Objectives: To determine how changes in mitochondrial calcium uniporter (MCU) complex (MCUC) function influence mitochondrial dynamics and contribute to PAH’s cancer-like phenotype.
Methods: PASMCs were isolated from patients with PAH and healthy control subjects and assessed for expression of MCUC subunits. Manipulation of the pore-forming subunit, MCU, in PASMCs was achieved through small interfering RNA knockdown or MCU plasmid-mediated up-regulation, as well as through modulation of the upstream microRNAs (miRs) miR-138 and miR-25. In vivo, nebulized anti-miRs were administered to rats with monocrotaline-induced PAH.
Measurements and Main Results: Impaired MCUC function, resulting from down-regulation of MCU and up-regulation of an inhibitory subunit, mitochondrial calcium uptake protein 1, is central to PAH’s pathogenesis. MCUC dysfunction decreases intramitochondrial calcium ([Ca2+]mito), inhibiting pyruvate dehydrogenase activity and glucose oxidation, while increasing [Ca2+]cyto, promoting proliferation, migration, and fission. In PAH PASMCs, increasing MCU decreases cell migration, proliferation, and apoptosis resistance by lowering [Ca2+]cyto, raising [Ca2+]mito, and inhibiting fission. In normal PASMCs, MCUC inhibition recapitulates the PAH phenotype. In PAH, elevated miRs (notably miR-138) down-regulate MCU directly and also by decreasing MCU’s transcriptional regulator cAMP response element–binding protein 1. Nebulized anti-miRs against miR-25 and miR-138 restore MCU expression, reduce cell proliferation, and regress established PAH in the monocrotaline model.
Conclusions: These results highlight miR-mediated MCUC dysfunction as a unifying mechanism in PAH that can be therapeutically targeted.
|Number of pages||15|
|Journal||American Journal of Respiratory and Critical Care Medicine|
|Early online date||20 Sep 2016|
|Publication status||Published - 15 Feb 2017|
- mitochondrial calcium uptake protein
- microRNA- 25- and -138-5p
- cAMP response element–binding protein
- pyruvate dehydrogenase
- pulmonary arterial hypertension (PAH)