NCBI Summary:
The product of this gene is a subunit of neuronal microtubule-associated MAP1A and MAP1B proteins, which are involved in microtubule assembly and important for neurogenesis. Studies on the rat homolog implicate a role for this gene in autophagy, a process that involves the bulk degradation of cytoplasmic component. [provided by RefSeq, Jul 2008]
General function
Comment
Cellular localization
Cytoskeleton
Comment
Autophagy is activated in the ovarian tissue of polycystic ovary syndrome. Li D et al. (2017) The importance of autophagy in polycystic ovary syndrome (PCOS)-related metabolic disorders is increasingly being recognized, but few studies have investigated the role of autophagy in PCOS. Here, transmission electron microscopy demonstrated that autophagy was enhanced in the ovarian tissue from both humans and rats with PCOS. Consistent with this, ovarian granulosa cells from PCOS rats showed increases in the autophagy marker protein light chain 3B (LC3B), whereas levels of the autophagy substrate SQSTM1/p62 were decreased. In addition, the ratio of LC3-II/LC3-I was markedly elevated in human PCOS ovarian tissue compared with normal ovarian tissue. Real-time PCR arrays indicated that 7 and 34 autophagy-related genes were down- and upregulated in human PCOS ovarian tissue, respectively. STRING, Signal-Net, and regression analysis suggested that there is a wide range of interactions among these 41 genes, and a potential network based on EGFR, ERBB2, FOXO1, MAPK1, NFKB1, IGF1, TP53, and MAPK9 may be responsible for autophagy activation in PCOS. Systematic functional analysis of 41 differential autophagy-related genes indicated that these genes are highly involved in specific cellular processes such as response to stress and stimulus, and are linked to four significant pathways, including the insulin, ERBB, and mTOR signalling pathways, and protein processing in the endoplasmic reticulum. This study provides evidence for a potential role of autophagy disorders in PCOS, in which autophagy may be an important molecular event in the pathogenesis of PCOS.//////////////////
Ovarian function
Follicle atresia
Comment
Abundances of autophagy-related protein LC3B in granulosa cells, cumulus cells, and oocytes during atresia of pig antral follicles. Gioia L et al. (2019) In mammals, apoptosis has been accepted as the type of programmed cell death (PCD) that occurs in ovarian follicles undergoing atresia. Results of recent studies, however, indicate autophagy may be an alternative mechanism involved in follicle depletion through independent or tandem actions with apoptosis. Western blotting and immunofluorescence procedures were used in the present study to investigate the abundances of LC3B protein in freshly collected granulosa cells (GCs), cumulus cells (CCs), and oocytes to evaluate whether autophagy is an important process of antral follicle atresia in sexually mature sows. Furthermore, apoptosis was analyzed using annexin V and TUNEL assays in the same cellular cohorts to evaluate the correlation between the two processes. Immunostaining results indicate autophagy was induced in the majority of GCs, CCs, and oocytes from early and advanced stage atretic follicles. The quantitative results of western blot analysis indicate there is a progressive increase (P < 0.05) in abundance of autophagy-related protein (LC3B-II) in these cells compared with cells in non-atretic follicles. Furthermore, there is confirmation that apoptosis occurs in the GCs of atretic follicles, thus indicating that in pigs apoptosis and autophagy are processes in GCs that regulate PCD and as a consequence antral follicle depletion. There was a greater abundance of LC3B-II in CCs and oocytes of atretic follicles, while apoptosis was not detected. It, therefore, is suggested that in these cells the two processes function independently, with autophagy having a cytoprotective rather than PCD mechanism of action.//////////////////
Heat Stress Induces Autophagy in Pig Ovaries during Follicular Development. Hale BJ et al. (2017) Hyperthermia or heat stress (HS) occurs when heat dissipation mechanisms are overwhelmed by external and internal heat production. Hyperthermia negatively affects reproduction and potentially compromises oocyte integrity and reduces developmental competence of ensuing embryos. Autophagy is the process by which cells recycle energy through the reutilization of cellular components and is activated by a variety of stressors. Study objectives were to characterize autophagy-related proteins in the ovary following cyclical HS during the follicular phase. Twelve gilts were synchronized and subjected to cyclical HS (n = 6) or thermal neutral (TN; n = 6) conditions for five days during the follicular phase. Ovarian protein abundance of BECN1 and LC3B-II were each elevated as a result of HS (P = 0.001 and 0.003, respectively). The abundance of the ATG12-ATG5 complex was decreased as a result of HS (P = 0.002). Regulation of autophagy and apoptosis occurs in tight coordination, and BCL2 and BCL2L1 are involved in regulating both processes. BCL2L1 protein abundance, as detected via immunofluorescence, was increased in both the oocyte (∼1.6-fold; P < 0.01) and granulosa cells of primary follicles (∼1.4-fold P < 0.05) of HS ovaries. These results suggest that ovarian autophagy induction occurs in response to HS during the follicular phase, and that HS increases anti-apoptotic signaling in oocytes and early follicles. These data contribute to the biological understanding of how HS acts as an environmental stress to affect follicular development and negatively impact reproduction.//////////////////