Regular Article

Cell and Tissue Research

, Volume 327, Issue 3, pp 539-551

Notch and HES5 are regulated during human cartilage differentiation

  • Camilla KarlssonAffiliated withInstitute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University HospitalDepartment of Clinical Chemistry, Bruna Stråket 16, Sahlgrenska Hospital, University of Gothenburg Email author 
  • , Marianne JonssonAffiliated withInstitute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital
  • , Julia AspAffiliated withInstitute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital
  • , Camilla BrantsingAffiliated withInstitute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital
  • , Ryoichiro KageyamaAffiliated withInstitute for Virus Research, Kyoto University, Shogoin-Kawahara
  • , Anders LindahlAffiliated withInstitute for Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital

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Abstract

The molecular mechanisms of cartilage differentiation are poorly understood. In a variety of tissues other than cartilage, members of the basic helix-loop-helix (bHLH) family of transcription factors have been demonstrated to play critical roles in differentiation. We have characterized the human bHLH gene HES5 and investigated its role during chondrogenesis. Blockage of the Notch signaling pathway with a γ-secretase inhibitor has demonstrated that the human HES5 gene is a downstream marker of Notch signaling in articular chondrocytes. Markers for the Notch signaling pathway significantly decrease during cartilage differentiation in vitro. Cell proliferation assayed by using BrdU has revealed that blockage of Notch signaling is associated with significantly decreased proliferation. Northern blot and reverse transcription/polymerase chain reaction of a panel of various tissues have shown that HES5 is transcribed as a 5.4-kb mRNA that is ubiquitously expressed in diverse fetal and adult tissues. Articular cartilage from HES5−/− and wild-type mice has been analyzed by using various histological stains. No differences have been detected between the wild-type and HES5−/− mice. Our data thus indicate that the human HES5 gene is coupled to the Notch receptor family, that expression of Notch markers (including HES5) decreases during cartilage differentiation, and that the blockage of Notch signaling is associated with significantly decreased cell proliferation.

Keywords

Articular cartilage HES5 Notch signaling Differentiation Helix-loop-helix genes Human