RhoA, JNK and p38MAPK participates in apoptosis mediated by Ang II AT2 receptors

MANZUR M JIMENA; KOTLER MONICA L; CIUFFO GLADYS M

Puerto Madryn

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

<!-- /* Font Definitions */@font-face{font-family:Corbel;panose-1:2 11 5 3 2 2 4 2 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-1610611985 1073783883 0 0 415 0;} /* Style Definitions */p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:12.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman";mso-ansi-language:ES;mso-fareast-language:ES;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-size:10.0pt;mso-ansi-font-size:10.0pt;mso-bidi-font-size:10.0pt;}@page WordSection1{size:612.0pt 792.0pt;margin:72.0pt 90.0pt 72.0pt 90.0pt;mso-header-margin:36.0pt;mso-footer-margin:36.0pt;mso-paper-source:0;}div.WordSection1{page:WordSection1;}-->Ang II AT2receptors are abundantly expressed in fetal tissues, suggesting a role of thesereceptors in growth and organogenesis. In the present study we report apossible signaling pathway of apoptosis induced via AT2 receptor activation,as a primary mechanism of tissue differentiation. As a model system we usedHela cells overexpressing Ang II AT2 receptors and studied the apoptotic mechanism.Following stimulation with Ang II (10-7M), we evaluated apoptosis by means of differentmethods. By immunofluorescence staining and confocal microscopy, we observedapoptotic cells after 30 min stimulation. Similarly, JNK phosphorylation andactivation appeared after 30 min of Ang II treatment. We evaluated activationof caspases 8 and 3. Cleavage of both caspases increased in a time dependentmanner beginning after 30 min stimulation. In order to study RhoA participationin apoptosis induction, we performed co-transfection assays with a constitutivelyactive RhoA mutant, the negative and wild-type RhoA. These experiments suggest theparticipation of RhoA GTPase, since apoptosis features appeared earlier incells expressing both, AT2 and V14RhoA, than in those expressing only AT2receptors. We also studied p38 MAPKparticipation in the signaling pathway activated by AT2 and find that inhibition of this protein elicits theapoptotic process. Apoptosis was confirmed by caspase 3 enzyme activationexperiments. In summary, the present results suggest the participation of RhoA,JNK and p38MAPK in the signaling pathway mediating apoptosis induced by Ang IIAT2receptors.