In situ enzymatic activity of transglutaminase isoforms on brain tissue sections of rodents: A new approach to monitor differences in post-translational protein modifications during neurodegeneration

Transglutaminase 6 Is Colocalized and Interacts with Mutant Huntingtin in Huntington Disease Rodent Animal Models

“…Here, the expression of the TG6 protein was highest in the cortex, especially in the piriform cortex, the lateral septum, the olfactory tubercle and the shell of the nucleus accumbens (Figure 2A; right panel). TG6 expression was specifically localized to neurons, but not to astrocytes or microglia, as we previously confirmed using the NeuN-, Iba1-and GFAP-specific antibodies [45]. Furthermore, the reaction products of TGs, the N-ε-(γ-glutamyl)-lysine isopeptide bonds (GGEL) (Dab-Ni, black staining), could also be found in neurons next to astrocytes (Figure 2B), which appeared in close proximity to TG6 (DAB, brown staining) positive neurons (Figure 2B; arrowheads).…”

“…Similar results as shown in the cerebral cortex of mice, were also obtained in the olfactory tubercle of old tgHD rats (data not shown). As expected, TG1-, TG2-and TG3-specific reactivity was mostly localized on blood vessels and meninges and no age-or genotype-specific differences were detected in the animal models investigated (Supplementary Figure S1) [45].…”

“…To assess specific TG6 enzymatic activity in situ, we adapted a protocol described by Esposito and colleagues for intestinal tissue [44,45]. As presented in Figure 1B (NC), no or negligible background reactivity was detectable in the absence of CaCl 2 .…”

“…The regional distribution of TG6 was also investigated in a second rodent model of Huntington disease, using an antibody whose specificity we recently confirmed [45]. Homozygous tgHD rats expressing a truncated 1962 bp Htt fragment with 51 repeats of the polyglutamine stretch under the control of the endogenous Htt rat promoter [42] were analyzed in comparison to wt littermates.…”

TGM6 variants in Parkinson's disease: clinical findings and functional evidence

“…TGs catalyze protein covalent cross-linking through transamination reactions, in which intra-or inter-molecular isopeptide bonds are formed between a glutamine residue and, usually, a lysine residue (Folk and Chung, 1973). TG6 is abundantly expressed in the brain, especially in the septal region, basal ganglia, and cerebellum Schulze-Krebs et al, 2016). Some TGs have been related to neurodegenerative diseases (AbdAlla et al, 2009;Andringa et al, 2004;Zainelli et al, 2003).…”