Structural and functional characterization of the interaction between the chaperone alphaB-crystallin and the tyrosine-phosphatase Shp2

Author(s)

Danieli Cristina Gonçalves

• Document type: Doctoral Thesis
• Institution: Universidade Estadual de Campinas, Instituto de Biologia
• Defense date: 2016
• Advisor: Kleber Gomes Franchini

Abstract

The study of cell signaling circuits activated during pathophysiological stimuli is an important challenge in cardiac hypertrophy and failure pathogenesis research. Previous studies from our group have investigated the role of proteins such as Shp2 (SH2 domain-containing tyrosine phosphatase 2), a tyrosine phosphatase critical in cardiac myocytes hypertrophic signaling, and CryAB (?B-Crystallin), a molecular chaperone highly expressed in heart, which interacts with and protects FAK (Focal Adhesion Kinase) from degradation, promoting cell survival. Here we show that CryAB interacts with and regulates the tyrosine-phosphatase Shp2 catalytic activity in stretched cardiomyocytes. We used a combination of pull-down, immunoprecipitation, FRET-FLIM and chemical cross-linking coupled to mass spectrometry to show that CryAB and Shp2 directly bind in vitro and in living cells. Docking and molecular modeling showed that the PTP and NSH2 domains of Shp2 bind ACD (alpha-crystallin domain) of oligomeric CryAB, which holds Shp2 in closed and inhibited conformation. Protein tyrosine-phosphatase assays showed that the binding of CryAB oligomer, but not the dimer, is important for Shp2 stability and function, and in addition, it attenuates Shp2 activity in a dose dependent mode. Stretched Neonate Rat Ventricular Myocytes (NRVMs) show a robust CryAB/Shp2 association and reduced Shp2 phosphatase activity. In addition, NRVMs subjected to CryAB knockdown followed by mechanical stress exhibited enhanced activity of Shp2. These results indicates that CryAB might act as a modulator of Shp2 phosphatase activity in cardiomyocytes under mechanical stress (AU)

• FAPESP's process: 13/05877-8 - Structural and functional characterization of the interaction between alphaB-Crystallin and Shp2 tyrosine-phosphatase protein.
• Grantee: Danieli Cristina Gonçalves
• Support type: Scholarships in Brazil - Doctorate