Dissection of the autophagic route in oocytes from atretic follicles

Abstract

Background Information Autophagy is a conserved process that functions as a cytoprotective mechanism; it may function as a cell death process called programmed cell death type II. There is considerable evidence for the presence of autophagic cell death during oocyte elimination in prepubertal rats. However, the mechanisms involved in this process have not been deciphered. Results Our observations revealed autophagic cell death in oocytes with increased labeling of the autophagic proteins Beclin 1, light chain 3 A (LC3 A), and lysosomal‐associated membrane protein 1 (Lamp1). Furthermore, mTOR and phosphorylated (p)‐mTOR (S2448) proteins were significantly decreased in oocytes with increased levels of autophagic proteins, indicating autophagic activation. Moreover, phosphorylated protein kinase B (p‐AKT) was not expressed by oocytes, but mitogen‐activated protein kinase/extracellular signalregulated kinase (MAPK/ERK) signaling was observed. Additionally, selective and elevated mitochondrial degradation was identified in altered oocytes. Conclusions All these results suggest that mTOR downregulation, which promotes autophagy, could be mediated by low energy levels and sustained starvation involving the phosphoinositide 3‐kinase (PI3K)/AKT/mTOR and MAPK/ERK pathways. Significance In this work, we analyzed the manner in which autophagy is carried out in oocytes undergoing autophagic cell death by studying the behavior of proteins involved in different steps of the autophagic pathway.

Proteomic Analysis Identifies Distinct Protein Patterns for High Ovulation in FecB Mutant Small Tail Han Sheep Granulosa Cells

“…Granulosa cells undergo proliferation and progressive differentiation throughout ovarian follicular development to facilitate the maturation of oocytes and subsequent ovulation [ 13 ]. It has been demonstrated that follicular atresia is due to the apoptosis of granulosa cells, resulting in a decrease in the number of follicles [ 14 , 15 ]. The BMP pathway to which BMPR1B belongs plays an important role in oocyte–granulosa cell interactions [ 16 , 17 ].…”