Probing tissue transglutaminase mediated vascular smooth muscle cell aging using a novel transamidation-deficient Tgm2-C277S mouse model

Abstract

Tissue transglutaminase (TG2), a multifunctional protein of the transglutaminase family, has putative transamidation-independent functions in aging-associated vascular stiffening and dysfunction. Developing preclinical models will be critical to fully understand the physiologic relevance of TG2’s transamidation-independent activity and to identify the specific function of TG2 for therapeutic targeting. Therefore, in this study, we harnessed CRISPR-Cas9 gene editing technology to introduce a mutation at cysteine 277 in the active site of the mouse Tgm2 gene. Heterozygous and homozygous Tgm2-C277S mice were phenotypically normal and were born at the expected Mendelian frequency. TG2 protein was ubiquitously expressed in the Tgm2-C277S mice at levels similar to those of wild-type (WT) mice. In the Tgm2-C277S mice, TG2 transglutaminase function was successfully obliterated, but the transamidation-independent functions ascribed to GTP, fibronectin, and integrin binding were preserved. In vitro, a remodeling stimulus led to the significant loss of vascular compliance in WT mice, but not in the Tgm2-C277S or TG2−/− mice. Vascular stiffness increased with age in WT mice, as measured by pulse-wave velocity and tensile testing. Tgm2-C277S mice were protected from age-associated vascular stiffening, and TG2 knockout yielded further protection. Together, these studies show that TG2 contributes significantly to overall vascular modulus and vasoreactivity independent of its transamidation function, but that transamidation activity is a significant cause of vascular matrix stiffening during aging. Finally, the Tgm2-C277S mice can be used for in vivo studies to explore the transamidation-independent roles of TG2 in physiology and pathophysiology.

Neonatal exposure to hypoxia induces early arterial stiffening via activation of lysyl oxidases

“…Mice exposed to neonatal hypoxia had higher PWV and passive modulus at P60 with a further increase by P120, without a change in blood pressure, when compared to normoxic controls. The elevated stiffness without BP changes in the neonatal hypoxia group were similar to those observed in middle-aged mice during aging (Steppan et al, 2019;Wang, Chen, et al, 2021), supporting the hypothesis that exposure to hypoxia during the neonatal period accelerates arterial aging. This is of particular interest, as prior clinical studies have clearly shown that arterial stiffening in childhood and adolescence due to obesity, diabetes, and congenital heart disease is predictive of early onset CVD in adulthood (Dangardt et al, 2013;Hacker et al, 2018;Madsen et al, 2021;Urbina et al, 2010).…”

Mapping the unicellular transcriptome of the ascending thoracic aorta to changes in mechanosensing and mechanoadaptation during aging

“…These observations fuel maturing evidence of augmented calcium signaling 68 and contractility 69,70 in SMCs embedded within a stiff matrix. Note, Retailleau et al reported that Piezo-1 signaling promotes thickening of the murine caudal artery by stimulating the Ca 2+ -dependent catalytic activity of transglutaminases 71 and tissue transglutaminase contributes to vascular stiffening during aging [72][73][74] . Therefore, modulation of the actin cytoskeletal architecture in vSMC (Figure 7A) may heighten contractility (Figure 7B-C) and contribute to ECM stiffening (Figure 6B-C; Table S3) by mediating expression and activation of mechanosensitive Piezo-1 in the ATA media during aging (Figure 7A).…”

Silencing Transglutaminase Genes TGase2 and TGase3 Has Infection-Dependent Effects on the Heart Rate of the Mosquito Anopheles gambiae

“…Other possibilities rely on comparisons with vertebrate animals. For example, transglutaminase causes age-associated vascular stiffening and dysfunction in mice, resulting in a loss of vascular compliance as this mammal ages [ 59 ]. It is possible that silencing mosquito TGase3 reduces heart stiffening, thereby increasing cardiac efficiency and reducing the heart rate in uninfected mosquitoes.…”