title: The paracrine effect of exogenous growth hormone alleviates dysmorphogenesis caused by tbx5 deficiency in zebrafish (Danio rerio) embryos.
abstract: BACKGROUND
  Dysmorphogenesis and multiple organ defects are well known in zebrafish (Danio rerio) embryos with T-box transcription factor 5 (tbx5) deficiencies, mimicking human Holt-Oram syndrome.
  
  
  METHODS
  Using an oligonucleotide-based microarray analysis to study the expression of special genes in tbx5 morphants, we demonstrated that GH and some GH-related genes were markedly downregulated. Zebrafish embryos microinjected with tbx5-morpholino (MO) antisense RNA and mismatched antisense RNA in the 1-cell stage served as controls, while zebrafish embryos co-injected with exogenous growth hormone (GH) concomitant with tbx5-MO comprised the treatment group.
  
  
  RESULTS
  The attenuating effects of GH in tbx5-MO knockdown embryos were quantified and observed at 24, 30, 48, 72, and 96 h post-fertilization. Though the understanding of mechanisms involving GH in the tbx5 functioning complex is limited, exogenous GH supplied to tbx5 knockdown zebrafish embryos is able to enhance the expression of downstream mediators in the GH and insulin-like growth factor (IGF)-1 pathway, including igf1, ghra, and ghrb, and signal transductors (erk1, akt2), and eventually to correct dysmorphogenesis in various organs including the heart and pectoral fins. Supplementary GH also reduced apoptosis as determined by a TUNEL assay and decreased the expression of apoptosis-related genes and proteins (bcl2 and bad) according to semiquantitative reverse-transcription polymerase chain reaction and immunohistochemical analysis, respectively, as well as improving cell cycle-related genes (p27 and cdk2) and cardiomyogenetic genes (amhc, vmhc, and cmlc2).
  
  
  CONCLUSIONS
  Based on our results, tbx5 knockdown causes a pseudo GH deficiency in zebrafish during early embryonic stages, and supplementation of exogenous GH can partially restore dysmorphogenesis, apoptosis, cell growth inhibition, and abnormal cardiomyogenesis in tbx5 knockdown zebrafish in a paracrine manner.
authors: Department of Medical Research and Education, National Yang-Ming University Hospital, Yilan, Taiwan, Republic of China.
authors: Tzu-Chun
authors: TC
authors: Tsai
authors: Jen-Kann
authors: JK
authors: Lu
authors: Sie-Lin
authors: SL
authors: Choo
authors: Shu-Yu
authors: SY
authors: Yeh
authors: Ren-Bing
authors: RB
authors: Tang
authors: Hsin-Yu
authors: HY
authors: Lee
authors: Jen-Her
authors: JH
authors: Lu
mesh_terms: D000015:Abnormalities, Multiple; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D047108:Embryonic Development / Q000187:drug effects / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000235:genetics; D013006:Growth Hormone / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D006321:Heart / Q000187:drug effects / Q000254:growth & development; D006330:Heart Defects, Congenital; D006344:Heart Septal Defects, Atrial; D006801:Humans; D038061:Lower Extremity Deformities, Congenital; D009024:Morphogenesis / Q000187:drug effects / Q000235:genetics; D060172:Morpholinos; D019899:Paracrine Communication; D016372:RNA, Antisense / Q000008:administration & dosage; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D038062:Upper Extremity Deformities, Congenital; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D060172:Morpholinos; D016372:RNA, Antisense; D013002:Somatomedins; D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5; D029961:Zebrafish Proteins; C431139:igf1 protein, zebrafish; D013006:Growth Hormone