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J Proteomics. 2017 Aug 23;166:127-137. doi: 10.1016/j.jprot.2017.07.008. Epub 2017 Jul 17.

A mass spectrometry-based proteomic analysis of Homer2-interacting proteins in the mouse brain.

Author information

1
Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, United States. Electronic address: goulding@scripps.edu.
2
Department of Psychological and Brain Sciences, Molecular, Cellular and Developmental Biology, The Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States.
3
Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States.
4
Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, United States.
5
Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.

Abstract

In the brain, the Homer protein family modulates excitatory signal transduction and receptor plasticity through interactions with other proteins in dendritic spines. Homer proteins are implicated in a variety of psychiatric disorders such as schizophrenia and addiction. Since long Homers serve as scaffolding proteins, identifying their interacting partners is an important first step in understanding their biological function and could help to guide the design of new therapeutic strategies. The present study set out to document Homer2-interacting proteins in the mouse brain using a co-immunoprecipitation-based mass spectrometry approach where Homer2 knockout samples were used to filter out non-specific interactors. We found that in the mouse brain, Homer2 interacts with a limited subset of its previously reported interacting partners (3 out of 31). Importantly, we detected an additional 15 novel Homer2-interacting proteins, most of which are part of the N-methyl-D-aspartate receptor signaling pathway. These results corroborate the central role Homer2 plays in glutamatergic transmission and expand the network of proteins potentially contributing to the behavioral abnormalities associated with altered Homer2 expression.

SIGNIFICANCE:

Long Homer proteins are scaffolding proteins that regulate signal transduction in neurons. Identifying their interacting partners is key to understanding their function. We used co-immunoprecipitation in combination with mass spectrometry to establish the first comprehensive list of Homer2-interacting partners in the mouse brain. The specificity of interactions was evaluated using Homer2 knockout brain tissue as a negative control. The set of proteins that we identified minimally overlaps with previously reported interacting partners of Homer2; however, we identified novel interactors that are part of a signaling cascade activated by glutamatergic transmission, which improves our mechanistic understanding of the role of Homer2 in behavior.

KEYWORDS:

Homer2; MS1 full-scan filtering; NMDAR; Skyline; co-immunoprecipitation; mass spectrometry

PMID:
28728878
PMCID:
PMC5722633
DOI:
10.1016/j.jprot.2017.07.008
[Indexed for MEDLINE]
Free PMC Article

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