Tissue transglutaminase is involved in mechanical load–induced osteogenic differentiation of human ligamentum flavum cells

Abstract

Mechanical load-induced osteogenic differentiation might be the key cellular event in the calcification and ossification of ligamentum flavum. The aim of this study was to investigate the influence of tissue transglutaminase (TGM2) on mechanical load-induced osteogenesis of ligamentum flavum cells. Human ligamentum flavum cells were obtained from 12 patients undergoing lumbar spine surgery. Osteogenic phenotypes of ligamentum flavum cells, such as alkaline phosphatase (ALP), Alizarin red-S stain, and gene expression of osteogenic makers were evaluated following the administration of mechanical load and BMP-2 treatment. The expression of TGM2 was evaluated by real-time PCR, Western blotting, and enzyme-linked immunosorbent assay (ELISA) analysis. Our results showed that mechanical load in combination with BMP-2 enhanced calcium deposition and ALP activity. Mechanical load significantly increased ALP and OC gene expression on day 3, whereas BMP-2 significantly increased ALP, OPN, and Runx2 on day 7. Mechanical load significantly induced TGM2 gene expression and enzyme activity in human ligamentum flavum cells. Exogenous TGM2 increased ALP and OC gene expression; while, inhibited TG activity significantly attenuated mechanical load-induced and TGM2-induced ALP activity. In summary, mechanical load-induced TGM2 expression and enzyme activity is involved in the progression of the calcification of ligamentum flavum.

Dysregulation of MicroRNAs in Hypertrophy and Ossification of Ligamentum Flavum: New Advances, Challenges, and Potential Directions

“…Extensive evidence has shown that genetic background (Hou et al, 2014;, mechanical stress (Hayashi et al, 2017;Shunzhi et al, 2017), aging and gender (Safak et al, 2010;Moon et al, 2015;Kim et al, 2018), endocrine and metabolic abnormalities (Dario et al, 2015;Shemesh et al, 2018;Chaput et al, 2019), local inflammation, and angiogenesis (Zhang K. et al, 2017;Sun et al, 2018;Yang et al, 2018a;Jezek et al, 2020) are potential predisposing factors in the development of HLF/OLF. In addition, intrinsic alterations in multiple cellular activities, growth factors, and molecular mediators have been implicated in this intricate process (Chao et al, 2016;Qu et al, 2016a;Sidon et al, 2019;Ye et al, 2019). However, the definitive pathogenesis remains largely unclear.…”

TGM2 accelerates migration and differentiation of BMSCs by activating Wnt/β-catenin signaling

“…TGM2 is distributed in bone and cartilage and can induce the hypertrophic differentiation of joint chondrocytes and osteoarthritis formation [ 19 , 20 ]. It is reported that TGM2 promotes the expression of osteogenic genes (OC, OPN, and Runx2) and enhances ALP activity [ 20 ], and TGM silencing reduces OC and collagen-I expression as well as ALP activity [ 21 ]. Consistently, TGM2 in this study was found to promote mRNA and protein levels of osteoblast-related genes (ALP, OCN, and RUNX2) in BMSCs.…”

Thoracic myelopathy caused by calcification of the ligamentum flavum

“…CPPD deposition predominantly occurs in the cervical spine of middle-aged to older women, and CLF from CPPD deposition tends to occur within a thickened and hypertrophic ligament, which is commonly caused by the degenerative changes of aging 1,4,5) . The mechanical load placed on the ligament causes the ligamentum flavum cell to deposit calcium 10) .…”