Haploinsufficiency of Sox9 results in defective cartilage primordia and premature skeletal mineralization

Department of Molecular Genetics and Graduate Program in Genes and Development, M. D. Anderson Cancer Center, University of Texas, Houston, TX 77030, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 07/2001; 98(12):6698-703. DOI: 10.1073/pnas.111092198
Source: PubMed

ABSTRACT In humans, SOX9 heterozygous mutations cause the severe skeletal dysmorphology syndrome campomelic dysplasia. Except for clinical descriptions, little is known about the pathogenesis of this disease. We have generated heterozygous Sox9 mutant mice that phenocopy most of the skeletal abnormalities of this syndrome. The Sox9(+/-) mice died perinatally with cleft palate, as well as hypoplasia and bending of many skeletal structures derived from cartilage precursors. In embryonic day (E)14.5 heterozygous embryos, bending of radius, ulna, and tibia cartilages was already prominent. In E12.5 heterozygotes, all skeletal elements visualized by using Alcian blue were smaller. In addition, the overall levels of Col2a1 RNA at E10.5 and E12.5 were lower than in wild-type embryos. We propose that the skeletal abnormalities observed at later embryonic stages were caused by delayed or defective precartilaginous condensations. Furthermore, in E18.5 embryos and in newborn heterozygotes, premature mineralization occurred in many bones, including vertebrae and some craniofacial bones. Because Sox9 is not expressed in the mineralized portion of the growth plate, this premature mineralization is very likely the consequence of allele insufficiency existing in cells of the growth plate that express Sox9. Because the hypertrophic zone of the heterozygous Sox9 mutants was larger than that of wild-type mice, we propose that Sox9 also has a role in regulating the transition to hypertrophic chondrocytes in the growth plate. Despite the severe hypoplasia of cartilages, the overall organization and cellular composition of the growth plate were otherwise normal. Our results suggest the hypothesis that two critical steps of the chondrocyte differentiation pathway are sensitive to Sox9 dosage. First, an early step presumably at the stage of mesenchymal condensation of cartilage primordia, and second, a later step preceding the transition of chondrocytes into hypertrophic chondrocytes.

Download full-text


Available from: Deanne J Whitworth, Sep 03, 2014
  • Source
    • "The ABC transporters are essential for many processes in the cell, driving the transport of various molecules through ATP hydrolysis (Dean et al., 2001). Previously associated with embryo development (Asou et al., 2002), the sex determining region Y box 9 gene (SOX9) causes severe bone defects and perinatal death in heterozygous mutant mice (Bi et al., 2001). The general but important activity of the ABC gene superfamily and the role of SOX9 on prenatal development make these "
    [Show abstract] [Hide abstract]
    ABSTRACT: Porcine reproductive and respiratory syndrome (PRRS) is the most economically significant disease impacting pig production in North America, Europe, and Asia, causing reproductive losses such as increased rates stillbirth and mummified piglets. The objective of this study was to explore the genetic basis of host response to the PRRS virus (PRRSV) in a commercial multiplier sow herd before and after a PRRS outbreak, using antibody response and reproductive traits. Reproductive data comprising number born alive (NBA), number alive at 24h (NA24), number stillborn (NSB), number born mummified (NBM), proportion born dead (PBD), number born dead (NBD), number weaned (NW), and number mortalities through weaning (MW) of 5,227 litters from 1,967 purebred Landrace sows, were used along with a pedigree comprising 2,995 pigs. The PRRS outbreak date was estimated from rolling averages of farrowing traits and used to split the data in a pre-PRRS phase and a PRRS phase. All 641 sows in the herd during the outbreak were blood sampled 46 days after the estimated outbreak date, and were tested for anti-PRRSV IgG using ELISA (sample-to-positive [S/P] ratio). Genetic parameters of traits were estimated separately for the pre-PRRS and PRRS phase data sets. Sows were genotyped using the PorcineSNP60 BeadChip, and genome-wide association studies (GWAS) were performed using method Bayes-B. Heritability estimates for reproductive traits ranged from 0.01 (NBM) to 0.12 (NSB), and from 0.01 (MW) to 0.12 (NBD) for the pre-PRRS and PRRS phases, respectively. S/P ratio had heritability (0.45) and strong genetic correlations with most traits, ranging from -0.72 (NBM) to 0.73 (NBA). In the pre-PRRS phase, regions associated with NSB and PBD explained 1.6% and 3% of the genetic variance, respectively. In the PRRS phase, regions associated with NBD, NSB, and S/P ratio explained 0.8%, 11%, and 50.6% of the genetic variance, respectively. For S/P ratio, two regions on SSC7 separated by 100 Mb explained 40% of the genetic variation, including a region encompassing the Major Histocompatibility Complex, which explained 25% of the genetic variance. These results indicate a significant genomic component associated with PRRSV antibody response and NSB in this dataset. Also, the high heritability and genetic correlation estimates for S/P ratio during the PRRS phase suggest that S/P ratio could be used as an indicator of the impact of PRRS on reproductive traits.
    Journal of Animal Science 05/2014; 92(7). DOI:10.2527/jas.2014-7821 · 1.92 Impact Factor
  • Source
    • "Hence, several conditional mouse lines have been generated in the past for this important developmental control gene (Yap et al. 2011; Kist et al. 2002). Furthermore, alleles with a knock-in of an IRES-lacZ (Bi et al. 2001) IRESenhanced green fluorescent protein (EGFP) (Chan et al. 2011; Nel-Themaat et al. 2009) or F2A-EGFP (Chan et al. 2011) as well as a tamoxifen-inducible Cre-recombinase (CreERT2) (Soeda et al. 2010) into the Sox9 locus have been described to facilitate the analyis of such a pleiotropic gene. While the existing Sox9-cKO alleles lack the insertion of a reporter gene, the existing Sox9 reporter gene knock-in lines are generated as non-conditional alleles. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Traditionally, conditional knockout studies in mouse have utilized the Cre or Flpe technology to activate the expression of reporter genes such as lacZ or PLAP. Employing these reporter genes, however, requires tissue fixation. To make way for downstream in vivo or in vitro applications, we have inserted enhanced green fluorescent protein (EGFP) into the endogenous Sox9 locus and generated a novel conditional Sox9 null allele, by flanking the entire Sox9 coding region with loxP sites and inserting an EGFP reporter gene into the 3'-UTR allowing for EGFP to be expressed upon Sox9 loss of function yet under the control of the endogenous Sox9 promoter. Mating this new allele to any Cre-expressing line, the fate of Sox9 null cells can be traced in the cell type of interest in vivo or in vitro after fluorescence-activated cell sorting.
    Biotechnology Letters 08/2013; 35(12). DOI:10.1007/s10529-013-1303-6 · 1.74 Impact Factor
  • Source
    • "SOX9 markedly inhibited activation of Wnt/í µí»½-catenin-dependent promoters and stimulated degradation of í µí»½-catenin [72] by directing intracellular degradation, thus, favoring chondrocyte differentiation and delaying hypertrophic chondrocytes differentiation [69]. Studies performed on embryos in different stages of gestation evidenced that SOX9 and Runx2 control the transition from prehypertrophic to hypertrophic chondrocytes [73]. It has been demonstrated that upregulation of type X collagen (col10a1), typical hypertrophic marker, is also regulated by overexpression of Wnt8c, Wnt9a and í µí»½-catenin that inhibited SOX9 and type II collagen (col2a1) and induced Runx2 trascription factor [74]. SOX9 and Runx2 physically interact in MSC and while SOX9 can inhibit Runx2 transactivation, on the other hand, Runx2 exerts reciprocal inhibition on SOX9 transactivity [72]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Human mesenchymal stem cells (hMSCs) are pluripotent adult stem cells capable of being differentiated into osteoblasts, adipocytes, and chondrocytes. The osteogenic differentiation of hMSCs is regulated either by systemic hormones or by local growth factors able to induce specific intracellular signal pathways that modify the expression and activity of several transcription factors. Runt-related transcription factor 2 (Runx2) and Wnt signaling-related molecules are the major factors critically involved in the osteogenic differentiation process by hMSCs, and SRY-related high-mobility-group (HMG) box transcription factor 9 (SOX9) is involved in the chondrogenic one. hMSCs have generated a great interest in the field of regenerative medicine, particularly in bone regeneration. In this paper, we focused our attention on the molecular mechanisms involved in osteogenic and chondrogenic differentiation of hMSC, and the potential clinical use of hMSCs in osteoarticular pediatric disease characterized by fracture nonunion and pseudarthrosis.
    Stem cell International 05/2013; 2013:312501. DOI:10.1155/2013/312501 · 2.81 Impact Factor
Show more