title: CLN3 deficient cells display defects in the ARF1-Cdc42 pathway and actin-dependent events.
abstract: Juvenile Batten disease (juvenile neuronal ceroid lipofuscinosis, JNCL) is a devastating neurodegenerative disease caused by mutations in CLN3, a protein of undefined function. Cell lines derived from patients or mice with CLN3 deficiency have impairments in actin-regulated processes such as endocytosis, autophagy, vesicular trafficking, and cell migration. Here we demonstrate the small GTPase Cdc42 is misregulated in the absence of CLN3, and thus may be a common link to multiple cellular defects. We discover that active Cdc42 (Cdc42-GTP) is elevated in endothelial cells from CLN3 deficient mouse brain, and correlates with enhanced PAK-1 phosphorylation, LIMK membrane recruitment, and altered actin-driven events. We also demonstrate dramatically reduced plasma membrane recruitment of the Cdc42 GTPase activating protein, ARHGAP21. In line with this, GTP-loaded ARF1, an effector of ARHGAP21 recruitment, is depressed. Together these data implicate misregulated ARF1-Cdc42 signaling as a central defect in JNCL cells, which in-turn impairs various cell functions. Furthermore our findings support concerted action of ARF1, ARHGAP21, and Cdc42 to regulate fluid phase endocytosis in mammalian cells. The ARF1-Cdc42 pathway presents a promising new avenue for JNCL therapeutic development.
authors.affiliation: Program of Molecular and Cellular Biology, University of Iowa, Iowa City, Iowa, United States of America; Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Schultz
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Luis
authors.initials: L
authors.lastname: Tecedor
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Colleen S
authors.initials: CS
authors.lastname: Stein
authors.affiliation: Department of Molecular Physiology and Biophysics, Iowa City, Iowa, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Stamnes
authors.affiliation: Program of Molecular and Cellular Biology, University of Iowa, Iowa City, Iowa, United States of America; Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America; Department of Molecular Physiology and Biophysics, Iowa City, Iowa, United States of America; Department of Neurology, Iowa City, Iowa, United States of America.
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Davidson
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement; D002478:Cells, Cultured; D004705:Endocytosis; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D017353:Gene Deletion; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; C102229:CLN3 protein, mouse; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D020823:ADP-Ribosylation Factor 1; D020764:cdc42 GTP-Binding Protein