Molecular characterization of variants in mitochondrial DNA encoded genes using next generation sequencing analysis and mitochondrial dysfunction in women with PCOS

Mitochondrial dysfunction results in enhanced adrenal androgen production in H295R cells

The role of mitochondria in steroidogenesis is well established. However, the specific effects of mitochondrial dysfunction on androgen synthesis are not fully understood. In this study, we investigate the effects of various mitochondrial and metabolic inhibitors in H295R adrenal cells and perform a comprehensive analysis of steroid and metabolite profiling. We report that mitochondrial complex I inhibition by rotenone shifts cells toward anaerobic metabolism with a concomitant hyperandrogenic phenotype characterized by rapid stimulation of dehydroepiandrosterone (DHEA, 2 h) and slower accumulation of androstenedione and testosterone (24 h). Screening of metabolic inhibitors confirmed DHEA stimulation, which included mitochondrial complex III and mitochondrial pyruvate carrier inhibition. Metabolomic studies revealed truncated tricarboxylic acid cycle with an inverse correlation between citric acid and DHEA production as a common metabolic marker of hyperandrogenic inhibitors. The current study sheds light on a direct interplay between energy metabolism and androgen biosynthesis that could be further explored to identify novel molecular targets for efficient treatment of androgen excess disorders.

New insights on mitochondrial heteroplasmy observed in ovarian diseases

BACKGROUND

The reportedly high mutation rate of mitochondrial DNA (mtDNA) may be attributed to the absence of histone protection and complete repair mechanisms. Mitochondrial heteroplasmy refers to the coexistence of wild-type and mutant mtDNA. Most healthy individuals carry a low point mutation load (<1 %) in their mtDNA, typically without any discernible phenotypic effects. However, as it exceeds a certain threshold, it may cause the onset of various diseases. Since the ovary is a highly energy-intensive organ, it relies heavily on mitochondrial function. Mitochondrial heteroplasmy can potentially contribute to a variety of significant ovarian disorders.

AIM OF REVIEW

In this review, we have elucidated the close relationship between mtDNA heteroplasmy and ovarian diseases, and summarized novel avenues and strategies for the potential treatment of these ovarian diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Mitochondrial heteroplasmy can potentially contribute to a variety of significant ovarian disorders, including polycystic ovary syndrome, premature ovarian insufficiency, and endometriosis. Current strategies related to mitochondrial heteroplasmy are untargeted and have low bioavailability. Nanoparticle delivery systems loaded with mitochondrial modulators, mitochondrial replacement/transplantation therapy, and mitochondria-targeted gene editing therapy may offer promising paths towards potentially more effective treatments for these diseases, despite ongoing challenges.

Assessment of ForenSeq mtDNA Whole Genome Kit for forensic application

Mitochondrial DNA (mtDNA) is an indispensable genetic marker in forensic genetics. The emergence and development of massively parallel sequencing (MPS) makes it possible to obtain complete mitochondrial genome sequences more quickly and accurately. The study evaluated the advantages and limitations of the ForenSeq mtDNA Whole Genome Kit in the practical application of forensic genetics by detecting human genomic DNA standards and thirty-three case samples. We used control DNA with different amount to determine sensitivity of the assay. Even when the input DNA is as low as 2.5 pg, most of the mitochondrial genome sequences could still be covered. For the detection of buccal swabs and aged case samples (bloodstains, bones, teeth), most samples could achieve complete coverage of mitochondrial genome. However, when ancient samples and hair samples without hair follicles were sequenced by the kit, it failed to obtain sequence information. In general, the ForenSeq mtDNA Whole Genome Kit has certain applicability to forensic low template and degradation samples, and these results provide the data basis for subsequent forensic applications of the assay. The overall detection process and subsequent analysis are easy to standardize, and it has certain application potential in forensic cases.

The serum steroid signature of PCOS hints at the involvement of novel pathways for excess androgen biosynthesis

CONTEXT

Polycystic ovary syndrome (PCOS) is defined by androgen excess and ovarian dysfunction in the absence of a specific physiological diagnosis. The best clinical marker of androgen excess is hirsutism, while the best biochemical parameter is still a matter of debate. Current consensus guidelines recommend, among other hormones, serum free testosterone as an important serum parameter to measure androgen excess. Recently, however, novel active androgens and androgen metabolic pathways have been discovered.

OBJECTIVE

To assess the contribution of novel androgens and related steroid biosynthetic pathways to the serum steroid pool in PCOS women in comparison to healthy controls.

DESIGN

This is a case control study, wherein PCOS was diagnosed according to the AE-PCOS 2009 criteria. Serum steroid profiling was performed by liquid chromatography high-resolution mass spectrometry.

SETTING

Yeditepe University and associated clinics in Istanbul, Turkey, together with Bern University Hospital Inselspital, Bern, Switzerland.

PARTICIPANTS

42 PCOS women and 42 matched, healthy control women.

MAIN OUTCOME MEASURES

Assessment of 34 steroids compartmentalized in four androgen related pathways: the classic androgen pathway, the backdoor pathway, the C11-oxy backdoor pathway, and the C11-oxy (11β-hydroxyandrostenedione) pathway.

RESULTS

Metabolites of all four pathways were identified in healthy and PCOS women. Highest concentrations were found for progesterone in controls and androstenedione in PCOS. Lowest levels were found for 11-ketotestosterone in controls compared to PCOS, and for 20α-hydroxyprogesterone in PCOS compared to controls. PCOS also had higher serum testosterone levels compared to the controls. PCOS women had overall higher levels of steroid metabolites of all four androgen pathways compared to healthy controls.

CONCLUSIONS

Novel alternative pathways contribute to the androgen production in healthy and PCOS women. Hyperandrogenism in PCOS is characterized by an overall increase of serum androgens in the classic, backdoor and C11-oxy pathways. While monogenetic disorders of steroid biosynthesis can be recognized by a specific pattern in the steroid profile, no diagnostic pattern or classifier was found in the serum for PCOS.

Mitochondrial dysfunction in the offspring of obese mothers and it's transmission through damaged oocyte mitochondria: Integration of mechanisms

In vivo and in vitro studies demonstrate that mitochondria in the oocyte, are susceptible to damage by suboptimal pre/pregnancy conditions, such as obesity. These suboptimal conditions have been shown to induce mitochondrial dysfunction (MD) in multiple tissues of the offspring, suggesting that mitochondria of oocytes that pass from mother to offspring, can carry information that can programme mitochondrial and metabolic dysfunction of the next generation. They also suggest that transmission of MD could increase the risk of obesity and other metabolic diseases in the population inter- and trans-generationally. In this review, we examined whether MD observed in offspring tissues of high energetic demand, is the result of the transmission of damaged mitochondria from obese mothers' oocytes to the offspring. The contribution of genome-independent mechanisms (namely mitophagy) in this transmission were also explored. Finally, potential interventions aimed at improving oocyte/embryo health were investigated, to see if they may provide an opportunity to halter the generational effects of MD.

Genome-wide association study for single nucleotide polymorphism associated with mural and cumulus granulosa cells of PCOS (polycystic ovary syndrome) and non-PCOS patients

Background

The genetic make-up of local granulosa cells and their function in the pathophysiology of polycystic ovary syndrome (PCOS) is crucial to a full comprehension of the disorder. The major purpose of this study was to compare the Single Nucleotide Polymorphism (SNP) of cumulus granulosa cells (CGCs) and mural granulosa cells (MGCs) between healthy individuals and women with PCOS using genome-wide association analysis (GWA). A case–control study was conducted in a total of 24 women diagnosed with PCOS and 24 healthy non-PCOS women of reproductive age aggregated into 4 samples of 6 patients each. GWA studies entail several processes, such as cell separation, cellular DNA extraction, library preparation followed by interpretation using bioinformatics databases. SNP locations were identified by reference gene also involves the use of Matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry (MS) (MALDI-TOF-MS) for the first sorting. Hybridization with the gene chip was followed by reading the SNP genotypes according to the publications in the literature. TASSEL (Trait Analysis by aSSociation, Evolution and Linkage) program and methods were used for GWA studies.

Results

An aggregate of 21,039 SNP calls were obtained from our samples. Genes of autoimmune illnesses, obesity, inflammatory illnesses, nervous system diseases such as retinitis pigmentosa, autism, neural tube defects, and Alzheimer's disease; and various malignancies such as lung cancer, colorectal cancer, breast cancer were also identified in these cells. Gene ranking score reveals that granulosa cells carry key genes of neurological system and reproductive systems especially in brain and testis, respectively.

Conclusions

Mural and Cumulus Granulosa cells were shown to have the PCOS directly and indirectly related genes MMP9, PRKAA2, COMT and HP. We found that the expression of ARID4B, MUC5AC, NID2, CREBBP, GNB1, KIF2C, COL18A1, and HNRNPC by these cells may contribute to PCOS.

Graphical abstract