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 1

ABL is required for osteoblast expansion, differentiation, and embryonic skeletal development.

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ABL is required for osteoblast expansion, differentiation, and embryonic...
(A–C) Whole-mount skeletons (A), calvarium (B), clavicles, and limb bones (C) of WT and Abl-KO (Abl–/–) newborn pups stained with alizarin red and Alcian blue. (D) Trichrome staining of tibiae from WT and Abl–/– newborn pups. The calcified tissue appears blue-green. Scale bars: 400 μm (left), 200 μm (right). (E) Histomorphometric analysis of osteoblast numbers per bone surface (No. Ob/BS) and trabecular bone volume per total volume (BV/TV) in WT and Abl–/– newborn pups. n = 5. (F) Primary murine osteoblasts infected with an empty vector control (Mock) or with a retroviral vector expressing WT FKBP-ABL (WT) or kinase-dead FKBP-ABL (KD) were cultured in osteogenic medium for 12 and 21 days and stained with alizarin red S solution. n = 3. ABL immune complexes were probed with an anti–p-ABL (Y245) or anti-ABL antibody. WCLs were probed with an anti-actin antibody as a loading control. (G) qPCR analysis of Bglap mRNA expression in cells in F cultured in osteogenic medium for 3 to 9 days. n = 3. (H) Growth curves of primary murine osteoblasts infected with an shRNA targeting GFP (shGFP) or Abl (shAbl) and cultured for 3 days. n = 3. (I) Primary murine osteoblasts in H were cultured in the presence of BrdU for 24 hours. Cells were subjected to fixation within the culture plate, and BrdU incorporation was determined by ELISA. n = 5. *P < 0.05, by ANOVA with a Tukey-Kramer post-hoc test (G) or by unpaired t test (E, H, and I). Data represent the mean ± SEM.