Aggrephagy is defined as the selective degradation of aggregated proteins by autophagosomes. Protein aggregation in organs and cells has been highlighted as a cause of multiple diseases, including neurodegenerative diseases, cardiac failure, and renal failure. Aggregates could pose a hazard for cell survival. Cells exhibit three main mechanisms against the accumulation of aggregates: protein refolding by upregulation of chaperones, reduction of protein overload by translational inhibition, and protein degradation by the ubiquitin–proteasome and autophagy–lysosome systems. Deletion of autophagy-related genes reportedly contributes to intracellular protein aggregation in vivo. Some proteins recognized in aggregates in preeclamptic placentas include those involved in neurodegenerative diseases. As aggregates are derived both intracellularly and extracellularly, special endocytosis for extracellular aggregates also employs the autophagy machinery. In this review, we discuss how the deficiency of aggrephagy and/or macroautophagy leads to poor placentation, resulting in preeclampsia or fetal growth restriction.

Autophagy is a fundamental process involved in regulating cellular homeostasis. Autophagy has been classically discovered as a cellular process that degrades cytoplasmic components non-selectively to produce energy. Over the past few decades, this process has been shown to work in energy production, as well as in the reduction of excessive proteins, damaged organelles, and membrane trafficking. It contributes to many human diseases, such as neurodegenerative diseases, carcinogenesis, diabetes mellitus, development, longevity, and reproduction. In this review, we provide important information for interpreting results related to autophagic experiments and present the role of autophagy in this field.

Poor placentation is closely related with the etiology of preeclampsia and may impact fetal growth restriction. For placental developmental growth, we have demonstrated that dysregulation of autophagy, a key mechanism to maintain cellular homeostasis, in trophoblasts contributes to the pathophysiology of preeclampsia, a severe pregnancy complication, associated with poor placentation. It remains, however, unknown whether autophagy inhibition affects trophoblast syncytialization. This study evaluated the effect of autophagy in an in vitro syncytialization method using BeWo cells and primary human trophoblasts (PHT). In this study, we observed that autophagic activity decreased in PHT and BeWo cells during syncytialization. This decreased activity was accompanied by downregulation of the transcription factor, TFEB. Next, bafilomycin A1, an inhibitor of autophagy via suppressing V-ATPase in lysosomes, inhibited hCG production, CYP11A1 expression (a marker of differentiation), p21 expression (a senescence marker), and cell fusion in BeWo cells and PHT cells. Finally, LLOMe, an agent inducing lysosomal damage, also inhibited syncytialization and led to TFEB downregulation. Taken together, the autophagy-lysosomal machinery plays an important role in cytotrophoblast fusion, resulting in syncytiotrophoblasts. As autophagy inhibition contributed to the failure of differentiation in cytotrophoblasts, this may result in the poor placentation observed in preeclampsia.

Aging drives excessive ovarian oxidative stress (OS), impairing fertility and affecting granulosa cells (GCs), which are involved in folliculogenesis. This study aims to clarify the relationship between OS and autophagy in GCs and to identify compounds that enhance OS resistance. We identified Rubicon, an autophagy suppressor, as a key mediator of DNA damage in GCs under OS. Hydrogen peroxide (H₂O₂) compromised cell viability via DNA damage in the human GC cell line, HGrC1, without affecting autophagic activity. However, autophagy activation increased OS resistance in HGrC1 cells, and vice versa. Among clinically safe materials, trehalose, a disaccharide, protected cells as an autophagy activator against H₂O₂-induced cytotoxicity. Trehalose significantly increased autophagic activity, accompanied by reduced Rubicon expression, compared to other carbohydrates. It also reduced the expression of DNA damage-responsive proteins and the production of reactive oxygen species. Rubicon knockdown mitigated OS-induced DNA damage, while Rubicon overexpression enhanced DNA damage and decreased HGrC1 cell viability. Trehalose enhanced OS resistance by activating autophagy and suppressing Rubicon in a bidirectional manner. As Rubicon expression increases in aged human ovaries, trehalose may improve ovarian function in patients with infertility and other OS-related diseases.

Aging increases oxidative stress (OS) in the ovaries, leading to infertility-related dis-orders. Granulosa cells (GCs), which support folliculogenesis in the ovaries, are chron-ically exposed to excessive OS under pathological conditions. Here, we demonstrate the significant role of Rubicon, an autophagy suppressor, as a DNA damage mediator in GCs under OS. Hydrogen peroxide (H2O2) decreased cell viability in the human GC cell line, HGrC1, due to DNA damage, without affecting autophagic activity. However, activation of autophagy increased OS resistance in HGrC1 cells, and vice versa. Among several materials that are considered safer for clinical use, trehalose, a disaccharide, exerted a protective effect as an autophagy activator against H2O2-induced cytotoxici-ty. Trehalose significantly increased autophagic activity, accompanied by a reduction in Rubicon, compared to other carbohydrates. It also reduced the expression of DNA damage-responsive proteins and the production of reactive oxygen species. The reduc-tion in Rubicon expression by siRNA mitigated DNA damage caused by OS, while overexpression of Rubicon enhanced DNA damage and decreased HGrC1 cell viability. Trehalose enhanced OS resistance by activating autophagy and suppressing Rubicon in a bidirectional manner. As Rubicon expression increases in aged human ovaries, tre-halose may improve ovarian function in patients with infertility and other OS-related diseases.