Related Experiment Videos
Expression of v-src alters the expression of myogenic regulatory factor genes
1Department of Microbiology, University of Pennsylvania, Philadelphia.
Abstract:
Inactivation of v-src in transformed chicken myoblasts induced changes in expression of the myogenic regulatory factors (MRF's), MyoD, myogenin and Myf5. Both MyoD and Myf5 were expressed in the transformed cells. The inactivation of v-src by a temperature up-shift resulted in the loss of Myf5 expression, a transient increase in MyoD, followed by a rise in myogenin mRNA levels. The increase in transcripts for the later muscle proteins, myosin heavy and light chains, alpha-actin and troponin T followed the sequence of changes in MRF expression suggesting that their induction was the result of altered MRF expression. Thus, v-src appears to operate through effects on MRF's and not directly on the expression of the late muscle-specific proteins. When v-src was reactivated in mature myotubes by a temperature down-shift, the pattern of expression was quite different, the late muscle-specific transcripts decreased before the loss of myogenin transcripts and before the rise of Myf5 transcripts.
Insights
The oncogene v-src influences muscle development by altering myogenic regulatory factors (MRFs). Inactivated v-src impacts MyoD, myogenin, and Myf5 expression, affecting muscle-specific gene induction.
Area of Science:
- Cellular and Molecular Biology
- Developmental Biology
- Oncogenesis
Background:
- The oncogene v-src is known to transform cells, but its precise role in regulating muscle differentiation is not fully understood.
- Myogenic regulatory factors (MRFs) are crucial transcription factors that control muscle gene expression and differentiation.
Purpose of the Study:
- To investigate the impact of v-src inactivation and reactivation on the expression of MRFs (MyoD, myogenin, Myf5) in chicken myoblasts and myotubes.
- To determine if v-src directly affects the expression of late muscle-specific proteins or acts indirectly through MRFs.
Main Methods:
- Utilized a temperature-sensitive mutant of v-src in chicken myoblasts.
- Monitored changes in mRNA levels of MRFs (MyoD, myogenin, Myf5) and late muscle-specific proteins (myosin heavy/light chains, alpha-actin, troponin T) following temperature shifts.
- Observed effects of v-src inactivation (up-shift) and reactivation (down-shift) on gene expression patterns.
Main Results:
- Inactivation of v-src led to loss of Myf5, transient increase in MyoD, and subsequent rise in myogenin mRNA.
- The induction of late muscle-specific transcripts followed the observed changes in MRF expression, suggesting an indirect effect of v-src.
- Reactivation of v-src in mature myotubes resulted in decreased late muscle-specific transcripts preceding changes in myogenin and Myf5.
Conclusions:
- v-src influences muscle differentiation primarily by modulating the expression of myogenic regulatory factors (MRFs).
- The oncogene v-src does not appear to directly regulate the expression of late muscle-specific proteins.
- The temporal dynamics of MRF and late muscle gene expression differ between v-src inactivation in myoblasts and reactivation in myotubes.