title: In vivo and in vitro assessment of cardiac beta-adrenergic receptors in larval zebrafish (Danio rerio).
abstract: β-Adrenergic receptors (βARs) are crucial for maintaining the rate and force of cardiac muscle contraction in vertebrates. Zebrafish (Danio rerio) have one β1AR gene and two β2AR genes (β2aAR and β2bAR). We examined the roles of these receptors in larval zebrafish in vivo by assessing the impact of translational gene knockdown on cardiac function. Zebrafish larvae lacking β1AR expression by morpholino knockdown displayed lower heart rates than control fish, whereas larvae deficient in both β2aAR and β2bAR expression exhibited significantly higher heart rates than controls. These results suggested a potential inhibitory role for one or both β2AR genes. By using cultured HEK293 cells transfected with zebrafish βARs, we demonstrated that stimulation with adrenaline or procaterol (a β2AR agonist) resulted in an increase in intracellular cAMP levels in cells expressing any of the three zebrafish βARs. In comparison with its human βAR counterpart, zebrafish β2aAR expressed in HEK293 cells appeared to exhibit a unique binding affinity profile for adrenergic ligands. Specifically, zebrafish β2aAR had a high binding affinity for phenylephrine, a classical α-adrenergic receptor agonist. The zebrafish receptors also had distinct ligand binding affinities for adrenergic agonists when compared with human βARs in culture, with zebrafish β2aAR being distinct from human β2AR and zebrafish β2bAR. Overall, this study provides insight into the function and evolution of both fish and mammalian β-adrenergic receptors.
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5. sstee057@uottawa.ca
authors.forename: Shelby L
authors.initials: SL
authors.lastname: Steele
authors.forename: Xiaodi
authors.initials: X
authors.lastname: Yang
authors.forename: Mélanie
authors.initials: M
authors.lastname: Debiais-Thibaud
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schwerte
authors.forename: Bernd
authors.initials: B
authors.lastname: Pelster
authors.forename: Marc
authors.initials: M
authors.lastname: Ekker
authors.forename: Mario
authors.initials: M
authors.lastname: Tiberi
authors.forename: Steve F
authors.initials: SF
authors.lastname: Perry
mesh_terms: D000375:Aging / Q000187:drug effects / Q000235:genetics; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D017403:In Situ Hybridization; D007814:Larva / Q000378:metabolism; D008024:Ligands; D008164:Luminescent Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000235:genetics / Q000378:metabolism*; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D019205:GTP-Binding Protein alpha Subunits, Gs; D008024:Ligands; D008164:Luminescent Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D029961:Zebrafish Proteins; D000097573:Red Fluorescent Protein