Biology subjects

Marchioretto, M.

Publications and source records attributed to Marchioretto, M..

4 recordsLinked to original sources

bioRxiv2025

Model-independent reorganization of translation in TDP-43 Amyotrophic Lateral Sclerosis

The RNA-binding protein TDP-43 is a major contributor and a pathological hallmark of Amyotrophic Lateral Sclerosis (ALS), yet how TDP-43 dysregulation mechanistically alters protein synthesis across neuronal compartments and disease models remains unclear. Here, we dissected TDP-43-driven translational alterations in both in vitro and in vivo TDP-43 models of ALS. Through ribosome and polysome profiling, computational, and biochemical analyses, we observed robust TDP-43-associated translational remodelling at cellular and subcellular resolution. Our findings reveal a conserved mechanism across models, characterized by enhanced ribosome recruitment on polysomes, elongation impairment, axonal downregulation and instability of TDP-43 target mRNAs and redistribution toward non-target transcripts. Notably, TDP-43 dysregulation alters ribosome dynamics and selectively impairs translation of TDP-43 target mRNAs, whilst favouring the translation of other transcripts. This process reflects a compensatory but maladaptive response to TDP-43-induced mRNA destabilization. Together, these data demonstrate that alterations in TDP-43 disrupts neuronal proteostasis through ribosome reorganization and loss of mRNA homeostasis, providing a unifying mechanistic framework for translational imbalance in ALS and revealing early molecular events that may underlie motor neuron vulnerability.

molecular biology↗

bioRxiv2023

Two neuronal models of TDP-43 proteinopathy display reduced axonal translation, increased oxidative stress, and defective exocytosis.

Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neurodegenerative disease mostly affecting people around 50-60 years of age. TDP-43, a ubiquitously expressed RNA-binding protein involved in pre-mRNA splicing and controlling mRNA stability and translation, forms neuronal cytoplasmic inclusions in an overwhelming majority of ALS patients, of both sporadic and familial origin, a phenomenon referred to as TDP-43 proteinopathy. These cytoplasmic aggregates disrupt the subcellular transport and localization of mRNA. The axon, like dendrites, is a site of mRNA translation, permitting the local synthesis of selected proteins, both constitutively and in response to stimuli reaching the axon and presynaptic terminal. This is especially relevant in upper and lower motor neurons, whose axon spans long distances, likely accentuating their susceptibility to ALS-related noxae. In this work we have generated and characterized two models of TDP-43 proteinopathy, consisting of virtually pure populations of mouse cortical neurons expressing a human TDP-43 fusion protein, wt or mutant, which accumulates as cytoplasmic aggregates. Neurons expressing human TDP-43 exhibit a global impairment in axonal protein synthesis, an increase in oxidative stress, and defects in presynaptic function and electrical activity. These changes correlate with deregulation in the axonal levels of polysome-engaged mRNAs playing relevant roles in those processes. Our data support the emerging notion that deregulation of mRNA metabolism and of axonal mRNA transport may trigger the dying-back neuropathy that initiates motor neuron degeneration in ALS.

neuroscience↗

bioRxiv2019

SMN-primed ribosomes modulate the translation of transcripts related to Spinal Muscular Atrophy

The contribution of ribosome heterogeneity and ribosome-associated factors to the molecular control of proteomes in health and disease remains enigmatic. We demonstrate that Survival Motor Neuron (SMN) protein, loss of which causes the neuromuscular disease spinal muscular atrophy (SMA), binds to ribosomes and that this interaction is tissue-dependent. SMN-primed ribosomes are positioned within the first five codons of a set of mRNAs which are enriched in IRES-like sequences in the 5UTR and rare codons at the beginning of their coding sequence. Loss of SMN at early-stages of SMA induces translational defects in vivo, characterized by ribosome depletion in rare codons at the third and fifth position of the coding sequence. These positional defects cause ribosome depletion from mRNAs bound by SMN-primed ribosomes and translational impairment of proteins involved in motor neuron function and stability, including acetylcholinesterase. Thus, SMN plays a crucial role in the regulation of ribosome fluxes along mRNAs which encode proteins relevant to SMA pathogenesis.

neuroscience↗

bioRxiv2018

Hfq CLASH uncovers sRNA-target interaction networks enhancing adaptation to nutrient availability

By shaping gene expression profiles, small RNAs (sRNAs) enable bacteria to very efficiently adapt to constant changes in their environment. To better understand how Escherichia coli acclimatizes to changes in nutrient availability, we performed UV cross-linking, ligation and sequencing of hybrids (CLASH) to uncover sRNA-target interactions. Strikingly, we uncovered hundreds of novel Hfq-mediated sRNA-target interactions at specific growth stages, involving many novel 3UTR-derived sRNAs and a plethora of sRNA-sRNA interactions. We discovered sRNA-target interaction networks that play a role in adaptation to changes in nutrient availability. We characterized a novel 3UTR-derived sRNA (MdoR), which is part of a regulatory cascade that enhances maltose uptake by (a) inactivating repressive pathways that block the accumulation of maltose transporters and (b) by reducing the flux of general porins to the outer membrane. Our work provides striking examples of how bacteria utilize sRNAs to integrate multiple regulatory pathways to enhance nutrient stress adaptation.

systems biology↗