Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Histone modifications induced by activated signalling cascades are crucial to cell-lineage decisions. Osteoblast and adipocyte differentiation from common mesenchymal stem cells is under transcriptional control by numerous factors. Although PPAR-gamma (peroxisome proliferator activated receptor-gamma) has been established as a prime inducer of adipogenesis, cellular signalling factors that determine cell lineage in bone marrow remain generally unknown. Here, we show that the non-canonical Wnt pathway through CaMKII-TAK1-TAB2-NLK transcriptionally represses PPAR-gamma transactivation and induces Runx2 expression, promoting osteoblastogenesis in preference to adipogenesis in bone marrow mesenchymal progenitors. Wnt-5a activates NLK (Nemo-like kinase), which in turn phosphorylates a histone methyltransferase, SETDB1 (SET domain bifurcated 1), leading to the formation of a co-repressor complex that inactivates PPAR-gamma function through histone H3-K9 methylation. These findings suggest that the non-canonical Wnt signalling pathway suppresses PPAR-gamma function through chromatin inactivation triggered by recruitment of a repressing histone methyltransferase, thus leading to an osteoblastic cell lineage from mesenchymal stem cells.
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PMID:A histone lysine methyltransferase activated by non-canonical Wnt signalling suppresses PPAR-gamma transactivation. 2535 53

Osteoblasts and adipocytes differentiate from a common precursor, the pluripotent mesenchymal stem cell (MSC) found in bone marrow (BMSC) and adipose tissue (AD-MSC). Numerous transcription factors and multiple extracellular and intracellular signals regulating adipogenesis and osteoblastogenesis have been identified and analyzed. Significantly, inducers of differentiation towards one lineage may inhibit cell differentiation into an alternative lineage. For example, the canonical Wnt/beta-catenin pathway induces osteoblastogenesis and inhibits adipogenesis, whereas the peroxisome proliferator activated receptor-gamma (PPAR-gamma) is a prime inducer of adipogenesis and, as shown in recent studies, inhibits osteoblastogenesis. We have identified two signaling pathways that switch the cell fate decision from adipocytes to osteoblasts by suppressing the transactivation function of PPAR-gamma. In the first pathway, the TNF-alpha- or IL-1-induced TAK1/TAB1/NIK signaling cascade attenuates PPAR-gamma-mediated adipogenesis by inhibiting the binding of PPAR-gamma to the DNA response element. The second is the noncanonical Wnt pathway through the CaMKII-TAK1/TAB2-NLK (nemo-like kinase) signaling cascade. Specifically, Wnt-5a-induced phosphorylation of NLK triggers formation of a complex with the histone methyltransferase SETDB1 (SET domain, bifurcated 1) that represses PPAR-gamma transactivation through histone H3-K9 methylation at the target genes. Thus, two signaling cascades promote osteoblastic differentiation from MSC through two distinct modes of PPAR-gamma transrepression.
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PMID:Molecular switching of osteoblastogenesis versus adipogenesis: implications for targeted therapies. 1939 78