In:
Biochemistry and Cell Biology, Canadian Science Publishing, Vol. 66, No. 10 ( 1988-10-01), p. 1110-1118
Kurzfassung:
Fusion-competent myoblasts can be prevented from fusing (differentiating) by reducing medium calcium concentrations from 1.65 mM to less than 50 μM. Fusion is completely retarded after 24 h but is noticeable after 48 h and significant after 72 h in low-calcium medium. After 24 h in low-calcium medium, a rapid, synchronous fusion can be initiated by return to normal (high-calcium) medium. Calcium content increases over threefold during myoblast differentiation and closely parallels the fusion process. Phospholipid content is also dependent upon the state of differentiation. Myotubes (fused myoblasts) have an almost twofold greater content of lipid phosphate per milligram of protein compared with that of myoblasts; this increase is localized to increased contents of phosphatidylcholine and pooled phosphatidylinositol – phosphatidylserine. Phospholipid synthesis ( 32 P i incorporation) is markedly stimulated four- to five-fold when myoblasts grown in low-calcium medium are switched to normal medium. These significant increases are observed in all the major phospholipids studied, predominantly in phosphatidylcholine and pooled phosphatidylinositol – phosphatidylserine, and most noticeably in phosphatidylinositol 4,5-bisphosphate. Furthermore, we show that phosphatidylinositol 4,5-bisphosphate prelabelled with myo-[2- 3 H]inositol is rapidly degraded after switching from low-calcium medium to normal medium. These changes are not observed in myotubes treated similarly, which suggests that the changes in phospholipid metabolism may be fusion related. These results support a proposal by another author, which suggests that phosphatidylinositol 4,5-bisphosphate breakdown may play an important regulating role in myoblast differentiation.
Materialart:
Online-Ressource
ISSN:
0829-8211
,
1208-6002
Sprache:
Englisch
Verlag:
Canadian Science Publishing
Publikationsdatum:
1988
SSG:
12
