Notch1, Jagged1, and HES5 are abundantly expressed in osteoarthritis.
BACKGROUND
Notch signalling controls differentiation and proliferation in various cell types and is associated with several diseases. We investigated the localization and regulation of several Notch markers in human osteoarthritic (OA) cartilage as well as identified genes controlled by Notch signalling.


METHODS
Immunolocalization and real-time PCR analysis of Notch markers in healthy and OA articular cartilage were performed. Genes regulated by Notch signalling were studied using microarray. Cytokine-induced transcription of Notch markers was analyzed using real-time PCR and its effect on cellular localization of the intracellular domain of Notch1 (NICD1) was investigated using immunohistochemistry, subcellular fractionation, and transfection. The effect of NFkappaB activation on HES5 transcription was studied using the NFkappaB inhibitor pyrrolidine dithiocarbamate.


RESULTS
Notch signalling was activated in OA cartilage and Notch1, Jagged1, and HES5 were abundantly expressed compared to healthy cartilage. Notch signalling regulated the expression of several genes associated with OA, like interleukin-8, lubricin, CD10, matrix metalloproteinase-9, and bone morphogenetic protein-2. Cytokines significantly affected the expression of several Notch markers and repressed expression of HES5, but did not affect the cellular localization of NICD1.


CONCLUSIONS
Notch signalling is dysregulated in OA, inducing and repressing transcription of genes that could potentially partly contribute to the OA phenotype.
Karlsson
C
C
Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden. camilla.karlsson@medic.gu.se
Brantsing
C
C
Egell
S
S
Lindahl
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000494:pharmacology; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000072099:Serrate-Jagged Proteins; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D051792:Basic Helix-Loop-Helix Proteins; D002135:Calcium-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D053583:Interleukin-1beta; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D051881:Receptor, Notch1; D012097:Repressor Proteins; D000072099:Serrate-Jagged Proteins; D014409:Tumor Necrosis Factor-alpha; C000606273:JAG1 protein, human; C497761:NOTCH1 protein, human; C077478:HES5 protein, human