iTRAQ-Based Proteomic Analysis of Neonatal Kidney from Offspring of Protein Restricted Rats Reveals Abnormalities in Intraflagellar Transport Proteins

Abstract

Background: It is well recognized that adverse events in utero can impair fetal development and lead to the development of kidney injury and hypertension in adulthood. We previously reported a lower kidney index, glomeruli number, and decreased glomerular filtration rate in intrauterine growth restriction (IUGR) offspring induced by maternal protein malnutrition. To explore the molecular mechanisms linking impaired fetal growth to renal diseases, we investigated differentially expressed proteins (DEPs) in the IUGR neonatal kidneys by isobaric tags for relative and absolute quantitation (iTRAQ) analysis. Methods: We induced IUGR through maternal protein malnutrition. Neonatal kidneys were collected; the protein was extracted; pooled before iTRAQ labeling, and subjected to mass spectrometric analysis. Mass spectrometry results were then further confirmed by assessing five representative proteins in individual specimens with quantitative PCR (qPCR), immunohistochemical (IHC) and / or western blot analysis. Results: A total of 367DEPs (263 up-regulated, 104 down-regulated.) with a threshold of a 1.2-fold change and a P value ≤ 0.05 between IUGR kidneys and control kidneys were identified. Further bioinformatics analysis revealed that these proteins play important roles in oxidative phosphorylation, purine metabolism, pyrimidine metabolism, RNA small body, spliceosome assembly and intraflagellar transport (IFT). IFT family proteins (IFT80, 88,144) and PKD2 were shown to be up-regulated in IUGR kidneys, confirmed by western blotting, IHC and Q-PCR. Epigenetic modulating factors SET and MYND domain containing 3 (SMYD3), a histone-lysine N-methyltransferase, and H3K4me3 level were also remarkably enhanced in IUGR neonatal kidneys. Conclusions: This first comprehensive analysis of the neonatal kidney proteome reveals new insights in nephridial development, and may make a valuable contribution towards the identification of the pathological mechanisms involved in the developmental origins of adult disease.