SA1/SA2 cohesion proteins and SIRT1-NAD+ deacetylase modulate telomere homeostasis in cumulus cells and are eligible biomarkers of ovarian aging

STUDY QUESTION

Are cohesins SA1/SA2 and the NAD-dependent deacetylase SIRT1 involved in telomere homeostasis of cumulus cells and thus eligible as biomarkers of follicular physiology and ovarian aging?

SUMMARY ANSWER

SA1/SA2 cohesins and SIRT1 are associated with telomere length in cumulus cells and may be eligible biomarkers of follicular physiology and ovarian aging.

WHAT IS KNOWN ALREADY

In somatic cells, cohesins SA1/SA2 mediate sister chromatid cohesion at the telomere termini (for SA1) and along chromatid arms (for SA2). The NAD+-dependent protein deacetylase Sirtuin 1 (SIRT1), which preserves DNA integrity from oxidative stress, may also modulate genome stability and telomere length.

STUDY DESIGN, SIZE, DURATION

Collectively 280 cumulus/oocyte complex samples were recovered from a total of 50 women undergoing in vitro fertilization.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cumulus cells were separated from the oocyte-cumulus complex. DNA and total mRNA were extracted from cumulus cells and assayed for telomere length and for SA1, SA2 and SIRT1 gene expression profiling. Telomere length was determined by quantitave PCR and analyzed relative to the single copy of the housekeeping gene (albumin) to generate a T/S ratio (Telomere/single copy gene). Gene expression levels of SA1, SA2 and SIRT1 mRNA were assayed by quantitative RT-PCR and confirmed by western blotting and immunofluorescent studies (SIRT1). SA1/SA2 and SIRT1 gene expression levels and telomere length analysis of patients/samples were ranked in relation to their clinical setting parameters (BMI, age) and to the number of oocyte retrieved.

MAIN RESULTS AND THE ROLE OF CHANCE

SA1 and SA2 transcripts were both detected in all cumulus cells analyzed and the relative amount showed a clear decreasing trend according to the age of patients. A significant increase in SA1 and SA2 was disclosed in high responder women (>6 oocytes retrieved) compared to poor responders (<4 oocytes) (P < 0.05). Furthermore, statistically significant positive correlations were also recorded between the transcripts levels of the two cohesin molecules (r = 0.89; P < 0.05) and, to a lesser extent, between telomere length and SA1 (r = 0.42; P < 0.001) and SA2 (r = 0.36; P < 0.001) mRNA levels. SIRT1 expression was also significantly increased in high responders (>6 oocytes) compared to poor responders. Significant correlations were found between SIRT1 and SA1 (r = 0.69; P < 0.001), between SIRT1 and SA2 (r = 0.78; P < 0.001), and between SIRT1 and telomere length (r = 0.36; P < 0.001). However, in the older patient group (>38 years), SIRT1 mRNA levels were twice as high as the levels recorded in the younger patient cohort (<34 years). Western blot analysis and immunofluorescent studies confirmed the increments in SIRT1 protein levels in patients over 38 years old.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Cumulus/oocyte complexes were retrieved by patients undergoing ovarian stimulation protocol for IVF. We cannot exclude the possibility that different stimulation protocols affect the correlations highlighted in this study. Future investigations should shed light on cumulus cells molecular profile according to different stimulation protocols.

WIDER IMPLICATIONS OF THE FINDINGS

The overall results of our study point to the involvement of cohesins SA1/SA2 and SIRT1 deacetylase in telomere homeostasis in cumulus cells and highlight their possible eligibility as biomarkers of follicular physiology and ovarian aging.

STUDY FUNDING/COMPETING INTEREST(S)

Merck Serono S.P.A Italy sponsored the study with financial support. There are no competing interests to declare.

PRMT1 arginine methyltransferase accumulates in cytoplasmic bodies that respond to selective inhibition and DNA damage

Protein arginine methyltransferases (PRMTs) are responsible for symmetric and asymmetric methylation of arginine residues of nuclear and cytoplasmic proteins. In the nucleus, PRMTs belong to important chromatin modifying enzymes of immense functional significance that affect gene expression, splicing and DNA repair. By time-lapse microscopy we have studied the sub-cellular localization and kinetics of PRMT1 after inhibition of PRMT1 and after irradiation. Both transiently expressed and endogenous PRMT1 accumulated in cytoplasmic bodies that were located in the proximity of the cell nucleus. The shape and number of these bodies were stable in untreated cells. However, when cell nuclei were microirradiated by UV-A, the mobility of PRMT1 cytoplasmic bodies increased their, size was reduced, and they disappeared within approximately 20 min. The same response occurred after γ-irradiation of the whole cell population, but with delayed kinetics. Treatment with PRMT1 inhibitors induced disintegration of these PRMT1 cytoplasmic bodies and prevented formation of 53BP1 nuclear bodies (NBs) that play a role during DNA damage repair. The formation of 53BP1 NBs was not influenced by PRMT1 over-expression. Taken together, we show that PRMT1 concentrates in cytoplasmic bodies, which respond to DNA injury in the cell nucleus, and to treatment with various PRMT1 inhibitors.

Adrenal adenoma and normal androgen levels in a young woman with polycystic ovaries: a case of idiopathic hirsutism?

A case of unusual combination of polycystic ovaries (PCO), adrenal non-functioning adenoma and severe hirsutism in a young woman from Southern Italy is reported here. A 18-yr-old woman was referred to our Department because of oligomenhorrea, acne and severe hirsutism. During evaluation of the cause of her symptoms, PCO and small left adrenal adenoma were revealed. Although adrenal androgen excess has been shown to dysregulate the hypothalamic-pituitary-gonadal axis, causing PCO-like syndrome, normal circulating androgen values were found. Androgens and cortisol levels were completely suppressed by low-dose dexamethasone test, excluding autonomous steroid secretion by the adrenal mass. Normal response of cortisol and adrenal androgens to corticotropin stimulation test permitted the exclusion of functional adrenal hyperandrogenism. Despite normal LH/FSH ratio, anovulatory cycles were revealed by persistently low progesterone values. Glucose and insulin response to oral glucose tolerance test did not differ from those of normal population. The patient showed an improvement of acne and hirsutism on therapy with estro-progestins (EP). In conclusion, despite normal pattern of serum androgens and LH/FSH ratio, this patient had anovulatory cycles and good response to the EP treatment. These findings suggest that ultrasonography evidence of PCO together with anovulatory cycles contributed to her clinical picture whereas adrenal adenoma seemed to have no relevant role. This case report underlines the need of cautious interpretation of imaging results and clinical signs of severe hirsutism, reminding one that the true cause of a medical problem may not be the most evident.

[Elevata prevalenza ma bassa incidenza della infezione da HGV in pazienti con epatite cronica C]

Objectives To determine 1. The prevalence and incidence of HGV infection in patients with chronic hepatitis C and 2. Its influence on the clinical outcome of chronic hepatitis C. Patients and methods Sixty-five patients with non-parenteral chronic hepatitis C virus infection were investigated for HGV infection using the polymerase chain reaction for HGV-RNA and by detecting serum antibodies against the E2 protein of HGV (anti-E2 antibodies). Results HGV-RNA in serum was found in 12 patients (18.4%) and anti-E2 antibodies in 4 (6.1%). No difference in age, sex, liver histology, basal ALT or ?GT was found between HGV positive and negative cases. Thirty-four patients (6 with HGV-RNA) were followed-up for 4 years; 4 of the 6 lost HGV-RNA, one of whom seroconverted to anti-E2. None of the 28 HGV-RNA negative cases presented HGV infection during the follow-up period. The presence of HGV infection did not influence either basal HCV viremia or the response of HCV to IFN therapy. Conclusions The study demonstrated that HGV had an intense circulation through non-classic parenteral routes, but its impact on HCV replication and liver disease is negligible.