Taguchi Katsutoshi, Kumanogoh Haruko, Nakamura Shun, Miyata Seiji, Maekawa Shohei
Division of Bioinformation, Department of Biosystems Science, Graduate School of Science and Technology, Kobe-University, Rokkodai-cho 1-1, Nada-ku, Kobe 657-8501, Japan.
J Mol Histol. 2007 Mar;38(1):79-85. doi: 10.1007/s10735-007-9080-y. Epub 2007 Feb 21.
Pituitary gland is a well-known endocrine tissue. The hypothalamo-neurohypophysial system, containing arginine vasopressin and oxytocin, shows a reversible morphological reorganization of both neurons and glial cells during chronic physiological stimulations. Since many signal transducing and cell adhesion molecules (CAMs) are recovered in membrane microdomain (MD) fractions, MDs are considered as signaling platforms of cells. In order to know the molecular background for these endocrine systems, we characterized MD-components derived from rat pituitary and found specific enrichment of several proteins in the fraction. One of them was identified as myelin protein zero (P0) with mass analysis and this result was further confirmed by a result that a specific antibody to this protein reacted to the authentic P0 protein in the myelin fraction of rat sciatic nerve. P0 is one of type-I transmembrane CAMs and a major structural component of mammalian peripheral nerve myelin. In mammals, expression of P0 has been considered to be restricted to peripheral nervous system. This result however indicates that P0 expresses more widely and its enrichment in the MD-fraction from rat pituitary suggests the participation in cell-cell communications.
垂体是一种著名的内分泌组织。下丘脑 - 神经垂体系统含有精氨酸加压素和催产素，在慢性生理刺激过程中，该系统的神经元和神经胶质细胞均会出现可逆的形态重组。由于许多信号转导分子和细胞黏附分子（CAMs）在膜微区（MD）组分中被发现，因此MD被认为是细胞的信号平台。为了了解这些内分泌系统的分子背景，我们对源自大鼠垂体的MD成分进行了表征，并在该组分中发现了几种蛋白质的特异性富集。其中一种通过质谱分析被鉴定为髓鞘蛋白零（P0），并且大鼠坐骨神经髓鞘组分中针对该蛋白的特异性抗体与真实的P0蛋白发生反应这一结果进一步证实了该结论。P0是I型跨膜CAMs之一，也是哺乳动物外周神经髓鞘的主要结构成分。在哺乳动物中，P0的表达一直被认为局限于外周神经系统。然而，这一结果表明P0的表达更为广泛，并且其在大鼠垂体MD组分中的富集表明它参与了细胞间通讯。
