👤 Mariana Dupont

Studies have shown that sarcopenia and its related parameters are associated with cognition. Preclinical evidence suggests that myokines, such as irisin, Brain-Derived Neurotrophic Factor(BDNF), myostatin and Insulin-like Growth Factor-1(IGF-1) might explain this relationship. This study aimed to explore the associations between sarcopenia-related parameters and cognition, and whether myokines influence this association. Exploratory, cross-sectional analysis of data from the Exercise and Nutrition for Healthy AgeiNg (ENHANce,NCT03649698) study. Participants were older adults(≥65 years) with EWGSOP2-defined sarcopenia. Cognitive functioning was assessed by Mini-Mental State Examination(MMSE), Repeatable Battery for the Assessment of Neuropsychological Status(RBANS), Trail Making Test A&B(TMT), Stroop and Maze Test. Sarcopenia-related parameters were measured: Handgrip Strength, Chair Stand Test, appendicular Lean Mass(aLM), Gait Speed (GS) and Short Physical Performance Battery(SPPB). Serum myokines(IGF-1, irisin, myostatin, BDNF) were determined through ELISA. Associations between cognition and sarcopenia-related parameters were analyzed using multivariable regression, adjusting for potential confounders including myokines. Fifty-eight participants were included in this analysis (76.2 ± 6.7 years, ♀:65.5%). After adjustment for age, sex, body mass index, aLM was associated with MMSE(β = 0.193,p = 0.012), RBANS Total(β = 0.196,p = 0.007) and RBANS Attention(β = 0.215,p = 0.002), CST was associated with RBANS Language(β = -0.314,p = 0.030), SPPB was associated with Maze time(β = -0.364,p = 0.004) and TMT-B (β = -0.333,p = 0.013) and GS was associated with TMT-A(β = -0.324,p = 0.045). After adjustments for BDNF& IGF-1, the association between GS and TMT-A became non-significant. Irisin and myostatin did not influence the sarcopenia-cognition associations. Sarcopenia-related parameters are associated with global and specific cognitive domains. BDNF may, partially, explain the association between muscle mass and MMSE. Additional research with larger sample size is needed to confirm these findings. Show less

Our previous studies have identified phoenixin-14 (PNX-14) and its receptor GPR173 in the porcine corpus luteum (CL) during the estrous cycle and their role in the endocrine function. This study explored PNX-14's impact on luteal angiogenesis, proliferation, and apoptosis. Luteal cells were cultured with PNX-14 at doses 1-1000 nM for 24-72 h. Then, the transcript level and secretion of angiogenic factors (VEGFA, bFGF2, ANG-1) and protein expression of their receptors (VEGFR1, VEGFR2, FGFR1, FGFR2, TIE2) were analysed. Cell proliferation was assessed using the alamarBlue assay, whereas DNA fragmentation and caspase 3/7 activity through Cell Death Detection ELISA and CaspaseGlo 3/7 assay, respectively. We also examined mRNA and protein levels of proliferating cell nuclear antigen (PCNA), cyclins, and apoptotic factors. Using pharmacological inhibitors of extracellular signal-regulated kinases 1/2 (ERK1/2), protein kinase B (AKT), 5'AMP-activated protein kinase (AMPK), and silencing of GPR173 by siRNA we checked their involvement in PNX-14 action in CL. The results showed that PNX-14 increased levels of bFGF2 and ANG-1, and protein expression of VEGFR2, FGFR1, and TIE2, while it decreased FGFR2. It enhanced luteal cell proliferation and PCNA expression, with variable effects on transcript and protein levels of cyclins. Moreover, PNX-14 decreased DNA fragmentation and caspase 3/7 activity, expression of caspases 3, 8, 9, and BAX, and increased BCL2. Additionally, GPR173 receptor and ERK1/2, AKT, and AMPK are involved in PNX-14 action on luteal function. In conclusion, PNX-14 acts as a luteotropic factor in the porcine CL by promoting angiogenesis, proliferation, and protection against apoptosis. Show less

Autophagic pathways cross with lipid homeostasis and thus provide energy and essential building blocks that are indispensable for liver functions. Energy deficiencies are compensated by breaking down lipid droplets (LDs), intracellular organelles that store neutral lipids, in part by a selective type of autophagy, referred to as lipophagy. The process of lipophagy does not appear to be properly regulated in fatty liver diseases (FLDs), an important risk factor for the development of hepatocellular carcinomas (HCC). Here we provide an overview on our current knowledge of the biogenesis and functions of LDs, and the mechanisms underlying their lysosomal turnover by autophagic processes. This review also focuses on nonalcoholic steatohepatitis (NASH), a specific type of FLD characterized by steatosis, chronic inflammation and cell death. Particular attention is paid to the role of macroautophagy and macrolipophagy in relation to the parenchymal and non-parenchymal cells of the liver in NASH, as this disease has been associated with inappropriate lipophagy in various cell types of the liver. Show less

Homo sapiens evolved under conditions of intermittent food availability and prolonged fasting between meals. Periods of fasting are important for recovery from meal-induced oxidative and metabolic stress, and tissue repair. Constant high energy-density food availability in present-day society contributes to the pathogenesis of chronic diseases, including diabetes and its complications, with intermittent fasting (IF) and energy restriction shown to improve metabolic health. We have previously demonstrated that IF prevents the development of diabetic retinopathy in a mouse model of type 2 diabetes (db/db); however the mechanisms of fasting-induced health benefits and fasting-induced risks for individuals with diabetes remain largely unknown. Sirtuin 1 (SIRT1), a nutrient-sensing deacetylase, is downregulated in diabetes. In this study, the effect of SIRT1 stimulation by IF, fasting-mimicking cell culture conditions (FMC) or pharmacological treatment using SRT1720 was evaluated on systemic and retinal metabolism, systemic and retinal inflammation and vascular and bone marrow damage. The effects of IF were modelled in vivo using db/db mice and in vitro using bovine retinal endothelial cells or rat retinal neuroglial/precursor R28 cell line serum starved for 24 h. mRNA expression was analysed by quantitative PCR (qPCR). SIRT1 activity was measured via histone deacetylase activity assay. NR1H3 (also known as liver X receptor alpha [LXRα]) acetylation was measured via western blot analysis. IF increased Sirt1 mRNA expression in mouse liver and retina when compared with non-fasted animals. IF also increased SIRT1 activity eightfold in mouse retina while FMC increased SIRT1 activity and expression in retinal endothelial cells when compared with control. Sirt1 expression was also increased twofold in neuronal retina progenitor cells (R28) after FMC treatment. Moreover, FMC led to SIRT1-mediated LXRα deacetylation and subsequent 2.4-fold increase in activity, as measured by increased mRNA expression of the genes encoding ATP-binding cassette transporter (Abca1 and Abcg1). These changes were reduced when retinal endothelial cells expressing a constitutively acetylated LXRα mutant were tested. Increased SIRT1/LXR/ABC-mediated cholesterol export resulted in decreased retinal endothelial cell cholesterol levels. Direct activation of SIRT1 by SRT1720 in db/db mice led to a twofold reduction of diabetes-induced inflammation in the retina and improved diabetes-induced visual function impairment, as measured by electroretinogram and optokinetic response. In the bone marrow, there was prevention of diabetes-induced myeloidosis and decreased inflammatory cytokine expression. Taken together, activation of SIRT1 signalling by IF or through pharmacological activation represents an effective therapeutic strategy that provides a mechanistic link between the advantageous effects associated with fasting regimens and prevention of microvascular and bone marrow dysfunction in diabetes. Show less

Beta cell failure and apoptosis following islet inflammation have been associated with autoimmune type 1 diabetes pathogenesis. As conveyors of biological active material, extracellular vesicles (EV) act as mediators in communication with immune effectors fostering the idea that EV from inflamed beta cells may contribute to autoimmunity. Evidence accumulates that beta exosomes promote diabetogenic responses, but relative contributions of larger vesicles as well as variations in the composition of the beta cell's vesiculome due to environmental changes have not been explored yet. Here, we made side-by-side comparisons of the phenotype and function of apoptotic bodies (AB), microvesicles (MV) and small EV (sEV) isolated from an equal amount of MIN6 beta cells exposed to inflammatory, hypoxic or genotoxic stressors. Under normal conditions, large vesicles represent 93% of the volume, but only 2% of the number of the vesicles. Our data reveal a consistently higher release of AB and sEV and to a lesser extent of MV, exclusively under inflammatory conditions commensurate with a 4-fold increase in the total volume of the vesiculome and enhanced export of immune-stimulatory material including the autoantigen insulin, microRNA, and cytokines. Whilst inflammation does not change the concentration of insulin inside the EV, specific Toll-like receptor-binding microRNA sequences preferentially partition into sEV. Exposure to inflammatory stress engenders drastic increases in the expression of monocyte chemoattractant protein 1 in all EV and of interleukin-27 solely in AB suggesting selective sorting toward EV subspecies. Functional Show less

Primary cilium-dependent macroautophagy/autophagy is induced by the urinary flow in epithelial cells of the kidney proximal tubule. A major physiological outcome of this cascade is the control of cell size. Some components of the ATG machinery are recruited at the primary cilium to generate autophagic structures. Shear stress induced by the liquid flow promotes PtdIns3P synthesis at the primary cilium, and this lipid is required both for ciliogenesis and initiation of autophagy. We showed that PtdIns3P is generated by PIK3C2A, but not by PIK3C3/VPS34, during flow-associated primary cilium-dependent autophagy, in a ULK1-independent manner. Along the same line BECN1 (beclin 1), a partner of PIK3C3 in starvation-induced autophagy, is not recruited at the primary cilium under shear stress. Thus, kidney epithelial cells mobilize different PtdIns 3-kinases, PtdIns3P: phosphatidylinositol-3-phosphate; PIK3C2A: class two alpha phosphatidylinositol 3-kinase; PIK3C3/VPS34: class three phosphatidylinositol 3-kinase; ATG: autophagy associated genes. Show less

Cells subjected to stress situations mobilize specific membranes and proteins to initiate autophagy. Phosphatidylinositol-3-phosphate (PI3P), a crucial lipid in membrane dynamics, is known to be essential in this context. In addition to nutriments deprivation, autophagy is also triggered by fluid-flow induced shear stress in epithelial cells, and this specific autophagic response depends on primary cilium (PC) signaling and leads to cell size regulation. Here we report that PI3KC2α, required for ciliogenesis and PC functions, promotes the synthesis of a local pool of PI3P upon shear stress. We show that PI3KC2α depletion in cells subjected to shear stress abolishes ciliogenesis as well as the autophagy and related cell size regulation. We finally show that PI3KC2α and VPS34, the two main enzymes responsible for PI3P synthesis, have different roles during autophagy, depending on the type of cellular stress: while VPS34 is clearly required for starvation-induced autophagy, PI3KC2α participates only in shear stress-dependent autophagy. Show less

Balanced chromosomal rearrangements associated with abnormal phenotype are rare events, but may be challenging for genetic counselling, since molecular characterisation of breakpoints is not performed routinely. We used next-generation sequencing to characterise breakpoints of balanced chromosomal rearrangements at the molecular level in patients with intellectual disability and/or congenital anomalies. Breakpoints were characterised by a paired-end low depth whole genome sequencing (WGS) strategy and validated by Sanger sequencing. Expression study of disrupted and neighbouring genes was performed by RT-qPCR from blood or lymphoblastoid cell line RNA. Among the 55 patients included (41 reciprocal translocations, 4 inversions, 2 insertions and 8 complex chromosomal rearrangements), we were able to detect 89% of chromosomal rearrangements (49/55). Molecular signatures at the breakpoints suggested that DNA breaks arose randomly and that there was no major influence of repeated elements. Non-homologous end-joining appeared as the main mechanism of repair (55% of rearrangements). A diagnosis could be established in 22/49 patients (44.8%), 15 by gene disruption ( Paired-end WGS is a valid strategy and may be used for structural variation characterisation in a clinical setting. Show less

To obtain mechanistic insights into the cross talk between lipolysis and autophagy, two key metabolic responses to starvation, we screened the autophagy-inducing potential of a panel of fatty acids in human cancer cells. Both saturated and unsaturated fatty acids such as palmitate and oleate, respectively, triggered autophagy, but the underlying molecular mechanisms differed. Oleate, but not palmitate, stimulated an autophagic response that required an intact Golgi apparatus. Conversely, autophagy triggered by palmitate, but not oleate, required AMPK, PKR and JNK1 and involved the activation of the BECN1/PIK3C3 lipid kinase complex. Accordingly, the downregulation of BECN1 and PIK3C3 abolished palmitate-induced, but not oleate-induced, autophagy in human cancer cells. Moreover, Becn1(+/-) mice as well as yeast cells and nematodes lacking the ortholog of human BECN1 mounted an autophagic response to oleate, but not palmitate. Thus, unsaturated fatty acids induce a non-canonical, phylogenetically conserved, autophagic response that in mammalian cells relies on the Golgi apparatus. Show less