Myogenic differentiation of p53- and Rb-deficient immortalized and transformed bovine fibroblasts in response to MyoD.
We have established in culture a spontaneously immortalized bovine embryonic fibroblast (BEF) cell line that has lost p53 and p16(INK4a) functions. MyoD is a muscle-specific regulator capable of inducing myogenesis in a number of cell types. When the BEF cells were transduced with MyoD they differentiated efficiently to desmin-positive myofibers in the presence of 2% horse serum and 1.7 nM insulin. The myogenic differentiation of this cell line was more rapid and obvious than that of C2C12 cells, as judged by morphological changes and expression of various muscle regulatory factors. To confirm that lack of the p53 and p16(INK4a) pathway does not prevent MyoD-mediated myogenesis, we established a cell line transformed with SV40LT (BEFV) and introduced MyoD into it. In the presence of 2% horse serum and 1.7 nM insulin, the MyoD-transduced BEFV cells differentiated like the MyoD-transduced BEFS cells, and displayed a similar pattern of expression of muscle regulatory proteins. Taken together, our results indicate that MyoD overexpression overcomes the defect in muscle differentiation associated with immortalization and cell transformation caused by the loss of p53 and Rb functions.
Jin
Xun
X
Laboratory of Cell Growth and Function Regulation, Korea University, Seoul 136-701, Korea.
Lee
Joong-Seub
JS
Kwak
Sungwook
S
Jung
Ji-Eun
JE
Kim
Tae-Kyung
TK
Xu
Chenxiong
C
Hong
Zhongshan
Z
Li
Zhehu
Z
Kim
Sun-Myoung
SM
Whang
Kwang Youn
KY
Hong
Ki-Chang
KC
You
Seungkwon
S
Choi
Yun-Jaie
YJ
Kim
Hyunggee
H