Functional role of autophagy in testicular and ovarian steroidogenesis

(D and E) Relative mRNA level of SR-BI in autophagy-deficient Leydig cells. (B and C) SR-BI was decreased in the autophagy-deficient Leydig cells. (E and G) The absorption curve of DiI-HDL in autophagy-deficient Leydig cells and control groups.
And very recently, another group of investigators demonstrated in the porcine ovary that FSH promotes progesterone production by enhancing autophagy through the upregulation of Beclin1 via the PI3K/JNK/c-Jun pathway to accelerate LD degradation in porcine GCs . In the absence of Sirt1, LC3 fails to deacetylate and translocate to the cytoplasm, resulting in disruption of autophagic flux, impaired cholesterol uptake and deficient testosterone biosynthesis . Another study in 2021 demonstrated that autophagic flux and autophagy-mediated testosterone synthesis are defective in SF1-Sirt1−/− mice. In 2019, an elegant study described autophagy-dependent steroid hormone (ecdysone) production in the Drosophila model by demonstrating that autophagy mediates lipid trafficking required for steroid synthesis . A Representative confocal images of the luteinized granulosa cells of the patients with normal and defective luteal function treated with hCG (10 IU/ml) w/wo chloroquine (CQ, 60 μM). Defective co-localization of BODYPY with lysosome became more obvious in the cells with defective LF when they were treated with an hCG+chloroquine combination (Fig. 8A, B, Supplementary Fig. S6 and Supplementary Movies S5 and S6) in comparison to the control cells with normal LF.
Notably, the ER-resident chaperone Sig-1R, concentrated at MAMs, governs calcium dynamics and responses to oxidative stress (Gottschalk et al., 2022), suggesting its potential as a therapeutic target for conditions linked to ROS-induced damage in Leydig cells. Mitochondrial contact sites with the ER are vital for regulating ROS in gonadal cells. Notably, there may be additional connections between testosterone and autophagy. Concurrently, there is an increase in total cholesterol (TC) and LD levels in serum-free media. Stress reduces lipid droplets but increases buy testosterone without prescription release, effects counteracted by inhibiting autophagy.
However, it has not previously been shown how ABP expression is regulated. ABP can increase the concentration of testosterone store in the seminiferous tubule to promote spermatogenesis. However, the increase of ABP by CQ under hypoxia was less than that in normal conditions (Fig. 4E), indicating that the autophagic clearance of ABP under hypoxia was lower and that hypoxia-induced autophagy did not clear more ABP. The results showed that CQ further up-regulated ABP expression in hypoxia (Fig. 4D, 4E, 4G). (D–G), Cells were treated with CQ (50 uM) or rapamycin (10 nM) in the presence or absence of hypoxia for 24 h.
Noticeably, mTORC1 is the main gateway to autophagy, connecting cellular nutrient sensing with environmental cues to preserve cellular homoeostasis. Additionally, unfavorable circumstances, such as hypoxia, UV, starvation, ROS, and the accumulation of unfolded proteins, can also provoke autophagy to become a cytoprotective mechanism . LCs can synthesize the estrogen, germ cells, and epididymal spermatozoa-expressed P450 aromatase (CYP19A1) and can actively synthesize estrogens from androgens as well . Interestingly, autophagy is also affected by the concentration of testosterone 54,109. More precisely, the autophagic degradation of ABP is only effective at the protein level. In a detailed study, both in vitro and in vivo experiments demonstrated that autophagy regulates ABP expression.
Our data revealed that METTL14 knockdown enhanced phosphorylation of PRKAA2, upregulated expression of LC3B-II, and decreased expression of SQSTM1 (Figure 6A); however, compound C effectively attenuated these changes (Figure 6A). Given that we identified a negative correlation between m6A methylation and autophagy, we next evaluated the possible relationship between m6A methylation and activation of AMPK in LCs. (B) m6A levels in LCs were assessed by immunofluorescence assay. We further demonstrated that HsCG decreased m6A levels and increased HSD3B levels in LCs using immunofluorescence analyses (Figure 4F). (A) m6A levels in LCs were assessed by immunofluorescence staining.
This is just the tip of the iceberg, and there are still many gaps between autophagy and male reproduction that are worthy of exploration. Despite the cumulative gains revealed, autophagy is blossoming in many aspects of male reproduction. On the other hand, testosterone inhibits autophagy in a negative feedback loop. In conclusion, the review presents the double-edged characteristics of autophagy in the most important processes involved in male reproduction.
C Representative blots for indicated proteins before and after treatment with hCG (10 IU/ml) w/wo CQ (60 μM). Dotted areas show the steroidogenic Leydig cells interspersed between seminiferous tubules with Sertoli cells and germ cells. Inhibition of autophagy with chloroquine significantly impaired basal and hCG-induced T production along with a marked accumulation of LC3B-II in immunoblot analysis (Fig. 6C, D).
Collectively, these results reveal that autophagy promotes cholesterol uptake into Leydig cells by eliminating NHERF2, suggesting that dysfunction of autophagy might be causal in the loss of testosterone production in some patients. In aged LCs, Li et al. observed that the levels of StAR and testosterone production were lower than in young cells, which was affected by autophagic activity. Eukaryotic cells primarily use two distinct mechanisms for large-scale degradation; one is proteasomes and the other is the lysosomal-dependent protein degradation pathway, pads.zapf.in namely autophagy.