title: Proteomic analysis identifies in vivo candidate matrix metalloproteinase-9 substrates in the left ventricle post-myocardial infarction.
abstract: Matrix metalloproteinase-9 (MMP-9) deletion has been shown to improve remodeling of the left ventricle post-myocardial infarction (MI), but the mechanisms to explain this improvement have not been fully elucidated. MMP-9 has a broad range of in vitro substrates, but relevant in vivo substrates are incompletely defined. Accordingly, we evaluated the infarct regions of wild-type (wt) and MMP-9 null (null) mice using a proteomic strategy. Wt and null groups showed similar infarct sizes (48+/-3 in wt and 45+/-3% in null), indicating that both groups received an equal injury stimulus. Left ventricle infarct tissue was homogenized and analyzed by 2-DE and MS. Of 31 spot intensity differences, the intensities of 9 spots were higher and 22 spots were lower in null mice compared to wt (all p<0.05). Several extracellular matrix proteins were identified in these spots by MS, including fibronectin, tenascin-C, thrombospondin-1, and laminin. Fibronectin was observed on the gels at a lower than expected molecular weight in the wt group, which suggested substrate cleavage, and the lower molecular weight spot was observed at lower intensity in the MMP-9 null group, which suggested cleavage by MMP-9. Immunoblotting confirmed the presence of fibronectin cleavage products in the wt samples and lower levels in the absence of MMP-9. In conclusion, examining infarct tissue from wt and MMP-9 null mice by proteomic analysis provides a powerful and unique method to identify in vivo candidate MMP substrates.
authors.affiliation: Department of Medicine, Division of Cardiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
authors.forename: Rogelio
authors.initials: R
authors.lastname: Zamilpa
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Lopez
authors.forename: Ying Ann
authors.initials: YA
authors.lastname: Chiao
authors.forename: Qiuxia
authors.initials: Q
authors.lastname: Dai
authors.forename: Gladys P
authors.initials: GP
authors.lastname: Escobar
authors.forename: Kevin
authors.initials: K
authors.lastname: Hakala
authors.forename: Susan T
authors.initials: ST
authors.lastname: Weintraub
authors.forename: Merry L
authors.initials: ML
authors.lastname: Lindsey
mesh_terms: D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D005109:Extracellular Matrix / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology; D006352:Heart Ventricles / Q000378:metabolism* / Q000473:pathology; D015151:Immunoblotting; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000378:metabolism* / Q000503:physiopathology; D040901:Proteomics / Q000379:methods*
chemical_list: D020780:Matrix Metalloproteinase 9