Biology subjects

Prola, A.

Publications and source records attributed to Prola, A..

7 recordsLinked to original sources

bioRxiv2026

Metabolic Heterogeneity of Muscle Stem Cells is Controlled by the Myofiber Niche

Metabolic pathways support biomass synthesis and provide substrates for epigenetic modifications of histones and DNA. These findings are particularly relevant for adult stem cells, where metabolic changes significantly impact functional behavior. However, assessing the metabolism of these cells in their native microenvironment is challenging as this typically necessitates dissociation prior to metabolic analysis. In this study, we focus on muscle stem cells (MuSCs) and show that removing these cells from the niche significantly alters their metabolic profile. To overcome this issue, we developed a novel enzymatic staining method for in situ metabolic profiling at a single-cell resolution. This approach reveals unexpected metabolic heterogeneity of MuSCs, identifying oxidative and glycolytic subsets, and demonstrates that their metabolism is directly modulated by adjacent myofibers. Accordingly, perturbing myofiber metabolism remodels the MuSC niche and drives metabolic adaptation in MuSCs. Finally, we define the kinetics by which myofiber-dependent metabolic regulation of MuSCs is re-established during muscle regeneration, thereby revealing how niche-imposed metabolic cues shape stem cell identity in vivo.

physiology↗

bioRxiv2025

Skeletal muscle fibre type determines mitochondrial and metabolic responses to hypoxia and pulmonary inflammation.

BackgroundChronic obstructive pulmonary disease (COPD) patients often experience skeletal muscle dysfunction that may result from a complex combination of mitochondrial dysfunction, metabolic reprogramming and fibre type transitions. Among other factors, pulmonary inflammation and hypoxia contribute to the COPD-associated muscle defects. Nevertheless, the precise molecular mechanisms and their effects across muscles with distinct metabolic profiles remain elusive. This study investigated the independent and combined effects of chronic pulmonary inflammation and chronic hypoxia on mitochondrial function, metabolic enzyme activity and fibre type composition in oxidative (soleus) and glycolytic (plantaris) muscles. MethodsAdult male Wistar rats were subjected to chronic hypoxia (FiO2=10%) and/or chronic pulmonary inflammation (induced by bi-weekly intratracheal instillations of lipopolysaccharides). After 4 weeks of exposure, mitochondria from both soleus and plantaris were isolated to measure oxygen consumption rates, reactive oxygen species (ROS) emission, calcium retention capacity (CRC), respiratory complex activities and fatty acid oxidation capacity. Cross-sections from both muscles were analysed for fibre typology, fibre cross-sectional area (fCSA) as well as succinate dehydrogenase (SDH) and glycerol-3-phosphate dehydrogenase (GPDH) activities. ResultsChronic hypoxia led to a decline in adenosine diphosphate-stimulated complex I (CI) respiration (p<0.01), Hydroxyacyl-Coenzyme A dehydrogenase activity (p<0.01), weight (p<0.05) and fCSA of type IIb fibres (p < 0.05) in plantaris. In contrast, chronic hypoxia increased CI-derived ROS emission (p<0.01) without changes in mitochondrial respiration or mass of soleus. No alterations in fibre typology were noticed in either muscle following the hypoxic exposure. Chronic pulmonary inflammation caused a reduction in mitochondrial CRC and an increase in GPDH activity in type IIa fibres of soleus (p<0.001) without any changes in fibre type distribution. Conversely, chronic pulmonary inflammation induced a downregulation of GPDH activity in plantaris type I and type IIa fibres, in parallel with an elevation in the SDH/GPDH ratio across all fibre types and a rise in the proportion of type IIx fibres. ConclusionsOur results demonstrate fundamental differences in the responses to chronic hypoxia and chronic pulmonary inflammation between soleus and plantaris. While hypoxia affects predominantly the mitochondrial function and mass of plantaris, pulmonary inflammation drives metabolic reprogramming in both muscles that opposes their intrinsic functional specialisation. Additionally, soleus appears more vulnerable to permeability transition pore opening following pulmonary inflammation. Notably, these mitochondrial alterations seem to occur independently of fibre type shifts highlighting the central role of intrinsic mitochondrial maladaptations in the COPD-associated muscle dysfunction.

physiology↗

bioRxiv2025

CtBP1 coordinates synaptic, metabolic and contractile changes induced by denervation in skeletal muscle

Nerve injury triggers dramatic atrophy of skeletal muscle, accompanied with synaptic and metabolic changes. Regulation of denervation-induced muscle fiber remodeling involves several factors governing genetic reprogramming and proteostasis changes. Here, we demonstrate that the transcriptional co-repressor CtBP1 coordinates synaptic and metabolic changes in muscle fibers upon denervation. CtBP1 was present both in sub- and non-synaptic myonuclei in innervated muscle. Although CtBP1 levels remained unchanged in denervated muscle, CtBP1 accumulated transiently in myonuclei after 2 days of denervation. Ctbp1 knockdown perturbed the expression of a large set of activity-independent and -dependent genes in innervated and denervated skeletal muscles. CtBP1 loss had limited effect on the expression of most synaptic genes, but increased transcript levels of Chrne, encoding the adult {varepsilon} sub-unit of acetylcholine receptors (AChR). However, it did not affect AChR turnover or maintenance of the post-synaptic compartment upon denervation. Importantly, we uncovered that Ctbp1 knockdown promotes denervation-induced changes in metabolic gene expression, including most genes encoding proteins of the respiratory chain complexes. Consistently, it enhanced the switch towards slower, oxidative fibers in fast muscle after 2 weeks of denervation. Moreover, CtBP1 loss precipitated the profound ultrastructural remodeling of mitochondria network induced after denervation. Hence, our study unveils the role of CtBP1 in the integrated muscle response to denervation, with important implications for CtBP1-related muscle diseases. One-sentence summaryLoss of CtBP1 perturbs synaptic, metabolic and contractile changes induced by denervation in skeletal muscle

physiology↗

bioRxiv2024

Cardiolipin deficiency disrupts CoQ redox state and induces steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to metabolic dysfunction-associated steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress. Specifically, mitochondrial cardiolipin (CL) was downregulated with MASLD/MASH in humans and in mice. Hepatocyte-specific CL synthase knockout (CLS-LKO) led to spontaneous and robust MASH with extensive steatotic and fibrotic phenotype. Loss of CL paradoxically increased mitochondrial respiratory capacity but also promoted electron leak primarily at sites IIIQO and IIF of the electron transport chain, reduced the formation of I+III2+IV respiratory supercomplex, and disrupted the propensity of coenzyme Q (CoQ) to become reduced. Thus, low mitochondrial CL disrupts electron transport chain to promote oxidative stress and contributes to pathogenesis of MASH.

biochemistry↗

bioRxiv2024

mTORC1-dependent SOCE activity regulates synaptic gene expression and muscle response to denervation

Neuromuscular junction (NMJ) instability is central in muscle dysfunction occurring in neuromuscular disorders and aging. NMJ maintenance requires regionalized regulation of synaptic genes, previously associated with Ca2+-dependent pathways. However, what sustains Ca2+ micro-domains in myofibers and allows a rapid response to denervation is not known. Here, we identify that Store-Operated Calcium Entry (SOCE) plays a critical role in synaptic gene regulation. SOCE components show differential enrichment in sub- and non-synaptic muscle regions. Especially, STIM1 accumulation at rough endoplasmic reticulum associates with functional SOCE at the endplate. Denervation increases SOCE in non- and sub-synaptic regions, together with reticulum remodeling. Stim1 knockdown hampers denervation-induced synaptic gene up-regulation, while STIM1 overexpression increases synaptic gene expression in innervated muscle. Finally, mTORC1 activation mimics the effect of denervation on SOCE capacity, STIM1 localization and reticulum remodeling. Together, our results reveal a decisive role of SOCE in sensing innervation and regulating muscle response to denervation. They further suggest that SOCE perturbation may contribute to neuromuscular integrity loss in pathological conditions associated with mTORC1 dysregulation.

physiology↗

bioRxiv2023

PINK1 Deficiency Alters Muscle Stem Cell Fate Decision And Muscle Regenerative Capacity.

Maintenance of optimal mitochondrial function plays a crucial role in the regulation of muscle stem cell (MuSC) behavior, but the underlying maintenance mechanisms remain ill defined. In this study, we explored the importance of mitophagy, as a mitochondrial quality control regulator, in MuSCs and the role this process plays in maintaining optimal muscle regenerative capacity. Here we show that MuSCs exhibit dynamic alterations in mitophagy under different physiological myogenic states. In particular, quiescent MuSCs exhibit high levels of PINK1/Parkin-dependent mitophagy, which is rapidly decreased upon transition to an early activation state. Genetic disruption of this pathway using Pink1 knockout mice reduced mitophagy in quiescent MuSCs, which was accompanied by increased mitochondrial ROS release and mitochondrial network fragmentation. These abnormalities led to hampered self-renewal of MuSCs which ultimately translated in a progressive loss of muscle regeneration following repetitive injury. However, proliferation and differentiation capacity were unaltered in the absence of PINK1, indicating that altered fate decisions is the main mechanism underlying impaired muscle regeneration. Impaired fate decisions in PINK1 deficient MuSCs could be restored by scavenging excess mitochondrial ROS. Together, these data shed new light on the regulation of mitophagy during MuSC state transitions and position the PINK1-dependent pathway as an important regulator of MuSC mitochondrial properties and fate decisions.

cell biology↗

bioRxiv2019

Alteration of cardiolipin-dependent mitochondrial coupling in muscle protects against obesity

The tubular shape of mitochondrial cristae depends upon a specific composition of the inner mitochondrial membrane, including cardiolipin that allows strong curvature and promotes optimal organization of ATP synthase. Here we identify Hacd1, which encodes an enzyme involved in very long chain fatty acid biosynthesis, as a key regulator of composition, structure and functional properties of mitochondrial membranes in muscle. In Hacd1-deficient mice, the reduced cardiolipin content was associated with dilation of cristae and caused defective phosphorylating respiration, characterized by absence of proton leak and oxidative stress.\n\nThe skeletal muscle-specific mitochondrial coupling defect produced a global elevation in basal energy expenditure with increased carbohydrate and lipid catabolism, despite decreased muscle mass and locomotor capacities. Mice were protected against diet-induced obesity despite reduced muscle activity, providing an in vivo proof of concept that reducing mitochondrial coupling efficiency in skeletal muscle might be an actionable mechanism in metabolic disease conditions.

cell biology↗