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Inactivation of lmpA, Encoding a LIMPII-related Endosomal Protein, Suppresses the Internalization and Endosomal Trafficking Defects in Profilin-null Mutants
Molecular Biology of the Cell
  • Lesly A. Temesvari, Louisiana State University Health Sciences Center - Shreveport
  • Linyi Zhang, Louisiana State University at Shreveport
  • Brent Fodera, Louisiana State University at Shreveport
  • Klaus-Peter Janssen, A.-Butenandt-Institut fuer Zellbiologie, Ludwig-Maximilians-Universtaet
  • Michael Schleicher, A.-Butenandt-Institut fuer Zellbiologie, Ludwig-Maximilians-Universtaet
  • James A. Caradelli, Louisiana State University at Shreveport
Document Type
Article
Publication Date
6-1-2000
Publisher
American Society for Cell Biology
Disciplines
Abstract

Profilin is a key phosphoinositide and actin-binding protein connecting and coordinating changes in signal transduction pathways with alterations in the actin cytoskeleton. Using biochemical assays and microscopic approaches, we demonstrate that profilin-null cells are defective in macropinocytosis, fluid phase efflux, and secretion of lysosomal enzymes but are unexpectedly more efficient in phagocytosis than wild-type cells. Disruption of the lmpA gene encoding a protein (DdLIMP) belonging to the CD36/LIMPII family suppressed, to different degrees, most of the profilin-minus defects, including the increase in F-actin, but did not rescue the secretion defect. Immunofluorescence microscopy indicated that DdLIMP, which is also capable of binding phosphoinositides, was associated with macropinosomes but was not detected in the plasma membrane. Also, inactivation of the lmpA gene in wild-type strains resulted in defects in macropinocytosis and fluid phase efflux but not in phagocytosis. These results suggest an important role for profilin in regulating the internalization of fluid and particles and the movement of material along the endosomal pathway; they also demonstrate a functional interaction between profilin and DdLIMP that may connect phosphoinositide-based signaling through the actin cytoskeleton with endolysosomal membrane trafficking events.

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This article has been published in the journal Molecular Biology of the Cell. Please find the published version here (note that a subscription is necessary to access this version):

http://www.molbiolcell.org/content/11/6/2019.full

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Please use publisher's recommended citation: http://www.molbiolcell.org/content/11/6/2019.full