SIRT3 ameliorates polycystic ovary syndrome through FOXO1/PGC-1α signaling pathway

Role of the mitophagy-apoptosis axis in the pathogenesis of polycystic ovarian syndrome

AIM

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by menstrual irregularities, androgen excess, and polycystic ovarian morphology, but its pathogenesis remains largely unknown. This review focuses on how androgen excess influences the molecular basis of energy metabolism, mitochondrial function, and mitophagy in granulosa cells and oocytes, summarizes our current understanding of the pathogenesis of PCOS, and discuss perspectives on future research directions.

METHODS

A search of PubMed and Google Scholar databases were used to identify relevant studies for this narrative literature review.

RESULTS

Female offspring born of pregnant animals exposed to androgens recapitulates the PCOS phenotype. Abnormal mitochondrial morphology, altered expression of genes related to glycolysis, mitochondrial biogenesis, fission/fusion dynamics, and mitophagy have been identified in PCOS patients and androgenic animal models. Androgen excess causes uncoupling of the electron transport chain and depletion of the cellular adenosine 5'-triphosphate pool, indicating further impairment of mitochondrial function. A shift toward mitochondrial fission restores mitochondrial quality control mechanisms. However, prolonged mitochondrial fission disrupts autophagy/mitophagy induction due to loss of compensatory reserve for mitochondrial biogenesis. Disruption of compensatory mechanisms that mediate the quality control switch from mitophagy to apoptosis may cause a disease phenotype. Furthermore, genetic predisposition, altered expression of genes related to glycolysis and oxidative phosphorylation, or a combination of these factors may also contribute to the development of PCOS.

CONCLUSION

In conclusion, fetuses exposed to a hyperandrogenemic intrauterine environment may cause the PCOS phenotype possibly through disruption of the compensatory regulation of the mitophagy-apoptosis axis.

Downregulation of Sirt3 contributes to β-cell dedifferentiation via FoxO1 in type 2 diabetic mellitus

AIMS

FoxO1 is an important factor in the β-cell differentiation in type 2 diabetes mellitus (T2DM). Sirt3 is found to be involved in FoxO1 function. This study investigated the role of Sirt3 in the β-cell dedifferentiation and its mechanism.

METHODS

Twelve-week-old db/db mice and INS1 cells transfected with Sirt3-specific short hairpin RNA (shSirt3) were used to evaluate the dedifferentiation of β-cell. Insulin levels were measured by enzyme linked immunosorbent assay. The proteins of Sirt3, T-FoxO1, Ac-FoxO1 and differentiation indexes such as NGN3, OCT4, MAFA were determined by western blot or immunofluorescence staining. The combination of Sirt3 and FoxO1 was determined by the co-immunoprecipitation assay. The transcriptional activity of FoxO1 was detected by dual luciferase reporter assay.

RESULTS

Both the in vivo and in vitro results showed that Sirt3 was decreased along with β-cell dedifferentiation and decreased function of insulin secretion under high glucose conditions. When Sirt3 was knocked down in INS1 cells, increased β-cell dedifferentiation and lowered insulin secretion were observed. This effect was closely related to the amount loss and the decreased deacetylation of FoxO1, which resulted in a reduction in transcriptional activity.

CONCLUSION

Downregulation of Sirt3 contributes to β-cell dedifferentiation in high glucose via FoxO1. Intervention of Sirt3 may be an effective approach to prevent β-cell failure in T2DM.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

Signaling pathways and targeted therapeutic strategies for polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among women of reproductive age. Although promising strides have been made in the field of PCOS over the past decades, the distinct etiologies of this syndrome are not fully elucidated. Prenatal factors, genetic variation, epigenetic mechanisms, unhealthy lifestyles, and environmental toxins all contribute to the development of this intricate and highly heterogeneous metabolic, endocrine, reproductive, and psychological disorder. Moreover, interactions between androgen excess, insulin resistance, disruption to the hypothalamic-pituitary-ovary (HPO) axis, and obesity only make for a more complex picture. In this review, we investigate and summarize the related molecular mechanisms underlying PCOS pathogenesis from the perspective of the level of signaling pathways, including PI3K/Akt, TGF-β/Smads, Wnt/β-catenin, and Hippo/YAP. Additionally, this review provides an overview of prospective therapies, such as exosome therapy, gene therapy, and drugs based on traditional Chinese medicine (TCM) and natural compounds. By targeting these aberrant pathways, these interventions primarily alleviate inflammation, insulin resistance, androgen excess, and ovarian fibrosis, which are typical symptoms of PCOS. Overall, we hope that this paper will pave the way for better understanding and management of PCOS in the future.

Peroxisom proliferator-activated receptor-γ coactivator-1α in neurodegenerative disorders: A promising therapeutic target

Neurodegenerative disorders (NDDs) are characterized by progressive loss of selectively vulnerable neuronal populations and myelin sheath, leading to behavioral and cognitive dysfunction that adversely affect the quality of life. Identifying novel therapies that attenuate the progression of NDDs would be of significance. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a widely expressed transcriptional regulator, modulates the expression of genes engaged in mitochondrial biosynthesis, metabolic regulation, and oxidative stress (OS). Emerging evidences point to the strong connection between PGC-1α and NDDs, suggesting its positive impaction on the progression of NDDs. Therefore, it is urgent to gain a deeper and broader understanding between PGC-1α and NDDs. To this end, this review presents a comprehensive overview of PGC-1α, including its basic characteristics, the post-translational modulations, as well as the interacting transcription factors. Secondly, the pathogenesis of PGC-1α in various NDDs, such as Alzheimer's (AD), Parkinson's (PD), and Huntington's disease (HD) is briefly discussed. Additionally, this study summarizes the underlying mechanisms that PGC-1α is neuroprotective in NDDs via regulating neuroinflammation, OS, and mitochondrial dysfunction. Finally, we briefly outline the shortcomings of current NDDs drug therapy, and summarize the functions and potential applications of currently available PGC-1α modulators (activator or inhibitors). Generally, this review updates our insight of the important role of PGC-1α on the development of NDDs, and provides a promising therapeutic target/ drug for the treatment of NDDs.

Mitochondrial Dysfunction in PCOS: Insights into Reproductive Organ Pathophysiology

Polycystic ovary syndrome (PCOS) is a complex, but relatively common endocrine disorder associated with chronic anovulation, hyperandrogenism, and micro-polycystic ovaries. In addition to reduced fertility, people with PCOS have a higher risk of obesity, insulin resistance, and metabolic disease, all comorbidities that are associated with mitochondrial dysfunction. This review summarizes human and animal data that report mitochondrial dysfunction and metabolic dysregulation in PCOS to better understand how mitochondria impact reproductive organ pathophysiology. This in-depth review considers all the elements regulating mitochondrial quantity and quality, from mitochondrial biogenesis under the transcriptional regulation of both the nuclear and mitochondrial genome to the ultrastructural and functional complexes that regulate cellular metabolism and reactive oxygen species production, as well as the dynamics that regulate subcellular interactions that are key to mitochondrial quality control. When any of these mitochondrial functions are disrupted, the energetic equilibrium within the cell changes, cell processes can fail, and cell death can occur. If this process is ongoing, it affects tissue and organ function, causing disease. The objective of this review is to consolidate and classify a broad number of PCOS studies to understand how various mitochondrial processes impact reproductive organs, including the ovary (oocytes and granulosa cells), uterus, placenta, and circulation, causing reproductive pathophysiology. A secondary objective is to uncover the potential role of mitochondria in the transgenerational transmission of PCOS and metabolic disorders.