JNK/ERK-AP-1/Runx2 induction "paves the way" to cartilage load-ignited chondroblastic differentiation.

Full Abstract

Chondro-osteogenesis and subsequently skeletal morphology are greatly influenced by mechanical loads. The exact mechanism(s) by which mechanical stimuli are transduced in chondrocytes remains obscure and appears to be equally complex with similar signal transducing systems. Here we investigated whether and to what extent the MAPK (JNK/ERK)-AP-1/Runx2 signaling pathways are engaged in this phenomenon, and assessed their involvement in the functional biology of articular cartilage. For this purpose, 14-day-old female Wistar rats were divided into 2 groups: the first group was fed hard diet (simulating physiologic temporomandibular joint (TMJ) loading), while the second group was fed soft diet (reduced TMJ loading). On day 21 (experiment initiation day - weaning day), biopsies from condyles of both groups were obtained after 6, 12 and 48 h of functional TMJ loading. Immunohistochemical methodology was employed to evaluate the expression levels of pc-Jun, c-Fos, JNK2, p-JNK, p-ERK and Runx2 due to alteration in functional load. Our data demsonstrate that the protein levels of all the aforementioned molecules were markedly increased in animals fed with the hard diet, throughout the experimental procedure. These results indicate that functional cartilage loading induces the AP-1 and Runx2 transcription factors through the JNK and ERK MAPK cascades. In as much as the above signaling mediators/effectors are considered to be crucial in the differentiation/maturation process of cartilage tissue, we pose that functional mechanical loading of condylar cartilage serves to "fine tune" chondroblastic differentiation/maturation.

Author information

Author/s: Papachristou, Dionysios J (DJ); Pirttiniemi, Pertti (P); Kantomaa, Tuomo (T); Papavassiliou, Athanasios G (AG); Basdra, Efthimia K (EK);

Affiliation: Department of Biochemistry, School of Medicine, University of Patras, Greece.

Journal and publication information

Publication Type: Journal Article

Journal: Histochemistry and cell biology (Histochem Cell Biol), published in Germany. (Language: eng)

Reference: 2005-Sep; vol 124 (issue 3-4) : pp 215-23

Dates: Created 2005/11/18; Completed 2006/01/20; Revised 2006/04/13;

PMID: 16041628, status: MEDLINE (last retrieved date: 2/18/2009)

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MeSH headings (categories)

This article was linked to the MeSH Headings (categories) shown below.

Animals
Biomechanics
Cartilage, Articular - cytology; metabolism
Cell Differentiation
Chondrocytes - cytology; metabolism
Core Binding Factor Alpha 1 Subunit - biosynthesis
Diet
Enzyme Induction
Extracellular Signal-Regulated MAP Kinases - biosynthesis
Female

Note: Bold headings indicate primary MeSH headings or qualifiers.

Associated Chemicals: Core Binding Factor Alpha 1 Subunit (0) ; Runx2 protein, rat (0) ; Transcription Factor AP-1 (0) ; Extracellular Signal-Regulated MAP Kinases (EC 2.7.1.37) ; JNK Mitogen-Activated Protein Kinases (EC 2.7.1.37) ; Mitogen-Activated Protein Kinase 9 (EC 2.7.1.37)

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