title: Shared gene expression profiles in developing heart valves and osteoblast progenitor cells.
abstract: The atrioventricular (AV) valves of the heart develop from undifferentiated mesenchymal endocardial cushions, which later mature into stratified valves with diversified extracellular matrix (ECM). Because the mature valves express genes associated with osteogenesis and exhibit disease-associated calcification, we hypothesized the existence of shared regulatory pathways active in developing AV valves and in bone progenitor cells. To define gene regulatory programs of valvulogenesis relative to osteoblast progenitors, we undertook Affymetrix gene expression profiling analysis of murine embryonic day (E)12.5 AV endocardial cushions compared with E17.5 AV valves (mitral and tricuspid) and with preosteoblast MC3T3-E1 (subclone4) cells. Overall, MC3T3 cells were significantly more similar to E17.5 valves than to E12.5 cushions, supporting the hypothesis that valve maturation involves the expression of many genes also expressed in osteoblasts. Several transcription factors characteristic of mesenchymal and osteoblast precursor cells, including Twist1, are predominant in E12.5 cushion. Valve maturation is characterized by differential regulation of matrix metalloproteinases and their inhibitors as well as complex collagen gene expression. Among the most highly enriched genes during valvulogenesis were members of the small leucine-rich proteoglycan (SLRP) family including Asporin, a known negative regulator of osteoblast differentiation and mineralization. Together, these data support shared gene expression profiles of the developing valves and osteoblast bone precursor cells in normal valve development and homeostasis with potential functions in calcific valve disease.
authors.affiliation: Division of Molecular Cardiovascular Biology, Cincinnati Children's Medical Center, Cincinnati, Ohio 45229, USA.
authors.forename: Santanu
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cheek
authors.forename: Bhuvaneswari
authors.initials: B
authors.lastname: Sakthivel
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Aronow
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Yutzey
mesh_terms: D000818:Animals; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D006023:Glycoproteins / Q000235:genetics; D006351:Heart Valves / Q000196:embryology* / Q000378:metabolism; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D064235:Matrilin Proteins; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: C511592:Aspn protein, mouse; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C577542:Matn2 protein, mouse; D064235:Matrilin Proteins; C512906:Ogn protein, mouse