BRG1 and BRM SWI/SNF ATPases redundantly maintain cardiomyocyte homeostasis by regulating cardiomyocyte mitophagy and mitochondrial dynamics in vivo

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• 作者：Scott J. Bultman^a ; ^b ; Darcy Wood Holley^a ; Gustaaf G. de Ridder^c ; Salvatore V. Pizzo^c ; Tatiana N. Sidorova^d ; Katherine T. Murray^d ; Brian C. Jensen^e ; Zhongjing Wang^e ; Ariana Bevilacqua^j ; Xin Chen^f ; Megan T. Quintana^g ; Manasi Tannu^h ; Gary B. Rosson^a ; Kumar Pandyaⁱ ; Monte S. Willis^e ; ^j ; ^k ; ^{monte_willis@med.unc.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：AL ; light chain ; ANF ; atrial natriuretic factor ; ß ; MHC ; beta myosin heavy chain ; BNP ; brain natriuretic peptide ; BRM ; Brahma (aka SMARCA2) ; BRG1 ; Brahma-related gene 1 (aka SMARCA4) ; CHOP ; CCAAT/-enhancer-binding protein homologous protein ; ER ; endoplasmic reticulum ; HDAC ; histone deacetylase ; HF ; heart failure ; PAO ; pre-amyloid oligomer ; SWI/SNF ; SWItch/Sucrose Non-Fermentable ; TAC ; trans-aortic constriction ; TEM ; transmission electron microscopy ; UPR ; unfolded protein response ; VEC ; vascu
• 刊名：Cardiovascular Pathology
• 出版年：2016
• 出版时间：May-June 2016
• 年：2016
• 卷：25
• 期：3
• 页码：258-269
• 全文大小：3035 K

文摘

There has been an increasing recognition that mitochondrial perturbations play a central role in human heart failure. Mitochondrial networks, whose function is to maintain the regulation of mitochondrial biogenesis, autophagy (‘mitophagy’) and mitochondrial fusion/fission, are new potential therapeutic targets. Yet our understanding of the molecular underpinning of these processes is just emerging. We recently identified a role of the SWI/SNF ATP-dependent chromatin remodeling complexes in the metabolic homeostasis of the adult cardiomyocyte using cardiomyocyte-specific and inducible deletion of the SWI/SNF ATPases BRG1 and BRM in adult mice (Brg1/Brm double mutant mice). To build upon these observations in early altered metabolism, the present study looks at the subsequent alterations in mitochondrial quality control mechanisms in the impaired adult cardiomyocyte. We identified that Brg1/Brm double-mutant mice exhibited increased mitochondrial biogenesis, increases in ‘mitophagy’, and alterations in mitochondrial fission and fusion that led to small, fragmented mitochondria. Mechanistically, increases in the autophagy and mitophagy-regulated proteins Beclin1 and Bnip3 were identified, paralleling changes seen in human heart failure. Evidence for perturbed cardiac mitochondrial dynamics included decreased mitochondria size, reduced numbers of mitochondria, and an altered expression of genes regulating fusion (Mfn1, Opa1) and fission (Drp1). We also identified cardiac protein amyloid accumulation (aggregated fibrils) during disease progression along with an increase in pre-amyloid oligomers and an upregulated unfolded protein response including increased GRP78, CHOP, and IRE-1 signaling. Together, these findings described a role for BRG1 and BRM in mitochondrial quality control, by regulating mitochondrial number, mitophagy, and mitochondrial dynamics not previously recognized in the adult cardiomyocyte. As critical to the pathogenesis of heart failure, epigenetic mechanisms like SWI/SNF chromatin remodeling seem more intimately linked to cardiac function and mitochondrial quality control mechanisms than previously realized.