LaPlante JM, Falardeau JL, Brown EM, Slaugenhaupt SA, Vassilev PM. The cation channel mucolipin-1 is a bifunctional protein that facilitates membrane remodeling via its serine lipase domain.
Exp Cell Res 2011;
317:691-705. [PMID:
21256127 PMCID:
PMC3103141 DOI:
10.1016/j.yexcr.2011.01.008]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 12/03/2010] [Accepted: 01/05/2011] [Indexed: 11/19/2022]
Abstract
Phospholipase modulators have been shown to affect the topology of lipid bilayers and the formation of tubulo-vesicular structures, but the specific endogenous phospholipases involved have yet to be identified. Here we show that TRPML1 (MLN1), a Ca(2+)-permeable channel, contributes to membrane remodeling through a serine lipase consensus domain, and thus represents a novel type of bifunctional protein. Remarkably, this serine lipase active site determines the ability of MLN1 to generate tubulo-vesicular extensions in mucolipin-1-expressing oocytes, human fibroblasts and model membrane vesicles. Our demonstration that MLN1 is involved in membrane remodeling and the formation of extensions suggests that it may play a role in the formation of cellular processes linked to the late endosome/lysosome (LE/L) pathway. MLN1 is absent or mutated in patients with mucolipidosis IV (MLIV), a lysosomal disorder with devastating neurological and other consequences. This study provides potential insight into the pathophysiology of MLIV.
Collapse