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Genetic regulation of cell-to-cell communication
1Department of Physiology and Biophysics, University of Miami School of Medicine, Florida 33101.
Abstract:
Overexpression of the cellular src gene in NIH-3T3 cells causes reduction of cell-to-cell transmission of molecules in the 400-700 dalton range. This down-regulation of gap junctional communication correlates with the activity of the gene product, the protein tyrosine kinase pp60c-src. The down-regulation is enhanced by point mutation of Tyr527 (a site phosphorylated in pp60c-src and which inhibits kinase activity) or by substitution of the viral- for the cellular-src carboxyl terminal coding region. Mutation of Tyr416 (a site phosphorylated upon Tyr527 mutation) suppresses both the down-regulation by Tyr527 mutation and that by gene overexpression. The regulation of communication by src may be important in the control of embryonic development and cellular growth.
Insights
Overexpression of the cellular src gene reduces cell communication. This down-regulation of gap junctional communication is linked to the protein tyrosine kinase pp60c-src activity and can be modulated by specific gene mutations.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell-to-cell communication is crucial for tissue function and organism development.
- Gap junctions mediate direct intercellular communication.
- The cellular src gene (c-src) encodes a protein tyrosine kinase (pp60c-src) involved in cell signaling and growth regulation.
Purpose of the Study:
- To investigate the effect of cellular src gene overexpression on gap junctional communication in NIH-3T3 cells.
- To determine the role of pp60c-src kinase activity in regulating cell-to-cell communication.
- To elucidate the impact of specific mutations within the c-src gene on communication pathways.
Main Methods:
- NIH-3T3 cells were utilized for experimental manipulation.
- Overexpression of the cellular src gene and its mutated variants was performed.
- Gap junctional communication was assessed by measuring the transmission of molecules in the 400-700 dalton range.
- Specific point mutations (Tyr527 and Tyr416) were introduced into the c-src gene.
Main Results:
- Overexpression of the cellular src gene led to a significant reduction in cell-to-cell transmission of molecules (400-700 Da).
- This down-regulation of gap junctional communication correlated directly with the kinase activity of pp60c-src.
- Mutations at Tyr527 (inhibitory phosphorylation site) or substitution with viral-src enhanced communication down-regulation.
- Mutation at Tyr416 (activating phosphorylation site) suppressed the down-regulatory effects observed with Tyr527 mutation and gene overexpression.
Conclusions:
- The src gene product, pp60c-src, plays a critical role in regulating gap junctional communication.
- Kinase activity of pp60c-src is a key determinant in the modulation of cell-to-cell communication.
- Regulation of communication by src may be important in controlling embryonic development and cellular growth processes.