title: Human heart rate: heritability of resting and stress values in twin pairs, and influence of genetic variation in the adrenergic pathway at a microribonucleic acid (microrna) motif in the 3'-UTR of cytochrome b561 [corrected].
abstract: OBJECTIVE
  The goal of this study was to understand the role of genetic variation in the catecholamine biosynthetic pathway for control of human heart rate (HR).
  
  
  BACKGROUND
  Human HR is an integrated cardiovascular trait predictive of morbidity and survival. Because the autonomic pathway exerts rapid control over the heart, we probed the role of heredity in the control of HR, focusing on a component of the autonomic sympathetic pathway already predictive of outflow responses: cytochrome b561 (CYB561), the electron shuttle in catecholamine vesicle membranes for transmitter biosynthesis.
  
  
  METHODS
  We studied hereditary control of HR with the twin pair design, at rest and during environmental (cold) stress. Single nucleotide polymorphism disruption of a microribonucleic acid (microRNA) recognition motif in the human CYB561 3'-UTR was identified computationally, and its differential effect on gene expression was demonstrated in a transfected luciferase reporter/3'-UTR variant. We exposed stem cell-derived human embryoid bodies to the microRNA mimic or antagomir oligonucleotides, and we observed the effects on contraction rate in proto-hearts.
  
  
  RESULTS
  Substantial heritability (h(2)) was demonstrated by using twin pair variance components for both basal/resting HR (h(2) 50.9 ± 6.4% of trait variation, p = 2.47 × 10(-10)) and stress-augmented HR (h(2) 55.1 ± 5.9%, p = 8.79 × 10(-13)), and the 2 HR traits shared genetic determination (genetic covariance ρG 0.747 ± 0.058, p = 2.85 × 10(-9)). CYB561 displayed 1 common genetic variant in the transcript region: A+1485G (rs3087776), in the 3'-UTR, 1485 bp downstream of the termination codon, in a conserved region, with the A-allele ancestral in primates. In a twin/sibling sample (n = 576), A+1485G influenced HR, both at rest (p = 0.010) and after environmental stress (p = 0.002), with the minor (A) allele displaying a recessive effect with lower HR. The effect of A+1485G on HR was extended by meta-analysis into 2 additional population samples (total n = 2,579), and the influence remained directionally consistent and significant (p = 0.007). A+1485G disrupted a microRNA (human microribonucleic acid-1294 [hsa-miR-1294]) recognition motif in the 3'-UTR, as demonstrated by a transfected luciferase reporter/human 3'-UTR variant system in 2 different neuronal/neuroendocrine cell types. The microRNA effect was further documented by cotransfection of an hsa-miR-1294 mimic, yielding an exaggerated decline in expression of the A-allele (better match) reporter (p = 4.3 × 10(-5)). Similar findings of differential 3'-UTR allelic susceptibility to hsa-miR-1294 were noted during expression of the full-length human CYB561 messenger ribonucleic acid with its cognate 3'-UTR. Finally, exposure of stem cell-derived human embryoid bodies to hsa-miR-1294 mimic or antagomir oligonucleotides yielded directionally opposite effects on contraction rate in proto-hearts.
  
  
  CONCLUSIONS
  HR is a substantially heritable trait, with genetic influence by variation in the adrenergic pathway, here shown for messenger ribonucleic acid translational control at the CYB561 step of transmitter formation. The results have implications for potentially modifiable autonomic pathways that influence this risk trait in the population.
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Kuixing
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Dekker C
authors.initials: DC
authors.lastname: Deacon
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Fangwen
authors.initials: F
authors.lastname: Rao
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Schork
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Maple M
authors.initials: MM
authors.lastname: Fung
authors.affiliation: Scripps Research Institute, La Jolla, California.
authors.forename: Jill
authors.initials: J
authors.lastname: Waalen
authors.affiliation: Scripps Research Institute, La Jolla, California.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Schork
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Nievergelt
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California; Institute for Genomic Medicine, University of California at San Diego, San Diego, California.
authors.forename: Neil C
authors.initials: NC
authors.lastname: Chi
authors.affiliation: Department of Medicine, University of California at San Diego, San Diego, California; Institute for Genomic Medicine, University of California at San Diego, San Diego, California; Department of Pharmacology, University of California at San Diego, San Diego, California; VA San Diego Healthcare System, San Diego, California. Electronic address: doconnor@ucsd.edu.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: O'Connor
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003080:Cold Temperature; D003573:Cytochrome b Group / Q000235:genetics*; D005260:Female; D017930:Genes, Reporter; D005838:Genotype; D006339:Heart Rate / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000378:metabolism; D012146:Rest / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology; D014162:Transfection; D055815:Young Adult
chemical_list: D020413:3' Untranslated Regions; D003573:Cytochrome b Group; C000604728:MIRN1294 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; C023646:cytochrome b561; D008156:Luciferases
keywords: 3′ (downstream of the open reading frame) untranslated region (of the human CYB561 messenger ribonucleic acid); 3′-UTR; A+1485G; CYB561; DBH; DNA; EB; ESC; HR; MAF; PCR; SNP; catecholamine; chromaffin; cytochrome b561; cytochrome b561 (electron shuttle for dopamine beta-hydroxylase); deoxyribonucleic acid; dopamine beta-hydroxylase; embryoid body; embryonic stem cells; h(2); heart rate; heritability; hsa-miR-1294; human micro-ribonucleic acid-1294; mRNA; messenger ribonucleic acid; microRNA; microribonucleic acid; minor allele frequency; polymerase chain reaction; single nucleotide polymorphism; single nucleotide polymorphism (rs3087776) in the human CYB561 3’-UTR