title: Alpha1B-adrenoceptor signaling and cell motility: GTPase function of Gh/transglutaminase 2 inhibits cell migration through interaction with cytoplasmic tail of integrin alpha subunits.
abstract: A multifunctional enzyme, G(h), is a GTP-binding protein that couples to the alpha(1B)-adrenoreceptor and stimulates phospholipase C-delta1 but also displays transglutaminase 2 (TG2) activity. G(h)/TG2 has been implicated to play a role in cell motility. In this study we have examined which function of G(h)/TG2 is involved in this cellular response and the molecular basis. Treatment of human aortic smooth muscle cell with epinephrine inhibits migration to fibronectin and vitronectin, and the inhibition is blocked by the alpha(1)-adrenoreceptor antagonist prazosin or chloroethylclonidine. Up-regulation or overexpression of G(h)/TG2 in human aortic smooth muscle cells, DDT1-MF2, or human embryonic kidney cells, HEK 293 cells, results in inhibition of the migratory activity, and stimulation of the alpha(1B)-adrenoreceptor with the alpha(1) agonist further augments the inhibition of migration of human aortic smooth muscle cells and DDT1-MF2. G(h)/TG2 is coimmunoprecipitated by an integrin alpha(5) antibody and binds to the cytoplasmic tail peptide of integrins alpha(5), alpha(v), and alpha(IIb) subunits in the presence of guanosine 5'-3-O-(thio)triphosphate (GTPgammaS). Mutation of Lys-Arg residues in the GFFKR motif, present in the alpha(5)-tail, significantly reduces the binding of GTPgammaS-G(h)/TG2. Moreover, the motif-containing integrin alpha(5)-tail peptides block G(h)/TG2 coimmunoprecipitation and reverse the inhibition of the migratory activity of HEK 293 cells caused by overexpression G(h)/TG2. These results provide evidence that G(h) function initiates the modulation of cell motility via association of GTP-bound G(h)/TG2 with the GFFKR motif located in integrin alpha subunits.
authors.affiliation: Oriental Herbal Research Institute, Dongkuk University, Seoul 156-756, Republic of Korea.
authors.forename: Sung Koo
authors.initials: SK
authors.lastname: Kang
authors.forename: Kye Sook
authors.initials: KS
authors.lastname: Yi
authors.forename: Nyoun Soo
authors.initials: NS
authors.lastname: Kwon
authors.forename: Kwang-Hyun
authors.initials: KH
authors.lastname: Park
authors.forename: Uh-Hyun
authors.initials: UH
authors.lastname: Kim
authors.forename: Kwang Jin
authors.initials: KJ
authors.lastname: Baek
authors.forename: Mie-Jae
authors.initials: MJ
authors.lastname: Im
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001011:Aorta / Q000378:metabolism; D001665:Binding Sites; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D039081:Integrin alpha5beta1 / Q000378:metabolism; D016023:Integrins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism; D009154:Mutation; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D012685:Sepharose / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D015854:Up-Regulation; D019096:Vitronectin / Q000378:metabolism
chemical_list: C547716:ADRA1B protein, human; D003902:Detergents; D005353:Fibronectins; D039081:Integrin alpha5beta1; D016023:Integrins; D018340:Receptors, Adrenergic, alpha-1; D019096:Vitronectin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D017830:Octoxynol; D012685:Sepharose; D020558:GTP Phosphohydrolases; D004837:Epinephrine