Systems proteomics of cardiac chromatin identifies nucleolin as a regulator of growth and cellular plasticity in cardiomyocytes.
Myocyte hypertrophy antecedent to heart failure involves changes in global gene expression, although the preceding mechanisms to coordinate DNA accessibility on a genomic scale are unknown. Chromatin-associated proteins alter chromatin structure by changing their association with DNA, thereby altering the gene expression profile. Little is known about the global changes in chromatin subproteomes that accompany heart failure, and the mechanisms by which these proteins alter chromatin structure. The present study tests the fundamental hypothesis that cardiac growth and plasticity in the setting of disease recapitulates conserved developmental chromatin remodeling events. We used quantitative proteomics to identify chromatin-associated proteins extracted via detergent and to quantify changes in their abundance during disease. Our study identified 321 proteins in this subproteome, demonstrating it to have modest conservation (37%) with that revealed using strong acid. Of these proteins, 176 exhibited altered expression during cardiac hypertrophy and failure; we conducted extensive functional characterization of one of these proteins, Nucleolin. Morpholino-based knockdown of nucleolin nearly abolished protein expression but surprisingly had little impact on gross morphological development. However, hearts of fish lacking Nucleolin displayed severe developmental impairment, abnormal chamber patterning and functional deficits, ostensibly due to defects in cardiac looping and myocyte differentiation. The mechanisms underlying these defects involve perturbed bone morphogenetic protein 4 expression, decreased rRNA transcription, and a shift to more heterochromatic chromatin. This study reports the quantitative analysis of a new chromatin subproteome in the normal and diseased mouse heart. Validation studies in the complementary model system of zebrafish examine the role of Nucleolin to orchestrate genomic reprogramming events shared between development and disease.
Department of Anesthesiology, University of California, Los Angeles, Los Angeles, California;
Emma
E
Monte
Kevin
K
Mouillesseaux
Haodong
H
Chen
Todd
T
Kimball
Shuxun
S
Ren
Yibin
Y
Wang
Jau-Nian
JN
Chen
Thomas M
TM
Vondriska
Sarah
S
Franklin
D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D006332:Cardiomegaly / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D055879:Gene Knock-In Techniques; D055785:Gene Knockdown Techniques; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D012335:RNA, Ribosomal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000097796:Nucleolin
D055415:Bone Morphogenetic Protein 4; D002843:Chromatin; D010750:Phosphoproteins; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; D029961:Zebrafish Proteins; D000097796:Nucleolin; C525813:bmp4 protein, zebrafish
BMP4; cardiac hypertrophy; chromatin; nucleolin; proteomics