RGD Reference Report - Polymerase-δ-interacting protein 2 activates the RhoGEF epithelial cell transforming sequence 2 in vascular smooth muscle cells. - Rat Genome Database

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Polymerase-δ-interacting protein 2 activates the RhoGEF epithelial cell transforming sequence 2 in vascular smooth muscle cells.

Authors: Huff, Lauren Parker  Kikuchi, Daniel Seicho  Faidley, Elizabeth  Forrester, Steven J  Tsai, Michelle Z  Lassègue, Bernard  Griendling, Kathy K 
Citation: Huff LP, etal., Am J Physiol Cell Physiol. 2019 May 1;316(5):C621-C631. doi: 10.1152/ajpcell.00208.2018. Epub 2019 Feb 6.
RGD ID: 124713559
Pubmed: (View Article at PubMed) PMID:30726115
DOI: Full-text: DOI:10.1152/ajpcell.00208.2018

Polymerase-δ-interacting protein 2 (Poldip2) controls a wide variety of cellular functions and vascular pathologies. To mediate these effects, Poldip2 interacts with numerous proteins and generates reactive oxygen species via the enzyme NADPH oxidase 4 (Nox4). We have previously shown that Poldip2 can activate the Rho family GTPase RhoA, another signaling node within the cell. In this study, we aimed to better understand how Poldip2 activates Rho family GTPases and the functions of the involved proteins in vascular smooth muscle cells (VSMCs). RhoA is activated by guanine nucleotide exchange factors. Using nucleotide-free RhoA (isolated from bacteria) to pulldown active RhoGEFs, we found that the RhoGEF epithelial cell transforming sequence 2 (Ect2) is activated by Poldip2. Ect2 is a critical RhoGEF for Poldip2-mediated RhoA activation, because siRNA against Ect2 prevented Poldip2-mediated RhoA activity (measured by rhotekin pulldowns). Surprisingly, we were unable to detect a direct interaction between Poldip2 and Ect2, as they did not coimmunoprecipitate. Nox4 is not required for Poldip2-driven Ect2 activation, as Poldip2 overexpression induced Ect2 activation in Nox4 knockout VSMCs similar to wild-type cells. However, antioxidant treatment blocked Poldip2-induced Ect2 activation. This indicates a novel reactive oxygen species-driven mechanism by which Poldip2 regulates Rho family GTPases. Finally, we examined the function of these proteins in VSMCs, using siRNA against Poldip2 or Ect2 and determined that Poldip2 and Ect2 are both essential for vascular smooth muscle cell cytokinesis and proliferation.

Annotation

Gene Ontology Annotations    

Biological Process

Objects Annotated

Genes (Rattus norvegicus)
Poldip2  (DNA polymerase delta interacting protein 2)

Objects referenced in this article
Gene Ceacam1 CEA cell adhesion molecule 1 Rattus norvegicus

Additional Information