title: Formation and characterization of spontaneously formed heterokaryons between quail myoblasts and 3T3-L1 preadipocytes: correlation between differential plasticity and degree of differentiation.
abstract: Skeletal muscle cells and adipose cells have a close relationship in developmental lineage. Our previous study has shown that the heterokaryons between quail myoblasts and undifferentiated 3T3-L1 cells (preadipocytes) normally differentiated into myotubes, whereas the heterokaryons between myoblasts and differentiated 3T3-L1 cells (adipocytes) failed myogenic differentiation. These results suggest differences between preadipocytes and adipocytes. The purpose of this study was to clarify whether preadipocytes have flexibility in differentiation before terminal adipose differentiation. Presumptive quail myoblasts transformed with a temperature-sensitive mutant of Rous sarcoma virus (QM-RSV cells) and mouse 3T3-L1 cells (either preadipocytes or adipocytes) were co-cultured for 48 h under conditions allowing myogenic differentiation. On co-culture between myoblasts and undifferentiated 3T3-L1 cells, heterokaryotic myotubes formed spontaneously, but not on co-culture with differentiated 3T3-L1 cells. In addition, the heterokaryotic myotubes expressed mouse myogenin derived from the 3T3-L1 cell gene. Our previous study indicated that the fusion sensitivity of differentiating myoblasts change with decreasing cholesterol of the cell membrane during myoblast fusion. Thus we compared the level of membrane cholesterol between undifferentiated and differentiated 3T3-L1 cells. The result showed that the level of membrane cholesterol in 3T3-L1 cells increases during adipose differentiation. Corresponding to the increase in membrane cholesterol content, differentiated 3T3-L1 cells had lower sensitivity to HVJ (Sendai virus)-mediated cell fusion than undifferentiated 3T3-L1 cells. This study demonstrated that 3T3-L1 cells at an undifferentiated state have a capacity for spontaneous fusion with differentiating myoblasts following myogenic differentiation, and that the capacity is lost after terminal adipose differentiation.
authors.affiliation: Institute of Molecular and Cellular Biology for Pharmaceutical Sciences, Kyoto Pharmaceutical University, Kyoto, Japan.
authors.forename: Nagako
authors.initials: N
authors.lastname: Sasao
authors.forename: Etsuko
authors.initials: E
authors.lastname: Hirayama
authors.forename: Jeman
authors.initials: J
authors.lastname: Kim
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology*; D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation; D002459:Cell Fusion; D019070:Cell Lineage; D002467:Cell Nucleus / Q000502:physiology*; D002784:Cholesterol / Q000378:metabolism; D018920:Coculture Techniques; D051379:Mice; D009154:Mutation; D032446:Myoblasts / Q000166:cytology*; D018008:Myogenin / Q000378:metabolism; D011784:Quail; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013696:Temperature; D013997:Time Factors
chemical_list: C503801:Myog protein, mouse; C503803:Myog protein, rat; D018008:Myogenin; D012333:RNA, Messenger; D002784:Cholesterol