title: Mechanistic insight into the microtubule and actin cytoskeleton coupling through dynein-dependent RhoGEF inhibition.
abstract: Actin-based stress fiber formation is coupled to microtubule depolymerization through the local activation of RhoA. While the RhoGEF Lfc has been implicated in this cytoskeleton coupling process, it has remained elusive how Lfc is recruited to microtubules and how microtubule recruitment moderates Lfc activity. Here, we demonstrate that the dynein light chain protein Tctex-1 is required for localization of Lfc to microtubules. Lfc residues 139-161 interact with Tctex-1 at a site distinct from the cleft that binds dynein intermediate chain. An NMR-based GEF assay revealed that interaction with Tctex-1 represses Lfc nucleotide exchange activity in an indirect manner that requires both polymerized microtubules and phosphorylation of S885 by PKA. We show that inhibition of Lfc by Tctex-1 is dynein dependent. These studies demonstrate a pivotal role of Tctex-1 as a negative regulator of actin filament organization through its control of Lfc in the crosstalk between microtubule and actin cytoskeletons.
authors.affiliation: Ontario Cancer Institute and the Campbell Family Cancer Research Institute, 101 College Street, Room 8-703 Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Meiri
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Marshall
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Greeve
authors.forename: Bryan
authors.initials: B
authors.lastname: Kim
authors.forename: Marc
authors.initials: M
authors.lastname: Balan
authors.forename: Fernando
authors.initials: F
authors.lastname: Suarez
authors.forename: Chris
authors.initials: C
authors.lastname: Bakal
authors.forename: Chuanjin
authors.initials: C
authors.lastname: Wu
authors.forename: Jose
authors.initials: J
authors.lastname: Larose
authors.forename: Noah
authors.initials: N
authors.lastname: Fine
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Ikura
authors.forename: Robert
authors.initials: R
authors.lastname: Rottapel
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D004398:Dyneins / Q000378:metabolism* / Q000502:physiology; D004622:Embryo, Mammalian / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008870:Microtubules / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D064067:Rho Guanine Nucleotide Exchange Factors
chemical_list: C577402:Arhgef2 protein, mouse; C533386:Dynlt1b protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D011518:Proto-Oncogene Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D017868:Cyclic AMP-Dependent Protein Kinases; D004398:Dyneins