title: Duplicated zebrafish co-orthologs of parathyroid hormone-related peptide (PTHrP, Pthlh) play different roles in craniofacial skeletogenesis.
abstract: In mammals, parathyroid hormone-related peptide (PTHrP, alias PTH-like hormone (Pthlh)) acts as a paracrine hormone that regulates the patterning of cartilage, bone, teeth, pancreas, and thymus. Beyond mammals, however, little is known about the molecular genetic mechanisms by which Pthlh regulates early development. To evaluate conserved pathways of craniofacial skeletogenesis, we isolated two Pthlh co-orthologs from the zebrafish (Danio rerio) and investigated their structural, phylogenetic, and syntenic relationships, expression, and function. Results showed that pthlh duplicates originated in the teleost genome duplication. Zebrafish pthlha and pthlhb were maternally expressed and showed overlapping and distinct zygotic expression patterns during skeletal development that mirrored mammalian expression domains. To explore the regulation of duplicated pthlh genes, we studied their expression patterns in mutants and found that both sox9a and sox9b are upstream of pthlha in arch and fin bud cartilages, but only sox9b is upstream of pthlha in the pancreas. Morpholino antisense knockdown showed that pthlha regulates both sox9a and sox9b in the pharyngeal arches but not in the brain or otic vesicles and that pthlhb does not regulate either sox9 gene, which is likely related to its highly degraded nuclear localization signal. Knockdown of pthlha but not pthlhb caused runx2b overexpression in craniofacial cartilages and premature bone mineralization. We conclude that in normal cartilage development, sox9 upregulates pthlh, which downregulates runx2, and that the duplicated nature of all three of these genes in zebrafish creates a network of regulation by different co-orthologs in different tissues.
authors: Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, USA.
authors: Yi-Lin
authors: YL
authors: Yan
authors: Poulomi
authors: P
authors: Bhattacharya
authors: Xin Jun
authors: XJ
authors: He
authors: Bhaskar
authors: B
authors: Ponugoti
authors: Ben
authors: B
authors: Marquardt
authors: Jason
authors: J
authors: Layman
authors: Melissa
authors: M
authors: Grunloh
authors: John H
authors: JH
authors: Postlethwait
authors: David A
authors: DA
authors: Rubin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016375:Antisense Elements (Genetics); D001934:Branchial Region / Q000196:embryology / Q000502:physiology; D002356:Cartilage / Q000196:embryology / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D005147:Facial Bones / Q000196:embryology / Q000502:physiology; D020440:Gene Duplication / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008969:Molecular Sequence Data; D010012:Osteogenesis / Q000235:genetics* / Q000502:physiology; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D055758:SOX9 Transcription Factor / Q000235:genetics; D012886:Skull / Q000196:embryology / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics
chemical_list: D016375:Antisense Elements (Genetics); D018076:DNA, Complementary; D044162:Parathyroid Hormone-Related Protein; C502546:Runx2b protein, zebrafish; D055758:SOX9 Transcription Factor; C504918:Sox9a protein, zebrafish; C504919:Sox9b protein, zebrafish; D014157:Transcription Factors; D029961:Zebrafish Proteins