title: The lysophosphatidic acid 2 receptor mediates down-regulation of Siva-1 to promote cell survival.
abstract: Lysophosphatidic acid (LPA) promotes cell survival through the activation of G protein-coupled LPA receptors. However, whether different LPA receptors activate distinct anti-apoptotic signaling pathways is not yet clear. Here we report a novel mechanism by which the LPA(2) receptor targets the proapoptotic Siva-1 protein for LPA-dependent degradation, thereby attenuating Siva-1 function in DNA damage response. The carboxyl-terminal tail of the LPA(2) receptor, but not LPA(1) or LPA(3) receptor, specifically associates with the carboxyl cysteine-rich domain of Siva-1. Prolonged LPA stimulation promotes the association of Siva-1 with the LPA(2) receptor and targets both proteins for ubiquitination and degradation. As a result, adriamycin-induced Siva-1 protein stabilization is attenuated by LPA in an LPA(2)-dependent manner, and the function of Siva-1 in promoting DNA damage-induced apoptosis is inhibited by LPA pretreatment. Consistent with this result, inhibition of the LPA(2) receptor expression increases Siva-1 protein levels and augments adriamycin-induced caspase-3 cleavage and apoptosis. Together, these findings reveal a critical and specific role for the LPA(2) receptor through which LPA directly inactivates a critical component of the death machinery to promote cell survival.
authors.affiliation: Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. flin@uab.edu
authors.forename: Fang-Tsyr
authors.initials: FT
authors.lastname: Lin
authors.forename: Yun-Ju
authors.initials: YJ
authors.lastname: Lai
authors.forename: Natalia
authors.initials: N
authors.lastname: Makarova
authors.forename: Gabor
authors.initials: G
authors.lastname: Tigyi
authors.forename: Weei-Chin
authors.initials: WC
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3 / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000502:physiology*; D008246:Lysophospholipids / Q000737:chemistry; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D049368:Receptors, Lysophosphatidic Acid / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
chemical_list: D051017:Apoptosis Regulatory Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D049368:Receptors, Lysophosphatidic Acid; C106549:SIVA1 protein, human; D053148:Caspase 3; C032881:lysophosphatidic acid