动物成肌分化及非编码RNA调控研究进展

肌细胞分化密切关系到肉用动物的肌肉产量,也与人类的一系列疾病(如肌肉萎缩、心脏病等)密切相关。胚胎成肌分化期决定了肌纤维数量,是动物骨骼肌发育的关键时期。动物成肌分化及骨骼肌发育严格受各种细胞信号分子和转录因子调控,其中microRNA(miRNA)和lncRNA发挥着重要作用。本文从动物胚胎成肌分化及调控途径、卫星细胞的分化及调控、非编码RNA对肌肉形成的调控等方面进行综述,并展望了畜禽动物骨骼肌生长发育分子调控机制的研究方向,为提高畜禽肌肉产量与质量提供一定的分子理论参考。     

羊生产性状相关microRNA的研究进展

microRNA是一类长约22 nt的内源性非编码单链RNA,它主要通过结合靶基因3'端非编码区,在细胞质中形成沉默复合物,降解靶基因或者阻碍靶基因的表达,从而参与机体内基因的转录和翻译水平调控。最新研究表明,microRNA参与生物体各种各样的调节通路,包括参与细胞的增殖、分化、凋亡、生长、免疫反应和离子转运等过程。文章对microRNA的合成、作用机理及近年来microRNA在山羊、绵羊的乳腺发育、泌乳性能、肌肉增殖、肌肉分化、毛囊发育和毛色发育等方面的研究进行综述,旨在了解microRNA调控动物生长发育的机制,探讨microRNA对山羊、绵羊的产奶量、羊肉品质和羊毛品质的影响,为我国山羊、绵羊品种的遗传资源保护及合理利用,生产性能的改善及提高提供有益的参考,促进我国养羊业的快速发展。     

MYH3基因在动物肌肉发育、能量代谢及生产性能中的研究进展

肌球蛋白重链3（myosin heavy chain 3,MYH3）基因编码胚胎型肌球蛋白重链蛋白,控制肌肉的牵引滑动。MYH3基因是肌肉分化的重要标志基因,能够调控肌肉发育及能量代谢,在动物整个肌肉发育过程中均发挥重要作用。MYH3基因在不同物种间高度保守,且在动物体内多组织中均有表达,在胚胎期肌肉组织和肌肉再生过程中表达量较高。它受转录因子、microRNA、lncRNA及环境营养因子等多种因素影响,也可调控其他基因的功能。MYH3基因突变可以改变TGF-β信号通路和MAPK信号通路相关蛋白的磷酸化水平;影响ATP酶活性,使ATP水解时间延长,延长横桥周期;影响肌肉的能量代谢,最终引发肌肉能量代谢疾病。MYH3基因拷贝数变化、突变或表达量变化与动物的体尺、胴体重、屠宰重、生长性能具有显著的相关性。MYH3基因在大理石花纹高、肌内脂肪高的肌肉组织中表达量高,被认为是影响动物肌肉嫩度、剪切力和肉色红度的重要候选基因。MYH3基因的高表达与骨骼肌中氧化Ⅰ型肌纤维的含量、肌纤维直径和慢肌纤维含量有关。作者介绍了MYH3基因的基本结构特点,指出了其与肌肉组织发育及相关影响因子之间的调控作用,阐述了MYH3基因与动物肌肉能量代谢、生长性能和肉品质之间的关系,为进一步研究MYH3基因与肌肉发育调控和肉质性能改良提供参考。     

microRNAs在动物皮肤及毛囊发育中的调控作用研究进展

基因表达调控是动物被毛生长和发育的决定性因素。microRNA作为一种新发现的基因调控元件,在多种哺乳动物皮肤及毛囊中均有表达,并在转录后水平调节皮肤和毛发的生长和发育过程。从microRNA水平上解析绵羊、山羊及羊驼等被毛生长特点及发生机理,为提高毛用型经济动物的毛发品质和产量提供新的思路,同时也为更深入地研究皮肤组织中microRNA的功能提供更多的理论依据。作者主要针对目前已报道的在绵羊、山羊及羊驼等哺乳动物皮肤及毛囊发育中microRNA的调控作用进行综述。     

鸡microRNAs研究进展

MicroRNA是一类长度约为22nt的内源性非编码单链小分子RNA,可以通过3′端非编码区碱基互补配对的方式识别靶基因,降解靶mRNA或者抑制靶mRNA的翻译,从而影响蛋白质的表达。在机体中,microRNA参与生长发育、免疫调控、肿瘤发生、细胞增殖和凋亡、组织器官发育、脂肪代谢等生命活动。文章综述了microRNA对鸡胚胎期发育、肌肉生长、脂肪代谢、疾病和繁殖的调控作用,旨在为深入探讨鸡microRNA功能及其作用机制提供参考。     

lncRNA作为竞争性内源分子的作用机制及研究进展

竞争性内源RNA （competing endogenous RNA,ceRNA）假说提出具有相同短序列非编码微小（microRNA,miRNA）应答元件（microRNA response element,MRE）的转录物通过竞争的方式结合miRNA,从而影响转录物的表达水平。ceRNA假说颠覆了miRNA与靶基因单向调控的传统观念,在RNA调控网络中具有重要的生物学意义。在众多转录物中,长链非编码RNA （long non-coding RNA,lncRNA）是一类序列长度超过200个核苷酸的非编码RNA,对lncRNA的研究涉及到遗传、分子生物、基因调控、疾病（癌症、神经系统疾病等）等领域。miRNA与lncRNA形成了一个相互作用的调控网络,lncRNA可作为ceRNA抑制miRNA的功能,从而影响后续基因的表达。近年来,随着生物信息学技术的发展,科研人员发现ceRNA作用机制不仅涉及到人类癌症疾病,而且在各种复杂动物的肌细胞分化、脂肪细胞分化和颗粒细胞凋亡等生物过程中也发挥重要的调控作用。作者追溯了ceRNA调控机制,分析了ceRNA网络调控的影响因素,综述了ceRNA在不同动物中调控miRNA的研究进展,为进一步研究lncRNA与miRNA的调控网络提供参考,为畜牧业发展及复杂动物疾病治疗提供新的思路。     

miRNA调控家畜肌肉组织生长发育的研究进展

miRNA(microRNA)是在线虫中发现的一类长度约20～25个核苷酸,对动物机体各生理机能具有重要调控作用的非编码RNA。miRNA对动物的肌肉组织的调节作用具有时空特异性。近年来,越来越多的miRNA在家畜的肌肉组织中被发现,其在调控家畜肌肉生长发育上的重要地位也逐渐被证实。本文综述了miRNA在不同家畜肌肉发育过程中的作用,并对其存在的问题以及发展方向进行了展望,旨在为今后肉用家畜的相关分子育种工作提供理论基础。     

microRNA在动物营养代谢调控中的研究进展

microRNA是一类真核生物内源性具有调控功能的小分子非编码单链RNA,参与构建了基因转录后水平的复杂调控网络,具有多种重要的生物学功能。本文综述了microRNA在动物三大营养物质脂类、糖类和蛋白质氨基酸代谢中调控作用的研究进展,为动物营养代谢的相关研究提供参考。     

miR-203的短暂表达及其对鸡骨骼肌细胞增殖和分化的抑制作用

胚胎期的肌肉发育受多种遗传和环境因素影响。microRNA是基因表达的重要调控因子,可通过靶向调控mRNA的表达,参与肌肉发育进程。华南农业大学的科研人员在研究中发现了一个"皮肤特异表达"的microRNA大量表达于鸡胚胎期骨骼肌中,并揭示了其表达模式及其在鸡骨骼肌细胞发育中的作用机制。相关研究于2014年7月在线发表于《Cell Death Disease》。     

microRNA与胎盘发育关系的研究进展

microRNA (miRNA)是一类大小约22 nt的内源性非编码RNA,它们通过剪切靶基因的转录产物或抑制靶基因转录产物的翻译,在转录后起到调控靶基因表达的作用。大量研究结果表明,动物体内的miRNA参与了胚胎的早期发育、脑和神经发育、心脏发育、肌肉及骨骼发育等动物发育的各个方面。已有证据表明,一些miRNA在胎盘中特异表达,在胎盘的正常发育过程中起到了重要作用。作者对参与胎盘发育的miRNAs进行了综述。     

Fasting regulates the expression of adiponectin receptors in young growing pigs

Adiponectin is an adipocyte-derived hormone that can improve insulin sensitivity. Its functions in regulating glucose utilization and fatty acid metabolism in mammals are mediated by 2 subtypes of adiponectin receptors (AdipoR1 and AdipoR2). This study was conducted to determine the effect of fasting on the expression of adiponectin and its receptors. The expression of adiponectin was not affected in s.c. adipose tissue, but adiponectin expression increased in visceral adipose tissue after fasting. In contrast, expression of both AdipoR mRNA was increased in the liver and s.c. adipose tissue of 24-h-fasted pigs compared with fed pigs, but the mRNA in muscle and visceral adipose tissue was not affected by fasting. A third putative adiponectin receptor, T-cadherin, was cloned and the mRNA expression was determined. T-Cadherin has been recognized to act as a vascular adiponectin receptor in vascular endothelial and smooth muscle cells. Our data showed that the expression of T-cadherin was decreased in the muscle of fasted pigs, suggesting that the expression of T-cadherin can be regulated by feeding status. In summary, in young pigs, adiponectin mRNA was up-regulated by fasting in visceral, but not s.c., adipose tissue, whereas AdipoR1 and AdipoR2 mRNA were increased in s.c., but not visceral, adipose tissue. The adiponectin receptor, T-cadherin, was expressed in s.c. and visceral adipose tissue and in muscle, but only muscle mRNA expression was decreased by fasting.     

Molecular cloning and tissue expression of chicken AdipoR1 and AdipoR2 complementary deoxyribonucleic acids

AdipoR1 and AdipoR2 belong to a novel class of transmembrane receptors that mediate the effects of adiponectin. We have cloned the chicken AdipoR1 and AdipoR2 complementary deoxyribonucleic acids (cDNA) and determined their expression in various tissues. We also investigated the effect of feed deprivation on the expression of AdipoR1 or AdipoR2 mRNA in the chicken diencephalon, liver, anterior pituitary gland, and adipose tissue. The chicken AdipoR1 and AdipoR2 cDNA sequences were 76-83% identical to the respective mammalian sequences. A hydrophobicity analysis of the deduced amino acid sequences of chicken AdipoR1/AdipoR2 revealed seven distinct hydrophobic regions representing seven transmembrane domains. By RT-PCR, we detected AdipoR1 and AdipoR2 mRNA in adipose tissue, liver, anterior pituitary gland, diencephalon, skeletal muscle, kidney, spleen, ovary, and blood. AdipoR1 or AdipoR2 mRNA expression in various tissues was quantified by real-time quantitative PCR, and AdipoR1 mRNA expression was the highest in skeletal muscle, adipose tissue and diencephalon, followed by kidney, ovary, liver, anterior pituitary gland, and spleen. AdipoR2 mRNA expression was the highest in adipose tissue followed by skeletal muscle, liver, ovary, diencephalon, anterior pituitary gland, kidney, and spleen. We also found that a 48 h feed deprivation significantly decreased AdipoR1 mRNA quantity in the chicken pituitary gland, while AdipoR2 mRNA quantity was significantly increased in adipose tissue (P<0.05). We conclude that the AdipoR1 and AdipoR2 genes are ubiquitously expressed in chicken tissues and that their expression is altered by feed deprivation in the anterior pituitary gland and adipose tissue.     

Novel findings regarding Glut-4 expression in adipose tissue and muscle in horses--a preliminary report

One of the hallmarks of insulin resistance is a reduction in glucose transporter-4 (Glut-4) expression in adipose tissue but not in skeletal muscle. However, while Glut-4 has been demonstrated in skeletal and cardiac muscles in horses it has not been demonstrated in adipose tissue. The initial objectives of the present study were: (1) to test the hypothesis that Glut-4 expression would vary between selected key skeletal muscles; (2) to test the hypothesis that it would also vary between representative adipose tissue depots, and (3) to see whether expression would be greater in adipose tissue compared to muscle. Glut-4 expression was determined by Western blot using samples obtained from post mortem biopsies obtained from four muscles (gluteus medius, semitendinosus, heart, and diaphragm), and four adipose tissues (subcutaneous, retroperitoneal, mesenteric, and omental) in three horses. There were no differences (P>0.05) in Glut-4 protein expression between the muscles sampled. Likewise there were no differences (P>0.05) in Glut-4 protein expression between fat depots. There was a significant difference (P=0.03) when pooled means for Glut-4 expression in muscle (58.8+/-2.5 densitometry units) were compared with adipose tissue (115.8+/-15.7). This difference in Glut-4 expression in these two tissues with distinctly different metabolic reasons for taking up glucose may warrant further investigation to see if there are more pronounced differences in Glut-4 expression in muscle and adipose tissue in various populations of horses.     

Effect of breed on fatty acid composition and stearoyl-CoA desaturase protein expression in the Semimembranosus muscle and subcutaneous adipose tissue of cattle

The present study investigated (i) the effect of breed on the expression of stearoyl-CoA desaturase (SCD) protein and fatty acid composition in Semimembranosus muscle and subcutaneous adipose tissue of beef cattle and (ii) the relationship between SCD expression, cis-9, trans-11 conjugated linoleic acid (CLA) content, and monounsaturated fatty acid (MUFA) level. The study was conducted on the following breeds: Longhorn (L), Charolais cross with Holstein–Friesian (CX), Hereford (H), Belted Galloway (BG) and Beef Shorthorn (BS). Significant breed differences in the total fatty acid content, saturated fatty acid (SFA) level, MUFA and n−3 PUFA content were observed in subcutaneous adipose tissue but not in muscle. In the case of CLA, the breed differences were observed in both muscle and subcutaneous adipose tissue, with the highest level in L and the lowest level in H. In the case of subcutaneous adipose tissue, the breed with the highest CLA content (L) also had the highest SCD protein expression. The breed-specific pattern of SCD expression in subcutaneous adipose tissue was similar to the breed-specific pattern of one of the products of an SCD-catalysed reaction, C16:1 (BS < BG < H < CX < L). It has been concluded that (i) the mechanisms regulating SCD protein expression and CLA level in beef cattle are tissue-specific; (ii) breed-specific variations in SCD expression might contribute to breed variations in MUFA and CLA content in subcutaneous adipose tissue but not in Semimembranosus muscle.     

布莱凯特黑牛CB1基因克隆测序及表达分析

本试验旨在研究布莱凯特黑牛CB1基因CDS区序列和表达情况,探讨CB1基因与脂肪沉积的关系.运用RT-PCR技术克隆CB1基因CDS区序列,并进行生物学分析;运用qRT-PCR技术检测不同组织的mRNA相对表达量;以及运用免疫组化技术对蛋白进行定位分析,运用Western blot技术检测CB1蛋白在不同组织的表达量....     

Bovine sirtuins: initial characterization and expression of sirtuins 1 and 3 in liver, muscle, and adipose tissue

Sirtuins, the mammalian homologs of the silent information regulator 2 gene of Saccharomyces cerevisiae, are members of the NAD(+)-dependent family of histone deacetylases. In vertebrates, 7 sirtuins have been described, with different cellular localizations and target proteins. Glucose and lipid metabolism are among the processes regulated by these enzymes. In ruminants, gluconeogenesis is the main biochemical pathway by which glucose is obtained. Because sirtuins in bovines have not been studied, the aim of this work was to obtain sequences coding for the 7 sirtuins and determine the expression patterns of sirtuin1 (Sirt1) and sirtuin3 (Sirt3) in the liver, muscle, and adipose tissue of calves and bulls. Using PCR amplification, we obtained sirtuin gene sequences and reported them to the National Center for Biotechnology Information GenBank. Characteristic sequence motifs corresponding to the sirtuin catalytic core domain were found, including the active and zinc-binding sites. Relative expression patterns of Sirt1 and Sirt3 in liver, muscle, and adipose tissue were quantified by real-time PCR, normalizing to the geometric mean of the housekeeping genes cyclophilin A and β-actin. Expression of Sirt1 was less in liver and muscle, whereas it was greater in adipose tissue of adult animals, with statistical differences (P=0.0071) only in the latter. In the case of Sirt3, expression was greater in all 3 adult tissues, but statistical differences were found only in liver (P=0.0141) and muscle (P=0.0017). The greatest expression was observed in liver for Sirt1 and in muscle for Sirt3, whereas the least expression was in muscle for Sirt1 and in adipose tissue for Sirt3. In other species, sirtuin expression (both Sirt1 and Sirt3) in liver is reported to be the greatest among these 3 tissues, a pattern different from what we measured. These differences in expression can be associated with metabolic differences between nonruminant and ruminant species. However, further research on the relationship between bovine sirtuins and ruminant metabolism is required for a better understanding of these fields.     

Changes in gene expression of glucose transporters in lactating and nonlactating cows

Glucose delivery and uptake by the mammary gland are a rate-limiting step in milk synthesis. It is thought that insulin-independent glucose uptake decreases in tissues, except for the mammary gland, and insulin resistance in the whole body increases following the onset of lactation. To study glucose metabolism in peak-, late-, and nonlactating cows, the expression of erythrocyte-type glucose transporter (GLUT1) and the insulin-responsive glucose transporter (GLUT4) in the mammary gland, adipose tissue, and muscle were assessed by Western blotting and real-time PCR. Our results demonstrated that the mammary gland of lactating cows expressed a large amount of GLUT1, whereas the mammary gland of nonlactating cows did not (P < 0.05). On the other hand, adipose tissue of late and nonlactating cows expressed a large amount of GLUT1, whereas the adipose tissue of peak-lactating cows did not (P < 0.05). There were no significant differences in the abundance of GLUT4 mRNA in adipose tissue and muscle, whereas GLUT4 mRNA was not detected in the mammary gland. The plasma insulin concentration was greater (P < 0.05) in nonlactating cows than in peak- and late-lactating cows. The results of the present study indicate that in lactation, GLUT1 expression in the mammary gland and adipose tissue is a major factor for insulin-independent glucose metabolism, and the expression of GLUT4 in muscle and adipose tissue is not an important factor in insulin resistance in lactation; however, the plasma insulin concentration may play a role in insulin-dependent glucose metabolism. Factors other than GLUT4 may be involved in insulin resistance.     

脂肪组织的内分泌功能及其与肌肉组织间的分子信号联系

脂肪组织不仅是机体储存能量的主要场所,还是一个活跃的内分泌器官;骨骼肌同样也具有分泌活性物质的功能,能表达、合成和分泌多种生物信号分子。这些活性因子与许多重要的生理、病理过程有密切的关系。对脂肪组织的内分泌功能及其与肌肉组织间的分子信号联系进行了综述。     

脂肪组织的内分泌功能及其与肌肉组织间的分子信号联系

脂肪组织不仅是机体储存能量的主要场所,还是一个活跃的内分泌器官;骨骼肌同样也具有分泌活性物质的功能,能表达、合成和分泌多种生物信号分子。这些活性因子与许多重要的生理、病理过程有密切的关系。对脂肪组织的内分泌功能及其与肌肉组织间的分子信号联系进行了综述。     

海南黑山羊CAST基因的时空表达分析

采用SYBR Green实时荧光定量PCR技术检测了CAST基因在1、2、3、4月龄和12月龄海南黑山羊骨骼肌、心肌、肝脏和脂肪组织中mRNA表达差异和发育规律,为揭示CAST基因的生物学功能及其对肉质的表达调控机理提供参考依据.结果表明,CAST基因在未成年羊的骨骼肌中mRNA表达量极显著高于其他组织（P＜0.01）,且在2月龄时达到最高水平;成年后在心肌、肝脏和脂肪中的表达量极显著升高（P＜0.01）,在骨骼肌中的表达量次之,但在脂肪中的表达量始终相对较低;该基因在3、4月龄各组织中的mRNA表达量相对较低,且四种组织在3、4月龄间表达差异不显著（P＞0.05）.