title: Modest overexpression of FOXO maintains cardiac proteostasis and ameliorates age-associated functional decline.
abstract: Heart performance declines with age. Impaired protein quality control (PQC), due to reduced ubiquitin-proteasome system (UPS) activity, autophagic function, and/or chaperone-mediated protein refolding, contributes to cardiac deterioration. The transcription factor FOXO participates in regulating genes involved in PQC, senescence, and numerous other processes. Here, a comprehensive approach, involving molecular genetics, novel assays to probe insect cardiac physiology, and bioinformatics, was utilized to investigate the influence of heart-restricted manipulation of dFOXO expression in the rapidly aging Drosophila melanogaster model. Modest dFOXO overexpression was cardioprotective, ameliorating nonpathological functional decline with age. This was accompanied by increased expression of genes associated predominantly with the UPS, relative to other PQC components, which was validated by a significant decrease in ubiquitinated proteins. RNAi knockdown of UPS candidates accordingly compromised myocardial physiology in young flies. Conversely, excessive dFOXO overexpression or suppression proved detrimental to heart function and/or organismal development. This study highlights D. melanogaster as a model of cardiac aging and FOXO as a tightly regulated mediator of proteostasis and heart performance over time.
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, 21205, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Blice-Baum
authors.affiliation: Department of Biopharmaceutical Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA.|Sanford Burnham Prebys Medical Discovery Institute, Development, Aging and Regeneration Program, La Jolla, CA, 92037, USA.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Zambon
authors.affiliation: Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Kaushik
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, 21205, USA.
authors.forename: Meera C
authors.initials: MC
authors.lastname: Viswanathan
authors.affiliation: Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Engler
authors.affiliation: Sanford Burnham Prebys Medical Discovery Institute, Development, Aging and Regeneration Program, La Jolla, CA, 92037, USA.
authors.forename: Rolf
authors.initials: R
authors.lastname: Bodmer
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, 21205, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Cammarato
mesh_terms: D000375:Aging / Q000235:genetics* / Q000473:pathology*; D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D017344:Genes, Insect; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D009928:Organ Specificity; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D014158:Transcription, Genetic; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; C477334:FOXO protein, Drosophila; D051858:Forkhead Transcription Factors; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex
keywords: 
  Drosophila
  ; 
  FOXO
  ; 
  UPS
  ; autophagy; cardiac aging; protein homeostasis