title: Tissue transglutaminase cross-links beclin 1 and regulates autophagy in MPP⁺-treated human SH-SY5Y cells.
abstract: Tissue transglutaminase (tTG) is a cross-linking enzyme involved in protein aggregation during Parkinson's disease (PD) pathogenesis. Autophagy is inhibited by tTG activation via a mechanism in which cross-linking of beclin 1, an autophagy initiator at the level of the endoplasmic reticulum (ER), has been implicated. We reported increased tTG protein levels and activity at the ER in both PD brain and in a PD-mimicking cell system. Here we characterized the interaction between tTG and beclin 1 at the ER membrane and the role of tTG in reduced autophagy in an in vitro model of PD, using differentiated SH-SY5Y neurons treated with the PD-mimic MPP(+). We found that under PD-mimicking conditions, beclin 1 and tTG partially colocalized at the ER, beclin 1 levels increased at the ER, and tTG readily cross-linked beclin 1 which was prevented by enzymatic blockade of tTG. Under these conditions, accumulation of beclin 1 at the ER was enhanced by inhibition of tTG activity. In line with these observations and the role of beclin 1 in autophagy, levels of the autophagy marker protein LC3II in MPP(+)-treated cells, were significantly increased by inhibition of tTG activity. Our data provide first evidence for a role of tTG-mediated regulation of beclin 1 and autophagy in MPP(+)-treated human SH-SY5Y cells.
authors: Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors: Robin
authors: R
authors: Verhaar
authors: Benjamin
authors: B
authors: Drukarch
authors: John G J M
authors: JG
authors: Bol
authors: Cornelis A M
authors: CA
authors: Jongenelen
authors: Micha M M
authors: MM
authors: Wilhelmus
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D000071186:Beclin-1; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases / Q000378:metabolism / Q000502:physiology*
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D015655:1-Methyl-4-phenylpyridinium