Lark 2015 Front Physiol

From Bioblast
Publications in the MiPMap
Lark DS, Reese LR, Ryan TE, Torres MJ, Smith CD, Lin CT, Neufer PD (2015) Protein kinase A governs oxidative phosphorylation kinetics and oxidant emitting potential at complex I.

Β» Front Physiol 6:332. PMID: 26635618 Open Access

Lark Daniel S, Reese Lauren R,  Ryan Terence E,  Torres Maria J,  Smith Cody D,  Lin Chien-Te,  Neufer P Darrell (2015) Front Physiol

Abstract: The mitochondrial electron transport system (ETS) is responsible for setting and maintaining both the energy and redox charges throughout the cell. Reversible phosphorylation of mitochondrial proteins, particularly via the soluble adenylyl cyclase (sAC)/cyclic AMP (cAMP)/Protein kinase A (PKA) axis, has recently been revealed as a potential mechanism regulating the ETS. However, the governance of cAMP/PKA signaling and its implications on ETS function are incompletely understood. In contrast to prior reports using exogenous bicarbonate, we provide evidence that endogenous CO2 produced by increased tricarboxylic acid (TCA) cycle flux is insufficient to increase mitochondrial cAMP levels, and that exogenous addition of membrane permeant 8Br-cAMP does not enhance mitochondrial respiratory capacity. We also report important non-specific effects of commonly used inhibitors of sAC which preclude their use in studies of mitochondrial function. In isolated liver mitochondria, inhibition of PKA reduced complex I-, but not complex II-supported respiratory capacity. In permeabilized myofibers, inhibition of PKA lowered both the Km and Vmax for complex I-supported respiration as well as succinate-supported H2O2 emitting potential. In summary, the data provided here improve our understanding of how mitochondrial cAMP production is regulated, illustrate a need for better tools to examine the impact of sAC activity on mitochondrial biology, and suggest that cAMP/PKA signaling contributes to the governance of electron flow through complex I of the ETS. β€’ Keywords: Adenylyl cyclase, cAMP, Complex I, Liver, Mitochondria, Protein kinase A, Respiration, Skeletal muscle β€’ Bioblast editor: Plangger M β€’ O2k-Network Lab: US CO Fort Collins Hamilton K, US NC Greenville Neufer PD

Labels: MiParea: Respiration 

Organism: Mouse  Tissue;cell: Skeletal muscle, Liver  Preparation: Permeabilized tissue, Isolated mitochondria 

Coupling state: LEAK, OXPHOS, ET  Pathway: N, S  HRR: Oxygraph-2k 


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