Synaptophysin: a marker protein for neuroendocrine cells and neoplasms.

TLDR

Synaptophysin is a 38 kDa integral membrane glycoprotein found in presynaptic vesicles of neurons and the adrenal medulla. Immunohistochemical and immunoblotting studies with a monoclonal antibody (SY38) revealed that synaptophysin is expressed in a wide range of neuroendocrine tumors—including pheochromocytomas, paragangliomas, islet‑cell adenomas/carcinomas, carcinoids, gastrointestinal and bronchial neuroendocrine carcinomas, and medullary thyroid carcinomas—colocalizing with neurofilaments or cytokeratin/desmoplakin filaments, and the authors propose it as an independent differentiation marker for tumor diagnosis.

Abstract

Synaptophysin is an integral membrane glycoprotein (Mr 38,000) that occurs in presynaptic vesicles of neurons and in similar vesicles of the adrenal medulla. By using a monoclonal antibody to this protein (SY38), we have found, by immunohistochemistry and immunoblotting, that an identical or similar protein is also expressed in neuroendocrine tumors of neural type, such as pheochromocytomas and paragangliomas. In addition, this protein occurs in certain neuroendocrine epithelial cells, such as pancreatic islet cells; in a variety of neuroendocrine epithelial tumors, including isletcell adenomas and carcinomas and several carcinoids and neuroendocrine carcinomas of the gastrointestinal and the bronchial tracts; and in medullary carcinomas of the thyroid. Our results show that synaptophysin, and the vesicles that contain it, can occur in normal and neoplastic neuroendocrine cells of neural type, as demonstrated by colocalization with neurofilaments, as well as in those of epithelial type, as shown by colocalization with cytokeratin filaments and desmoplakins. We conclude that synaptophysin is expressed independently of other neuronal differentiation markers and propose that it be used as a differentiation marker in tumor diagnosis.