Cellular localization of IL-18 and IL-18 receptor in pig anterior pituitary gland

Pro-inflammatory cytokine interleukin 18 (IL-18) has been proposed to have a role in modulating immuno-endocrine functions. Our previous study showed that IL-18 and IL-18 receptor (IL-18R) colocalized in somatotrophs of the bovine anterior pituitary gland, and the possibility that IL-18 acts on somatotrophs as an autocrine factor. In the present study, we investigated the localization of IL-18 and IL-18R in the pig anterior pituitary gland. RT-PCR analysis showed the expression of IL-18 and IL-18R mRNAin the pig anterior pituitary gland. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs, mammotrophs, thyrotrophs and gonadotrophs. IL-18R was localized in somatotrophs and thyrotrophs. Furthermore, the somatotrophs immunoreactive for IL-18 did not contain IL-18R. Thus, IL-18R and IL-18 were not colocalized in an identical somatotroph. These findings suggest that the localization of IL-18 in pig somatotrophs is different from that in bovine somatotrophs, although IL-18 closely associates with somatotrophs in the anterior pituitary glands in both species.     

肌生成抑制素基因研究进展

肌生成抑制素是 1 997年发现的骨骼肌生长发育负调控因子 ,肌生成抑制素不仅在骨骼肌中表达 ,还可在心肌和浦肯野纤维等多种组织中表达。研究表明 ,大鼠骨骼肌在体内的再生 ,对 MSTN m RNA的表达表现出明显的时间依赖性 ,并且 m RNA的表达不必由功能性神经支配。通过对不同品种双肌表型牛 MSTN基因的研究 ,发现其骨胳肌增大的共同特点是肌生成抑制素基因发生了突变 ,如布鲁牛 MSTN基因在编码区外显子 3发生 1 1 bp的缺失 ,导致MSTN此位点后的阅读框架改变 ,并在此点后的 1 4个密码子处终止了阅读框架 ,从而使MSTN被截短 ,MSTN蛋白活性区域消失 ,活性丧失 ,结果肌肉大量增加。目前 ,已分别对人、牛和猪的 MSTN基因进行了定位研究 ,猪肌生成抑制素基因定位研究表明 ,猪 MSTN基因位于1 5号染色体上。     

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.     

MSTN基因的研究进展

肌生成抑素(MSTN)是1997年发现的一种新的生长因子,其基因产物对骨骼肌的生长具有负调控作用,该基因缺失会导致骨骼肌增生.本文综述了MSTN基因的结构、在畜禽中的表达情况、作用机理以及研究意义.     

Interaction between myostatin and extracellular matrix components

Myostatin, a member of the TGF-β superfamily, is a negative regulator of skeletal muscle mass. We have recently demonstrated that decorin binds to myostatin in vitro , and that immobilized decorin within the collagen matrix prevents myostatin-mediated inhibition of myoblast proliferation. However, little is known about other ECM molecules that bind to myostatin and modulate its activity. Thus, in the present study, we investigated the interaction of several other ECM molecules with myostatin. We here show that fibromodulin, fibronectin and laminin bind to myostatin in the presence of Zn²⁺ with a dissociation constant ( K_D ) of 10⁻¹⁰∼10⁻⁸ mol/L. Fibromodulin shows the highest affinity for myostatin among them. These results suggest that these ECM molecules may modulate myostatin activity like decorin does.     

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。     

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。     

基于Web of science和CNKI对全球MSTN基因的研究进展分析

肌肉生长抑制素(Myostatin, MSTN)作为动物肌肉生长的负调节因子,对提高动物的肌肉量和瘦肉率具有重要意义。该文采用文献计量学方法,以" MSTN/GDF-8/Myostatin " 为检索词对2000—2020年期间Web of Science核心合集数据库和CNKI中国学术期刊全文数据库收录的相关论文进行主题检索,并使用Excel 2016、GraphPad Prism 8.4.0 和 VOS viewer 软件对数据进行可视化处理。结果显示,通过 Web of Science 平台共检索到相关MSTN的SCI论文4404篇,其中中国发表的论文675篇。CNKI中国学术期刊全文数据库内检索出759篇论文。全球关于MSTN的发文量在2000—2020年呈现总体上升的趋势,美国和一些畜牧业发达的国家对MSTN的研究较为深入;中国学者的发文量虽多但其篇均被引频次较低,需从不同维度开展该领域研究并加强机构间合作,提高文章水平,进而缩小差距。目前关于MSTN的研究集中于分子生物学、农学、遗传学、生物技术与微生物学四大领域。对于农学领域提高肉类品质和产量依旧十分重要,因此需要提高对MSTN如何影响肌肉发育及脂肪蓄积方面的认识。本文通过统计分析及可视化处理,为我国科研人员了解MSTN相关的研究动态和研究方向、并以此开展优良品种培育提供信息帮助。     

肌肉生长抑制素基因在不同动物中的研究进展

肌肉生长抑制素(myostatin,MSTN)基因也叫生长分化因子(growth differentiation factor-8,GDF8),其作为肌肉生长发育及分化的负向调控因子,可通过抑制正向调控因子--生肌决定因子(myogenic determination gene,MyoD)的转录活性来抑制成肌细胞的增殖和分化。MSTN基因在进化过程中具有较高的突变性,在不同动物中的表达量和表达范围均不相同。作者就该基因的表达、生物学功能、作用机制及在不同动物中的研究进展进行了详细阐述。     

Localization of leptin and leptin receptor in the bovine adenohypophysis

The present study was carried out to detail the cellular localization of leptin (Lep) and the leptin receptor (LepR) in the bovine adenohypophysis. Lep immunoreactivity (Lep-ir) was found in about 30% of adenohypophysial cells in the gland. Immunochemistry of Lep and specific hormones using serial sections revealed that Lep-ir was present in 60.4% of somatotrophs, 15.9% of gonadotrophs, 6.5% of mammotrophs, 6.5% of thyrotrophs and 2.4% of corticotrophs. Both the common short isoform (OBRa) and the long isoform (OBRb) of LepR mRNA were expressed in the bovine adenohypophysis. LepR immunoreactivity (LepR-ir) was found in only 2.8% of the adenohypophysial cells and over 50% of LepR-ir cells were gonadotrophs, in which most of the cells were distributed in the zona tuberalis. The findings on Lep and LepR in the adenohypophysial cells indicate that Lep may regulate gonadotroph function through autocrine/paracrine pathway in the bovine adenohypophysis.     

肌肉生长抑制素对骨骼肌作用研究进展

肌肉生长抑制素(MSTN)是转化生长因子β超家族的成员之一,又称生长分化因子8。MSTN主要在骨骼肌中广泛表达,并可在心肌、脂肪、乳腺等多个组织中表达,其作用主要体现在抑制骨骼肌生长发育、诱发肌萎缩等方面。MSTN可以通过多种途径协同作用于骨骼肌,即通过激活TGF-β、p38MAPK、ERK1/2、JNK等信号途径以及抑制IGF-AKT、Wnt信号途径来抑制肌细胞增殖分化;通过调控AKT途径、泛素-蛋白水解酶系统、自噬溶酶体系统来影响骨骼肌蛋白的合成与分解;MSTN还参与了与骨骼肌生成相关的脂肪代谢及骨形成等生理活动。论文重点阐述MSTN在肌细胞增殖分化、肌蛋白合成与分解、脂肪代谢、骨骼发育等方面的作用机制,并对其应用前景进行展望,为相关科学研究提供参考。     

MSTN抑制剂及其应用研究进展

肌生成抑制素（MSTN）是肌肉生长的一种负调控因子,隶属于TGF-β超家族,具有TGF-β超家族所有特点。MSTN突变产生的双肌现象给畜牧生产和医药业带来巨大影响。作者综述了近些年来用分子技术研究MSTN抑制剂的成果以及MSTN主要抑制剂的特点,并对MSTN在农业生产和医学领域的发展趋势和应用前景等进行了展望。     

Characterization and expression of the bovine growth hormone-releasing hormone (GHRH) receptor

The hypothalamic hormone, growth hormone-releasing hormone (GHRH) and its pituitary receptor are principal regulators of pituitary growth hormone (GH) synthesis and release. In the present study, we cloned and sequenced a complete bovine pituitary GHRH receptor cDNA in order to study its expression in cattle. The lengths of the exons in the bovine GHRH receptor gene were determined by comparison of the cloned cDNA with genomic sequences obtained from a bovine genomic library clone. As in other species, the bovine cDNA sequence encodes a 423-amino acid protein containing seven hydrophobic domains characteristic of a G protein-coupled receptor. The predicted bovine amino acid sequence shares 93, 90, 89, 87, and 85% identity with the ovine, porcine, human, rat and mouse sequences, respectively. Expression of the receptor in bovine ileum, ovary, anterior pituitary, testis, hypothalamus, pancreas and liver was examined by RT-PCR. Of those tissues examined, GHRH receptor expression was detected in the anterior pituitary gland and hypothalamus. To gain a better understanding of GHRH receptor gene regulation in ruminants, we examined the effect of bovine somatotropin (bST) treatment on pituitary GHRH receptor expression in dairy heifers using relative and real-time RT-PCR. In the present study, bST treatment of dairy heifers resulted in no significant decline in pituitary GHRH receptor expression.     

绵羊Myostatin基因真核表达载体的构建及在其原代成纤维细胞中的瞬时表达

Myostatin(MSTN)基因是胚胎期肌肉形成和出生后骨骼肌生长的主要调控因子之一,通过抑制肌细胞的扩增和分化而调控肌肉的生长和发育。为了进一步揭示MSTN在绵羊成纤维细胞中的生物学功能,采用RT-PCR从绵羊肌肉组织中扩增MSTN基因,将其cDNA终止密码子TGA删除,采用定向克隆技术连接到带有水母绿色荧光蛋白(AcGFP)报告基因的真核表达载体pAcGFP-N1中,构建融合蛋白重组质粒,经XhoⅠ/SacⅡ双酶切、测序鉴定后,用脂质体介导质粒转染绵羊原代成纤维细胞,观测荧光表达及用RT-PCR和Western blotting方法检测基因转录、蛋白质表达情况。结果表明,成功克隆绵羊MSTN基因,通过PCR方法在MSTN阅读框两端引入了XhoⅠ和SacⅡ克隆位点,成功构建pAcGFP-MSTN融合蛋白真核表达载体,重组质粒转染绵羊成纤维细胞24 h后在荧光显微镜下观察到绿色荧光,通过RT-PCR扩增出1138 bp的转录产物,并用Western blotting检测到78 ku目的蛋白的表达。本试验为研究MSTN基因在成纤维细胞和脂肪分化调控中的具体机制奠定基础。     

鸽MSTN基因mRNA表达的发育性变化及组织差异研究

通过研究公、母鸽肉质性状候选基因肌肉抑制素(Myostatin,MSTN)在不同组织、不同发育阶段的表达变化规律,为研究鸽肉质性状的遗传调控机理提供依据。采用荧光探针RT-PCR,定量分析MSTN mRNA在公、母鸽的多个组织、多个发育时间点的表达量。RT-PCR结果表明,MSTN mRNA表达量在3个生理时期表现出先降低后升高的变化趋势,母鸽峰值出现较早。公鸽MSTN mRNA表达量最高的组织为肾脏,睾丸中表达丰度最低,青年期肝脏、心肌MSTN mRNA表达量极显著高于其它时期的表达量,但在睾丸中没有检测到基因的表达。对不同生理时期母鸽MSTN mRNA的表达量比较后发现,青年期MSTN mRNA表达最高,显著高于其它时期。MSTN mRNA表达量受到组织、发育阶段和品种影响,该基因的表达在物种之间存在差异。     

不同品种猪抑肌素基因启动区的RFLP分析

瘦肉率是猪育种中重要的目标性状之一 ,其大小与骨骼肌的量密切相关。猪抑肌素基因是与瘦肉率有关的基因之一 ,本研究以大白、长白、杜洛克、民猪、三江白猪和军牧Ⅰ号为研究对象 ,采用限制性酶切片段生长度多态性 (RFLP)分子标记法对抑肌素基因的启动区进行了酶切多态性分析。结果表明 :大白、长白、杜洛克以等位基因T为主 :三江白猪和军牧Ⅰ号全部是TT型 ;民猪 3种基因型均有且频率近乎相等     

Myostatin down‐regulates the IGF‐2 expression via ALK‐Smad signaling during myogenesis in cattle

Myostatin (MSTN) is a negative regulator during muscle differentiation, whereas insulin‐like growth factors (IGFs) are essential for muscle development. MSTN and IGFs act oppositely during myogenesis, but there is little information on the mutual relationship of MSTN and IGFs. The present study was conducted to examine whether MSTN affects IGF expression during early myogenesis in cattle. IGF‐1 mRNA was similarly expressed in M. longissimus thoracis of double‐muscled (DM) and normal (NM) Japanese shorthorn cattle. IGF‐2 mRNA expression was consistently higher in the normal and regenerating muscle of DM cattle than those of NM cattle. When myoblasts were isolated from regenerating M. longissimus thoracis, IGF‐2 mRNA expression showed a significant increase in differentiating DM derived myoblasts (DM‐myoblasts) as compared with differentiating NM derived myoblasts (NM‐myoblasts). An addition of recombinant mouse myostatin (rMSTN) to myoblast cultures attenuated IGF‐2 mRNA expression and decreased myotube formation, but did not effect IGF‐1 mRNA expression. An activin‐like kinase (ALK) inhibitor, SB431542, mediates MSTN action, suppressed the translocation of Smad2/3 into the nucleus in DM‐myoblasts, and restored the attenuated IGF‐2 mRNA expression and the decreased myotube formation induced by rMSTN in myoblast cultures. The findings indicate that MSTN may negatively regulate myoblast differentiation by suppressing IGF‐2 expression via ALK‐Smad signaling.     

Cellular changes in the anterior pituitary of the domestic fowl during growth, sexual maturity and laying

All the cell types in the hen's anterior pituitary varied in number during the period from 10 weeks to adulthood; there was often an associated change in apparent functional activity. The cells most affected were the gonadotrophs (both FSH and LH) and luteotrophs; changes in these cells were associated with the onset and maintenance of sexual maturity. Follicle‐stimulating hormone cells were the first to increase in number and activity and this was correlated with a general increase in steroid output from the ovary, as measured by the oviduct weight increase. With the onset of follicular maturation LH cells became obvious. Prolactin cells increased in number with the presumed general increase in circulating oestrogen. Acidophilic somatotrophs decreased with increasing age; thyrotrophs became more numerous about sexual maturity and it is thought that this reflects the general increase in metabolic rate which occurs at this time.     

Localization of the N-methyl-D-aspartate R1 Receptor in the Pituitary Gland of Immature Rainbow Trout (Oncorhynchus mykiss)

A study was conducted on the selective immunostaining of pituitary cells and pars nervosa of immature rainbow trout by antibody raised against the R1 subunit of the rat ionotropic N-methyl-D-aspartate (NMDA) receptor. In the pars distalis, the mammotrophs of the rostral pars distalis exhibited the most marked imunoreactivity, with the somatotrophs of the proximal pars distalis showing a consistently lower degree of immunoreactivity. No imunoreactivity was associated with the corticotrophs, thyrotrophs or gonadotrophs. In the pars intermedia, the melanotrophs showed no evidence of immunoreactivity, whereas the putative somatomammotrophs exhibited a wide inter-animal range of immunoreactivity. Some imunostaining was also evident in the anterior and posterior part of the pars nervosa, at the interface of the pars distalis or pars intermedia with the pars nervosa.     

猪肌生成抑制素成熟蛋白编码序列真核表达载体的构建

从猪肌生成抑制素(MSTN)cDNA序列中设计引物。以pMD18-T-MSTN质粒为模板，PCR扩增猪MSTN成熟蛋白编码序列，该片段全长1095bp。将所得片段与pMD18-T载体连接，构建重组质粒pMT—mpMSTN，将其转化到大肠杆菌DH5a中，成功地筛选到阳性克隆。双酶切重组质粒pMT—mpMSTN和真核表达载体pcDNA3．1，连接目的片段与载体pcDNA3．1，转化大肠杆菌DH5a，经酶切、PCR及测序分析，表明成功地构建了真核表达质粒pcDNA3．1-mpMSTN。