Evidence for regulation of cartilage differentiation by the homeobox gene Hoxc-8.
Homeobox genes of the Hox class are required for proper patterning of skeletal elements, but how they regulate the differentiation of specific tissues is unclear. We show here that overexpression of a Hoxc-8 transgene causes cartilage defects whose severity depends on transgene dosage. The abnormal cartilage is characterized by an accumulation of proliferating chondrocytes and reduced maturation. Since Hoxc-8 is normally expressed in chondrocytes, these results suggest that Hoxc-8 continues to regulate skeletal development well beyond pattern formation in a tissue-specific manner, presumably by controlling the progression of cells along the chondrocyte differentiation pathway. The comparison to Hoxd-4 and Isl-1 indicates that this role in chondrogenesis is specific to proteins of the Hox class. Their capacity for regulation of cartilage differentiation suggests that Hox genes could also be involved in human chondrodysplasias or other cartilage disorders.
Department of Biochemistry and Molecular Biology, Samuel C. Johnson Medical Research Center, Mayo Clinic Scottsdale, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA.
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Gardner
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Kappen
D000818:Animals; D002356:Cartilage / Q000002:abnormalities / Q000196:embryology* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D003433:Crosses, Genetic; D005097:Exostoses, Multiple Hereditary / Q000196:embryology / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D005838:Genotype; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D010641:Phenotype; D011247:Pregnancy
C489815:HOXC8 protein, human; D018398:Homeodomain Proteins; C489816:Hoxc8 protein, mouse