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 2

Active ABL assembles the RUNX2-TAZ transcription factor complex required for osteoblast differentiation.

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Active ABL assembles the RUNX2-TAZ transcription factor complex required...
(A) Primary murine osteoblasts were cultured in osteogenic medium for 14 days, and phosphotyrosine immune complexes were probed with an anti-ABL antibody. WCLs were probed with the indicated antibodies for Western blot analysis. (B) HEK293T cells were cotransfected with Flag-TAZ and RUNX2, with or without ABL (PP or KD). Flag-TAZ immune complexes were probed with an anti-RUNX2 antibody. (C) Luciferase activity from a BGLAP reporter assay in HEK293T cells cotransfected with the indicated constructs. n = 3. (D and E) HEK293T cells were cotransfected with the indicated constructs, and RUNX2 (D) or ABL (E) immune complexes were probed with an anti-ABL (D) or anti-Flag (E) antibody. (F) HEK293T cells infected with shGFP or shABL were cotransfected with RUNX2 and Flag-TAZ. The nuclear compartment was extracted from the cells, and Flag-TAZ immune complexes were probed with an anti-RUNX2 antibody. (G and H) HEK293T cells were cotransfected with WT or YF RUNX2 (G) or Flag-TAZ (H), with or without ABL (PP). RUNX2 (G) or Flag-TAZ (H) immune complexes were probed with an anti–p-Tyr antibody. (I) Primary murine osteoblasts infected with shGFP or shABL were cultured in osteogenic medium. p-Tyr or RUNX2 immune complexes were probed with an anti-RUNX2 or anti-TAZ antibody. (J) Luciferase activity from a Bglap reporter assay in primary murine osteoblasts in the presence of shGFP or shABL. n = 3. (K and L) Saos-2 cells infected with an empty vector control or an FKBP-ABL–expressing retroviral vector in the presence of shGFP (K and L), shRUNX2 (K), or shTAZ (L) were cultured in growth medium containing 50 nM FK1012. Cells were stained with alizarin red S solution. n = 3. *P < 0.05, by ANOVA with a Tukey–Kramer post-hoc test. Data represent the mean ± SEM.