Antisense oligonucleotides targeting Notch2 ameliorate the osteopenic phenotype in a mouse model of Hajdu-Cheney syndrome

Ernesto Canalis,Tamar R Grossman,Michele Carrer,Lauren Schilling,Jungeun Yu

doi:10.1074/jbc.ra119.011440

Abstract

Notch receptors play critical roles in cell-fate decisions and in the regulation of skeletal development and bone remodeling. Gain-of-function NOTCH2 mutations can cause Hajdu-Cheney syndrome, an untreatable disease characterized by osteoporosis and fractures, craniofacial developmental abnormalities, and acro-osteolysis. We have previously created a mouse model harboring a point 6955C→T mutation in the Notch2 locus upstream of the PEST domain, and we termed this model Notch2tm1.1Ecan Heterozygous Notch2tm1.1Ecan mutant mice exhibit severe cancellous and cortical bone osteopenia due to increased bone resorption. In this work, we demonstrate that the subcutaneous administration of Notch2 antisense oligonucleotides (ASO) down-regulates Notch2 and the Notch target genes Hes-related family basic helix-loop-helix transcription factor with YRPW motif 1 (Hey1), Hey2, and HeyL in skeletal tissue from Notch2tm1.1Ecan mice. Results of microcomputed tomography experiments indicated that the administration of Notch2 ASOs ameliorates the cancellous osteopenia of Notch2tm1.1Ecan mice, and bone histomorphometry analysis revealed decreased osteoclast numbers in Notch2 ASO-treated Notch2tm1.1Ecan mice. Notch2 ASOs decreased the induction of mRNA levels of TNF superfamily member 11 (Tnfsf11, encoding the osteoclastogenic protein RANKL) in cultured osteoblasts and osteocytes from Notch2tm1.1Ecan mice. Bone marrow-derived macrophage cultures from the Notch2tm1.1Ecan mice displayed enhanced osteoclastogenesis, which was suppressed by Notch2 ASOs. In conclusion, Notch2tm1.1Ecan mice exhibit cancellous bone osteopenia that can be ameliorated by systemic administration of Notch2 ASOs.

Highlights

Notch receptors play critical roles in cell-fate decisions and in the regulation of skeletal development and bone remodeling
There was evidence of enhanced Notch signaling in skeletal tissue from Notch2tm1.1Ecan mice, and the Notch target genes helix transcription factor with YRPW motif 1 (Hey1), Hey2, and HeyL were induced in bone extracts from mutant mice in relationship to control littermates (Fig. 2)
The mRNA levels of Hey1, Hey2, and HeyL in tibiae from Notch2tm1.1Ecan mice treated with Notch2 antisense oligonucleotides (ASO) approached the levels found in tibiae from WT mice treated with control ASOs

Summary

Introduction

Notch receptors play critical roles in cell-fate decisions and in the regulation of skeletal development and bone remodeling. We demonstrate that the subcutaneous administration of Notch antisense oligonucleotides (ASO) down-regulates Notch and the Notch target genes Hes-related family basic helix–loop– helix transcription factor with YRPW motif 1 (Hey1), Hey, and HeyL in skeletal tissue from Notch2tm1.1Ecan mice. Notch ASOs decreased the induction of mRNA levels of TNF superfamily member 11 (Tnfsf, encoding the osteoclastogenic protein RANKL) in cultured osteoblasts and osteocytes from Notch2tm1.1Ecan mice. Bone marrowderived macrophage cultures from the Notch2tm1.1Ecan mice displayed enhanced osteoclastogenesis, which was suppressed by Notch ASOs. In conclusion, Notch2tm1.1Ecan mice exhibit cancellous bone osteopenia that can be ameliorated by systemic administration of Notch ASOs. Notch receptors are four single-pass transmembrane proteins that play a critical function in cell fate determination [1, 2]. NOTCH2 has unique properties and impairs osteoblast maturation and induces osteoclastogenesis by acting directly on cells of the myeloid lineage and by inducing receptor activator of NF-␬B ligand (RANKL) in cells of the osteoblast lineage [10, 12, 15]

Objectives

Results

Conclusion