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Negative regulation of glial engulfment activity by Draper terminates glial responses to axon injury

Nature Neuroscience volume 15, pages 722730 (2012) | Download Citation

Abstract

Neuronal injury elicits potent cellular responses from glia, but molecular pathways modulating glial activation, phagocytic function and termination of reactive responses remain poorly defined. Here we show that positive or negative regulation of glial responses to axon injury is molecularly encoded by unique isoforms of the Drosophila melanogaster engulfment receptor Draper. Draper-I promotes engulfment of axonal debris through an immunoreceptor tyrosine–based activation motif (ITAM). In contrast, Draper-II, an alternative splice variant, potently inhibits glial engulfment function. Draper-II suppresses Draper-I signaling through a previously undescribed immunoreceptor tyrosine–based inhibitory motif (ITIM)-like domain and the tyrosine phosphatase Corkscrew (Csw). Intriguingly, loss of Draper-II–Csw signaling prolongs expression of glial engulfment genes after axotomy and reduces the ability of glia to respond to secondary axotomy. Our work highlights a novel role for Draper-II in inhibiting glial responses to neurodegeneration, and indicates that a balance of opposing Draper-I and Draper-II signaling events is essential to maintain glial sensitivity to brain injury.

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Acknowledgements

We thank T. Awasaki, M. Simon, E. Perkins, B. Dickson and the Vienna Drosophila RNAi Center (VDRC) for sharing fly lines and antibodies. We thank K. Kerr for technical advice and expertise. This work was supported by US National Institutes of Health (NIH) Grant 1RO1NS053538 (M.R.F.), NIH New Faculty Recruitment Grant P30NS069346 P30 (M.A.L.), an American Cancer Society Postdoctoral Fellowship (PF-07-258-01-CSM) (M.A.L.) and the Medical Research Foundation of Oregon (M.A.L.). M.R.F. is a Howard Hughes Medical Institute Early Career Scientist.

Author information

Author notes

    • Mary A Logan
    •  & Sean D Speese

    Present address: Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, Oregon, USA.

Affiliations

  1. Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

    • Mary A Logan
    • , Rachel Hackett
    • , Johnna Doherty
    • , Amy Sheehan
    • , Sean D Speese
    •  & Marc R Freeman
  2. Howard Hughes Medical Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

    • Marc R Freeman

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Contributions

M.A.L. and M.R.F. developed the overall concept and design of the project. M.A.L. performed, analyzed and interpreted the majority of the experiments and wrote the initial version of the manuscript. R.H. performed the immunoprecipitation and western blot experiments with S2 cells and adult flies. J.D. performed the experiments with cswva199 and provided intellectual input for the study. S.D.S. performed and analyzed the qRT-PCR time course of Draper-I, Draper-I and Csw expression after injury and assisted with double injury experiments. A.S. generated the extracellular-intracellular Draper domain swap constructs.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Mary A Logan.

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DOI

https://doi.org/10.1038/nn.3066

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