title: Posttranslational nitrotyrosination of alpha-tubulin induces cell cycle arrest and inhibits proliferation of vascular smooth muscle cells.
abstract: Hyperproliferation of vascular smooth muscle cells is a hallmark of atherosclerosis and related vascular complications. Microtubules are important for many aspects of mammalian cell responses including growth, migration and signaling. alpha-Tubulin, a component of the microtubule cytoskeleton, is unique amongst cellular proteins in that it undergoes a reversible posttranslational modification whereby the C-terminal tyrosine residue is removed (Glu-tubulin) and re-added (Tyr-tubulin). Whereas the reversible detyrosination/tyrosination cycle of alpha-tubulin has been implicated in regulating various aspects of cell biology, the precise function of this posttranslational modification has remained poorly characterized. Herein, we provide evidence suggesting that alpha-tubulin detyrosination is a required event in the proliferation of vascular smooth muscle cells. Proliferation of rat aortic smooth muscle cells in response to serum was temporally associated with the detyrosination of alpha-tubulin, but not acetylation of alpha-tubulin; Glu-tubulin reached maximal levels between 12 and 18h following cell cycle initiation. Inclusion of 3-nitro-l-tyrosine (NO(2)Tyr) in the culture medium resulted in the selective nitrotyrosination of alpha-tubulin, that was paralleled by decreased elaboration of Glu-tubulin, decreased expression of cyclins A and E, decreased association of the microtubule plus-end binding protein EB1, and inhibited cell proliferation. Nitrotyrosination of alpha-tubulin did not induce necrotic or apoptotic death of rat aortic smooth muscle cells, but instead led to cell cycle arrest at the G(1)/S boundary coincident with decreased DNA synthesis. Collectively, these results suggest that the C-terminus of alpha-tubulin and its detyrosination are functionally important as a molecular switch that regulates cell cycle progression in vascular smooth muscle cells.
authors.affiliation: Department of Internal Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Anh D
authors.initials: AD
authors.lastname: Phung
authors.forename: Karel
authors.initials: K
authors.lastname: Soucek
authors.forename: Lukás
authors.initials: L
authors.lastname: Kubala
authors.forename: Richart W
authors.initials: RW
authors.lastname: Harper
authors.forename: J
authors.initials: J
authors.lastname: Chloë Bulinski
authors.forename: Jason P
authors.initials: JP
authors.lastname: Eiserich
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000378:metabolism; D008870:Microtubules / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D051381:Rats; D014404:Tubulin / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D014404:Tubulin; C002744:3-nitrotyrosine; D018698:Glutamic Acid; D014443:Tyrosine