title: Identification of microtubule growth deceleration and its regulation by conserved and novel proteins.
abstract: Microtubules (MTs) are cytoskeletal polymers that participate in diverse cellular functions, including cell division, intracellular trafficking, and templating of cilia and flagella. MTs undergo dynamic instability, alternating between growth and shortening via catastrophe and rescue events. The rates and frequencies of MT dynamic parameters appear to be characteristic for a given cell type. We recently reported that all MT dynamic parameters vary throughout differentiation of a smooth muscle cell type in intact Caenorhabditis elegans. Here we describe local differences in MT dynamics and a novel MT behavior: an abrupt change in growth rate (deceleration) of single MTs occurring in the cell periphery of these cells. MT deceleration occurs where there is a decrease in local soluble tubulin concentration at the cell periphery. This local regulation of tubulin concentration and MT deceleration are dependent on two novel homologues of human cylicin. These novel ORFs, which we name cylc-1 and -2, share sequence homology with stathmins and encode small, very basic proteins containing several KKD/E repeats. The TOG domain-containing protein ZYG-9(TOGp) is responsible for the faster polymerization rate within the cell body. Thus we have defined two contributors to the molecular regulation for this novel MT behavior.
authors.affiliation: Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France asm@unc.edu benjamin.lacroix@ijm.fr.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lacroix
authors.affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3C 3J7, Canada.
authors.forename: Joël
authors.initials: J
authors.lastname: Ryan
authors.affiliation: Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Dumont
authors.affiliation: Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Maddox
authors.affiliation: Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France asm@unc.edu benjamin.lacroix@ijm.fr.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Maddox
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002923:Cilia / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D003654:Deceleration; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D008958:Models, Molecular; D058105:Polymerization; D050777:Stathmin; D014404:Tubulin / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D050777:Stathmin; D014404:Tubulin