Identification of novel SHOX target genes in the developing limb using a transgenic mouse model.

Katja U Beiser,Gudrun A Rappold,Isabell Scholl,Norbert Gretz,Kerstin Kleinschmidt,Anne Glaser,Ralph Röth,Gunhild Mechtersheimer,Marcel Karperien,Wiltrud Richter,Antonio Marchini,Li Li

doi:10.1371/journal.pone.0098543

Abstract

Deficiency of the human short stature homeobox-containing gene (SHOX) has been identified in several disorders characterized by reduced height and skeletal anomalies such as Turner syndrome, Léri-Weill dyschondrosteosis and Langer mesomelic dysplasia as well as isolated short stature. SHOX acts as a transcription factor during limb development and is expressed in chondrocytes of the growth plates. Although highly conserved in vertebrates, rodents lack a SHOX orthologue. This offers the unique opportunity to analyze the effects of human SHOX expression in transgenic mice. We have generated a mouse expressing the human SHOXa cDNA under the control of a murine Col2a1 promoter and enhancer (Tg(Col2a1-SHOX)). SHOX and marker gene expression as well as skeletal phenotypes were characterized in two transgenic lines. No significant skeletal anomalies were found in transgenic compared to wildtype mice. Quantitative and in situ hybridization analyses revealed that Tg(Col2a1-SHOX), however, affected extracellular matrix gene expression during early limb development, suggesting a role for SHOX in growth plate assembly and extracellular matrix composition during long bone development. For instance, we could show that the connective tissue growth factor gene Ctgf, a gene involved in chondrogenic and angiogenic differentiation, is transcriptionally regulated by SHOX in transgenic mice. This finding was confirmed in human NHDF and U2OS cells and chicken micromass culture, demonstrating the value of the SHOX-transgenic mouse for the characterization of SHOX-dependent genes and pathways in early limb development.

Highlights

Height is a complex trait defined by multiple biological and environmental factors that are involved in bone formation and growth
The homeodomain transcription factor stature homeobox-containing gene (SHOX) is involved in different human short stature syndromes (Turner syndrome, Leri-Weill dyschondrosteosis LWD [MIM 127300] and Langer mesomelic dysplasia [MIM 249700]) and isolated short stature [MIM 300582] [1,2,3,4,5,6,7]
While the phenotypic features are sparse in these animals, we demonstrate that Ctgf, among other genes, is regulated by SHOX in transgenic mice as well as in human and chicken cell cultures

Summary

Introduction

Height is a complex trait defined by multiple biological and environmental factors that are involved in bone formation and growth. The homeodomain transcription factor SHOX is involved in different human short stature syndromes (Turner syndrome, Leri-Weill dyschondrosteosis LWD [MIM 127300] and Langer mesomelic dysplasia [MIM 249700]) and isolated (idiopathic) short stature [MIM 300582] [1,2,3,4,5,6,7]. Mutations and deletions of the SHOX gene and its enhancers have been identified as etiologic for the short stature and skeletal anomalies in these disorders [8,9,10,11,12,13]. Comprehensive case studies have shown that SHOX defects have been identified in the more common nonsyndromic (isolated) forms of short stature with a prevalence of 5–17% in geographically different populations [6,12,14]. An overdosage of SHOX as in patients with Triple-X or Klinefelter syndrome results in tall stature [15]

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Results

Conclusion