Impact of gestational low-protein intake on embryonic kidney microRNA expression and in the nephron progenitor cells of the male offspring fetus

Abstract

Authors have demonstrated that gestational low-protein (LP) intake offspring showed a lower birth weight, reduced nephrons numbers and renal salt excretion, chronic renal failure, and arterial hypertension development when compared to normal (NP) protein intake group in adult life. The current study was aimed to evaluate the miRNAs and predicted gene expression patterns in the fetal kidney at 17 days of gestational (17-DG) protein-restricted male offspring (LP) in an attempt to elucidate the possible molecular pathways and disorders involved in renal cell proliferation and differentiation during kidney development. By NGS and RT-qPCR were identified, 44 differentially expressed miRNAs, which 19 miRNA were up- and 25 downregulated in LP compared to NP offspring metanephros. Among the top 10 deregulated miRNAs, the study selected 7 miRNAs which its biological targets were related to proliferation, differentiation, and cellular apoptosis processes. As could be seen below, both miRNA-Seq and TaqMan data analysis have shown a consistent change of miRNA expression in LP animals relative to control NP age-matched animals. By immunofluorescence, the LP fetus showed a significant 28% reduction of Six-2 labeled cells when compared to NP offspring associated with a reduced percentage of cell number and c-Myc metanephogenic cap and ureter bud immunostained cells in LP relative to NP offspring.

Additionally, the Ki-67 labeled area in CM was 48% lesser in LP compared to NP age-matched fetus. On the other hand, in LP, the CM and UB β-catenin marked area were 154 and 85% raised, respectively. Mtor immunoreactivity was also significantly higher in LP CM (139%) and UB (104%) compared to the NP fetus. In the LP offspring, the TGFβ-1 in UBs cells staining increased (about 30%). In contrast, Zeb1 metanephros-stained, located in the CM nuclei cells, enhanced 30% in LP and Zeb2 immunofluorescence, although present in whole metanephros structures, was similar in both experimental groups. In conclusion, the present study demonstrates that the miRNAs, mRNAs, and proteins are modified in LP animals with 17 DGs leading to the reduction of the reciprocal induction between CM and UB, and hence the number of nephrons. These findings will facilitate new functional approaches and further studies to elucidate the regulatory mechanisms involved in the processes of proliferation, differentiation, and apoptosis that occurs during renal development.