MCUB Regulates the Molecular Composition of the Mitochondrial Calcium Uniporter Channel to Limit Mitochondrial Calcium Overload During Stress.
Circulation
; 140(21): 1720-1733, 2019 11 19.
Article
em En
| MEDLINE
| ID: mdl-31533452
ABSTRACT
BACKGROUND:
The mitochondrial calcium uniporter (mtCU) is an ≈700-kD multisubunit channel residing in the inner mitochondrial membrane required for mitochondrial Ca2+ (mCa2+) uptake. Here, we detail the contribution of MCUB, a paralog of the pore-forming subunit MCU, in mtCU regulation and function and for the first time investigate the relevance of MCUB to cardiac physiology.METHODS:
We created a stable MCUB knockout cell line (MCUB-/-) using CRISPR-Cas9n technology and generated a cardiac-specific, tamoxifen-inducible MCUB mutant mouse (CAG-CAT-MCUB x MCM; MCUB-Tg) for in vivo assessment of cardiac physiology and response to ischemia/reperfusion injury. Live-cell imaging and high-resolution spectrofluorometery were used to determine intracellular Ca2+ exchange and size-exclusion chromatography; blue native page and immunoprecipitation studies were used to determine the molecular function and impact of MCUB on the high-molecular-weight mtCU complex.RESULTS:
Using genetic gain- and loss-of-function approaches, we show that MCUB expression displaces MCU from the functional mtCU complex and thereby decreases the association of mitochondrial calcium uptake 1 and 2 (MICU1/2) to alter channel gating. These molecular changes decrease MICU1/2-dependent cooperative activation of the mtCU, thereby decreasing mCa2+ uptake. Furthermore, we show that MCUB incorporation into the mtCU is a stress-responsive mechanism to limit mCa2+ overload during cardiac injury. Indeed, overexpression of MCUB is sufficient to decrease infarct size after ischemia/reperfusion injury. However, MCUB incorporation into the mtCU does come at a cost; acute decreases in mCa2+ uptake impair mitochondrial energetics and contractile function.CONCLUSIONS:
We detail a new regulatory mechanism to modulate mtCU function and mCa2+ uptake. Our results suggest that MCUB-dependent changes in mtCU stoichiometry are a prominent regulatory mechanism to modulate mCa2+ uptake and cellular physiology.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canais de Cálcio
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Traumatismo por Reperfusão Miocárdica
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Cálcio
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Sinalização do Cálcio
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Proteínas Mitocondriais
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Miócitos Cardíacos
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Proteínas de Membrana
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Mitocôndrias Cardíacas
Tipo de estudo:
Prognostic_studies
Limite:
Animals
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article