Reference genes for mesangial cell and podocyte qPCR gene expression studies under high-glucose and renin-angiotensin-system blocker conditions

Abstract

BackgroundReal-time PCR remains currently the gold standard method for gene expression studies. Identification of the best reference gene is a key point in performing high quality qPCR, providing strong support for results, as well as performing as a source of bias when inappropriately chosen. Mesangial cells and podocytes, as essential cell lines to study diabetic kidney disease (DKD) physiopathology, demand accurate analysis of the reference genes used so far to enhance validity of gene expression studies, especially regarding high glucose (HG) and DKD treatments, with angiotensin II receptor blockers (e.g. Losartan) being the most commonly used. This study aimed to evaluate the suitability and define the most stable reference gene for mesangial cells and podocytes studies of an in vitro DKD model of disease and its treatment. MethodsFive software packages (RefFinder, NormFinder, GeNorm, Bestkeeper, and DataAssist) and the comparative {Delta}Ct method were selected to analyze six different candidate genes: HPRT, ACTB, PGAM-1, GAPDH, PPIA, and B2M. RNA was extracted and cDNA was synthesized from immortalized mouse mesangial cells and podocytes cultured in 4 groups: control (n=5; 5mM glucose), mannitol (n=5; 30mM, as osmotic control), HG (n=5; 30mM glucose), and HG + losartan (n=5; 30mM glucose and 10-4 mM of losartan). Real-time PCR was performed according to MIQE guidelines. ResultsWe identified that the use of 2 genes is the best combination for qPCR normalization for both mesangial cell and podocytes. For mesangial cells, the combination of HPRT and ACTB presented higher stability values. For podocytes, HPRT and GAPDH showed the best results. ConclusionThis analysis provides support for the use of HPRT and ACTB as reference genes in mouse mesangial cell studies of gene expression via real-time PCR technique, while for podocytes, HPRT and GAPDH should be chosen.