Sequential testicular atrophy involves changes in cellular proliferation and apoptosis associated with variations in aromatase P450 expression levels in Irs‐2‐deficient mice

Abstract

Insulin receptor substrate 2 (Irs‐2) is an intracellular protein susceptible to phosphorylation after activation of the insulin receptor. Its suppression affects testis development and its absence induces peripheral resistance to insulin. The aim of this study was to identify changes induced by the deletion of Irs‐2 in the testicular structure and by the altered expression of cytochrome P450 aromatase, a protein necessary for the development and maturation of germ cells. Adult knockout (KO) mice (Irs‐2−/−, 6 and 12 weeks old) and age‐matched wild‐type (WT) mice were used in this study. Immunohistochemistry and Western blot analyses were performed to study proliferation (PCNA), apoptosis (active caspase‐3) and P450 aromatase expression in testicular histological sections. Deletion of Irs‐2 decreased the number of epithelial cells in the seminiferous tubule and rete testis. Aberrant cells were frequently detected in the epithelia of Irs‐2−/− mice, accompanied by variations in spermatogonia, which were shown to exhibit small hyperchromatic nuclei as well as polynuclear and anuclear structures. The amount of cell proliferation was significantly lower in Irs‐2−/− mice than in WT mice, whereas apoptotic processes were more common in Irs‐2−/− mice. Aromatase P450 reactivity was higher in 6‐week‐old KO mice than in WT mice of the same age and was even higher at 12 weeks. Our results suggest that Irs‐2 is a key element in spermatogenesis because silencing Irs‐2 induces the sequential development of testicular atrophy. The effects are observed mainly in germ cells present in the seminiferous tubule, which may be due to changes in cytochrome P450 aromatase expression.

The Slingshot phosphatase 2 is required for acrosome biogenesis during spermatogenesis in mice

“…We also detected round spermatids with malformed acrosomal structures in Ssh2 KO testes, which suggests that the acrosome formation was also affected. Furthermore, clustered round spermatids and apoptotic-like germ cells exhibiting small hyperchromatic nuclei and polynuclear structures, which are known indicators of apoptosis (Catalano-Iniesta et al, 2019), were observed in Ssh2 KO tubules (Figure 2A).…”

GH Overexpression Alters Spermatic Cells MicroRNAome Profile in Transgenic Zebrafish

“…Therefore, a reduction in the miRNAs targeting foxo3a suggests a positive regulation of this transcription factor, consequently activating the FoxO signaling pathway. In addition, several other genes downstream from the coding region for foxo3a transcription factor have also shown to be targeted by the down-regulated miRNAs, further implying their importance in this pathway (by themselves or in association with PI3K/Akt signaling pathway) in spermatic cells of gh + zebrafish ( Griffeth et al, 2013 ; Capra et al, 2017 ; Zhang et al, 2017b ; Catalano-Iniesta et al, 2019 ).…”