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Transcriptional regulation by MAP kinases
1Department of Biochemistry and Molecular Biology, Howard Hughes Medical Institute, University of Massachusetts Medical Center, Worcester, MA 01605, USA.
Molecular Reproduction and Development
|December 1, 1995
Summary
The mitogen-activated protein (MAP) kinase pathway transmits signals from growth factor receptors to the nucleus, regulating gene expression. This pathway involves key proteins like Ras and Raf, leading to MAP kinase activation and nuclear translocation to modify transcription factors.
Area of Science:
- Molecular Biology
- Cell Signaling
- Genetics
Background:
- Growth factor receptors initiate intracellular signaling cascades.
- The mitogen-activated protein (MAP) kinase pathway is crucial for cellular responses to external stimuli.
- This pathway links cell surface receptors to nuclear gene expression regulation.
Purpose of the Study:
- To elucidate the mechanism of MAP kinase activation by growth factor receptors.
- To identify and characterize MAP kinase homologs in humans and yeast.
- To explore the diversity and evolutionary relationships within the MAP kinase gene family.
Main Methods:
- Investigated the role of Grb2, Sos, and Ras in MAP kinase activation.
- Identified and cloned human MAP kinase homologs (Erk1, Erk2, Erk3).
- Analyzed gene loci and expression patterns of human MAP kinases.
- Compared human MAP kinases with homologs in Saccharomyces cerevisiae.
- Examined the relationship between c-Jun NH2-terminal kinase (Jnk) and MAP kinases.
Main Results:
- MAP kinase activation involves a cascade initiated by Ras binding to Raf kinase.
- Human MAP kinases Erk1 and Erk2 are widely expressed, while Erk3 is primarily in heart and brain.
- Human MAP kinase genes (erk1, erk2, erk3-related) are located on different chromosomes.
- Yeast harbors a more diverse set of MAP kinase homologs than currently identified human Erks.
- Jnk is identified as a distant relative of MAP kinases, activated by dual phosphorylation.
Conclusions:
- The MAP kinase pathway is a significant signal transduction mechanism from cell surface to nucleus.
- Human MAP kinases represent a subgroup of a larger, more diverse gene family.
- Further research is needed to fully understand the extended MAP kinase family and their functions.