Tissue transglutaminase catalyzes the formation of alpha‐synuclein crosslinks in Parkinson's disease

Abstract

In Parkinson's disease (PD), conformational changes in the alpha-synuclein monomer precede the formation of Lewy bodies. We examined postmortem PD and undiseased (control) substantia nigra for evidence of pathological crosslinking of alpha-synuclein by tissue transglutaminase (tTG) using immunohistochemistry, immunoprecipitation, and Western blot. Consistent with previous reports, we found that both tTG and its substrate-characteristic N(epsilon)-(gamma-glutamyl)-lysine crosslink are increased in PD nigral dopamine neurons. Furthermore, both the tTG protein and its substrate crosslink coprecipitated with alpha-synuclein in extracts of PD substantia nigra. Unexpectedly, the isodipeptide crosslink was detected in the alpha-synuclein monomer as well as in higher molecular mass oligomers of alpha-synuclein. Although the intramolecularly crosslinked alpha-synuclein monomer was present in control tissue, it was highly enriched in PD substantia nigra. Conversely, significantly less uncrosslinked alpha-synuclein remained in the postimmunoprecipitate lysate of PD tissue than in control. Crosslinked alpha-synuclein, formed at the expense of the total alpha-synuclein monomer, correlated with disease progression. These results demonstrate that much of the alpha-synuclein monomer in PD nigra is crosslinked by tTG and thus may be functionally impaired. This modification appears to be an early step in PD pathogenesis, preceding the aggregation of alpha-synuclein in Lewy bodies.

Expression of breast cancer specific gene-1 (BCSG-1/γ-synuclein) is associated with tumour grade but not with clinical outcome of patients with breast cancer

“…Moreover, higher levels of BCSG-1 also correlated with levels of transglutaminase-3. Tissue transglutaminase has been reported to catalyse the cross link of the synucleins and contribute to disease progression in Parkinson's disease (14,15). Western blotting analysis failed to detect any of the synucleins in normal breast and ovarian tissues, but found synucleins in 82% of latestage breast tumours and 87% of ovarian tumours (16).…”

Transglutaminase-Catalyzed Transamidation: A Novel Mechanism for Rac1 Activation by 5-Hydroxytryptamine2AReceptor Stimulation

“…The 81D4 antibody is well characterized, and it has been previously shown to be specific for the N-ε-(␥-L-glutamy)-L-lysine isopeptide and N-ε-(␥-L-glutamy)-L-lysine isopeptide cross-link generated by TGase (Sá rvá ri et al, 2002;Thomas et al, 2004). The 81D4 antibody has been extensively used to demonstrate increases in TGase-catalyzed bonds (Citron et al, 2002;Junn et al, 2003;Andringa et al, 2004). The use of the 81D4 antibody in a competitive enzyme-linked immunosorbent assay was shown to result in isodipeptide cross-link measurements that correlate well to those measured by high-performance liquid chromatography analysis but provide more sensitivity than the high-performance liquid chromatography approach (Sár-vá ri et al, 2002).…”

Tau Protein Is Cross-Linked by Transglutaminase in P301L Tau Transgenic Mice

“…Additionally, the 81D4 antibody has been used to quantitate ⑀-(␥-glutamyl) lysine bonds in AD tissue using a competitive ELISA (Nemes et al, 2004). This antibody has also been used extensively in immunoprecipitation experiments that demonstrate the presence of ⑀-(␥-glutamyl) lysine cross-links in AD, PSP, and Parkinson's disease tissue but not in control tissue (Norlund et al, 1999;Zemaitaitis et al, 2000;Andringa et al, 2004). The most convincing support for the specificity of the 81D4 antibody for ⑀-(␥-glutamyl) lysine cross-links comes from in vitro and cell culture experiments.…”