title: Critical role of lysosomes in the dysfunction of human Cardiac Stem Cells obtained from failing hearts.
abstract: The in vivo reparative potential of Cardiac Stem Cells (CSC), cultured from explanted failing hearts (E-), is impaired by cellular senescence. Moreover, E-CSC are characterized, with respect to CSC obtained from healthy donors (D-), by an arrest in the autophagic degradation. Although the lysosome plays a pivotal role in cellular homeostasis and defects of this organelle may be associated with aging and heart failure, the lysosomal function of CSC has never been investigated. The aim of this work was to focus on the Lysosomal Compartment (LC) of E-CSC, evaluating elements that could jeopardize lysosome functionality.
  
  
  RESULTS
  Bioinformatics analysis conducted on genes differentially expressed between D- and E-CSC identified lysosomal-related gene sets as significantly enriched. Moreover, 29 differentially expressed genes were part of CLEAR (Coordinated Lysosomal Expression and Regulation) gene network, by which Transcription Factor EB (TFEB) regulates cellular clearance. Consistently, live cell imaging and flow cytometry analyses showed that the lysosomes of E-CSC are less acidic than the D-CSC ones. Furthermore, confocal microscopy showed in E-CSC: an accumulation of intralysosomal lipofuscins, a reduction of cathepsin B activity, evidence of lysosome membrane permeabilization, and the reduction of the nuclear active TFEB. The use of Rapamycin (TORC1 inhibitor) was able on one hand to increase TFEB activation and, on the other hand, to reduce lipofuscin mass, potentiating the lysosomal functionality.
  
  
  CONCLUSIONS
  This study demonstrated for the first time that E-CSC are characterized by a blunted activation of TFEB and an altered proteostasis. TORC1 hyperactivation plays a central role in this phenomenon.
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gianfranceschi
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Caragnano
authors.affiliation: Laboratorio Nazionale Consorzio Italiano Biotecnologie (LNCIB), Trieste, Italy.
authors.forename: Silvano
authors.initials: S
authors.lastname: Piazza
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Manini
authors.affiliation: Laboratorio Nazionale Consorzio Italiano Biotecnologie (LNCIB), Trieste, Italy.
authors.forename: Yari
authors.initials: Y
authors.lastname: Ciani
authors.affiliation: Laboratorio Nazionale Consorzio Italiano Biotecnologie (LNCIB), Trieste, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Verardo
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Toffoletto
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Finato
authors.affiliation: Department of Experimental Medical and Clinical Sciences, University of Udine, Udine, Italy.
authors.forename: Ugolino
authors.initials: U
authors.lastname: Livi
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Carlo Alberto
authors.initials: CA
authors.lastname: Beltrami
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Giacinto
authors.initials: G
authors.lastname: Scoles
authors.affiliation: Cardiology Department, University of Trieste, Trieste, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Sinagra
authors.affiliation: Cardiology Department, University of Trieste, Trieste, Italy.
authors.forename: Aneta
authors.initials: A
authors.lastname: Aleksova
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy. Electronic address: daniela.cesselli@uniud.it.
authors.forename: Daniela
authors.initials: D
authors.lastname: Cesselli
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy. Electronic address: antonio.beltrami@uniud.it.
authors.forename: Antonio Paolo
authors.initials: AP
authors.lastname: Beltrami
mesh_terms: D000328:Adult; D000368:Aged; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics; D002478:Cells, Cultured; D019295:Computational Biology / Q000379:methods; D005260:Female; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D006333:Heart Failure / Q000235:genetics / Q000473:pathology*; D006801:Humans; D008247:Lysosomes / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C064972:TFEB protein, human
keywords: Cell senescence; Heart failure; Lysosome; Stem cells; TFEB