This program continues to study the tissue specific and developmental regulation of the osteocalcin (OC) gene and the factors that contribute to induction and progression of osteoblast (OB) maturation. In the current program period, we discovered a regulatory network of homeodomain (HD) proteins that provide molecular switches for mediating the temporal expression of OC with a pivotal activating role for Dlx3 at the onset of OC transcription. A novel regulatory element for the Hox transcription factors was discovered that binds Hoxa10 for activation of OC transcription. Hoxa10 and Dlx3 are bound to the OC gene prior to Runx2 and increase again with Runx2 binding. In addition, these factors can activate the OC gene in Runx2 null cells, thus providing evidence for molecular events contributing to expression of the OC and bone related genes upstream of Runx2. These findings justify further investigation of their functional roles in osteoblasts in vivo and in vitro. We postulate that these two regulatory factors have key roles in regulating gene expression throughout OB differentiation, a function distinct from their activities in embryonic patterning of the skeleton. We will identify these OB- related functions by determining the mechanism by which they regulate developmental expression of OC which include contributing to chromatin remodeling, regulating activation and repression of gene transcription through interactions with co-regulatory factors, and functioning both independent of Runx2 and coordinated with Runx2 for establishment of the OB phenotype.
Aim1 tests the hypothesis that dynamic association/dissociation of these factors with osteocalcin chromatin occurs at specific stages of phenotype development due to formation of transcription factor complexes modifying chromatin architecture of OC.
Aim 2 addresses the hypothesis that Hoxa10 functions upstream of Runx2 to promote epigenetic marking of the OC gene for tissue specific activation, and regulation of target gene expression in OBs. Its deletion from OB in vitro and in vivo is postulated to alter OB maturation and contribute to a mild bone phenotype in adult mice.
Aim 3 postulates that Dlx3 has a transient role in gene regulation, responsible for the timing of transcription of the OC gene and coordinated occupancy of Runx2 which will be addressed ex vivo in cells from the Dlx3 null and conditional knockout mice. We further postulate that the human Dlx3 tricho-dento-osseous (TDO) mutation alters the transient function of Dlx3 in osteoblasts as a result of loss-of-function of interacting co-regulatory proteins. These studies will identify novel mechanisms and regulatory pathways required for induction and regulation of OC and regulation of OB maturation to the differentiated phenotype in a mineralizing matrix.
We have identified two novel regulatory factors that support expression of bone specific genes for bone formation, named Dlx3 and Hoxa10, and are important for normal development and patterning of the skeleton. The mechanisms mediated by these proteins in promoting the differentiation of bone forming cells, as well as the discovery of novel target genes for these factors is knowledge that can be applied to approaches for treatment of bone abnormalities and genetic disorders of the skeleton being investigated in these studies.
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| Tracy, Kirsten M; Tye, Coralee E; Ghule, Prachi N et al. (2018) Mitotically-Associated lncRNA (MANCR) Affects Genomic Stability and Cell Division in Aggressive Breast Cancer. Mol Cancer Res 16:587-598 |
| Hong, Deli; Fritz, Andrew J; Finstad, Kristiaan H et al. (2018) Suppression of Breast Cancer Stem Cells and Tumor Growth by the RUNX1 Transcription Factor. Mol Cancer Res 16:1952-1964 |
| Lavoie, B; Roberts, J A; Haag, M M et al. (2018) Gut-derived serotonin contributes to bone deficits in colitis. Pharmacol Res : |
| Tracy, Kirsten M; Tye, Coralee E; Page, Natalie A et al. (2018) Selective expression of long non-coding RNAs in a breast cancer cell progression model. J Cell Physiol 233:1291-1299 |
| Hong, Deli; Fritz, Andrew J; Gordon, Jonathan A et al. (2018) RUNX1-dependent mechanisms in biological control and dysregulation in cancer. J Cell Physiol : |
| Maeda, Yukiko; Farina, Nicholas H; Matzelle, Melissa M et al. (2017) Synovium-Derived MicroRNAs Regulate Bone Pathways in Rheumatoid Arthritis. J Bone Miner Res 32:461-472 |
| Farina, Nicholas H; Ramsey, Jon E; Cuke, Melissa E et al. (2017) Development of a predictive miRNA signature for breast cancer risk among high-risk women. Oncotarget 8:112170-112183 |
| Wu, Hai; Gordon, Jonathan A R; Whitfield, Troy W et al. (2017) Chromatin dynamics regulate mesenchymal stem cell lineage specification and differentiation to osteogenesis. Biochim Biophys Acta Gene Regul Mech 1860:438-449 |
| Barutcu, A Rasim; Lian, Jane B; Stein, Janet L et al. (2017) The connection between BRG1, CTCF and topoisomerases at TAD boundaries. Nucleus 8:150-155 |
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