Salt-inducible kinases dictate parathyroid hormone 1 receptor action in bone development and remodeling
Shigeki Nishimori, … , Henry M. Kronenberg, Marc N. Wein
Shigeki Nishimori, … , Henry M. Kronenberg, Marc N. Wein
Published August 20, 2019
Citation Information: J Clin Invest. 2019;129(12):5187-5203. https://doi.org/10.1172/JCI130126.
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Research Article Bone biology Endocrinology

Salt-inducible kinases dictate parathyroid hormone 1 receptor action in bone development and remodeling

Abstract

The parathyroid hormone 1 receptor (PTH1R) mediates the biologic actions of parathyroid hormone (PTH) and parathyroid hormone–related protein (PTHrP). Here, we showed that salt-inducible kinases (SIKs) are key kinases that control the skeletal actions downstream of PTH1R and that this GPCR, when activated, inhibited cellular SIK activity. Sik gene deletion led to phenotypic changes that were remarkably similar to models of increased PTH1R signaling. In growth plate chondrocytes, PTHrP inhibited SIK3, and ablation of this kinase in proliferating chondrocytes rescued perinatal lethality of PTHrP-null mice. Combined deletion of Sik2 and Sik3 in osteoblasts and osteocytes led to a dramatic increase in bone mass that closely resembled the skeletal and molecular phenotypes observed when these bone cells express a constitutively active PTH1R that causes Jansen’s metaphyseal chondrodysplasia. Finally, genetic evidence demonstrated that class IIa histone deacetylases were key PTH1R-regulated SIK substrates in both chondrocytes and osteocytes. Taken together, our findings establish that SIK inhibition is central to PTH1R action in bone development and remodeling. Furthermore, this work highlights the key role of cAMP-regulated SIKs downstream of GPCR action.

Authors

Shigeki Nishimori, Maureen J. O’Meara, Christian D. Castro, Hiroshi Noda, Murat Cetinbas, Janaina da Silva Martins, Ugur Ayturk, Daniel J. Brooks, Michael Bruce, Mizuki Nagata, Wanida Ono, Christopher J. Janton, Mary L. Bouxsein, Marc Foretz, Rebecca Berdeaux, Ruslan I. Sadreyev, Thomas J. Gardella, Harald Jüppner, Henry M. Kronenberg, Marc N. Wein

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Figure 1

Sik3 deletion rescues perinatal lethality of Pthrp-deficient mice.

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Sik3 deletion rescues perinatal lethality of Pthrp-deficient mice. (A) ...
(A) Primary rib chondrocytes isolated from newborn WT mice were treated with vehicle or PTH (1–34, 100 nM) for 30 minutes, followed by immunoblotting as indicated. Phosphorylated HDAC4-Ser245 (p-HDAC4-Ser245), p-HDAC5-Ser250, and p-HDAC7-Ser178 represent the residues in mouse HDAC4 protein. Here, contemporaneous immunoblots were run in parallel. This experiment was performed twice, and representative results are shown. (B, top) H&E staining of proximal tibia at birth (original magnification, ×100) demonstrates that the lethal phenotype of the Pthrp-KO mouse is rescued by Sik3 gene deletion. Each mouse genotype shown is defined as follows: Sik3fl/+, Pthrp-KO (universal Pthrp–/–), Sik3-cHET (Sik3fl/+ Col2a1-Cre), Sik3-cKO Pthrp-KO (Sik3fl/fl Pthrp–/– Col2a1-Cre), and Sik3-cKO (Sik3fl/fl Col2a1-Cre). Numbers represent the average length of the proliferating chondrocyte region (black lines) (mean ± SEM, n = 3, biological triplicates; we measured the average length using 6–9 sections per mouse). *P < 0.01, **P < 0.001 by 1-way ANOVA followed by Dunnett’s test for multiple comparisons, when the Pthrp-KO measurement is control. (B, bottom) Col10a1 mRNA in situ hybridization of the anterior rib cage at birth (original magnification, ×40). Abnormal Col10a1 mRNA expression in the Pthrp-KO mice is reduced or absent with combined Sik3 gene deletion (red arrowheads). Normal Col10a1 mRNA expression in the sternum is missing in the Pthrp and Sik3 double-KO mouse and the Sik3-KO mouse (black arrowheads). S indicates the lower end of the sternum. (C) H&E staining of proximal tibia (top) and anterior rib cage (bottom) at P26 (original magnification, ×40) from surviving postnatal mice. Bone formation is severely affected in the Sik3 and Pthrp double-KO mouse and the Sik3-cKO mouse: secondary ossification center (black arrowheads in the top panels) and bone formation in the sternum (black arrowheads in the bottom panels) are missing. Abnormal chondrocyte hypertrophy in the anterior rib is not seen in the Sik3 and Pthrp double-KO mouse (red arrowheads). Scale bars (red lines): 500 μm.