Pot1 promotes telomere DNA replication via the Stn1-Ten1 complex in fission yeast.

Telomeres are nucleoprotein complexes that protect the chromosome-ends from eliciting DNA repair while ensuring their complete duplication. Pot1 is a subunit of telomere capping complex that binds to the G-rich overhang and inhibits the activation of DNA damage checkpoints. In this study, we explore new functions of fission yeast Pot1 by using a pot1-1 temperature sensitive mutant. We show that pot1 inactivation impairs telomere DNA replication resulting in the accumulation of ssDNA leading to the complete loss of telomeric DNA. Recruitment of Stn1 to telomeres, an auxiliary factor of DNA lagging strand synthesis, is reduced in pot1-1 mutants and overexpression of Stn1 rescues loss of telomeres and cell viability at restrictive temperature. We propose that Pot1 plays a crucial function in telomere DNA replication by recruiting Stn1-Ten1 and Polα-primase complex to telomeres via Tpz1, thus promoting lagging-strand DNA synthesis at stalled replication forks.

XPERT® breast cancer STRAT4 as an alternative method of identifying breast cancer phenotype in Cape Verde (preliminary results).

Introduction: Breast cancer (BC) is a public health problem in developing countries, including Cape Verde. Immunohistochemistry (IHC) is the gold standard technique used for BC phenotypic characterisation to support efficient therapeutic decisions. However, IHC is a demanding technique that requires knowledge, trained technicians, expensive antibodies and reagents, controls, and results validation. The low number of cases in Cape Verde increases the risk of expiring the validity of the antibodies, and manual procedures often jeopardise the quality of the results. Thus, IHC is limited in Cape Verde, and an alternative technically easy solution is needed. A point-of-care messenger RNA (mRNA) STRAT4 BC assay to assess estrogen (ER), progesterone (PR), hormone growth factor 2 receptor (HER2), and Ki67, using the GeneXpert platform, has been recently validated on tissues from internationally accredited laboratories, showing excellent concordance with IHC results.To assess whether this technology can be implemented in Cape Verde to guide BC treatment we decided to study the level of agreement between the findings yielded by BC STRAT4 and the results are the same cases obtained by IHC. Methods: Formalin-fixed and paraffin-embedded (FFPE) tissue samples from 29 Cabo Verdean BC patients diagnosed in Agostinho Neto University Hospital were analysed by applying IHC and BC STRAT4 assay. The time between sample collection and pre-analytic procedures is unknown. All the samples were pre-processed in Cabo Verde (fixed in formalin and embedded in paraffin). IHC studies were performed in referenced laboratories in Portugal. STRAT4 and IHC result concordance was assessed by calculating the percentage of results agreement and Cohen's Kappa (K) statistics. Results: STRAT4 assay failed in 2 out of the 29 analysed samples. Of the 27 successfully analysed samples, STRAT4/IHC results for ER, PR, HER2, and Ki67 were concordant in 25, 24, 25, and 18 cases, respectively. Ki67 was indeterminate in three cases, and PR was indeterminate once.The percentage of agreement between STRAT4 and IHC results for ER, PR, HER2, and Ki67 was 92.59%, 92.31%, 92.59% and 81.82%, respectively. The Cohen's K statistic coefficients for each biomarker were 0.809, 0.845, 0.757 and 0.506, respectively. Conclusions: According to our preliminary results, a point-of-care mRNA STRAT4 BC assay may be an alternative in laboratories unable to provide quality and/or cost-efficient IHC services. However, more data and improvement on sample pre-analytic processes are required to implement this BC STRAT4 Assay in Cape Verde.

Individuals with isolated congenital GH deficiency due to a GHRH receptor gene mutation appear to cope better with SARS-CoV-2 infection than controls.

PURPOSE: Several interactions exist between the GH/IGF axis and the immune system, including effects on innate immunity and humoral and cellular response. Acquired GH deficiency (GHD) has been recently proposed as a risk factor for severity of COVID-19 infections. However, acquired GHD is often associated to other factors, including pituitary tumors, surgery, radiotherapy, and additional pituitary hormones deficits and their replacements, which, together, may hinder an accurate analysis of the relationship between GHD and COVID-19. Therefore, we decided to assess the seroprevalence of SARS-CoV-2 antibodies and the frequency of symptomatic cases of COVID-19 in adults subjects with untreated isolated GHD (IGHD) due to a homozygous null mutation in the GHRH receptor gene. METHODS: A cross-sectional study was carried out in 27 adult IGHD subjects and 27 age- and gender-matched local controls. Interview, physical examination, bio-impedance, hematological and SARS-CoV-2 IgM and IgG antibodies were analyzed. RESULTS: There was no difference in the prevalence of positivity of anti-SARS-CoV-2 IgM and IgG antibodies between the two groups. Conversely, no IGHD individual had a previous clinical diagnosis of COVID-19 infection, while 6 control subjects did (p = 0.023). CONCLUSION: The production of anti-SARS-CoV-2 antibodies was similar between IGHD subjects due to a GHRH receptor gene mutation and controls, but the evolution to symptomatic stages of the infection and the frequency of confirmed cases was lower in IGHD subjects than in GH sufficient individuals.