MO426: Elucidation of Mechanism of Low-Birth-Weight-Related Fsgs in Rats by Rna-Seq Analysis of Cultured Podocytes From Low-Birth-Weight Rats

Abstract

Abstract BACKGROUND AND AIMS The pathogenesis of low-birth-weight (LBW)-related nephropathy has been considered to be the result of intra-glomerular hyperfiltration during growth due to the presence of low nephron numbers. On the other hand, we hypothesized that there may be pathogenic factor(s) other than low nephron number in LBW individuals [1]. We reported the results of proteomic analysis of the renal cortex of LBW rats to show that metabolic abnormalities should exist in the kidneys of LBW individuals [2]. However, our result of the previous study was obtained by analysis using the renal cortex, which did not allow us to interpret the mechanism of focal segmental glomerulosclerosis (FSGS) formation, the most typical pathological picture of LBW-related nephropathy. METHOD A total of 5 LBW rats (birth weight 4.38±0.08) were obtained by 55% caloric restriction to pregnant maternal rats. The normal-birth-weight (NBW) rats (birth weight 6.48±0.18) were obtained by feeding normal diets to pregnant maternal rats. Kidneys were removed at 4 weeks of age, and after isolation of the glomeruli by sieving of kidneys, primary culture of glomerular epithelial cells (podocytes) was performed. Then, mRNAs were extracted from the cultured podocytes after 7 days and RNA-seq analysis was performed using these mRNAs from LBW podocytes and NBW podocytes. RESULTS Gene expression of Nphs1 (nephrin), Nphs2 (podocin) Podxl (podocalyxin) was detected in all samples of both groups, confirming that podocytes were cultured. The number of transcripts detected was 17 967 genes. In addition, by comparison of mRNA expression levels between LBW podocytes and NBW podocytes, 107 genes (102 genes decreased in the LBW group and 5 genes increased in the LBW group) showed a False Discovery Rate (FDR) P -value (q-value) < 0.05 between the two groups. Furthermore, IPA (Ingenuity® Pathway Analysis) by using these 107 genes was performed. As a result, five candidates for the upstream master regulator were identified: TNF, SIRT1, SH2B1, C5 and GDF15 as shown in the Figure. The downstream of all these pathways contain TCS2. This gene has been implicated in FSGS formation, as we recently reported [3]. CONCLUSION It is possible that TCS2 is involved in the mechanism of FSGS formation in LBW-related nephropathy.