title: A chondrogenesis-related lipocalin cluster includes a third new gene, CALgamma.
abstract: We have previously reported the modulation, during chondrogenesis and/or inflammation, of two chicken genes laying in the same genomic locus and coding for two polypeptides of the lipocalin protein family, the extracellular fatty acid binding protein (ExFABP) and the chondrogenesis associated lipocalin beta (CALbeta). A third gene, located within the same cluster and coding for a new lipocalin, CALgamma, has been identified and is here characterized. Tissue distribution analyzed by real-time quantitative reverse transcriptase-polymerase chain reaction in chicken embryos shows a ubiquitous expression with predominant levels of mRNA transcripts in the liver and the brain. In the developing tibia, a high expression of CALgamma mRNA was evidenced by in situ hybridization within the pre-hypertrophic and the hypertrophic zones of the bone-forming cartilage. In agreement, dedifferentiated chondrocytes in vitro express the transcripts to the highest level when they re-differentiate reaching hypertrophy. Such peculiar developmental pattern of expression that is analogous to those already described for Ex-FABP and CALbeta suggests that all three proteins may act synergistically in the process of endochondral bone formation. Moreover, like Ex-FABP and CALbeta, CALgamma is also highly induced in dedifferentiated chondrocytes upon stimulation with lypopolysaccharides, indicating that the whole cluster quite possibly is transcriptionally activated not only in physiological morphogenic differentiation but also in pathological acute phase response.
authors.affiliation: Dipartimento di Oncologia, Biologia e Genetica, Università di Genova, Genova, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Pagano
authors.forename: Richard
authors.initials: R
authors.lastname: Crooijmans
authors.forename: Martien
authors.initials: M
authors.lastname: Groenen
authors.forename: Nadia
authors.initials: N
authors.lastname: Randazzo
authors.forename: Barbara
authors.initials: B
authors.lastname: Zerega
authors.forename: Ranieri
authors.initials: R
authors.lastname: Cancedda
authors.forename: Beatrice
authors.initials: B
authors.lastname: Dozin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D003094:Collagen / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008099:Liver / Q000196:embryology / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013977:Tibia / Q000196:embryology / Q000378:metabolism; D013997:Time Factors
chemical_list: D002352:Carrier Proteins; D012333:RNA, Messenger; D003094:Collagen; D004247:DNA