The regulation of runt-related transcription factor 2 by fibroblast growth factor-2 and connexin43 requires the inositol polyphosphate/protein kinase Cδ cascade
| Autor: | Carla Hebert, Corinne Niger, Atum M. Buo, Joseph P. Stains, Vy Ma, Maria A Luciotti |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
musculoskeletal diseases
Inositol Hexakisphosphate Kinase 1 Endocrinology Diabetes and Metabolism Osteoblast Inositol trisphosphate receptor Biology RUNX2 chemistry.chemical_compound medicine.anatomical_structure chemistry Biochemistry embryonic structures Second messenger system cardiovascular system medicine Orthopedics and Sports Medicine Inositol MC3T3 biological phenomena cell phenomena and immunity Protein kinase A |
| Zdroj: | Journal of Bone and Mineral Research. 28:1468-1477 |
| ISSN: | 0884-0431 |
| DOI: | 10.1002/jbmr.1867 |
| Popis: | Connexin43 (Cx43) plays a critical role in osteoblast function and bone mass accrual, yet the identity of the second messengers communicated by Cx43 gap junctions, the targets of these second messengers and how they regulate osteoblast function remain largely unknown. We have shown that alterations of Cx43 expression in osteoblasts can impact the responsiveness to fibroblast growth factor-2 (FGF2), by modulating the transcriptional activity of Runx2. In this study, we examined the contribution of the phospholipase Cγ1/inositol polyphosphate/PKCδ cascade to the Cx43-dependent transcriptional response of MC3T3 osteoblasts to FGF2. Knockdown of expression and/or inhibition of function of phospholipase Cγ1, inositol polyphosphate multikinase, which generates InsP4 and InsP5, and inositol hexakisphosphate kinase 1/2, which generates inositol pyrophosphates, prevented the ability of Cx43 to potentiate FGF2-induced signaling through Runx2. Conversely, overexpression of phospholipase Cγ1 and inositol hexakisphosphate kinase 1/2 enhanced FGF2 activation of Runx2 and the effect of Cx43 overexpression on this response. Disruption of these pathways blocked the nuclear accumulation of PKCδ and the FGF2-dependent interaction of PKCδ and Runx2, reducing Runx2 transcriptional activity. These data reveal that FGF2-signaling involves the inositol polyphosphate cascade, including IP6K, and demonstrate that IP6K regulates Runx2 and osteoblast gene expression. Additionally, these data implicate the water-soluble inositol polyphosphates as mediators of the Cx43-dependent amplification of the osteoblast response to FGF2, and suggest that these low molecular weight second messengers may be biologically relevant mediators of osteoblast function that are communicated by Cx43-gap junctions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text