Sex differences in neuromuscular and biological determinants of isometric maximal force

AIM

Force expression is characterized by an interplay of biological and molecular determinants that are expected to differentiate males and females in terms of maximal performance. These include muscle characteristics (muscle size, fiber type, contractility), neuromuscular regulation (central and peripheral factors of force expression), and individual genetic factors (miRNAs and gene/protein expression). This research aims to comprehensively assess these physiological variables and their role as determinants of maximal force difference between sexes.

METHODS

Experimental evaluations include neuromuscular components of isometric contraction, intrinsic muscle characteristics (proteins and fiber type), and some biomarkers associated with muscle function (circulating miRNAs and gut microbiome) in 12 young and healthy males and 12 females.

RESULTS

Male strength superiority appears to stem primarily from muscle size while muscle fiber-type distribution plays a crucial role in contractile properties. Moderate-to-strong pooled correlations between these muscle parameters were established with specific circulating miRNAs, as well as muscle and plasma proteins.

CONCLUSION

Muscle size is crucial in explaining the differences in maximal voluntary isometric force generation between males and females with similar fiber type distribution. Potential physiological mechanisms are seen from associations between maximal force, skeletal muscle contractile properties, and biological markers.

Effects of a 4400 km ultra-cycling non-competitive race and related training on body composition and circulating progenitors differentiation

Background

NorthCape4000 (NC4000) is the most participated ultra-endurance cycling race. Eight healthy male Caucasian amateur cyclists were evaluated: (a) before starting the preparation period; (b) in the week preceding NC4000 (after the training period); (c) after NC4000 race, with the aim to identify the effects of ultra-cycling on body composition, aerobic capacity and biochemical parameters as well as on the differentiation of progenitor cells.

Methods

Bioelectrical impedance analysis (BIA) and dual energy x-ray absorptiometry (DEXA) assessed body composition; cardiopulmonary exercise test (CPET) evaluated aerobic capacity. Differentiation of circulating progenitor cells was evaluated by analyzing the modulation in the expression of relevant transcription factors. In addition, in vitro experiments were performed to investigate the effects of sera of NC4000 participants on adipogenesis and myogenesis. The effects of NC4000 sera on Sestrins and Sirtuin modulation and the promotion of brown adipogenesis in progenitor cells was investigated as well. Two-tailed Student’s paired-test was used to perform statistical analyses.

Results

We observed fat mass decrease after training as well as after NC4000 performance; we also recorded that vitamin D and lipid profiles were affected by ultra-cycling. In addition, our findings demonstrated that post-NC4000 participant’s pooled sera exerted a positive effect in stimulating myogenesis and in inducing brown adipogenesis in progenitor cells.

Conclusions

The training program and Ultra-cycling lead to beneficial effects on body composition and biochemical lipid parameters, as well as changes in differentiation of progenitor cells, with significant increases in brown adipogenesis and in MYOD levels.

Abstract 5198: 5AZA and decitabine exhibit different molecular effects on non-Hodgkin lymphoma cells: Involvement of DNMT3a

Introductory sentence. Demethylating drugs represent a powerful tool for epigenetic modulation of chromatin structure in cancer cells. 5-azacytidine (5-AZA) and 5-aza-2’-deoxycytidine (decitabine) are promising therapeutic solutions also in mature B-cell neoplasms, although the molecular mechanisms of action have yet to be elucidated. Here we describe their effects on non-Hodgkin lymphoma cells and demonstrate how hypomethylation is not homogeneous across the genome. Experimental procedures. Toledo (GC-derived) and NU-DUL-1 (ABC-like) diffuse large-B cell lymphoma (DLBCL; non-Hodgkin) cell lines. Peripheral blood mononuclear cells (PBMCs) isolation. Epitect methyl II methylation qPCR and global chromatin methylation quantitative assays. Immunoblottings. Proliferation assays. CpG islands bioinformatics analysis. Comet assay and phosphorylation of gamma-H2AX histone assay. Gene silencing through siRNAs. New data. A panel of 9 CpG islands within a set of genes that we previously identified has been investigated as a potential target for hypomethylating activity of 5AZA and decitabine. KLF4, DAPK1 and SPG20 promoters (located on chr. n°9 the first two and n°3 the latter) are not affected by a single dose of 5AZA after 48h or 7 days of incubation (the CpG islands within these promoters are fully unmethylated in healthy PBMCs). However, global chromatin demethylation is clearly visible either after 48h or 7 days in both cell lines. By comparison, decitabine demethylating effects return to the initial values after 7 days. MZB1 promoter results demethylated by both treatments, while MGMT is demethylated only in NU-DUL-1 by decitabine but not 5AZA. These data suggest that hypomethylating agents act selectively on discrete regions of the genome. 5AZA and decitabine markedly down-regulate DNMT1 in a dose-dependent fashion and activate PARP. Despite DNMT1 downregulation, KLF4, DAPK1 and SPG20 promoters result unaffected. DNMT1 silencing in our cells do not cause any change in the promoter methylation of the selected targets. The de novo methyltransferase DNMT3a is expressed only by NU-DUL-1 and its silencing leads to a partial MZB1 demethylation and to the significant decrease in global chromatin methylation whereas DNMT1 silencing does not. In order to assess an involvement of the genotoxic damage, Comet assays were performed up to 24 hours of incubation with the drugs. We demonstrate that 5AZA does not induce any significant genotoxic damage while decitabine causes a tail formation starting at 6h after drug administration. Conclusions. Our data show that 5AZA and decitabine exhibit different mechanisms of action on lymphoma cells. Different DLBCL-derived cell lines display different changes when exposed to single doses of hypomethylating drugs, underlying the fact that cell of origin may play a role during the response. DNMT3a contributes to chromatin methylation in lymphoma cells.

Citation Format: Raffaele Frazzi, Tonia De Simone, Olga Serra, Annamaria Buschini, Laura Canovi, Tiziana De Luca, Francesco Merli. 5AZA and decitabine exhibit different molecular effects on non-Hodgkin lymphoma cells: Involvement of DNMT3a [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5198.

Abstract 5334: Spg20 (Spartin) promoter methylation identifies tumor B lymphocytes

Introductory sentence. The layer of regulation represented by gene promoter methylation is being investigated in Non-Hodgkin lymphoma (NHL) cell lines, primary B lymphocytes and peripheral blood mononuclear cells (PBMCs). The aim is to assess whether the panel of differentially methylated genes we previously identified is able to distinguish normal B lymphocytes from lymphoma cells.

Experimental procedures. Quantitative, gene-specific methylation assays. Immunosorting of human B lymphocytes. Proliferation assays. 5-azacytidine treatment. NHL-derived cell lines.

New data. Here we show that NHL-derived cell lines display a characteristic profile of promoter methylation on specific tumor suppressors and target genes. A panel of 9 target promoters was selected previously and assessed on a series of healthy and tumor primary B lymphocytes. 4 out of 5 NHL-cell lines show a highly methylated profile on KLF4, DAPK1 and SPG20, at variance with normal B lymphocytes (lymph-node derived) and PBMCs where these targets are completely unmethylated. Interestingly, PBMCs from healthy donors display the same methylation pattern as the one shown by B lymphocytes immunologically sorted from follicular hyperplasias. Spartin (SPG20) emerges here as a differentially methylated gene associated to lymphocyte malignancy, at variance with other tumor suppressors in our panel that show variability among different cell lines. SPG20 is completely or highly methylated in all the tested NHL-cell lines. According to this observation, SPG20 results not methylated in PBMCs as well as sorted non-tumor B lymphocytes. On the contrary, the methylation status of three different BCL6 CpG islands (assessed with the same technique) may vary among different cell lines. In order to investigate what's the functional role of these specific promoters methylation, we treated Toledo and NU-DUL-1 cell lines with the demethylating agent 5-azacytidine (5AZA). We observe that the dose-dependent inhibition of proliferation upon 5AZA is accompanied by a small but reproducible decrease in SPG20 and MZB1 promoter methylation. Experiments aimed at assessing any involvement of DNA methyltransferases DNMT1 and DNMT3a are currently ongoing.

Conclusions. Our data show a consistent methylation profile of 9 gene promoters on 5 different NHL-derived cell lines. Spartin emerges as a completely methylated promoter in the tested tumor cells. PBMCs show a consistent unmethylated profile of Spartin and of all the target genes. The epigenetic regulation of these genes in B-derived lymphomas warrants further investigation.

Citation Format: Raffaele Frazzi, Tonia De Simone, Mariaelena Pistoni, Francesco Merli. Spg20 (Spartin) promoter methylation identifies tumor B lymphocytes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5334.