Biology subjects

Blaauw, B.

Publications and source records attributed to Blaauw, B..

6 recordsLinked to original sources

bioRxiv2026

Gut Microbiota Fuel Aging Induced by Mitochondrial Dysfunction

Aging is characterized by hallmarks whose mechanistic interdependencies remain poorly defined. Here, we investigate the bi-directional communication between gut microbiota and host mitochondria in the context of immune regulation, healthspan and lifespan. Using a mitochondrial dysfunction PolgAmut mouse model of accelerated aging, we tested the role of mitochondrial dysfunction in modulating microbial homeostasis and aging. We find that impairment of mitochondrial function hastens the decline of microbiota structure over time and induces immune dysregulation and inflammation through metabolic reprogramming of the myeloid immune subset. Further, we find that gut microbiota drives a paradoxical energy state by reducing mitochondrial function systemically while simultaneously driving energy-intensive programs including immune remodelling and protein synthesis, through mTOR signaling. Thus, aging emerges from the progressive imbalance between microbiota-driven energetic demand and declining mitochondrial energy supply. We postulate that microbiota promote host early-life fitness, at the cost of amplifying metabolic stress and inflammation later in life.

microbiology↗

bioRxiv2025

Antxr2-mediated fine-tuning of Collagen VI ensures skeletal muscle function

Tissue function relies on the extracellular matrix (ECM) that surrounds cells, providing structural and biochemical support. The complex ECM composition depends on an adequately tuned balance between the deposition and degradation of each of its components. Disequilibrium may cause disease, as observed for Collagen VI (COL6), for which mutations lead to muscular dystrophy. Here, we investigated the role of Anthrax Toxin Receptor 2 (ANTXR2/CMG2), a receptor that controls the turnover of COL6, in skeletal muscle. We show that ANTXR2 is mostly expressed by fibro-adipogenic precursors and that its deficiency in ANTXR2 null (Antxr2-/-) mice leads to a premature and irregular COL6 accumulation in intramuscular connective tissue. This results in tissue stiffening and gradual, non-functional muscle hypertrophy, marked by impaired locomotion and myopathic signs. Our findings further indicate that COL6 accretion drives these alterations, as revealed by Antxr2-/-::Col6a1-/- double knockout mice, highlighting the essential role of ANTXR2-mediated COL6 remodeling in maintaining ECM homeostasis and muscle functionality. SIGNIFICANCE STATEMENTRemodelling of the extracellular matrix (ECM) was long thought to rely almost exclusively on extracellular proteases. Increasing evidence, however, indicates that some ECM components may undergo intracellular degradation following receptor-mediated endocytosis, as we have found for Collagen VI (COL6). Here, we identify the COL6 receptor ANTXR2 as a critical regulator of ECM turnover in skeletal muscle.. When ANTXR2 is absent, COL6 builds up, followed by the accumulation of fibrillar collagens, without changes in gene expression. These alterations in muscle ECM lead to increased stiffness, myofiber defects and impaired locomotor activity. Our findings establish ANTXR2 as a key regulator in ECM remodelling, offering new insights into potential treatments for conditions associated with defective ECM remodeling, such as aging and congenital muscular dystrophies.

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↗

bioRxiv2023

Mitochondrial Calcium Uptake Declines during Aging and is Directly Activated by Oleuropein to Boost Energy Metabolism and Skeletal Muscle Performance

Mitochondrial calcium (mtCa2+) uptake via the Mitochondrial Calcium Uniporter (MCU) couples the regulation of calcium homeostasis to energy production. mtCa2+ uptake is rate-limiting for mitochondrial activation during muscle contraction, but how MCU is affected during physiopathology and whether it can be stimulated therapeutically remains largely uncharacterized. By profiling human and preclinical aging of skeletal muscle, we discovered a conserved down-regulation of MCUR1 during aging that decreases mtCa2+ uptake and drives sarcopenia. Through a screen of 5000 bioactive nutrients, we identify the natural polyphenol Oleuropein as a specific MCU activator that stimulates mitochondrial respiration via binding to MICU1. Oleuropein activates mtCa2+ uptake and oxidative energy metabolism to enhance endurance and limit fatigue in vivo both in young and aged. These effects of Oleuropein are mediated by an MCU-dependent mechanism in skeletal muscle as they are lost upon muscle-specific MCU KO. Our work demonstrates that impaired mtCa2+ uptake causes mitochondrial dysfunction during aging and establishes Oleuropein as a novel nutrient that specifically targets MCU to stimulate mitochondrial bioenergetics and muscle performance.

physiology↗

bioRxiv2020

Biofabricating murine and human myo-substitutes for rapid volumetric muscle loss restoration

The importance of skeletal muscle tissue is undoubted being the controller of several vital functions including respiration and all voluntary locomotion activities. However, its regenerative capability is limited and significant tissue loss often leads to a chronic pathologic condition known as volumetric muscle loss. Here, we propose a biofabrication approach to rapidly restore skeletal muscle mass, 3D histoarchitecture and functionality. By recapitulating muscle anisotropic organization at the microscale level, we demonstrate to efficiently guide cell differentiation and myobundle formation both in vitro and in vivo. Of note, upon implantation, the biofabricated myo-substitutes support the formation of new blood vessels and neuromuscular junctions - pivotal aspects for cell survival and muscle contractile functionalities - together with an advanced along with muscle mass and force recovery. Together, these data represent a solid base for further testing the myo-substitutes in large animal size and a promising platform to be eventually translated into clinical scenarios.

bioengineering↗

bioRxiv2019

Polyglutamine-expanded androgen receptor disrupts muscle triad, calcium dynamics and the excitation-contraction coupling gene expression program

Spinal and bulbar muscular atrophy (SBMA) is caused by polyglutamine (polyQ) expansions in the androgen receptor (AR) gene. Although clinical and experimental evidence highlight a primary role for skeletal muscle in the onset, progression, and outcome of disease, the pathophysiological and molecular processes underlying SBMA muscle atrophy are poorly understood. Here we show that polyQ-expanded AR alters intrinsic muscle force generation before denervation. Reduced muscle force was associated with a switch in fiber-type composition, disrupted muscle striation, altered calcium (Ca++) dynamics in response to muscle contraction, and aberrant expression of excitation-contraction coupling (ECC) machinery genes in transgenic, knock-in and inducible SBMA mice and patients. Importantly, treatment to suppress polyQ-expanded AR toxicity restored ECC gene expression back to normal. Suppression of AR activation by surgical castration elicited similar ECC gene expression changes in normal mice, suggesting that AR regulates the expression of these genes in physiological conditions. Bioinformatic analysis revealed the presence of androgen-responsive elements on several genes involved in muscle function and homeostasis, and experimental evidence showed AR-dependent regulation of expression and promoter occupancy of the most up-regulated gene from transcriptomic analysis in SBMA muscle, i.e. sarcolipin, a key ECC gene. These observations reveal an unpredicted role for AR in the regulation of expression of genes involved in muscle contraction and Ca++ dynamics, a level of muscle function regulation that is disrupted in SBMA muscle, yet restored by pharmacologic treatment.

neuroscience↗