Wound healing in jellyfish striated muscle involves rapid switching between two modes of cell motility and a change in the source of regulatory calcium
Ycj. Lin et al., Wound healing in jellyfish striated muscle involves rapid switching between two modes of cell motility and a change in the source of regulatory calcium, DEVELOP BIO, 225(1), 2000, pp. 87-100
Small wounds (1.2 mm in diameter) made in the sheet of myoepithelial cells
forming the "swimmintg" muscle of the jellyfish, Polyorchis penicillatus, w
ere closed within 10 h by epithelial cells migrating centripetally to the w
ound center. Some 24 to 48 h later these cells redifferentiated into fully
contractile muscle cells. Labeling with bromodeoxyuridine failed to reveal
any cell proliferation during this process. Phenotype switching (within 1 h
) from contractile muscle cells to migratory cells did not require synthesi
s of new protein as shown by treatment with 40 mu M cycloheximide. Excitati
on-contraction coupling in undamaged muscle depended on entry of Ca2+ throu
gh voltage-gated ion channels, as shown by a block of contractility by 40 m
u M nitrendipine and also on calcium released from intracellular stores sin
ce caffeine (10 mM) caused a 25% reduction in contractile force. In contras
t, migratory cells did not require a source of extracellular calcium since
migration was unimpeded by low (1 mu M) free Ca2+ or nitrendipine. Instead,
modulatory calcium was derived from intracellular stores since caffeine (1
0 mM) and thapsigargin (10 mu M) slowed migration. This lack of dependence
on calcium influx in migratory cells was further confirmed by a dramatic do
wn-regulation in voltage-gated inward current as shown by whole-cell patch
recordings. (C) 2000 Academic Press.