Transcription factor CREB3L1 mediates cAMP and glucocorticoid regulation of arginine vasopressin gene transcription in the rat hypothalamus

Abstract

BackgroundArginine vasopressin (AVP), a neuropeptide hormone that functions in the regulation of water homeostasis by controlling water re-absorption at kidneys, is synthesised in supraoptic nucleus and paraventricular nucleus of the hypothalamus. An increase in plasma osmolality stimulates secretion of AVP to blood circulation and induces AVP synthesis in these nuclei. Although studies on mechanism of AVP transcriptional regulation in hypothalamus proposed that cAMP and glucocorticoids positively and negatively regulate Avp expression, respectively, the molecular mechanisms have remained elusive. Recently, we identified CREB3L1 (cAMP-responsive element binding protein 3 like 1) as a putative transcription factor of Avp transcription in the rat hypothalamus. However the mechanism of how CREB3L1 is regulated in response of hyperosmotic stress in the neurons of hypothalamus has never been reported. This study aims to investigate effect of previously reported regulators (cAMP and glucocorticoid) of Avp transcription on transcription factor CREB3L1 in order to establish a molecular explanation for cAMP and glucocorticoids effect on AVP expression.ResultsThe effect of cAMP and glucocorticoid treatment on Creb3l1 was investigated in both AtT20 cells and hypothalamic organotypic cultures. The expression of Creb3l1 was increased in both mRNA and protein level by treatment with forskolin, which raises intracellular cAMP levels. Activation of cAMP by forskolin also increased Avp promoter activity in AtT20 cells and this effect was blunted by shRNA mediated silencing of Creb3l1. The forskolin induced increase in Creb3l1 expression was diminished by combined treatment with dexamethasone, and, in vivo, intraperitoneal dexamethasone injection blunted the increase in Creb3l1 and Avp expression induced by hyperosmotic stress.ConclusionHere we shows that cAMP and glucocorticoid positively and negatively regulate Creb3l1 expression in the rat hypothalamus, respectively, and regulation of cAMP on AVP expression is mediated through CREB3L1. This data provides the connection between CREB3L1, a newly identified transcription factor of AVP expression, with the previously proposed mechanism of Avp transcription which extends our understanding in transcription regulation of Avp in the hypothalamus.

Transcription factor Creb3l1 regulates the synthesis of prohormone convertase enzyme PC1/3 in endocrine cells

“…To identify new transcriptional targets of Creb3l1, we performed RNA sequencing on our previously reported Creb3l1 knockdown AtT20 stable cell line 8 . The result showed that 5706 genes were significantly changed ( P adjusted < 0.01) in expression by Creb3l1 knockdown (see Supporting information, Table S2).…”

“…Mouse pituitary cell line AtT‐20/D16v‐F2 (# 94050406; Sigma, St Louis, MO, USA) was maintained in a humidified incubator at 37°C with 5% CO 2 in Dulbecco's modified Eagle's medium (# D6546; Sigma), supplemented with 10% heat‐inactivated fetal bovine serum, 100 μg mL ‐1 penicillin/streptomycin and 2 mmol L ‐1 l ‐glutamine. Creb3l1 knockdown cell lines were established using lentivirus expressing shRNAs as described previously 8 . The sequences of all oligonucleotides and primers used in this study are provided in the Supporting information (Table S1).…”

“…Indeed, recent reports suggest that Creb3l1 is involved in cellular processes such as secretion, hormone synthesis, the formation of the extracellular matrix and cellular proliferation 2‐5 . This is backed up by studies showing that Creb3l1 expression can be regulated by transforming growth factor beta, glucocorticoids and progesterone 6‐8 . These studies suggest that ER stress is one of many mechanisms through which Creb3l1 protein can be activated.…”

“…To direct our candidate search towards secretory cells, we compared the AtT20 cell gene list with previously published transcriptomic data from the dehydrated rat and mouse SON 11 . Creb3l1 is increased in the SON by dehydration 8,12,15,16 . Thus, we considered genes that increased in the SON in response to dehydration and decreased in AtT20 cells following stable knockdown of Creb3l1 .…”

An LHX1-Regulated Transcriptional Network Controls Sleep/Wake Coupling and Thermal Resistance of the Central Circadian Clockworks

“…RGS16 drives cAMP rhythms required for normal phasing of SCN subdomains [28]. CREB3L1 couples the core clock to Avp expression downstream of cAMP signaling [29,30]. And DUSP4 gates pERK responses to light input, likely mediating lost gating of light responses in Vip −/− mice [16,31].…”