title: Cold exposure increases the biosynthesis and proteolytic processing of prothyrotropin-releasing hormone in the hypothalamic paraventricular nucleus via beta-adrenoreceptors.
abstract: Different physiological conditions affect the biosynthesis and processing of hypophysiotropic proTRH in the hypothalamic paraventricular nucleus, and consequently the output of TRH. Early studies suggest that norepinephrine (NE) mediates the cold-induced activation of the hypothalamic-pituitary-thyroid axis at a central level. However, the specific role of NE on the biosynthesis and processing of proTRH has not been fully investigated. In this study, we found that NE affects gene transcription, protein biosynthesis, and secretion in TRH neurons in vitro; these changes were coupled with an up-regulation of prohormone convertase enzymes (PC) 1/3 and PC2. In vivo, NE is the main mediator of the cold-induced activation of the hypothalamic-pituitary-thyroid axis at the hypothalamic level, in which it potently stimulates the biosynthesis and proteolytic processing of proTRH through a coordinated up-regulation of the PCs. This activation occurs via beta-adrenoreceptors and phosphorylated cAMP response element binding signaling. In contrast, alpha-adrenoreceptors regulate TRH secretion but not proTRH biosynthesis and processing. Therefore, this study provides novel information on the molecular mechanisms of control of hypophysiotropic TRH biosynthesis.
authors.affiliation: Division of Endocrinology, Brown Medical School/Rhode Island Hospital, 55 Claverick Street, Providence, RI 02903, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Perello
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Stuart
authors.forename: Charles A
authors.initials: CA
authors.lastname: Vaslet
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Nillni
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003080:Cold Temperature; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D045664:Proprotein Convertase 1 / Q000235:genetics / Q000378:metabolism; D045706:Proprotein Convertase 2 / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D015398:Signal Transduction; D013973:Thyrotropin-Releasing Hormone / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D010446:Peptide Fragments; D011498:Protein Precursors; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D013973:Thyrotropin-Releasing Hormone; C046418:pro-thyrotropin releasing hormone; D010447:Peptide Hydrolases; D045664:Proprotein Convertase 1; D045706:Proprotein Convertase 2; D011761:Pyrrolidonecarboxylic Acid; D009638:Norepinephrine