title: Calcium influx determines the muscular response to electrotransfer.
abstract: Cell membrane permeabilization by electric pulses (electropermeabilization), results in free exchange of ions across the cell membrane. The role of electrotransfer-mediated Ca(2+)-influx on muscle signaling pathways involved in degeneration (β-actin and MurF), inflammation (IL-6 and TNF-α), and regeneration (MyoD1, myogenin, and Myf5) was investigated, using pulse parameters of both electrochemotherapy (8 HV) and DNA delivery (HVLV). Three pulsing conditions were used: 8 high-voltage pulses (8 HV), resulting in large permeabilization and ion flux, and a combination of one high-voltage pulse and one low-voltage pulse (HVLV), either alone or in combination with injection of DNA. Mice and rats were anesthetized before pulsing. At the times given, animals were killed, and intact tibialis cranialis muscles were excised for analysis. Uptake of Ca(2+) was assessed using (45)Ca as a tracer. Using gene expression analyses and histology, we showed a clear association between Ca(2+) influx and muscular response. Moderate Ca(2+) influx induced by HVLV pulses results in activation of pathways involved in immediate repair and hypertrophy. This response could be attenuated by intramuscular injection of EGTA reducing Ca(2+) influx. Larger Ca(2+) influx as induced by 8-HV pulses leads to muscle damage and muscle fiber regeneration through recruitment of satellite cells. The extent of Ca(2+) influx determines the muscular response to electrotransfer and, thus, the success of a given application. In the case of electrochemotherapy, in which the objective is cell death, a large influx of Ca(2+) may be beneficial, whereas for DNA electrotransfer, muscle recovery should occur without myofiber loss to ensure preservation of plasmid DNA.
authors.affiliation: Department of Biomedicine, Univ. of Aarhus, Århus C, Denmark. hgh@fi.au.dk
authors.forename: Pernille
authors.initials: P
authors.lastname: Hojman
authors.forename: Camilla
authors.initials: C
authors.lastname: Brolin
authors.forename: Hanne
authors.initials: H
authors.lastname: Gissel
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D018274:Electroporation; D005260:Female; D018014:Gene Transfer Techniques; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D017570:MyoD Protein / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5 / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism; D015398:Signal Transduction; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D000199:Actins; D015850:Interleukin-6; D009124:Muscle Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D051787:Myogenic Regulatory Factor 5; C413644:Rnf30 protein, mouse; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha; C499086:Trim63 protein, rat; D044767:Ubiquitin-Protein Ligases; D002118:Calcium