Genetic deletion of the ghrelin receptor (GHSR) impairs growth and blunts endocrine response to fasting in Ghsr-IRES-Cre mice.
Genetic deletion of the ghrelin receptor (GHSR) impairs growth and blunts endocrine response to fasting in Ghsr-IRES-Cre mice.
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DOI：
10.1016/j.molmet.2021.101223
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发表时间：
2021-09
影响因子：
8.1
通讯作者：
Dickson SL
中科院分区：
文献类型：
--
作者：
Peris-Sampedro F;Stoltenborg I;Le May MV;Zigman JM;Adan RAH;Dickson SL
促食欲激素ghrelin通过结合并激活生长激素促分泌素受体（GHSR）来发挥其生理作用。最近开发的Ghsr-IRES-Cre基因敲入小鼠系已经能够从遗传上接近表达GHSR的神经元。然而，使用敲入策略插入Cre构建体，即使是在上游内部核糖体进入位点（IRES）之后，也会干扰靶基因的表达，从而导致表型出现。本研究的目的是表型，无论是身体和代谢，杂合和纯合Ghsr-IRES-Cre小鼠，以期发现在何种程度上的ghrelin信号系统仍然在这些小鼠的功能。我们评估了野生型、杂合型和纯合型Ghsr-IRES-Cre小鼠对外周给予的胃饥饿素的反应，即进食和弓状核（Arc）Fos激活。我们还表征了它们的发育和生长表型，以及它们在过夜禁食后的代谢反应。将IRES-Cre盒插入Ghsr基因的3′-非翻译区导致Arc中基因剂量的GHSR缺失。而杂合子保持生长素释放肽反应和更接近野生型，生长素释放肽降低食欲的功效，并未能诱导弧Fos表达在纯合子同窝出生。与野生型和杂合子同窝仔相比，纯合子具有较低的体重，伴随着较短的体长、较少的脂肪组织含量、改变的骨参数和较低的胰岛素样生长因子-1水平。此外，与野生型相比，杂合和纯合Ghsr-IRES-Cre小鼠都缺乏通常的禁食诱导的生长激素（GH）升高，并且显示出血糖和胰岛素的过度下降。出乎意料的是，空腹酰基-胃饥饿素水平等位基因依赖性增加。我们的数据表明，（i）杂合子而非纯合子Ghsr-IRES-Cre小鼠保留了对给予的ghrelin的通常反应性，（ii）禁食对GH释放和葡萄糖稳态的影响发生改变，即使只有一个拷贝的Ghsr基因无功能（如杂合子Ghsr-IRES-Cre小鼠），（iii）纯合子Ghsr-IRES-Cre小鼠表现出生长迟缓。在生长激素释放肽信号传导受抑制的许多转基因模型中，Ghsr-IRES-Cre小鼠最能代表预期表型在体重、生长和代谢参数方面的全部范围。突变型Ghsr-IRES-Cre小鼠在Arc中表现出基因剂量GHSR耗竭。杂合子Ghsr-IRES-Cre小鼠，但不是纯合子，保留ghrelin反应。禁食诱导的GH释放和葡萄糖稳态在杂合子和纯合子中同样受损。纯合子Ghsr-IRES-Cre小鼠表现出生长迟缓。空腹酰基饥饿素水平是等位基因依赖性增加。
The orexigenic hormone ghrelin exerts its physiological effects by binding to and activating the growth hormone secretagogue receptor (GHSR). The recent development of a Ghsr-IRES-Cre knock-in mouse line has enabled to genetically access GHSR-expressing neurons. Inserting a Cre construct using a knock-in strategy, even when following an upstream internal ribosome entry site (IRES) can, however, interfere with expression of a targeted gene, with consequences for the phenotype emerging. This study aimed to phenotype, both physically and metabolically, heterozygous and homozygous Ghsr-IRES-Cre mice, with a view to discovering the extent to which the ghrelin signalling system remains functional in these mice. We assessed feeding and arcuate nucleus (Arc) Fos activation in wild-type, heterozygous and homozygous Ghsr-IRES-Cre mice in response to peripherally-administered ghrelin. We also characterised their developmental and growth phenotypes, as well as their metabolic responses upon an overnight fast. Insertion of the IRES-Cre cassette into the 3′-untranslated region of the Ghsr gene led to a gene-dosage GHSR depletion in the Arc. Whereas heterozygotes remained ghrelin-responsive and more closely resembled wild-types, ghrelin had reduced orexigenic efficacy and failed to induce Arc Fos expression in homozygous littermates. Homozygotes had a lower body weight accompanied by a shorter body length, less fat tissue content, altered bone parameters, and lower insulin-like growth factor-1 levels compared to wild-type and heterozygous littermates. Moreover, both heterozygous and homozygous Ghsr-IRES-Cre mice lacked the usual fasting-induced rise in growth hormone (GH) and displayed an exaggerated drop in blood glucose and insulin compared to wild-types. Unexpectedly, fasting acyl-ghrelin levels were allele-dependently increased. Our data suggest that (i) heterozygous but not homozygous Ghsr-IRES-Cre mice retain the usual responsiveness to administered ghrelin, (ii) the impact of fasting on GH release and glucose homeostasis is altered even when only one copy of the Ghsr gene is non-functional (as in heterozygous Ghsr-IRES-Cre mice) and (iii) homozygous Ghsr-IRES-Cre mice exhibit growth retardation. Of the many transgenic models of suppressed ghrelin signalling, Ghsr-IRES-Cre mice emerge as best representing the full breadth of the expected phenotype with respect to body weight, growth, and metabolic parameters. Mutant Ghsr-IRES-Cre mice exhibit a gene-dosage GHSR depletion in the Arc. Heterozygous Ghsr-IRES-Cre mice, but not homozygotes, retain ghrelin-responsiveness. Fasting-induced GH release and glucose homeostasis are similarly impaired in heterozygotes and homozygotes. Homozygous Ghsr-IRES-Cre mice exhibit growth retardation. Fasting acyl-ghrelin levels are allele-dependently increased.
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影响因子：
3.5
作者：
Joye, Deborah A. M.;Rohr, Kayla E.;Keller, Danielle;Inda, Thomas;Telega, Adam;Pancholi, Harshida;Carmona-Alcocer, Vania;Evans, Jennifer A.
通讯作者：
Evans, Jennifer A.
影响因子：
3.7
作者：
Ma X;Lin L;Qin G;Lu X;Fiorotto M;Dixit VD;Sun Y
通讯作者：
Sun Y
DOI：
10.1152/ajpendo.00582.2003
发表时间：
2004-08-01
影响因子：
5.1
作者：
Cummings, DE;Frayo, RS;Chapelot, D
通讯作者：
Chapelot, D
影响因子：
3.2
作者：
Qi, XA;Reed, J;Greeley, GH
通讯作者：
Greeley, GH
影响因子：
4.8
作者：
Rodriguez, Juan A.;Bruggeman, Emily C.;Zigman, Jeffrey M.
通讯作者：
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