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Quantitative proteomic analysis of Survival Motor Neuron (SMN) missense mutants in Drosophila

ABSTRACT: Spinal Muscular Atrophy (SMA) is a devastating neuromuscular disease caused by hypomorphic loss of function in the Survival Motor Neuron (SMN) protein. SMA presents across broad spectrum of disease severity. Unfortunately, vertebrate models of intermediate SMA have been difficult to generate and are thus unable to address key aspects of disease etiology. To address these issues, we developed a Drosophila model system that recapitulates the full range of SMA severity, allowing studies of pre-onset biology as well as late-stage disease processes. In this study, TMT-based quantitative proteomic profiling was performed on mild and intermediate Drosophila models of SMA to elucidate proteins and pathways that contribute to the disease. Using this approach, we elaborated a role for the SMN complex in the regulation of innate immune signaling.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Drosophila Melanogaster (fruit Fly)

TISSUE(S): Whole Body

SUBMITTER: Laura Herring

LAB HEAD: Greg Matera

PROVIDER: PXD046801 | Pride | 2024-04-11

REPOSITORIES: Pride

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Transcriptomic comparison of Drosophila snRNP biogenesis mutants reveals mutant-specific changes in pre-mRNA processing: implications for Spinal Muscular Atrophy

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Project description:Spinal muscular atrophy (SMA) is a neuromuscular disease caused by mutations in the survival of motor neuron (SMN) gene. Although the primary manifestation of SMA is degeneration of motor neurons in a dying-back manner, deficient SMN intrinsic to motor neurons does not cause severe motor neuron loss, as is the case in SMA mouse models. Thus, the involvement of non-neuronal cells in the pathogenesis of SMA has been suggested. Here, we report that a novel subset of fibro-adipogenic progenitors expressing Dpp4 (Dpp4+ FAPs) is required for the survival of motor neurons, in which BRCA1-associating protein 1 (Bap1) is crucial for the stabilization of SMN by preventing its ubiquitination-dependent degradation. Inactivation of Bap1 in FAPs decreased SMN levels and accompanied degeneration of the neuromuscular junction, leading to dying-back loss of motor neurons and muscle atrophy, reminiscent of SMA pathogenesis. Overexpression of ubiquitination-resistant SMN variant, SMNK186R, in Bap1-null FAPs completely prevented neuromuscular degenerations. In addition, transplantation of Dpp4+ FAPs, but not Dpp4- FAPs, completely rescued neuromuscular defects in the mutant mice. Our data revealed that Bap1-mediated stabilization of SMN in Dpp4+ FAPs is crucial for the survival of motor neurons and provided a new therapeutic approach to treat SMA.

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Ribosome profiling of SMN-primed ribosomes and active ribosome profiling from brains of a mouse model of severe SMA

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