Regulation of cell proliferation by fast Myosin light chain 1 in myoblasts derived from extraocular muscle, diaphragm and gastrocnemius

Increased ocular plasma cells induce damaging α-synuclein+ microglia in autoimmune uveitis

Autoimmune uveitis (AIU) is an immune-inflammatory disease that can lead to blindness. However, incomplete understanding of the involved immune cell subsets and their contributions to retinal injury has hindered the development of effective AIU therapies. Using single-cell RNA sequencing and immunofluorescence, we identified α-synuclein+ microglia as the primary subset of damaged ocular cells in the eyes of the experimental autoimmune uveitis (EAU) mouse model. Ocular-infiltrating plasma cells (PCs) were shown to express multiple inflammatory factors, particularly TNF-α, which promoted the production of α-synuclein+ microglia. Studies of heterogeneous PC subtypes revealed that MUC1- PCs represent the primary pathogenic subset, secreting multiple cytokines. Although MUC1+ PCs expressed TGF-β, they exhibited long-lived characteristics and secreted IgG and IgM, thereby prolonging disease progression. Finally, the small G protein Rab1A, also expressed in the PCs of Vogt-Koyanagi-Harada (VKH) patients, was found to mediate autophagy and NF-κB expression, influencing PCs survival and inflammatory responses. Silencing or knocking down Rab1A in PCs inhibited their survival. This study elucidates potential mechanisms underlying the neuroimmune inflammatory response and highlights the previously unrecognized role of infiltrating PCs in AIU, offering novel therapeutic targets for this disease.

Mass Spectrometric Profiling of Extraocular Muscle and Proteomic Adaptations in the mdx-4cv Model of Duchenne Muscular Dystrophy

Extraocular muscles (EOMs) represent a specialized type of contractile tissue with unique cellular, physiological, and biochemical properties. In Duchenne muscular dystrophy, EOMs stay functionally unaffected in the course of disease progression. Therefore, it was of interest to determine their proteomic profile in dystrophinopathy. The proteomic survey of wild type mice and the dystrophic mdx-4cv model revealed a broad spectrum of sarcomere-associated proteoforms, including components of the thick filament, thin filament, M-band and Z-disk, as well as a variety of muscle-specific markers. Interestingly, the mass spectrometric analysis revealed unusual expression levels of contractile proteins, especially isoforms of myosin heavy chain. As compared to diaphragm muscle, both proteomics and immunoblotting established isoform MyHC14 as a new potential marker in wild type EOMs, in addition to the previously identified isoforms MyHC13 and MyHC15. Comparative proteomics was employed to establish alterations in the protein expression profile between normal EOMs and dystrophin-lacking EOMs. The analysis of mdx-4cv EOMs identified elevated levels of glycolytic enzymes and molecular chaperones, as well as decreases in mitochondrial enzymes. These findings suggest a process of adaptation in dystrophin-deficient EOMs via a bioenergetic shift to more glycolytic metabolism, as well as an efficient cellular stress response in EOMs in dystrophinopathy.