The ERG1a potassium channel increases basal intracellular calcium concentration and calpain activity in skeletal muscle cells
| Autor: | Amber L. Pond, Gregory H. Hockerman, Wen-Horng Wang, Mariam N. Hashmi, Kevin S. Bradley, Evan P.S. Pratt, Rod Weilbaecher, Judith K. Davie, Albert K. Urazaev, Luke B. Anderson, Sawyer M. Latour, Clayton Whitmore |
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| Rok vydání: | 2019 |
| Předmět: |
0301 basic medicine
Male medicine.medical_specialty ERG1 Potassium Channel lcsh:Diseases of the musculoskeletal system Muscle Fibers Skeletal Calpains chemistry.chemical_element Calcium Protein degradation Calcium in biology Cell Line 03 medical and health sciences Mice 0302 clinical medicine Atrophy Internal medicine Gene expression medicine Animals Orthopedics and Sports Medicine Molecular Biology Intracellular calcium Calpastatin ERG1A biology Calpain Research Calcium-Binding Proteins Skeletal muscle Cell Biology medicine.disease 030104 developmental biology medicine.anatomical_structure Endocrinology chemistry biology.protein lcsh:RC925-935 030217 neurology & neurosurgery Skeletal muscle atrophy |
| Zdroj: | Skeletal Muscle Skeletal Muscle, Vol 10, Iss 1, Pp 1-15 (2020) |
| ISSN: | 2044-5040 |
| Popis: | Background Skeletal muscle atrophy is the net loss of muscle mass that results from an imbalance in protein synthesis and protein degradation. It occurs in response to several stimuli including disease, injury, starvation, and normal aging. Currently, there is no truly effective pharmacological therapy for atrophy; therefore, exploration of the mechanisms contributing to atrophy is essential because it will eventually lead to discovery of an effective therapeutic target. The ether-a-go-go related gene (ERG1A) K+ channel has been shown to contribute to atrophy by upregulating ubiquitin proteasome proteolysis in cachectic and unweighted mice and has also been implicated in calcium modulation in cancer cells. Methods We transduced C2C12 myotubes with either a human ERG1A encoded adenovirus or an appropriate control virus. We used fura-2 calcium indicator to measure intracellular calcium concentration and Calpain-Glo assay kits (ProMega) to measure calpain activity. Quantitative PCR was used to monitor gene expression and immunoblot evaluated protein abundances in cell lysates. Data were analyzed using either a Student’s t test or two-way ANOVAs and SAS software as indicated. Results Expression of human ERG1A in C2C12 myotubes increased basal intracellular calcium concentration 51.7% (p n = 177). Further, it increased the combined activity of the calcium-activated cysteine proteases, calpain 1 and 2, by 31.9% (p n = 24); these are known to contribute to degradation of myofilaments. The increased calcium levels are likely a contributor to the increased calpain activity; however, the change in calpain activity may also be attributable to increased calpain protein abundance and/or a decrease in levels of the native calpain inhibitor, calpastatin. To explore the enhanced calpain activity further, we evaluated expression of calpain and calpastatin genes and observed no significant differences. There was no change in calpain 1 protein abundance; however, calpain 2 protein abundance decreased 40.7% (p n = 6). These changes do not contribute to an increase in calpain activity; however, we detected a 31.7% decrease (p n = 6) in calpastatin which could contribute to enhanced calpain activity. Conclusions Human ERG1A expression increases both intracellular calcium concentration and combined calpain 1 and 2 activity. The increased calpain activity is likely a result of the increased calcium levels and decreased calpastatin abundance. |
| Databáze: | OpenAIRE |
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