Abstract
The establishment of a proper musculoskeletal system depends on the well-organized and synchronized development of muscle, tendon and cartilage/bone. In tendon biology, a great progress in identifying tendon-specific genes (Scleraxis, Mohawk, Tenomodulin) had been made in the last decade. However, there are many open questions regarding the exact function of genes in tendon development and homeostasis. The purpose of this study was to perform a systematic review of publications describing tendon-related genes, which were studied in-depth and characterized by using knockout technologies and the respectively generated transgenic mouse. Method: Literature search was carried out in Pubmed using “tendon” and “mouse knockout” and “phenotype” and was not limited to year. Results: We report in a tabular manner, that from a total of 25 tendon-related genes, in 23 of the respective knockout mouse models phenotypic changes were detected. Additionally, in some of the models it was described at which developmental stages these changes appeared and progressed. Interestingly, so far only loss of Scleraxis and TGFbeta signaling led to severe tendon developmental phenotypes, while mice deficient for various proteoglycans, Mohawk, EGR1 and 2, and Tenomodulin exhibited mild phenotypes. This suggests that in general the tendon developmental program is well backup and specifically that among the members of the proteoglycan family there are clear compensatory effects. In future, it will be of great importance to discover additional master tendon transcription factors as well as genes that play indispensable roles in tendon development.
