Open AccessIndian Hedgehog Roles in Post-natal TMJ Development and Organization
Author(s) -
Takanaga Ochiai,
Yoshihiro Shibukawa,
Motohiko Nagayama,
Christina Mundy,
Tadashi Yasuda,
Takahiro Okabe,
Kengo Shimono,
Manabu Kanyama,
Hiromasa Hasegawa,
Yukiko Maeda,
Beate Lanske,
Maurizio Pacifici,
Eiki Koyama
Publication year - 2010
Publication title -
journal of dental research
Language(s) - English
Resource type - Journals
eISSN - 1544-0591
pISSN - 0022-0345
DOI - 10.1177/0022034510363078
Subject(s) - indian hedgehog , condyle , cartilage , temporomandibular joint , primordium , sonic hedgehog , anatomy , hedgehog , endocrinology , microbiology and biotechnology , medicine , biology , dentistry , chondrocyte , genetics , signal transduction , gene
Indian hedgehog (Ihh) is essential for embryonic mandibular condylar growth and disc primordium formation. To determine whether it regulates those processes during post-natal life, we ablated Ihh in cartilage of neonatal mice and assessed the consequences on temporomandibular joint (TMJ) growth and organization over age. Ihh deficiency caused condylar disorganization and growth retardation and reduced polymorphic cell layer proliferation. Expression of Sox9, Runx2, and Osterix was low, as was that of collagen II, collagen I, and aggrecan, thus altering the fibrocartilaginous nature of the condyle. Though a disc formed, it exhibited morphological defects, partial fusion with the glenoid bone surface, reduced synovial cavity space, and, unexpectedly, higher lubricin expression. Analysis of the data shows, for the first time, that continuous Ihh action is required for completion of post-natal TMJ growth and organization. Lubricin overexpression in mutants may represent a compensatory response to sustain TMJ movement and function.