Impaired membrane resealing and autoimmune myositis in synaptotagmin VII–deficient mice

S Chakrabarti, KS Kobayashi, RA Flavell… - The Journal of cell …, 2003 - rupress.org
S Chakrabarti, KS Kobayashi, RA Flavell, CB Marks, K Miyake, DR Liston, KT Fowler…
The Journal of cell biology, 2003rupress.org
Members of the synaptotagmin family have been proposed to function as Ca2+ sensors in
membrane fusion. Syt VII is a ubiquitously expressed synaptotagmin previously implicated in
plasma membrane repair and Trypanosoma cruzi invasion, events which are mediated by
the Ca2+-regulated exocytosis of lysosomes. Here, we show that embryonic fibroblasts from
Syt VII–deficient mice are less susceptible to trypanosome invasion, and defective in
lysosomal exocytosis and resealing after wounding. Examination of mutant mouse tissues …
Members of the synaptotagmin family have been proposed to function as Ca2+ sensors in membrane fusion. Syt VII is a ubiquitously expressed synaptotagmin previously implicated in plasma membrane repair and Trypanosoma cruzi invasion, events which are mediated by the Ca2+-regulated exocytosis of lysosomes. Here, we show that embryonic fibroblasts from Syt VII–deficient mice are less susceptible to trypanosome invasion, and defective in lysosomal exocytosis and resealing after wounding. Examination of mutant mouse tissues revealed extensive fibrosis in the skin and skeletal muscle. Inflammatory myopathy, with muscle fiber invasion by leukocytes and endomysial collagen deposition, was associated with elevated creatine kinase release and progressive muscle weakness. Interestingly, similar to what is observed in human polymyositis/dermatomyositis, the mice developed a strong antinuclear antibody response, characteristic of autoimmune disorders. Thus, defective plasma membrane repair in tissues under mechanical stress may favor the development of inflammatory autoimmune disease.
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