Expression and cellular localization of the transcription factor NeuroD1 in the developing and adult rat pineal gland.
Circadian rhythms govern many aspects of mammalian physiology. The daily pattern of melatonin synthesis and secretion is one of the classic examples of circadian oscillations. It is mediated by a class of neuroendocrine cells known as pinealocytes which are not yet fully defined. An established method to evaluate functional and cytological characters is through the expression of lineage-specific transcriptional regulators. NeuroD1 is a basic helix-loop-helix transcription factor involved in the specification and maintenance of both endocrine and neuronal phenotypes. We have previously described developmental and adult regulation of NeuroD1 mRNA in the rodent pineal gland. However, the transcript levels were not influenced by the elimination of sympathetic input, suggesting that any rhythmicity of NeuroD1 might be found downstream of transcription. Here, we describe NeuroD1 protein expression and cellular localization in the rat pineal gland during development and the daily cycle. In embryonic and perinatal stages, protein expression follows the mRNA pattern and is predominantly nuclear. Thereafter, NeuroD1 is mostly found in pinealocyte nuclei in the early part of the night and in cytoplasm during the day, a rhythm maintained into adulthood. Additionally, nocturnal nuclear NeuroD1 levels are reduced after sympathetic disruption, an effect mimicked by the in vivo administration of α- and β-adrenoceptor blockers. NeuroD1 phosphorylation at two sites, Ser(274) and Ser(336) , associates with nuclear localization in pinealocytes. These data suggest that NeuroD1 influences pineal phenotype both during development and adulthood, in an autonomic and phosphorylation-dependent manner.
Laboratory of Neurobiology: Chronobiology Section, Institute of Histology and Embryology of Mendoza (IHEM-CONICET), School of Medicine, National University of Cuyo, Mendoza, Argentina.
Analía E
AE
Castro
Sergio G
SG
Benitez
Luz E
LE
Farias Altamirano
Luis E
LE
Savastano
Sean I
SI
Patterson
Estela M
EM
Muñoz
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism*; D015153:Blotting, Western; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008297:Male; D010870:Pineal Gland / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D011224:Prazosin / Q000494:pharmacology; D011247:Pregnancy; D011433:Propranolol / Q000494:pharmacology; D021381:Protein Transport; D051381:Rats
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D051792:Basic Helix-Loop-Helix Proteins; D011224:Prazosin; D011433:Propranolol; C490555:Neurod1 protein, rat
NeuroD1; nuclear-cytoplasmic partitioning; phosphorylation; pineal gland; post-translational modifications; serine residues