Grumolato Luca, Ghzili Hafida, Montero-Hadjadje Maité, Gasman Stéphane, Lesage Jean, Tanguy Yannick, Galas Ludovic, Ait-Ali Djida, Leprince Jérôme, Guérineau Nathalie C, Elkahloun Abdel G, Fournier Alain, Vieau Didier, Vaudry Hubert, Anouar Youssef
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen 76821 Mont-St.-Aignan, France.
FASEB J. 2008 Jun;22(6):1756-68. doi: 10.1096/fj.06-075820. Epub 2008 Jan 15.
Selenoproteins contain the essential trace element selenium, the deficiency of which is associated with cancer or accelerated aging. Although selenoproteins are thought to be instrumental for the effects of selenium, the biological function of many of these proteins remains unknown. Here, we studied the role of selenoprotein T (SelT), a selenocysteine (Sec) -containing protein with no known function, which we have identified as a novel target gene of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) during PC12 cell differentiation. SelT was found to be ubiquitously expressed throughout embryonic development and in adulthood in rat. Immunocytochemical analysis revealed that SelT is mainly localized to the endoplasmic reticulum through a hydrophobic domain. PACAP and cAMP induced a rapid and long-lasting increase in SelT gene expression in PC12 cells, in a Ca(2+)-dependent manner. These results suggested a possible role of SelT in PACAP signaling during PC12 cell differentiation. Indeed, overexpression of SelT in PC12 cells provoked an increase in the concentration of intracellular Ca(2+) (Ca(2+)) that was dependent on the Sec residue. Conversely, SelT gene knockdown inhibited the PACAP-induced increase in Ca(2+) and reduced hormone secretion. These findings demonstrate the implication of a selenoprotein in the regulation of Ca(2+) homeostasis and neuroendocrine secretion in response to a cAMP-stimulating trophic factor.
硒蛋白含有必需的微量元素硒，硒的缺乏与癌症或加速衰老有关。尽管硒蛋白被认为对硒的作用至关重要，但其中许多蛋白质的生物学功能仍不清楚。在这里，我们研究了硒蛋白T（SelT）的作用，它是一种含硒代半胱氨酸（Sec）的蛋白质，功能未知，我们已将其鉴定为PC12细胞分化过程中神经肽垂体腺苷酸环化酶激活多肽（PACAP）的一个新靶基因。我们发现SelT在大鼠胚胎发育全过程及成年期均广泛表达。免疫细胞化学分析显示，SelT通过一个疏水结构域主要定位于内质网。PACAP和cAMP以Ca(2+)依赖的方式诱导PC12细胞中SelT基因表达快速且持久地增加。这些结果提示SelT在PC12细胞分化过程中的PACAP信号传导中可能发挥作用。事实上，PC12细胞中SelT的过表达导致细胞内Ca(2+)（Ca(2+)）浓度升高，这依赖于Sec残基。相反，SelT基因敲低抑制了PACAP诱导的Ca(2+)升高并减少了激素分泌。这些发现证明了一种硒蛋白在响应cAMP刺激的营养因子时对Ca(2+)稳态和神经内分泌分泌调节中的作用。
