Maspin Is an Intracellular Serpin That Partitions into Secretory Vesicles and Is Present at the Cell Surface

The tumor suppressor maspin (mammary serpin) was originally identified as a component of human mammary epithelial cells that is downregulated as mammary tumor cells progress from the benign to the invasive and metastatic states. Maspin inhibits cellular invasion, motility, and proliferation, but its...

Full description

Saved in:

Bibliographic Details
Published in:	The journal of histochemistry and cytochemistry Vol. 45; no. 12; pp. 1697 - 1706
Main Authors:	Pemberton, Philip A, Tipton, A. Rene, Pavloff, Nadine, Smith, Jason, Erickson, James R, Mouchabeck, Zahi M, Kiefer, Michael C
Format:	Journal Article
Language:	English
Published:	Los Angeles, CA Histochemical Soc 01-12-1997 SAGE Publications
Subjects:	Blotting, Northern Breast - metabolism Cells, Cultured Cytoplasm - metabolism Cytoplasmic Granules - metabolism DNA Primers - chemistry Epithelium - metabolism Female Genes, Tumor Suppressor Humans Immunohistochemistry Intestines - metabolism Male Membrane Proteins - metabolism Proteins - genetics Proteins - immunology Proteins - metabolism RNA, Messenger - metabolism Serpins - genetics Serpins - immunology Serpins - metabolism Subcellular Fractions - metabolism Tissue Distribution Tumor Cells, Cultured secretion maspin subcellular localization paracrine signaling tissue distribution
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	The tumor suppressor maspin (mammary serpin) was originally identified as a component of human mammary epithelial cells that is downregulated as mammary tumor cells progress from the benign to the invasive and metastatic states. Maspin inhibits cellular invasion, motility, and proliferation, but its mechanism of action is currently unknown. Because the cellular machinery responsible for these processes is cytoplasmic, we have reexamined the tissue distribution and subcellular localization of maspin. We find that maspin, or a maspin-like protein, is present in many human organs, in which it localizes to epithelia. In cultured human mammary myoepithelial cells, maspin is predominantly a soluble cytoplasmic protein that associates with secretory vesicles and is present at the cell surface. In vitro assays show that the vesicle association is due to the existence of an uncleaved facultative secretion signal that allows small amounts of maspin to partition into the endoplasmic reticulum. These results demonstrate that maspin is more widespread than previously believed. The subcellular localization studies indicate that soluble intracellular and vesicle-associated maspin probably play an important role in controlling the invasion, motility, and proliferation of cells expressing it, whereas extracellular maspin may also regulate these processes in adjacent cells.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0022-1554 1551-5044
DOI:	10.1177/002215549704501213