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The nonhuman primate kidney transcriptome during fetal development

ABSTRACT: Little is known about the repertoire of nonhuman primate kidney genes expressed throughout development. The present work establishes an understanding of the primate renal transcriptome at different stages of fetal development and defines the framework of gene expression in the context of renal maturation, which provides a basis for identifying deviations in transcriptome expression resulting from suboptimal conditions during renal development. The baboon kidney transcriptome was characterized at 60 days gestation (DG), 90DG, 125DG, 160DG and adulthood (6-12 years) using human genome arrays to identify differential gene expression in the context of biological pathways and hierarchical clusters. Whole genome expression profiling showed 11,331 genes that were expressed during kidney development, 4,698 of which were differentially expressed among the developmental time points. Pathway analysis indicated activation of annotated pathways previously reported to be important to kidney development and pathways not reported as relevant to kidney development. QRT-PCR for genes central to these pathways validated expression profiles and revealed differences between males and females at specific times in gestation. Hierarchical clustering indicated that two clusters best fit the data, one containing genes that increased in expression from 60DG to adult and one that decreased. Cluster analysis also revealed gene splice variants with discordant expression profiles during development. For example, SMAD4, which is central to Wnt signaling, TGF-β signaling and cell cycle, showed up-regulation of the full-length splice variant during development and down-regulation of a shorter variant that is missing DNA binding and protein heterotrimerization domains suggesting decreased inhibition of cell proliferation, which may impact renal cell number and maturation. This study provides the first detailed genetic analysis of the developing primate kidney, and our findings of discordant expression of gene splice variants suggest that gene arrays likely provide a simplified view and demonstrate the need to study the fetal renal proteome.

ORGANISM(S): Papio hamadryas Homo sapiens

PROVIDER: GSE65162 | GEO | 2018/01/20

REPOSITORIES: GEO

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Project description:Preterm neonates are at high risk for nephron loss under adverse clinical conditions (e.g., cardiocirculatory decompensation, nephrotoxic drugs). Importantly, the onset of renal damage potentially collides with the proceeding nephrogenesis of prematurity prior 36 weeks of gestation. Recent animal studies suggest that early nephron loss within this vulnerable phase is associated with more severe glomerular and tubulointerstitial alterations later in life, irrespective of the occurrence of arterial hypertension. It is known that nephrogenic pathways are reactivated after acute kidney injury supporting renal repair and regeneration. In this study we hypothesized that nephron loss during nephrogenesis leads to an alteration of the kidney developmental program which in turn impairs homeostasis and repair and thus aggravates kidney injury later in life. Preterm infants prior to 36 weeks of gestation show an active nephrogenesis after birth. In rats, nephrogenesis is still active until day 10 of life. Mimicking the human situation of acute nephron loss in preterm neonates with ongoing nephrogenesis, rats were uninephrectomized at day 1 of life (UNXd1). A second group of animals was uninephrectomized at day 14 of life (UNXd14), which resembles a nephron loss after terminated nephrogenesis. Age-matched control groups were sham operated. Three days after uninephrectomy the animals were sacrificed. Transcriptional renal changes were analyzed by RNAseqencing, followed by in silico functional pathway analysis. In UNXd1 animals 1182 genes were differentially regulated compared to the respective control group. The functional groups “renal development” and “kidney injury” were among the most differentially regulated groups and revealed distinctive alterations in UNXd1 animals. Reduced expression levels of candidate genes concerning renal development (Bmp7, Gdnf, Pdgf-B, Wt1) and kidney injury (nephrin, podocin, Tgf-β1) were detected in the kidney of UNXd1 animals. The downregulation of Bmp7 and Gdnf expression in the remaining kidney of UNXd1 animals persisted until day 28 of life. In UNXd14 rats Six2 was upregulated and Pax22 downregulated compared to controls. We conclude that neonatal nephron loss during active nephrogenesis affects renal development and induces persistently reduced expression levels of genes which in turn might hinder tissue repair after kidney injury later in life.