Sleep deprivation and diet affect human GH gene expression in transgenic mice in vivo

Abstract

Human (h) growth hormone (GH) production studies are largely limited to effects on secretion. How pituitary hGH gene (hGH-N/GH1) expression is regulated is important in our understanding of the role hGH plays in physiology and disease. Here we assess for the first time the effect of sleep deprivation (SD) and high-fat diet (HFD) on hGH-N expression in vivo using partially humanized 171hGH/CS transgenic (TG) mice, and attempted to elucidate a role for DNA methylation. Activation of hGH-N expression requires interactions between promoter and upstream locus control region (LCR) sequences including pituitary-specific hypersensitive site (HS) I/II. Both SD and diet affect hGH secretion, but the effect of SD on hGH-N expression is unknown. Mice fed a HFD or regular chow diet for three days underwent SD (or no SD) for 6 hours at zeitgeber time (ZT) 3. Serum and pituitaries were assessed over 24 hours at 6-hour intervals beginning at ZT 14. SD and HFD caused significant changes in serum corticosterone and insulin, as well as hGH and circadian clock-related gene RNA levels. No clear association between DNA methylation and the negative effects of SD or diet on hGH RNA levels was observed. However, a correlation with increased methylation at a CpG (cytosine paired with a guanine) in a putative E-box within the hGH LCR HS II was suggested in situ. Methylation at this site also increased BMAL1/CLOCK-related nuclear protein binding in vitro. These observations support an effect of SD on hGH synthesis at the level of gene expression.

Mice with gene alterations in the GH and IGF family

“…Studies using these mice reveal that hGH production is impacted by the circadian rhythm via direct binding of circadian transcription factors at an enhancer motif in the hGH promoter locus. GH production is suppressed in these mice by acute sleep deprivation [137] and by HFD feeding only during the light (inactive) stage of daily cycle [138].…”

Sleep

“…During non-REM sleep, blood supply increases to muscles, energy is restored, tissues grow and are repaired, and children release growth hormones. Therefore, sleep deprivation can impact growth 18,19…”

“…Therefore, sleep deprivation can impact growth. 18,19 Inadequate sleep can result from a child' s environment or amphetaminebased medications prescribed for attention-deficit hyperactivity disorder (ADHD). 20 Paradoxically, children exhibiting signs and symptoms of sleep deprivation, such as an inability to concentrate, may be misdiagnosed with ADHD.…”

Increased capacity to maintain glucose homeostasis in a transgenic mouse expressing human but not mouse growth hormone with developing high fat diet-related insulin resistance, steatosis and adipose dysfunction

“…Previously, transgenic CD-1[mGH.hGH] mice with a single copy of the hGH gene locus in addition to the endogenous mGH gene were described [11, 27]. The transgene includes the hGH locus control region required for pituitary-specific expression in vivo and, as a result, these mice have been used to study the response of the hGH gene to hormone treatments [28, 29], diet [30], light/day cycle [31, 32] and sleep deprivation [33] in a physiological context. Here, we have removed the endogenous mGH gene from CD-1[mGH.hGH] mice by crossing it with the Ghtm1(KOMP)Vlcg mouse (UCDAVIS KOMP repository; also referred to as C57BL/6[Gh tm1Vlcg ] or GH −/− mouse [34]) to generate CD-1[ΔmGH.hGH] mice, which allow the effects of hGH, without mGH, to be assessed in vivo .…”