肌肉生长抑制素(MSTN)基因的研究进展

肌肉生长抑制素(myostatin,MSTN)是一类在骨骼肌中广泛表达的糖蛋白,其功能和表达量的变化可能会通过调节靶基因的表达来改变肌肉的纤维组成及造成肌肉重量的变化。MSTN对骨骼肌的生长有调节作用,其基因在猪、人、绵羊和牛已被定位和标记。在畜禽育种过程中,对畜禽生长速度过度     

猪肌肉生长抑制素基因启动子的克隆与鉴定

利用PCR方法从猪基因组DNA中扩增了1.2 kb的肌肉生长抑制素(myostatin)基因启动子序列。并进一步以绿色荧光蛋白(GFP)为报告基因,构建了真核表达载体MSTNPro-EGFP;通过转染C2C12小鼠骨骼肌成肌细胞和猪成纤维细胞,对猪myostatin基因启动子的转录调控活性进行鉴定。结果表明:猪myostatin基因启动子可以启动GFP在C2C12细胞中的转录和表达,而将猪MSTNPro-EGFP载体转染猪胎儿成纤维细胞后并未观察到GFP的表达,说明myostatin基因表达的肌肉特异性源于启动子的转录特异性。     

肌肉生长抑制素调控肌肉和脂肪组织代谢的研究进展

肌肉生长抑制素(myostatin,MSTN),又名生长分化因子-8(growth differentiation factor 8,GDF-8),是一种主要由骨骼肌分泌的蛋白质,在肌肉生长发育过程中起负调控作用。若MSTN基因编码区碱基突变或缺失,可以导致肌肉异常肥大,出现典型的"双肌"性状。近年来研究还发现,MSTN在脂肪组织中也表达,并在脂肪沉积的过程中发挥重要调控作用。因此,本文将从MSTN的基因结构、组织分布、作用机制以及功能等几个方面的相关研究进展进行综述,重点阐述其在肌肉和脂肪组织中的调控作用及机制,以期更深入了解MSTN,为畜牧业新品种的改良和肉质性状的改善奠定理论基础。     

MSTN基因外显子3的多态性及其与边鸡生长性状的关联分析

采用PCR-SSCP技术检测边鸡及2个对照鸡群体(京海黄鸡和尤溪麻鸡)肌肉生长抑制素(myostatin,MSTN)基因外显子3的单核苷酸多态性,并与边鸡的生长性状进行相关性分析。结果表明,在MSTN基因外显子3的8527—8528 bp处检测到一个TC的插入。在边鸡和京海黄鸡中只检测到2种基因型(AA和AB基因型),在尤溪麻鸡中检测到3种基因型(AA、AB和BB基因型)。在3个鸡品种中都以A等位基因为优势等位基因。最小二乘分析结果表明,边鸡2种基因型个体的6~16周龄体重均无显著差异(P>0.05)。     

如皋鸡不同时期肌肉组织生长相关基因的表达谱分析

旨在了解如皋鸡不同时期肌肉生长发育机制。本研究利用基因芯片技术,分析在不同生长阶段下(2～12周龄)如皋鸡肌肉组织基因的表达情况。获得了13 379个基因的差异表达动态图谱。在不同生长阶段下肌肉组织生长基因的表达发生变化,与2周龄相比,4和12周龄下调表达的基因数量多于上调表达的基因数量,6、8和10周龄下调表达的基因数量少于上调表达的基因数量。同时对杂交数据进行多种聚类分析。利用实时荧光定量PCR验证4个基因的差异表达,其结果和芯片杂交分析的结果基本一致。初步建立了不同时期肌肉生长应答基因的动态表达谱,比较全面地获得了肌肉生长应答基因,初步揭示了如皋鸡不同时期肌肉生长发育机制。     

MSTN基因外显子3的多态性及其与边鸡生长性状的关联分析

采用PCR-SSCP技术检测边鸡及2个对照鸡群体(京海黄鸡和尤溪麻鸡)肌肉生长抑制素(myostatin, MSTN)基因外显子3的单核苷酸多态性,并与边鸡的生长性状进行相关性分析。结果表明,在MSTN基因外显子3的8527—8528 bp处检测到一个TC的插入。在边鸡和京海黄鸡中只检测到2种基因型(AA和AB基因型),在尤溪麻鸡中检测到3种基因型(AA、AB和BB基因型)。在3个鸡品种中都以A等位基因为优势等位基因。最小二乘分析结果表明,边鸡2种基因型个体的6～16周龄体重均无显著差异(P>0.05)。     

肌抑素基因的结构、功能及应用

肌抑素(myostatin)属于TGF-β超家族成员,是动物骨骼肌生长的主要负调控因子。对肌抑素基因及其功能的研究,有助于提高畜禽的产肉性能和肉品质,也有利于治疗人类肌萎缩症等肌肉疾病。另外,肌抑素还具有降低脂肪含量,修复骨组织等功能。本文对肌抑素基因的结构、功能及应用进行了简要概述。     

Myostatin基因研究进展

肌肉生长抑制素基因（Myostatin,MSTN）是1997年发现的骨骼肌生长发育负调控因子,属于TGF-β家族.研究证实人的Myostatin基因由3个外显子和2个内含子组成,在骨骼肌中特异性表达.目前,该基因已分别在人、牛和猪的染色体上定位.Myostatin是肌肉生长的负性调控因子,通过抑制成肌细胞的增殖而发挥作用.Myostatin突变或缺失均可异致肌肉质量的显著增加.文章主要阐述了肌肉生长抑制素基因的结构,功能,及其定位,并对其在畜牧业及医学上的应用前景作了综合论述.     

东北民猪Myostatin基因5’调控区的克隆和RFLP分析

东北民猪是我国的地方猪种，具有肉质鲜美、产仔数多的优点，但瘦肉率相对较低，不符合现代人的消费习惯。骨骼肌生长抑制素基因（myostatin，又名GDF8）最先由McPherron A C等通过简并引物PCR法发现，属于TGF-β超家族，仅在骨骼肌中特异表达。通过基因敲除法培育的突变纯合体小鼠骨骼肌重量比野生型小鼠重2-3倍，证明myostatln是骨骼肌生长的负调控元。1998年，SomtegardTS等将猪的myostatin定位于15号染色体长臂的15 q 2．3。该文以东北民猪为研究对象，克隆了myostatin基因的5’调控区，测定了其核苷酸序列，并根据StrailA等发现的突变位点对该区域进行了酶切多态性分析，为进一步研究猪myostatin基因的结构与功能奠定基础。     

肌肉生成抑制素（MSTN）基因研究进展

肌肉生成抑制素(myostatin,MSTN),又称GDF-8（growth differentiation factor 8),是控制肌肉生长的负调控因子,也是近些年研究发现的又一影响畜禽瘦肉率、改善肉质性状的重要营养基因。它通过抑制MyoD家族成员转录活性负向调控肌细胞的生长发育,它的表达量与肌肉重量的变化呈负相关。本研究就MSTN的发现、基础研究及其在各种动物中的研究进展进行了综述,并讨论了该基因的应用前景。     

Expression profile of myostatin mRNA during the embryonic organogenesis of domestic chicken (Gallus gallus domesticus)

Myostatin is a potent growth and differentiation factor involved in skeletal muscle tissue formation in vertebrates. However, recent studies in chicken embryo suggested that the myostatin was expressed even before the establishment of myogenic lineage. No studies have thus far been reported in birds to define the role of myostatin during the embryonic organogenesis. The present experiment was designed for studying the expression profiles of myostatin mRNA in the chicken liver, heart, brain, and intestine during their morphogenesis, using real-time PCR. The myostatin mRNA expression was significantly upregulated in liver during E15-E18. Similar results were observed during the development of chicken heart. In brain, the expression of myostatin was upregulated from E4 onwards. In intestine, the expression of myostatin was significantly increased many folds on E9-E18. Therefore, the increase in myostatin expression might be related to the growth of liver and heart on days E12-E18; morphogenesis and growth of brain during E15-E18; and morphogenesis and differentiation of intestine during E9-E18. In the present study, the tissue-specific expression of myostatin gene in chicken is similar to fishes, but different from that in mammals. Further, the inspection of chicken genome also suggested that there is no differentiation of GDF-8 and -11. A recent finding suggests that the chicken myostatin gene is closely related to mammals than fishes. Therefore, we propose that the chicken myostatin gene might have diverged in its function between teleosts and mammals. Indeed it is possible that its function might have only become fully differentiated to serve as a control of muscle mass in mammals.     

Temporal expression of transforming growth factor-beta2 and myostatin mRNA during embryonic myogenesis in Indian broilers

TGF-beta2 and myostatin, the members of TGF family, act through both autocrine and paracrine mechanisms to regulate the growth and differentiation at various developmental stages in chicken. The kinetics and expression profile of these two growth factors were investigated by semi-quantitative RT-PCR, during the myogenesis of Indian broiler chickens. Total RNA was isolated from whole embryos on each of embryonic days (E) 0-6 (n=3 per day) and from the biceps femoris muscle at E7-E18 (n=3 per day). The expression of TGF-beta2 was noticed on E2 that remained at the same level until E6. In biceps femoris muscle, higher level of TGF-beta2 expression was observed during E7-E12, which decreased gradually thereafter. These findings suggested that TGF-beta2 might be a regulatory factor participating in the myogenesis of chicken embryos. Initial myostatin expression was noticed on E1, even before the myogenic lineage is established in embryo. This finding suggested an additional role of myostatin in early chicken embryo development, other than myogenesis. Furthermore, myostatin expression was significantly higher on E3 as compared to earlier studies, where initial higher level was observed at E2, suggesting the differential expression of myostatin among breeds. Higher and almost static myostatin expression was noticed in biceps femoris muscle during the entire period of myogenesis (E7-E18). In the present study, the ontogeny of myostatin expression coincided with myogenesis of chicken. Therefore, it may be hypothesized that myostatin is not only a major determinant of muscle mass, but also involved in early embryogenesis in chickens.     

边鸡MSTN基因C.234位点对生长性状的遗传效应分析

采用PCR-RFLP技术检测连续2个世代边鸡群体肌肉生长抑制素基因外显子1的多态性,分析了多态位点对边鸡生长性状的遗传效应。结果表明,边鸡MSTN基因的C.234位点存在多态性,在外显子1编码区的234bp处发生G→A的碱基突变,产生了GG、GA和AA 3种基因型。关联分析表明,无论是一世代还是二世代的边鸡群体,在6~16周龄时,AA和GA基因型边鸡的体质量均显著或极显著的高于GG基因型（P〈0.05或P〈0.01）。结果提示,MSTN基因外显子1的C.234位点突变对边鸡的生长性状具有显著的遗传效应,初步推断该位点可用于边鸡生长性状的标记辅助选择。     

肌肉抑制素与“双肌”表型关系的研究进展

肌肉抑制素是特异性表达于骨骼肌的一种细胞因子,属于TGF-β超家族成员,可以抑制骨骼肌的发育,并同多种疾病有关。肌肉抑制素在不同物种间高度保守,其抑制功能的丧失可以导致骨骼肌显著增生,即动物产生"双肌"表型。具有"双肌"表型的动物则表现出肌肉产量显著增加、饲料转化率高、肌肉嫩度增加、脂肪含量少、而脂肪酸组成中不饱和脂肪酸比例显著增加等优秀性状,这些性状是动物育种计划中的理想育种目标。本文从"双肌"表型的起源及特点、肌肉抑制素的发现及功能等方面对肌肉抑制素与"双肌"表型关系的研究进展进行了综述。     

Laminin binds to myostatin and attenuates its signaling

Myostatin is a growth and differentiation factor and acts as a negative regulator of skeletal muscle mass. Although the mechanism whereby myostatin controls muscle cell growth is mostly clarified, the regulation of myostatin activity after its secretion into the extracellular matrix (ECM) is still unclear. In the present study, we investigated the interaction between laminin and myostatin and the effect of laminin on myostatin signaling in vitro. The surface plasmon resonance assay showed that laminin bound to mature myostatin and activin receptor type IIB (ActRIIB), but did not bind to latency‐associated protein, which remains non‐covalently linked to mature myostatin. Furthermore, kinetic analysis demonstrated that the affinity of mature myostatin for laminin was similar to that for ActRIIB. Next, we examined the action of laminin on the myostatin signaling pathway using a conventional reporter assay. The luciferase activity of myostatin‐treated cells was repressed significantly (P < 0.05) by coincubation of laminin. These results suggest that laminin has a potential to regulate myostatin activity through binding to mature myostatin and/or its receptor ActRIIB.     

Role of serum myostatin during the lactation period

Myostatin, also known as GDF-8 (Growth/Differentiation Factor-8), is a member of the TGF-beta superfamily that negatively regulates skeletal muscle mass in mammals. Mutation of the myostatin gene in mice, cattle, and humans causes a massively developed skeletal muscle, characterized by muscle hypertrophy and hyperplasia. Although myostatin is predominantly expressed in skeletal muscle tissue, several recent studies have shown the presence of myostatin protein in blood and suggested a possible role for circulating myostatin in the regulation of skeletal muscle mass. In the present study, we examined changes in the levels of active form myostatin (13 kDa) in serum after birth by Western blot analysis to predict the role of serum myostatin in early postnatal muscle growth in the rat. Interestingly, the amount of active form myostatin in serum increased after birth and then decreased along with ageing after weaning. To clarify the role of increased serum myostatin during the postnatal period, we administrated follistatin, an inhibitor of myostatin activity, into postnatal rats intraperitoneally just after birth. Follistatin-administration during the postnatal period caused selective hypertrophy of type II muscle fibers in the soleus muscle. These results demonstrate that myostatin in serum acts on skeletal muscle and negatively regulates early postnatal muscle growth.     

Analysis of myostatin and its related factors in various porcine tissues

Myostatin is expressed in skeletal muscle tissue where it functions to suppress myoblast proliferation and myofiber hypertrophy. Recently, myostatin was detected in the tendon, mammary gland, and adipose tissue of mice. We sought to determine whether myostatin is expressed in the liver, spleen, lung, and kidney of pigs. Real-time PCR and Western blots demonstrated that myostatin, follistatin, decorin, and activin receptor IIB (ActRIIB) mRNA and proteins were expressed in skeletal muscle, heart muscle, and adipose tissue, and also in liver, spleen, lung, kidney, and cultured fibroblasts. The relative abundance of myostatin was closely related to follistatin and decorin in porcine tissues. Immunohistochemical analysis further demonstrated the presence of myostatin, follistatin, and decorin in the skeletal muscle, adipose tissue, heart muscle, liver, spleen, lung, and kidney of pigs. These results suggest that myostatin could be associated with certain functions of the internal organs, such as energy metabolism or fibrosis. We conclude that myostatin is a factor broadly expressed in the internal organs and muscle tissues of pigs.     

肌肉生长抑制素对动物肌肉、脂肪和骨骼的影响

肌肉生长抑制素是转化生长因子 β超家族成员之一,具有众多的生理功能。近来的研究表明,肌肉生长抑制素除对肌肉生长有负调控作用外,还对脂肪的沉积和骨骼的生长发育具有调节作用,甚至还能影响肌腱和韧带的强硬度。本文主要从肌肉生长抑制素的结构、基因表达及其对动物肌肉、脂肪和骨骼的作用等方面进行综述。