Moriyama Y, Hayashi M, Yamada H, Yatsushiro S, Ishio S, Yamamoto A
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
J Exp Biol. 2000 Jan;203(Pt 1):117-25. doi: 10.1242/jeb.203.1.117.
Microvesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H(+)-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate l-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use l-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion.
内分泌细胞中的微囊泡在形态和功能上等同于神经元突触囊泡。微囊泡通过由液泡H(+)-ATP酶提供能量的递质特异性囊泡转运体积累各种神经递质。我们发现，哺乳动物的松果体细胞（合成并分泌褪黑素的内分泌细胞）在其微囊泡中积累L-谷氨酸，并通过胞吐作用将其分泌。松果体细胞以受体介导的方式将L-谷氨酸用作旁分泌或自分泌样化学递质，从而抑制褪黑素的合成。在本文中，我们简要描述了松果体中微囊泡介导的信号转导机制的总体特征，并讨论了酸性细胞器在激素合成和分泌的新型调节机制中的重要作用。
