PMID- 29269412 OWN - NLM STAT- MEDLINE DCOM- 20190205 LR - 20210205 IS - 1083-351X (Electronic) IS - 0021-9258 (Print) IS - 0021-9258 (Linking) VI - 293 IP - 7 DP - 2018 Feb 16 TI - The ubiquitin-proteasome system functionally links neuronal Tomosyn-1 to dendritic morphology. PG - 2232-2246 LID - 10.1074/jbc.M117.815514 [doi] AB - Altering the expression of Tomosyn-1 (Tomo-1), a soluble, R-SNARE domain-containing protein, significantly affects behavior in mice, Drosophila, and Caenorhabditis elegans Yet, the mechanisms that modulate Tomo-1 expression and its regulatory activity remain poorly defined. Here, we found that Tomo-1 expression levels influence postsynaptic spine density. Tomo-1 overexpression increased dendritic spine density, whereas Tomo-1 knockdown (KD) decreased spine density. These findings identified a novel action of Tomo-1 on dendritic spines, which is unique because it occurs independently of Tomo-1's C-terminal R-SNARE domain. We also demonstrated that the ubiquitin-proteasome system (UPS), which is known to influence synaptic strength, dynamically regulates Tomo-1 protein levels. Immunoprecipitated and affinity-purified Tomo-1 from cultured rat hippocampal neurons was ubiquitinated, and the levels of ubiquitinated Tomo-1 dramatically increased upon pharmacological proteasome blockade. Moreover, Tomo-1 ubiquitination appeared to be mediated through an interaction with the E3 ubiquitin ligase HRD1, as immunoprecipitation of Tomo-1 from neurons co-precipitated HRD1, and this interaction increases upon proteasome inhibition. Further, in vitro reactions indicated direct, HRD1 concentration-dependent Tomo-1 ubiquitination. We also noted that the UPS regulates both Tomo-1 expression and functional output, as HRD1 KD in hippocampal neurons increased Tomo-1 protein level and dendritic spine density. Notably, the effect of HRD1 KD on spine density was mitigated by additional KD of Tomo-1, indicating a direct HRD1/Tomo-1 effector relationship. In summary, our results indicate that the UPS is likely to participate in tuning synaptic efficacy and spine dynamics by precise regulation of neuronal Tomo-1 levels. CI - (c) 2018 by The American Society for Biochemistry and Molecular Biology, Inc. FAU - Saldate, Johnny J AU - Saldate JJ AUID- ORCID: 0000-0003-4912-6299 AD - From the Neuroscience Graduate Program and. FAU - Shiau, Jason AU - Shiau J AD - the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624. FAU - Cazares, Victor A AU - Cazares VA AD - the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624. FAU - Stuenkel, Edward L AU - Stuenkel EL AUID- ORCID: 0000-0001-8225-5725 AD - From the Neuroscience Graduate Program and esterm@umich.edu. AD - the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624. LA - eng GR - F31 NS087883/NS/NINDS NIH HHS/United States GR - R01 NS097498/NS/NINDS NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural DEP - 20171221 PL - United States TA - J Biol Chem JT - The Journal of biological chemistry JID - 2985121R RN - 0 (Nerve Tissue Proteins) RN - 0 (R-SNARE Proteins) RN - 0 (Stxbp5 protein, rat) RN - 0 (Ubiquitin) RN - EC 2.3.2.27 (Syvn1 protein, rat) RN - EC 2.3.2.27 (Ubiquitin-Protein Ligases) RN - EC 3.4.25.1 (Proteasome Endopeptidase Complex) SB - IM MH - Animals MH - Cells, Cultured MH - Dendritic Spines/enzymology/genetics/*metabolism MH - Female MH - Hippocampus/cytology/enzymology MH - Male MH - Nerve Tissue Proteins/genetics/*metabolism MH - Neurons/enzymology/*metabolism MH - Post-Synaptic Density/genetics/metabolism MH - Proteasome Endopeptidase Complex/genetics/*metabolism MH - Protein Binding MH - R-SNARE Proteins/genetics/*metabolism MH - Rats MH - Rats, Sprague-Dawley MH - Ubiquitin/*metabolism MH - Ubiquitin-Protein Ligases/genetics/metabolism MH - Ubiquitination PMC - PMC5818180 OTO - NOTNLM OT - E3 ubiquitin ligase OT - HRD1 OT - Tomosyn OT - dendritic spine OT - hippocampus OT - neuron OT - synapse OT - ubiquitin-proteasome system COIS- The authors declare that they have no conflicts of interest with the contents of this article EDAT- 2017/12/23 06:00 MHDA- 2019/02/06 06:00 PMCR- 2019/02/16 CRDT- 2017/12/23 06:00 PHST- 2017/08/31 00:00 [received] PHST- 2017/12/02 00:00 [revised] PHST- 2017/12/23 06:00 [pubmed] PHST- 2019/02/06 06:00 [medline] PHST- 2017/12/23 06:00 [entrez] PHST- 2019/02/16 00:00 [pmc-release] AID - S0021-9258(20)31690-2 [pii] AID - M117.815514 [pii] AID - 10.1074/jbc.M117.815514 [doi] PST - ppublish SO - J Biol Chem. 2018 Feb 16;293(7):2232-2246. doi: 10.1074/jbc.M117.815514. Epub 2017 Dec 21.