生长激素受体基因表达的研究进展

生长激素(growth hormone,GH)在促进动物生长、发育等代谢过程中起着重要作用。长期以来人们在研究动物生长发育机制及其调控时,主要着眼于提高生长激素水平。然而GH必须与靶器官上生长激素受体(growth hormone receptor,GHR)结合,由GHR介导将信号传入细胞内才能发挥作用。大量研究结果显示,动物生长速度与GH水平并不完全平行,但与肝脏GHR呈明显正相关。生长快的肉鸡血液中GH和垂体GH mRNA水平比生长慢的蛋鸡低,而肝脏GHR水平比蛋鸡高;患侏儒症动物血液中GH浓度却比正常动物高,而GHR胞外部分缺失或功能不全。可见GHR基因表达对动物生长发育调控起着至关重要的作用。     

生长激素激活受体机理的研究进展

生长激素(growth hormone,GH)是一种含有191个氨基酸的多肽类激素,分子质量为22 ku,由垂体前叶分泌进入血液循环,与靶细胞膜表面以二聚体形式存在的生长激素受体(growth hormone receptor,GHR)相结合。对于受体的激活来说,仅是二聚化还不够,还需在GH的诱导下发生构象变化,进而才能诱发Janus激酶2(Janus kinase 2,JAK2)的酪氨酸磷酸化,并通过4条不同的路径将信号传入细胞内,从而发挥代谢、增殖及分化等一系列生理效应。作者就生长激素与受体的结构、作用机理、信号转导通路的进展进行综述。     

生长激素促进细胞增殖机理的研究进展

生长激素(growth hormone,GH)对动物的生长发育具有重要的作用,其直接或间接通过诱导胰岛素样生长因子1(insulin-like growth factor 1,IGF-1)促进干细胞的活化、细胞增殖和分化,并通过细胞膜受体发挥作用启动一系列信号通路.文章就生长激素对细胞增长的作用和功能进行简要概述.     

畜禽生长激素受体基因的研究进展

生长激素受体（GHR）是一种跨膜糖蛋白,GHR可以与脑垂体产生的生长激素（GH）相结合,启动细胞内的信号转导机制,增加胰岛素样生长因子-1(IGF-1)的表达,促进细胞增殖,最终发挥调控动物骨骼肌生长发育的作用。本文综述了GHR基因的功能与结构、GHR基因在羊、牛、猪、家禽及其他动物中的最新研究进展，为更深入研究GHR基因对动物生产性能的影响提供参考。     

贵州本地鸡内源生长激素（GH）的测定

鸡的生长激素（growth hormone,GH）是由脑垂体前叶合成与分泌,其生理功能通过它与生长激素受体（GHR）结合作用产生胰岛素样生长因子-I（IGF-I）等反应来实现,对鸡的生长发育发挥重要的调控作用。从对各种动物进行皮下埋植、注射外源GH等的研究表明：GH对动物具有显著加快肌肉、骨骼生长,促进生长发育,降低饲料报酬的作用。     

生长激素受体激活剂和拮抗剂的研究进展及应用

<正>生长激素受体(growth hormone recepter,GHR)属于I类细胞因子受体,是调节机体后天生长的主要因子,生长激素(growth hormone,GH)只有在与受体结合后,才能启动信号转导,参与调节机体的代谢、发育、繁殖以及免疫等生理功能[1]。由于分泌激素的异常性及需求性的不同,人们开始试图通过利用免疫学技术制备抗独特型抗体或抗受体单克隆抗体以及利用基因工程技术对天     

生长激素与生长激素受体基因的表达

在动物生长轴中，GH是调控动物生长发育的核心激素，它具有促生长作用。但GH发挥生理作用的第一步是与靶细胞膜表面的GH受体(GHR)结合，由GHR介导将信号传入细胞内从而产生一系列生理效应。在生理激素浓度下，GH 与GHR 以1／2相结合。在超生理激素浓度下，激素饱和了所有的受体分子形成1／1的复合物，阻止了受体二聚化和信息传递。当GH水平提高而GHR基因表达没改善时，不仅GH的作用不能完全发挥，而且可能因为GH过剩而产生负反馈调节，影响其他生理功能。这可能是某些促生长激素轴功能的添加剂在使用一段时间后效果减弱的原因之一。因此，在直接或间接提高GH水平的同时，应该提高GHR基因表达水平，才能最大限度发挥GH的作用。促进GHR基因表达有促进动物生长发育和发展的趋势，可使畜禽生产性能在较高水平的情况下再上新台阶。     

鸡生长激素受体基因的研究进展

生长激素GH是由脑垂体前叶合成和分泌的多肽类激素,是调控整个机体的重要激素,对动物有显著加快肌肉、骨骼生长,降低脂肪含量,促进生长发育及提高饲料报酬的作用。GH在组织和细胞水平发挥其生理作用的第一步是与靶细胞膜表面的生长激素受体(GHR)结合,激活后使两个生长激素受体形成二聚体,从而形成GH(GHR)2复合物(GH分子上有两个GHR结合位点,每一个GH分子能结合两个GHR分子),并激活一系列生化事件,最终产生生物效应。     

饥饿对鼠肝细胞胞内生长激素相关信号转导通路的影响

生长激素对动物的生长发育具有重要作用。而肝脏是生长激素发挥生理作用的重要靶器官。生长激素在肝细胞上发挥生理作用的主要信号转导通路是JAK-STATs、ERK等。在饥饿应激条件下,生长激素的作用减弱,动物机体IGF-1的分泌量大大减少,但其减少的原因尚不清楚。本研究通过饥饿大鼠使其处于应激状态,在饥饿应激模型上研究生长激素对肝脏细胞一些主要信号通路的影响。将大鼠分为2组,一组为正常饲喂组(48h),另外一组为饥饿组(48h),通过门静脉注射重组人生长激素,在注射后的0和25min时进行离体肝脏灌流并分析胞内信号分子磷酸化水平的变化。结果显示,正常饲喂条件下,注射生长激素组鼠肝脏细胞的JAK2、STAT1/3/5、ERK1/2等胞内信号分子会发生明显磷酸化,但在饥饿组,只能观察到肝细胞JAK2和STAT1/3/5微弱的磷酸化,ERK1/2磷酸化程度没有变化。此外,饥饿并没有改变细胞内蛋白总量和肝脏细胞表面受体的数量。因此,本研究表明,饥饿应激下大鼠对生长激素不敏感是由于生长激素介导的胞内信号通路改变引起。     

贵州香猪生长激素cDNA的克隆及原核表达

应用RT-PCR技术从香猪垂体mRNA中扩增出完整的生长激素(growth hormone,GH)cDNA片段,将其克隆入载体质粒pTYB11中,构建了重组质粒pTYB11-xGH,经过IPTG诱导,在大肠杆菌ER2566中获得表达,并确定了最佳表达条件.通过亲合柱层析,得到了完整的香猪生长激素,为香猪GH的结构、功能及其分子水平的作用机制奠定了基础.     

抗生长激素受体单克隆抗体的功能特点

The growth hormone receptor (GHR) is the key regulator of postnatal growth which belongs to the type Ⅰ cytokine receptor that mediates many functions regulated by growth hormone (GH). Monoclonal antibodies (mAb) to the GHR have been important tools for the study of this receptor. All these anti-GHR mAbs, designated 1H2, 1A9, 2C3 and mAb263, are highly reactive with GHR, but 1A9 does not promote growth in hypophysectomized rats, 2C3 can do and this effect will be inhibited in the presence of GH. mAb263 as the commercial monoclonal antibody that binding to the receptor has a similar effect with GH, not only can recognise GHR,but also can induce a conformational change of the receptor in a similar manner, but not identical with GH.     

Growth hormone receptor (GHR) RNAi decreases proliferation and enhances apoptosis in CMT-U27 canine mammary carcinoma cell line

Canine mammary gland has been identified as a major site of the extrapituitary growth hormone (GH) production. This finding is linked to its role in tumourigenesis of the mammary gland. Our previous studies indicated the role of GH and GH receptor (GHR) in regulation of proliferation and apoptosis. Thus, we have optimized the ghr RNA interference method in canine mammary carcinoma cell line CMT-U27. We have analysed the effect of GHR reduction on the intracellular signalling and the cell cycle and apoptosis. The results showed that GHR reduction decreased the p-ERK1/2 expression and caused increase of apoptosis and decrease in number of cells at S and G2M phases. This study indicates that GHR besides proliferative effect promotes growth by increasing cell survival. It can tilt the balance between proliferation and death in cancer cells.     

Comparative Aspects of the Endotoxin- and Cytokine-Induced Endocrine Cascade Influencing Neuroendocrine Control of Growth and Reproduction in Farm Animals

Disease in animals is a well-known inhibitor of growth and reproduction. Earlier studies were initiated to determine the effects of endotoxin on pituitary hormone secretion. These studies found that in sheep, growth hormone (GH) concentration was elevated, whereas insulin-like growth factor-I (IGF-I) was inhibited, as was luteinizing hormone (LH). Examination of the site of action of endotoxin in sheep determined that somatotropes expressed the endotoxin receptor (CD14) and that both endotoxin and interleukin-Iβ activated GH secretion directly from the pituitary. In the face of elevated GH, there is a reduction of IGF-I in all species examined. As GH cannot activate IGF-I release during disease, there appears to be a downregulation of GH signalling at the liver, perhaps related to altered nitration of Janus kinase (JAK). In contrast to GH downregulation, LH release is inhibited at the level of the hypothalamus. New insights have been gained in determining the mechanisms by which disease perturbs growth and reproduction, particularly with regard to nitration of critical control pathways, with this perhaps serving as a novel mechanism central to lipopolysaccharide suppression of all signalling pathways. This pathway-based analysis is critical to the developing novel strategies to reverse the detrimental effect of disease on animal production.     

Cloning of the growth hormone receptor and its muscle-specific mRNA expression in black Muscovy duck (Cairina moschata)

1. The cDNA sequence of the growth hormone receptor (GHR) from the black Muscovy duck was obtained and compared to the mRNA expression of growth hormone (GH) in the breast and leg muscles during 2–13 weeks of age using quantitative RT-PCR.

2. The cDNA sequence of the Muscovy duck GHR gene is 1903 bp in length, with an 1830 bp coding region that encodes 609 amino acids. It exhibits > 92.9% homology with the poultry GHR cDNA and amino acid sequences.

3. Overall, GHR mRNA expression was the highest at 2 weeks and the lowest at 13 weeks of age, exhibiting different profiles in different muscles. In the breast muscles, the GHR mRNA level declined sharply at 2–4 weeks, maintained at a plateau at 4–10 weeks and decreased slightly at 10–13 weeks. In the leg muscles, a gradual and slow decrease was observed during the whole period of 2–13 weeks.

4. Robust extra-pituitary GH mRNA expression was detected in the muscles and the expression profile was highly correlated with that of GHR mRNA, in contrast to the inverse correlation between the pituitary GH and tissue GHR levels shown previously.

5. These data suggest that the locally synthesised GH in the muscles, rather than the pituitary GH, is more closely associated with GHR and may be more critical for the regulation of muscle growth and contribute to the tissue-specific effects of GH.

     

Regulation of protein and energy metabolism by the somatotropic axis.

The somatotropic axis plays a key role in the co-ordination of protein and energy metabolism during postnatal growth. This review discusses the complexity of the regulation of protein and energy metabolism by the somatotropic axis using three main examples: reduced nutrition, growth hormone (GH) treatment and insulin-like growth factor-1 (IGF-1) treatment. Decreased nutrition leads to elevated GH secretion, but it reduces hepatic GH receptor (GHR) number and plasma levels of IGF-1; it also changes the relative concentrations of IGF binding proteins (IGFBPs) in plasma. GH treatment improves the partitioning of nutrients by increasing protein synthesis and decreasing protein degradation and by modifying carbohydrate and lipid metabolism. However, these well-established metabolic responses to GH can change markedly in conditions of reduced nutritional supply or metabolic stress. Short-term infusion of IGF-1 in lambs reduces protein breakdown and increases protein synthesis. However, long-term IGF-1 administration in yearling sheep does not alter body weight gain or carcass composition. The lack of effect of IGF-1 treatment can be explained by activation of feedback mechanisms within the somatotropic axis, which lead to a reduction in GH secretion and hepatic GHR levels. The somatotropic axis has multiple levels of hormone action, with complex feedback and control mechanisms, from gene expression to regulation of mature peptide action. Given that GH has a much wider range of biologic functions than previously recognized, advances in research of the somatotropic axis will improve our understanding of the normal growth process and metabolic disorders.     

Study on the Change Trend of Growth Hormone (GH) and Growth Hormone Receptor (GHR) in Serum at Different Months in Mashen and Large White Pigs

The purpose of this study was to understand the change trend of growth hormone (GH) and growth hormone receptor (GHR) in serum of Mashen and Large White pigs during the period from 0 to 6 months of age,and to analyze the influence of GH and GHR on growth rate.The method of ELISA was used to detect the concentration of GH and GHR in serum of Mashen and Large White pigs from 0 to 6 months of age.The results showed that the variation trends of GH in Mashen pig was roughly the same as in Large White pig,the GH concentration was increased with age increasing after birth and reached the peaks at 4 and 5 months of age for Mashen and Large White pigs,respectively,and then decreased gradually.The serum GH concentration in Mashen pig was a little greater than that in Large White pig at 3 and 4 months of age,on the contrary,the serum GH concentration in Large White pig was greater than that in Mashen pig at other months.During the period from 0 to 6 months of age,the difference of GHR concentration in serum was not significant in Mashen pig (P>0.05).In Large White pig,the serum GHR concentration at 1 month of age was lowest,and was significantly lower than that at 4 and 6 months of age (P<0.01;P<0.05).During the period of 0 to 2 months of age,the GHR concentration in Mashen pig was greater than that in Large White pig,but the difference was extremely significant only at 1 month of age (P<0.01).Conversely,the serum GHR concentration in Large White pig was greater than those in Mashen pig during the period from 3 to 6 month of age,there was significant difference at 4 and 6 months of age (P<0.05),and there was extremely significant at 5 months of age(P<0.01).The concentration of GH and GHR in serum was related to the developmental stages and genetic background of pig,and its change trend was in accordance with the trend of growth rate.