达,加重损伤骨骼肌纤维化,损害骨骼肌再生。而Wnt7a通过多条非经典Wnt信号通路刺激肌卫星细胞扩增、迁移,促进骨骼肌损伤修复,并能激活Akt/mTOR信号通路而诱导肌纤维肥大。     

Tetanic contraction induces enhancement of fatigability and sarcomeric damage in atrophic skeletal muscle and its underlying molecular mechanisms

Muscle unloading due to long-term exposure of weightlessness or simulated weightlessness causes atrophy, loss of functional capacity, impaired locomotor coordination, and decreased resistance to fatigue in the antigravity muscles of the lower limbs. Besides reducing astronauts＇ mobility in space and on returning to a gravity environment, the molecular mechanisms for the adaptation of skeletal muscle to unloading also play an important medical role in conditions such as disuse and paralysis. The tail-suspended rat model was used to simulate the effects of weightlessness on skeletal muscles and to induce muscle unloading in the rat hindlimb. Our series studies have shown that the maximum of twitch tension and the twitch duration decreased significantly in the atrophic soleus muscles, the maximal tension of high-frequency tetanic contraction was significantly reduced in 2-week unloaded soleus muscles, however, the fatigability of high- frequency tetanic contraction increased after one week of unloading. The maximal isometric tension of intermittent tetanic contraction at optimal stimulating frequency did not alter in 1- and 2-week unloaded soleus, but significantly decreased in 4-week unloaded soleus. The 1-week unloaded soleus, but not extensor digitorum Iongus （EDL）, was more susceptible to fatigue during intermittent tetanic contraction than the synchronous controls. The changes in K＋ channel characteristics may increase the fatigability during high-frequency tetanic contraction in atrophic soleus muscles. High fatigability of intermittent tetanic contraction may be involved in enhanced activity of sarcoplasmic reticulum Ca2＋-ATPase （SERCA） and switching from slow to fast isoform of myosin heavy chain, tropomyosin, troponin I and T subunit in atrophic soleus muscles. Unloaded soleus muscle also showed a decreased protein level of neuronal nitric oxide synthase （nNOS）, and the reduction in nNOS-derived NO increased frequency of calcium sparks and elevated intracellular resting Ca2＋ concentration （[Ca2＋]i） in unloaded soleus muscles. High [Ca2＋]i activated calpain-1 which induced a higher degradation of desmin. Desmin degradation may loose connections between adjacent myofibrils and further misaligned Z-disc during repeated tetanic contractions. Passive stretch in unloaded muscle could preserve the stability of sarcoplasmic reticulum Ca2＋ release channels by means of keeping nNOS activity, and decrease the enhanced protein level and activity of calpain to control levels in unloaded soleus muscles. Therefore, passive stretch restored normal appearance of Z-disc and resisted in part atrophy of unloaded soleus muscles. The above results indicate that enhanced fatigability of high-frequency tetanic contraction is associated to the alteration in K＋ channel characteristics, and elevated SERCA activity and slow to fast transition of myosin heavy chain （MHC） isoforms increases fatigability of intermittent tetanic contraction in atrophic soleus muscle. The sarcomeric damage induced by tetanic contraction can be retarded by stretch in atrophic soleus muscles.     

骨骼肌条件培养液对恶性肿瘤抑制作用的初步研究

目的：研究骨骼肌微环境因素对恶性肿瘤细胞增殖的影响,评价其在骨骼肌转移瘤罕见性中的意义。方法：原代培养新生Wistar大鼠骨骼肌细胞,用MTT法分析、比较其条件性上清液（MMCM）对恶性肿瘤细胞（小鼠实体瘤-肉瘤、细胞株S180-V、小鼠骨髓瘤细胞株SP2／0、人食管癌细胞Eca109）及正常非肿瘤细胞（金黄地鼠肾细胞株BHK-21）的体外抑瘤作用。结果：MMCM与S180—V、SP2／0、Eca109及BHK-21共同培养后,三株恶性肿瘤细胞株的增殖均显著受抑,而正常非肿瘤细胞株则不受影响。结论：新生大鼠骨骼肌细胞可产生选择性抑制恶性肿瘤细胞增殖的抑瘤物质,这种抑瘤物质可能是临床上骨骼肌内罕见转移瘤现象的生物学基础。     

肌源干细胞及其应用研究进展

研究证实,肌肉中存在2种类型的干细胞,即肌卫星细胞和多能干细胞,后者又可分为不同的细胞亚群。这些细胞群表现出自我更新能力和多潜能性,可分化为血细胞、成骨细胞、神经细胞等不同胚层的组织细胞。由于肌源干细胞具有治疗包括骨骼肌和心肌在内的肌肉疾病的可能性,并且潜在地可促进其他组织,如骨和软骨的再生和愈合,因此近几年来的相关研究取得很大进展。     

Autophagy is not required to sustain exercise and PRKAA1/AMPK activity but is important to prevent mitochondrial damage during physical activity

Physical activity has been recently documented to play a fundamental physiological role in the regulation of autophagy in several tissues. It has also been reported that autophagy is required for exercise itself and for training-induced adaptations in glucose homeostasis. These autophagy-mediated metabolic improvements are thought to be largely dependent on the activation of the metabolic sensor PRKAA1/AMPK. However, it is unknown whether these important benefits stem from systemic adaptations or are due solely to alterations in skeletal muscle metabolism. To address this we utilized inducible, muscle-specific, atg7 knockout mice that we have recently generated. Our findings indicate that acute inhibition of autophagy in skeletal muscle just prior to exercise does not have an impact on physical performance, PRKAA1 activation, or glucose homeostasis. However, we reveal that autophagy is critical for the preservation of mitochondrial function during damaging muscle contraction. This effect appears to be gender specific affecting primarily females. We also establish that basal oxidative stress plays a crucial role in mitochondrial maintenance during normal physical activity. Therefore, autophagy is an adaptive response to exercise that ensures effective mitochondrial quality control during damaging physical activity.     

Autophagy is not required to sustain exercise and PRKAA1/AMPK activity but is important to prevent mitochondrial damage during physical activity

Physical activity has been recently documented to play a fundamental physiological role in the regulation of autophagy in several tissues. It has also been reported that autophagy is required for exercise itself and for training-induced adaptations in glucose homeostasis. These autophagy-mediated metabolic improvements are thought to be largely dependent on the activation of the metabolic sensor PRKAA1/AMPK. However, it is unknown whether these important benefits stem from systemic adaptations or are due solely to alterations in skeletal muscle metabolism. To address this we utilized inducible, muscle-specific, atg7 knockout mice that we have recently generated. Our findings indicate that acute inhibition of autophagy in skeletal muscle just prior to exercise does not have an impact on physical performance, PRKAA1 activation, or glucose homeostasis. However, we reveal that autophagy is critical for the preservation of mitochondrial function during damaging muscle contraction. This effect appears to be gender specific affecting primarily females. We also establish that basal oxidative stress plays a crucial role in mitochondrial maintenance during normal physical activity. Therefore, autophagy is an adaptive response to exercise that ensures effective mitochondrial quality control during damaging physical activity.