title: Top-down quantitative proteomics identified phosphorylation of cardiac troponin I as a candidate biomarker for chronic heart failure.
abstract: The rapid increase in the prevalence of chronic heart failure (CHF) worldwide underscores an urgent need to identify biomarkers for the early detection of CHF. Post-translational modifications (PTMs) are associated with many critical signaling events during disease progression and thus offer a plethora of candidate biomarkers. We have employed a top-down quantitative proteomics methodology for comprehensive assessment of PTMs in whole proteins extracted from normal and diseased tissues. We systematically analyzed 36 clinical human heart tissue samples and identified phosphorylation of cardiac troponin I (cTnI) as a candidate biomarker for CHF. The relative percentages of the total phosphorylated cTnI forms over the entire cTnI populations (%P(total)) were 56.4 ± 3.5%, 36.9 ± 1.6%, 6.1 ± 2.4%, and 1.0 ± 0.6% for postmortem hearts with normal cardiac function (n = 7), early stage of mild hypertrophy (n = 5), severe hypertrophy/dilation (n = 4), and end-stage CHF (n = 6), respectively. In fresh transplant samples, the %P(total) of cTnI from nonfailing donor (n = 4), and end-stage failing hearts (n = 10) were 49.5 ± 5.9% and 18.8 ± 2.9%, respectively. Top-down MS with electron capture dissociation unequivocally localized the altered phosphorylation sites to Ser22/23 and determined the order of phosphorylation/dephosphorylation. This study represents the first clinical application of top-down MS-based quantitative proteomics for biomarker discovery from tissues, highlighting the potential of PTMs as disease biomarkers.
authors.affiliation: School of Medicine and Public Health and School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zhang
authors.forename: Moltu J
authors.initials: MJ
authors.lastname: Guy
authors.forename: Holly S
authors.initials: HS
authors.lastname: Norman
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Chen
authors.forename: Qingge
authors.initials: Q
authors.lastname: Xu
authors.forename: Xintong
authors.initials: X
authors.lastname: Dong
authors.forename: Huseyin
authors.initials: H
authors.lastname: Guner
authors.forename: Sijian
authors.initials: S
authors.lastname: Wang
authors.forename: Takushi
authors.initials: T
authors.lastname: Kohmoto
authors.forename: Ken H
authors.initials: KH
authors.lastname: Young
authors.forename: Richard L
authors.initials: RL
authors.lastname: Moss
authors.forename: Ying
authors.initials: Y
authors.lastname: Ge
mesh_terms: D000595:Amino Acid Sequence; D015415:Biomarkers / Q000032:analysis* / Q000737:chemistry; D002908:Chronic Disease; D006333:Heart Failure / Q000378:metabolism*; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D010641:Phenotype; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D040901:Proteomics / Q000379:methods*; D019210:Troponin I / Q000032:analysis* / Q000737:chemistry
chemical_list: D015415:Biomarkers; D019210:Troponin I