Reciprocal stabilization of ABL and TAZ regulates osteoblastogenesis through transcription factor RUNX2
Yoshinori Matsumoto, … , Ann Marie Pendergast, Robert Rottapel
Yoshinori Matsumoto, … , Ann Marie Pendergast, Robert Rottapel
Published October 31, 2016
Citation Information: J Clin Invest. 2016;126(12):4482-4496. https://doi.org/10.1172/JCI87802.
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Research Article Bone biology Cell biology

Reciprocal stabilization of ABL and TAZ regulates osteoblastogenesis through transcription factor RUNX2

Abstract

Cellular identity in metazoan organisms is frequently established through lineage-specifying transcription factors, which control their own expression through transcriptional positive feedback, while antagonizing the developmental networks of competing lineages. Here, we have uncovered a distinct positive feedback loop that arises from the reciprocal stabilization of the tyrosine kinase ABL and the transcriptional coactivator TAZ. Moreover, we determined that this loop is required for osteoblast differentiation and embryonic skeletal formation. ABL potentiated the assembly and activation of the RUNX2-TAZ master transcription factor complex that is required for osteoblastogenesis, while antagonizing PPARγ-mediated adipogenesis. ABL also enhanced TAZ nuclear localization and the formation of the TAZ-TEAD complex that is required for osteoblast expansion. Last, we have provided genetic data showing that regulation of the ABL-TAZ amplification loop lies downstream of the adaptor protein 3BP2, which is mutated in the craniofacial dysmorphia syndrome cherubism. Our study demonstrates an interplay between ABL and TAZ that controls the mesenchymal maturation program toward the osteoblast lineage and is mechanistically distinct from the established model of lineage-specific maturation.

Authors

Yoshinori Matsumoto, Jose La Rose, Oliver A. Kent, Melany J. Wagner, Masahiro Narimatsu, Aaron D. Levy, Mitchell H. Omar, Jiefei Tong, Jonathan R. Krieger, Emily Riggs, Yaryna Storozhuk, Julia Pasquale, Manuela Ventura, Behzad Yeganeh, Martin Post, Michael F. Moran, Marc D. Grynpas, Jeffrey L. Wrana, Giulio Superti-Furga, Anthony J. Koleske, Ann Marie Pendergast, Robert Rottapel

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Figure 3

Nuclear ABL is required for the RUNX2-TAZ complex transcriptional activity.

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Nuclear ABL is required for the RUNX2-TAZ complex transcriptional activi...
(A) Primary murine osteoblasts were cultured in growth medium, osteogenic medium, or growth medium supplemented with 10 mM β-glycerophosphate, 10 nM dexamethasone, or 100 μg/ml ascorbic acid and stained by immunofluorescence. Scale bars: 20 μm. The images of intracellular ABL (green) and nuclei (blue) are representative of 3 independent experiments. (B) Primary murine osteoblasts were cultured in growth medium or osteogenic medium and stained by immunofluorescence. Scale bars: 20 μm. The images of intracellular TAZ (green), RUNX2 (red), and nuclei (blue) are representative of 3 independent experiments. (C and D) qPCR of chromatin immunoprecipitates from Saos-2 cells (C) or Saos-2 cells infected with shGFP or shRUNX2 (D). Amplicons were designed to flank the RUNX2-binding site within the BGLAP promoter. Fold enrichment represents the signal obtained after IP with a nonspecific IgG antibody. n = 3. (E) Luciferase activity from a BGLAP reporter assay in HEK293T cells cotransfected with the indicated constructs. n = 3. *P < 0.05, by ANOVA with a Tukey-Kramer post-hoc test. Data represent the mean ± SEM.