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Mae mediates MAP kinase phosphorylation of Ets transcription factors in Drosophila
D A Baker1, B Mille-Baker, S M Wainwright
1Cell Signalling Unit, Institute of Reproductive and Developmental Biology, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK. d.baker@ic.ac.uk
Abstract:
The evolutionarily conserved Ras/mitogen-activated protein kinase (MAPK) cascade is an integral part of the processes of cell division, differentiation, movement and death. Signals received at the cell surface are relayed into the nucleus, where MAPK phosphorylates and thereby modulates the activities of a subset of transcription factors. Here we report the cloning and characterization of a new component of this signal transduction pathway called Mae (for modulator of the activity of Ets). Mae is a signalling intermediate that directly links the MAPK signalling pathway to its downstream transcription factor targets. Phosphorylation by MAPK of the critical serine residue (Ser 127) of the Drosophila transcription factor Yan depends on Mae, and is mediated by the binding of Yan to Mae through their Pointed domains. This phosphorylation is both necessary and sufficient to abrogate transcriptional repression by Yan. Mae also regulates the activity of the transcriptional activator Pointed-P2 by a similar mechanism. Mae is essential for the normal development and viability of Drosophila, and is required in vivo for normal signalling of the epidermal growth factor receptor. Our study indicates that MAPK signalling specificity may depend on proteins that couple specific substrates to the kinase.
Insights
A new protein, Mae, acts as a crucial link in the Ras/mitogen-activated protein kinase (MAPK) pathway, controlling cell processes by regulating transcription factors like Yan. This discovery is vital for understanding cell signaling and development.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The Ras/mitogen-activated protein kinase (MAPK) cascade is a fundamental signaling pathway regulating cell division, differentiation, movement, and death.
- MAPK relays extracellular signals to the nucleus, modulating transcription factor activity through phosphorylation.
Purpose of the Study:
- To identify and characterize novel components of the MAPK signal transduction pathway.
- To elucidate the role of a newly discovered protein, Mae (modulator of the activity of Ets), in linking MAPK signaling to transcription factors.
Main Methods:
- Cloning and characterization of the Mae protein.
- Investigating the interaction between Mae, MAPK, and transcription factors Yan and Pointed-P2.
- Assessing the in vivo function of Mae in Drosophila development and epidermal growth factor receptor signaling.
Main Results:
- Mae directly links the MAPK pathway to transcription factors, specifically regulating the phosphorylation of Drosophila's Yan protein at Ser 127.
- Phosphorylation of Yan by MAPK, mediated by Mae, abrogates its transcriptional repression activity.
- Mae also modulates the activity of the transcriptional activator Pointed-P2.
- Mae is essential for Drosophila development and viability, and for epidermal growth factor receptor signaling in vivo.
Conclusions:
- Mae acts as a critical signaling intermediate, coupling the MAPK pathway to specific transcription factor substrates.
- This mechanism enhances MAPK signaling specificity by ensuring appropriate regulation of downstream targets.
- Mae plays a vital role in developmental processes and signal transduction in Drosophila.
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