Renal repair and regeneration: Study of a candidate gene HCaRG

Abstract

Introduction An important process in renal regeneration after injury is the conversion of tubular cells to a migratory phenotype; surviving cells migrate to denuded areas, proliferate and differentiate in order to restore nephron structure and function. Beside its effect on renal cell proliferation and differentiation, our previous studies support a role for HCaRG (hypertension-related calcium-regulated gene) in the motile behavior increment of kidney cells. Results To better understand the evolvement of HCaRG in this phenomenon, we used the Yeast 2–hybrid technique to screen human kidney proteins that interact with HCaRG. Screening using HCaRG as bait revealed its interaction with β-actin, Na+/K+ATPase and NKCC. This direct protein interaction was confirmed by several techniques, and their co-localization at the leading edge of migrating cells was found by immunocytochemistry. This stimulatory effect of HCaRG on migration could be due to actin reorganisation coupled to ions transport activation. We produced two stable kidney cell lines (HEK293 and MDCK-C7) overexpressing HCaRG to help us identify its function. We used oligonucleotide microarray analysis to determine changes in gene expression between HCaRG over expressing cells and their controls. Microarray results for selected genes were confirmed by quantitative RT-PCR. HCaRG affects the expression of several genes implicated in cell motility. Conclusion A better comprehension of the mechanisms and molecular pathways involved in the functions of HCaRG will enable us to conceive better means of stimulating the regeneration of renal function after a lesion. Supported by CIHR.