Regulation of microtubule assembly by betagamma subunits of G proteins
The βγ subunit of G proteins (Gβγ) is known to transfer signals from cell surface receptors to intracellular effector molecules. Recent results suggest Gβγ also interacts with microtubules and participate in cell division and differentiation. α and βγ subunits of G proteins have been shown to modulate microtubule assembly in vitro. While Gα inhibits microtubule assembly and increases microtubule dynamics by activating intrinsic GTPase of tubulin; Gβγ promotes microtubule assembly. The goal of the present research is to understand the possible relationship between Gβγ signaling and microtubule assembly in vivo. Using biochemical, pharmacological, and immunoconfocal methodologies, I have demonstrated the activation of G protein-coupled receptors (β-and α2-adrenergic receptors) stimulate microtubule assembly and promote the association of Gβγ with microtubules in NIH3T3 cells. Further studies by synchronizing NIH3T3 cells at S, G2 and M phases of cell cycle indicate the stimulation of microtubule assembly by agonist activation is cell cycle dependent. Stabilization of microtubules by the drug taxol promotes the association of Gβγ to polymerized tubulin. These results suggest extracellular signals coupled to G proteins modulate microtubule assembly by altering the associations between Gβγ and tubulin/microtubules. I propose that Gβγ-microtubule interaction is an important step for G protein-mediated cell activation. ^
Gutierrez, Christina, "Regulation of microtubule assembly by betagamma subunits of G proteins" (2006). ETD Collection for University of Texas, El Paso. AAI1436517.