Development of severe skeletal defects in induced SHP-2-deficient adult mice: a model of skeletal malformation in humans with SHP-2 mutations

Timothy J Bauler,Eric Langewisch,Philip D King,Yuji Mishina,Gen-Sheng Feng,Nobuhiro Kamiya,John E Wilkinson,Philip E Lapinski

doi:10.1242/dmm.006130

Abstract

SUMMARYSHP-2 (encoded by PTPN11) is a ubiquitously expressed protein tyrosine phosphatase required for signal transduction by multiple different cell surface receptors. Humans with germline SHP-2 mutations develop Noonan syndrome or LEOPARD syndrome, which are characterized by cardiovascular, neurological and skeletal abnormalities. To study how SHP-2 regulates tissue homeostasis in normal adults, we used a conditional SHP-2 mouse mutant in which loss of expression of SHP-2 was induced in multiple tissues in response to drug administration. Induced deletion of SHP-2 resulted in impaired hematopoiesis, weight loss and lethality. Most strikingly, induced SHP-2-deficient mice developed severe skeletal abnormalities, including kyphoses and scolioses of the spine. Skeletal malformations were associated with alterations in cartilage and a marked increase in trabecular bone mass. Osteoclasts were essentially absent from the bones of SHP-2-deficient mice, thus accounting for the osteopetrotic phenotype. Studies in vitro revealed that osteoclastogenesis that was stimulated by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa B ligand (RANKL) was defective in SHP-2-deficient mice. At least in part, this was explained by a requirement for SHP-2 in M-CSF-induced activation of the pro-survival protein kinase AKT in hematopoietic precursor cells. These findings illustrate an essential role for SHP-2 in skeletal growth and remodeling in adults, and reveal some of the cellular and molecular mechanisms involved. The model is predicted to be of further use in understanding how SHP-2 regulates skeletal morphogenesis, which could lead to the development of novel therapies for the treatment of skeletal malformations in human patients with SHP-2 mutations.

Highlights

SHP-2 is a broadly expressed Src homology2 domain (SH2)-containing protein tyrosine phosphatase (PTP) that has been implicated in signal transduction initiated by multiple growth factor and cytokine receptors (Chong and Maiese, 2007; Matozaki et al, 2009)
Induced deletion of SHP-2 from adult mice results in early lethality To examine the effect of global deletion of SHP-2 in adults, we generated ptpn11 exon 4 floxed mice that carry an ubiquitin-promoter-driven ert2-cre transgene
Administration of the estrogen antagonist tamoxifen to these mice was predicted to result in nuclear translocation of the ERT2-Cre fusion protein and recombination at the floxed ptpn11 locus to yield a null ptpn11 allele in all tissues. 6- to 8-week-old ptpn11fl/fl ert2-cre mice were administered tamoxifen via intraperitoneal injection on two consecutive days

Summary

Introduction

SHP-2 (encoded by PTPN11) is a broadly expressed Src homology domain (SH2)-containing protein tyrosine phosphatase (PTP) that has been implicated in signal transduction initiated by multiple growth factor and cytokine receptors (Chong and Maiese, 2007; Matozaki et al, 2009). The mutant PTP is thought to act in a dominantnegative fashion to inhibit SHP-2 expressed from the normal PTPN11 allele (Digilio et al, 2002; Gorlin et al, 1969; Hanna et al, 2006; Kontaridis et al, 2006; Tartaglia et al, 2006). Clinical features of these syndromes that have been recognized include facial dysmorphia, short stature, cardiovascular defects, pulmonary stenosis, lentigines and skeletal abnormalities including lateral curvature (scoliosis) and dorsal curvature (kyphosis) of the spine. It has recently been demonstrated that Costello syndrome and cardio-facio-cutaneous syndrome, both of which share clinical features with NS and LS, are caused by germline mutations in genes that encode components of this

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