Renal proteomic analysis of RGC-32 knockout mice reveals the potential mechanism of RGC-32 in regulating cell cycle.

This study aimed to investigate the exact function of RGC-32 in kidney diseases and explore the potential mechanism of RGC-32 in regulating cell cycle. RGC-32 knockout (RGC-32-/-) mice were generated from C57BL/6 embryonic stem cells. Differentially expressed proteins in the kidney were investigated with the isobaric tags for relative and absolute quantification (iTRAQ) technique. Gene ontology analyses (GO), Kyoto encyclopedia of genes and genomes (KEGG) pathway mapping analysis and functional network analysis were also performed. The expressions of Smc3, Smad 2-3, DNA-PK were further confirmed by qPCR. Results showed that 4690 proteins were quantified on the basis of 25165 unique peptides. Comparative proteomic analysis revealed 361 differentially expressed proteins in RGC-32-/- mice (knockout/wild ratio >+/- 1.2 and P<0.05). GO and KEGG pathway mapping analyses showed differentially expressed proteins were involved in spliceosome, fluid shear stress and atherosclerosis protein processing in endoplasmic reticulum, pathways in cancer, viral carcinogenesis, epithelial cell signaling in Helicobacter pylori infection, HTLV-I infection, PI3K-Akt signaling pathway, ubiquitin mediated proteolysis, Parkinson's disease, MAPK signaling pathway, carbon metabolism, Alzheimer's disease, NOD-like receptor signaling pathway, tight junction, Proteoglycans in cancer, phagosome, ribosome, mTOR signaling pathway, and AMPK signaling pathway. Differentially expressed proteins Smc3 (0.821), DNA-PK (0.761), Smad 2-3 (0.631) were involved in cell cycle regulation. mRNA expression of Smad2-3, DNA-PK, and Smc3 was consistent with that from iTRAQ. It is concluded that RGC-32 may affect the expression of many proteins (76 up-regulated and 285 down-regulated) in the kidney, and may regulate the expression of Smc3, DNA-PK and Smad 2-3 to affect the cell cycle.