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Scleraxis is required for the development of a functional tendon enthesis
Author(s) -
Killian Megan L.,
Thomopoulos Stavros
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.14-258236
Subject(s) - enthesis , fibrocartilage , myostatin , tendon , microbiology and biotechnology , conditional gene knockout , anatomy , andrology , biology , pathology , medicine , skeletal muscle , biochemistry , gene , alternative medicine , phenotype , osteoarthritis , articular cartilage
The attachment of dissimilar materials is a major engineering challenge, yet this challenge is seemingly overcome in biology. This study aimed to determine how the transcription factor Scleraxis ( Scx ) influences the development and maturation of the tendon‐to‐bone attachment (enthesis). Mice with conditional knockout (cKO) for Scx ( Scx flx/‐ , Prx1Cre + ) and wild‐type [(WT) Scx flx/ + or Scx flx/flx ] littermates were killed at postnatal days 7‐56 (P7‐P56). Enthesis morphometry, histology, and collagen alignment were investigated throughout postnatal growth. Enthesis tensile mechanical properties were also assessed. Laser microdissection of distinct musculoskeletal tissues was performed at P7 for WT, cKO, and muscle‐unloaded (botulinum toxin A treated) attachments for quantitative PCR. cKO mice were smaller, with altered bone shape and impaired enthesis morphology, morphometry, and organization. Structural alterations led to altered mechanical properties; cKO entheses demonstrated reduced strength and stiffness. In P7 attachments, cKO mice had reduced expression of transforming growth factor (TGF) superfamily genes in brocartilage compared with WT mice. In conclusion, deletion of Scx led to impairments in enthesis structure, which translated into impaired functional ( i. e. , mechanical) outcomes. These changes may be driven by transient signaling cues from mechanical loading and growth factors.—Killian, M. L., Thomopoulos, S. Scleraxis is required for the development of a functional tendon enthesis. FASEB J. 30, 301‐311 (2016). www.fasebj.org