Formation of toxic protein aggregates is a common feature and mainly contributes to the pathogenesis of neurodegenerative diseases (NDDs), which include amyotrophic lateral sclerosis (ALS), Alzheimer's, Parkinson's, Huntington's, and prion diseases. The transglutaminase 2 (TG2) gene encodes a multifunctional enzyme, displaying four types of activity, such as transamidation, GTPase, protein disulfide isomerase, and protein kinase activities. Many studies demonstrated that the calcium-dependent transamidation activity of TG2 affects the formation of insoluble and toxic amyloid aggregates that mainly consisted of NDD-related proteins. So far, many important and NDD-related substrates of TG2 have been identified, including amlyoid-β, tau, α-synuclein, mutant huntingtin, and ALS-linked trans-activation response (TAR) DNA-binding protein 43. Recently, the formation of toxic inclusions mediated by several TG2 substrates were efficiently inhibited by TG2 inhibitors. Therefore, the development of highly specific TG2 inhibitors would be an important tool in alleviating the progression of TG2-related brain disorders. In this review, the authors discuss recent advances in TG2 biochemistry, several mechanisms of molecular regulation and pleotropic signaling functions, and the presumed role of TG2 in the progression of many NDDs.
Bibliographical noteFunding Information:
We apologize to the authors whose work could not be referenced due to space limitation. This work was supported by grants from the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2014M3C7A1064545 to K.C.C.) and from the Korea Healthcare Technology RandD Project through the Korea Health Industry Development Institute (KHIDI) funded by the Ministry of Health and Welfare (HI17C0936 to K.C.C.), Republic of Korea. This work was also supported in part by the NRF grant (2015R1A2A2A01003080 to K.C.C.).
All Science Journal Classification (ASJC) codes
- Molecular Biology