Biology subjects

Moro, C.

Publications and source records attributed to Moro, C..

6 recordsLinked to original sources

bioRxiv2025

Mobilizable adipose stromal cells fuel regenerative adipogenesis in injured muscle

Skeletal muscle regeneration is a highly orchestrated process involving the dynamic interplay of multiple cell types. Among these, fibro-adipogenic progenitors (FAPs), a population of resident mesenchymal stromal cells (MSCs), are essential for creating a supportive microenvironment that promotes satellite cell differentiation and modulates immune responses. Our recent work revealed that adipose stromal cells (ASCs) from subcutaneous adipose tissue (ScAT) infiltrate the injured muscle within the first 24h post-injury, contributing significantly to the regenerative process. Consequently, the FAP population in the regenerating muscle comprises both resident FAPs and infiltrated ASCs. In the present study, using single cell RNA-seq in a mouse model with trackable KikGR+ ASCs and bioinformatics analyses, we identify Limch1+/Prg4+ ASCs as the primary Mobilizable ASCs (Mob-ASCs) that migrate to and infiltrate the injury site. Notably, this migration is detectable as early as 14 hours post-injury. We demonstrate that these cells are pre-activated within the ScAT, primed to initiate both migratory and regenerative programs. Intriguingly, bioinformatic inference of key activated transcription factors suggested that adipogenesis is also activated in these cells. Leveraging supervised machine learning, we tracked the fate of Mob-ASCs within the regenerating muscle post-injury, where they continue to execute these programs. Importantly, these cells lineage is cued towards a fate of adipogenesis. In vivo, we observed transient generation of adipocytes with a peak at 7-9 days post-injury to which infiltrated ASCs contributed. In vitro, conditioned media assays further revealed that adipocytes derived from ASCs--but not those from FAPs--enhance myoblasts fusion. Collectively, our findings establish Limch1+/Prg4+ ASCs as the Mobilizable ASC population and suggest that their transient adipogenic differentiation is beneficial for muscle regeneration.

physiology↗

bioRxiv2025

MyoFuse: A fully AI-based workflow for automated quantification of skeletal muscle cell fusion in vitro

BackgroundThe myogenic fusion index (FI) is commonly used in skeletal muscle cell culture to assess the ability of myoblasts to form myotubes, as the ratio of myoblast nuclei fused with myotubes over the total number of myoblasts. The manual quantification of the FI from 2D microscopy images is tedious and biased, thus several automated methods have been developed. However, they still face challenges such as efficient nucleus segmentation and classification of fused and isolated myoblast nuclei. Here, we developed a novel workflow entirely based on AI for fully automated and unbiased quantification of the FI. ResultsUsing current methods, we show that myoblast nuclei located above or below myotubes can significantly corrupt accurate FI computation. To circumvent this issue, we developed MyoFuse which enables an accurate and high-throughput segmentation and classification of myonuclei. It comprises a nuclei segmentation step using Cellpose, followed by a classification network trained with Svetlana. MyoFuse demonstrated strong accuracy when tested against manual annotation in mouse C2C12 and human primary myotubes. The trained classifier is able to differentiate myotube nuclei from myoblast nuclei based on myotube cytoplasm staining only. Experimental comparisons also highlighted that the previously developed methods lead to a significant overestimation of the FI. ConclusionIn summary, we underscore the lack of accuracy of traditional methods for automated FI quantification. MyoFuse enables a direct and accurate segmentation of nuclei even in nuclei clusters frequently observed in myotubes. This workflow thus offers a new and more reliable method to evaluate the FI. It also limits the selection bias by processing large images.

cell biology↗

bioRxiv2024

ALTERATIONS IN PEROXISOMAL-MITOCHONDRIAL INTERPLAY IN SKELETAL MUSCLE ACCELERATES MUSCLE DYSFUNCTION

Whole-body energy expenditure, as well as glucose and lipid metabolism, are regulated by skeletal muscles, which account for 40-50% of human body mass. Peroxisomes are dynamic organelles that play a crucial role in lipid metabolism and clearance of reactive oxygen species, however their role in muscles remains poorly understood. To clarify this issue, we generated a muscle-specific transgenic mouse line with peroxisome import deficiency resulting from deletion of peroxisomal biogenesis factor 5 (Pex5). Pex5 inhibition disrupted the tethering between peroxisomes and mitochondria, impaired lipid metabolism and reduced muscle force and exercise performance. Moreover, mitochondrial content and function were also altered, accelerating age-related structural defects, neuromuscular junction degeneration, and muscle atrophy. Altogether, our findings show the importance of preserving peroxisomal function and their contact sites with mitochondria to maintain muscle health during aging.

cell biology↗

bioRxiv2021

Nuclear HMGB1 protects from non-alcoholic fatty liver diseases through negative regulation of liver X receptor

Dysregulations of lipid metabolism in the liver may trigger steatosis progression leading to potentially severe clinical consequences such as non-alcoholic fatty liver diseases (NAFLD). Molecular mechanisms underlying liver lipogenesis are very complex and fine-tuned by chromatin dynamics and the activity of multiple key transcription factors. Here, we demonstrate that the nuclear factor HMGB1 acts as a strong repressor of liver lipogenesis during metabolic stress in NAFLD. Mice with liver-specific Hmgb1-deficiency display exacerbated liver steatosis and hepatic insulin resistance when subjected to a high-fat diet or after fasting/refeeding. Global transcriptome and functional analysis revealed that the deletion of Hmgb1 gene enhances LXR activity resulting in increased lipogenesis. HMGB1 repression is not mediated through nucleosome landscape re-organization but rather via a preferential DNA occupation in region carrying genes regulated by LXR. Together these findings suggest that hepatocellular HMGB1 protects from liver steatosis development. HMGB1 may constitute a new attractive option to therapeutically target LXR axis during NAFLD.

pathology↗

bioRxiv2020

GREM1 is epigenetically reprogrammed in muscle cells after exercise training and controls myogenesis and metabolism

Exercise training improves skeletal muscle function, notably through tissue regeneration by muscle stem cells. Here, we hypothesized that exercise training reprograms the epigenome of muscle cell, which could account for better muscle function. Genome-wide DNA methylation of myotube cultures established from middle-aged obese men before and after endurance exercise training identified a differentially methylated region (DMR) located downstream of Gremlin 1 (GREM1), which was associated with increased GREM1 expression. GREM1 expression was lower in muscle satellite cells from obese, compared to lean mice, and exercise training restored GREM1 levels to those of control animals. We show that GREM1 regulates muscle differentiation through the negative control of satellite cell self-renewal, and that GREM1 controls muscle lineage commitment and lipid oxidation through the AMPK pathway. Our study identifies novel functions of GREM1 and reveals an epigenetic mechanism by which exercise training reprograms muscle stem cells to improve skeletal muscle function.

cell biology↗

bioRxiv2019

Atrial natriuretic peptide orchestrates a coordinated physiological response to fuel non shivering thermogenesis

Atrial natriuretic peptide (ANP) is a cardiac hormone controlling blood volume and arterial pressure in mammals. It is unclear whether and how ANP controls cold-induced thermogenesis in vivo. Here we show that acute cold exposure induces cardiac ANP secretion in mice and humans. Genetic inactivation of ANP promotes cold intolerance and suppresses about half of cold-induced brown adipose tissue (BAT) activation in mice. While white adipocytes are resistant to ANP-mediated lipolysis at thermoneutral temperature in mice, cold exposure renders white adipocytes fully responsive to ANP to activate lipolysis and a thermogenic program, a physiological response which is dramatically suppressed in ANP null mice. ANP deficiency also blunts liver triglycerides and glycogen metabolism thus impairing fuel availability for BAT thermogenesis. ANP directly increases mitochondrial uncoupling and thermogenic genes expression in human white and brown adipocytes. Together, these results indicate that ANP is a major physiological trigger of BAT thermogenesis upon cold exposure in mammals.

physiology↗