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The Drosophila lethal(2)giant larvae tumor suppressor protein is a component of the cytoskeleton
D Strand1, I Raska, B M Mechler
1Department of Developmental Genetics, Deutsches Krebsforschungszentrum, Germany.
Abstract:
Tumor suppressor genes act as recessive determinants of cancer. In Drosophila these genes play a role in normal development and are essential for regulating cell growth and differentiation. Mutations in the gene, lethal(2)giant larvae, l(2)gl, besides causing malignant tumors in the brain and imaginal discs, generate developmental defects in a number of other tissues. Much of the uncertainty regarding the function of the l(2)gl gene product, p127, results from a lack of knowledge as to the precise location of this protein in the cell. We have investigated the cellular and subcellular localization of p127, using confocal and electron microscopy as well as biochemical and cell fractionation procedures. Our analyses indicate that p127 is located entirely within the cell in both the cytoplasm and bound to the inner face of lateral cell membranes in regions of cell junctions. On the membrane, p127 can form large aggregates which are resistant to solubilization by nonionic detergents, indicating that p127 is participating in a cytoskeletal matrix. These findings suggest that the changes in cell shape and the loss of apical-basal polarity observed in tumorous tissues are a direct result of alterations in the cytoskeleton organization caused by l(2)gl inactivation and also suggest that p127 is involved in a cytoskeletal-based intercellular communication system directing cell differentiation.
Insights
The lethal(2)giant larvae (l(2)gl) gene product, p127, is crucial for cell structure. Its localization at cell junctions suggests a role in cytoskeletal organization and intercellular communication, impacting cell differentiation and tumor suppression.
Area of Science:
- Developmental Biology
- Cell Biology
- Cancer Genetics
Background:
- Tumor suppressor genes are recessive regulators of cancer.
- The lethal(2)giant larvae (l(2)gl) gene in Drosophila controls development and cell growth.
- The function of the l(2)gl gene product, p127, is poorly understood due to unknown localization.
Purpose of the Study:
- To determine the cellular and subcellular localization of the p127 protein.
- To elucidate the role of p127 in cell structure and function.
Main Methods:
- Confocal and electron microscopy
- Biochemical analyses
- Cell fractionation procedures
Main Results:
- p127 is localized in the cytoplasm and on the inner face of lateral cell membranes at cell junctions.
- p127 forms detergent-resistant aggregates on the membrane, indicating cytoskeletal association.
- l(2)gl inactivation leads to altered cytoskeleton organization and loss of cell polarity.
Conclusions:
- p127 is a component of the cell cytoskeleton, involved in maintaining cell shape and polarity.
- p127's localization suggests a role in a cytoskeletal-based intercellular communication system regulating cell differentiation.
- Dysregulation of p127 contributes to tumor formation by disrupting cytoskeletal organization.