Project Title

The role of the Rbf1 tumor suppressor in the differentiation and maintenance of Drosophila muscles.

Presenters

Academic department under which the project should be listed

CSM - Molecular and Cellular Biology

Faculty Sponsor Name

Anton Bryantsev

Additional Faculty

Maria Chechenova, Molecular Cell Biology, mchechen@kennesaw.edu

Not applicable

Abstract (300 words maximum)

Retinoblastoma protein (pRb) is expressed virtually in all cell types with the main purpose of cell cycle control. A growing number of reports demonstrate that pRb is also implemented in early steps of myogenesis, but whether this function is independent from its role as cell cycle regulator remains unclear. To clarify this issue, we used a temperature-sensitive expression system to address the importance of fly pRb homolog, Rbf1, at different stages of adult muscle development. When the Rbf1 gene was downregulated in myoblasts (early knockdown), it caused muscle weakness and flighlessness in flies.

We next determined the role of Rbf1 at later stages of myogenesis by delaying Rbf1 knockdown by several hours (late knockdown). Under these conditions, all muscles, including jump muscles, developed normally and were functional in young adults. However, after 2 weeks the experimental flies developed muscle weakness that affected their flying, jumping, and climbing abilities. This decline in muscle functionality was paralleled by a reduction in mitochondrial gene expression. Specifically, the expression of mitochondrial IV subunit COX5A in flight muscles was downregulated by 85%, while the expression of other mitochondrial components (e.g. RFeSP, SdhB, Idh, and Adk1) was down by 30-40%.

Our data demonstrate that the Rbf1 gene is involved at different stages of myogenesis. Although in early myogenesis Rbf1 functions as cell cycle regulator, later it becomes the maintenance factor, supporting muscles in the differentiation state. Further studies, performed on this model, will explore the mechanisms mediating this transition in Rbf1 functioning.

Project Type

Poster

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The role of the Rbf1 tumor suppressor in the differentiation and maintenance of Drosophila muscles.

Retinoblastoma protein (pRb) is expressed virtually in all cell types with the main purpose of cell cycle control. A growing number of reports demonstrate that pRb is also implemented in early steps of myogenesis, but whether this function is independent from its role as cell cycle regulator remains unclear. To clarify this issue, we used a temperature-sensitive expression system to address the importance of fly pRb homolog, Rbf1, at different stages of adult muscle development. When the Rbf1 gene was downregulated in myoblasts (early knockdown), it caused muscle weakness and flighlessness in flies.

We next determined the role of Rbf1 at later stages of myogenesis by delaying Rbf1 knockdown by several hours (late knockdown). Under these conditions, all muscles, including jump muscles, developed normally and were functional in young adults. However, after 2 weeks the experimental flies developed muscle weakness that affected their flying, jumping, and climbing abilities. This decline in muscle functionality was paralleled by a reduction in mitochondrial gene expression. Specifically, the expression of mitochondrial IV subunit COX5A in flight muscles was downregulated by 85%, while the expression of other mitochondrial components (e.g. RFeSP, SdhB, Idh, and Adk1) was down by 30-40%.

Our data demonstrate that the Rbf1 gene is involved at different stages of myogenesis. Although in early myogenesis Rbf1 functions as cell cycle regulator, later it becomes the maintenance factor, supporting muscles in the differentiation state. Further studies, performed on this model, will explore the mechanisms mediating this transition in Rbf1 functioning.