Main physiological functions of mitochondria

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Beverly McCormick
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4 Main physiological functions of mitochondria Energy conservation =ATP production Thermoregulatory = energy dissipation as heat Substrate production & decomposition Reactive oxygen species (ROS) Skulachev(1998) xidative phosphorylation { coupling uncoupling

10 Substrate oxidation glucose fatty acid Mitochondrial DNA UCP H Mitochondria play key roles: H inner membrane acetylcoa ADP Pi ATP TCA cycle CO 2 NADH succinate fumarate H 2 O O 2 NAD II I Q III IV C ATPase ΔΨ H ATP production Energy conservation crosstalk H H H H H Oxidative Phosphorylation Reactive oxygen species (ROS) Thermogenesis /UCPs/ Proton leak

11 In this section F, D & P

12 glucose fatty acid Mitochondrial DNA UCP H Papers roughly grouped inner membrane acetylcoa ADP Pi ATP TCA cycle CO 2 NADH succinate fumarate H 2 O O 2 NAD II I Q III IV H H H H H C ATPase ΔΨ H H ATP production Energy conservation O2 O3 Oxidative Phosphorylation P5 P10 P7 P12 Reactive oxygen species (ROS) O4 P9 Substrate oxidation Thermogenesis /UCPs/ Proton leak P6 P8 P11

13 #O3 Effects of a diet enriched in trans fatty acids (trans MUFA) on muscle mitochondrial functions and development of insulin resistance in rodents Tardy et al, INRA, France Wistar rats (400g) fed different fat sources: oleic acid :C18:19 cis, OLE elaidic acid :C18:19 trans, ELA vaccenic acid :C18:111 trans, VAC 4% of total energy for 8 wks C18:19 cis trans C18:111 trans Results with muscle mitochondria State State ATP P/O OXPHOS capacities glutamate, malate succinate Enzyme activities ROS production

14 Oxygen consumption rates of mitochondria 100 O 2 consumption 0 Substrate ADP ADP > ATP O Time STATE3 STATE4 C18:19 cis trans C18:111 trans Results (cisfed) (transfed) State State ATP P/O Reasons: decrease 1) could be from uncoupling 2) may be the possibility of reduced integrity of the ATPase

#O5 Relationships between hepatic mitochondrial function and residual feed intake in growing beef calves Lancaster et al, Texas A&M Univ., Washington State Univ., Ohio State Univ.

15 #O5 Relationships between hepatic mitochondrial function and residual feed intake in growing beef calves Lancaster et al, Texas A&M Univ., Washington State Univ., Ohio State Univ., USA Two strains calves Angus heifers (n=29; BW=256kg) Santa Gertrudis steers (n=119; initial BW=308.4 kg) Growing calves with low and high Residual feed Intake (RFI) were selected after feeding for 70 d Exp.1/2 Group less Mitochondria: liver biopsy samples OXPHOS capacities Membrane potential Proton leak *dry matter intake liver mitochondria Gordon E. Carstens

oxidation rate Efficiency of oxidative phosphorylation Phosphorylating system Proton leak Proton leak State 3 Phosphorylation% Membrane potential 102 90 State 4 Proton leak% Growing calves with low

16 oxidation rate Efficiency of oxidative phosphorylation Phosphorylating system Proton leak Proton leak State 3 Phosphorylation% Membrane potential State 4 Proton leak% Growing calves with low and high Residual feed Intake DMI kg/d 8.9 vs 10.3 OXPHOS capacities of liver mitochondria State numerically State FCCP RCR Membrane potetial mv O 2 Proton leak Efficiency of OXPHOS O 2 consumption for phosphorylation total O 2 consumption

17 glucose fatty acid Mitochondrial DNA UCP H inner membrane acetylcoa ADP Pi ATP TCA cycle CO 2 NADH succinate fumarate H 2 O O 2 NAD II I Q III IV H H H H H C ATPase ΔΨ H H ATP production Energy conservation O2 O3 Oxidative Phosphorylation P5 P10 P7 P12 Reactive oxygen species (ROS) O4 P9 Substrate oxidation Thermogenesis /UCPs/ Proton leak P6 P8 P11

18 Porter & Brand, Nature 362: 628 (1993) Proton leak kinetics in liver mitochondria isolated from mammals of different body mass small mouse Respiration rate Phosphorylating system Proton leak State 3 Phosphorylation% proton leak State 4 H proton leak rat ferret pig hamster sheep rabbit horse Proton leak Proton leak% Membrane potential membrane potential big Differences in proton leak may partly explain the differences in metabolic rate between mammals of different mass.

19 #P10 Variation in animal energy expenditure and mitochondrial function and protein expression (among Angus, Holstein, Wagyu) Michal et al, Washington State Univ., USA Angus, Holstein, Wagyu heifers (n=8/breed; 10 mo) Angus and Wagyu heifers at the Low level of intake were studied for mitochondrial function Mitochondria: liver biopsy samples simultaneous measurement of oxygen consumption membrane potential Kristen A. Johnson Proton leak rate (nmol H/min/mg protein) Angus Wagyu Membrane potential (mv) MEm, kcal/kġ UCP3 Angus Wagyu

: Psoas major Mitochondrial respiration study: isolated permeabilised fibres isolated mitochondoria Palmitate/Hydroxynonenal HNE GDP

20 #P08 Expression of uncoupling proteins and mitochondrial activity are dependent on muscular fibre type in rabbits and chickens Joubert et al, INRA, France Chicken Slow: Adductor superficialis Fast : Pectoralis major Rabbit Slow: Semimembranosus proprius Fast : Psoas major Mitochondrial respiration study: isolated permeabilised fibres isolated mitochondoria Palmitate/Hydroxynonenal HNE GDP Chicken Without BSA State 4 State 4 50uMpalm 50uMpalm 2.5mMGDP 2.5mMGDP 5mMGDP 5mMGDP UCPmRNA expression study: Realtime RTPCR muscle types

glucose fatty acid Mitochondrial DNA UCP H inner membrane acetylcoa ADP Pi ATP TCA cycle CO 2 NADH succinate fumarate H 2 O O 2 NAD II I Q III IV H H H H H C ATPase ΔΨ H H ATP

21 glucose fatty acid Mitochondrial DNA UCP H inner membrane acetylcoa ADP Pi ATP TCA cycle CO 2 NADH succinate fumarate H 2 O O 2 NAD II I Q III IV H H H H H C ATPase ΔΨ H H ATP production Energy conservation O2 O3 Oxidative Phosphorylation P5 P10 P7 P12 Reactive oxygen species (ROS) O4 P9 Substrate oxidation Thermogenethis /UCPs/ Proton leak P6 P8 P11

27 #P09 Regulation of mitochondrial and tissue oxidations by thyroid hormones in chicken muscle Collin et al, INRA,France; Katholieke Univ. Leuven, Belgium Chicken, 1wk of age HADHmRNA Chicken Control MMI: methimazole 1 g/kg feed thyroid grand inhibitor T 3 : triiodothyronine 1 mg/kg feed for 3 wks Gene expression Muscular mitochondrial oxidations mrna expression MCPT1 and LCPT1 hydroxyacyl dh HAD cytochrome oxidase COX AMPK assay Oxidative stress COXmRNA TBARS b a b Control MMI T 3 Thyroid treatment

28 #P09 Regulation of mitochondrial and tissue oxidations by thyroid hormones in chicken muscle Collin et al, INRA,France; Katholieke Univ. Leuven, Belgium Chicken, 1wk of age Control MMI: methimazole 1 g/kg feed thyroid grand inhibitor T 3 : triiodothyronine 1 mg/kg feed for 3 wks Muscular mitochondrial oxidations mrna expression MCPT1 and LCPT1 hydroxyacyl dh HAD cytochrome oxidase COX AMPK assay Oxidative stress Their previous results Collin et al. AJP 284:E771 (2003) avucpmrna TBARS b b Control MMI T 3 b Thyroid treatment c a a

29 #P09 Regulation of mitochondrial and tissue oxidations by thyroid hormones in chicken muscle Collin et al, INRA,France; Katholieke Univ. Leuven, Belgium Oxidative Damage Mitochondrial ROS Lipid Peroxidation Reactive aldehydes Activation of UCPs substrate Their previous oxidation results Collin et al. AJP 284:E771 (2003) avucpmrna 200 b 100 c 0 a High Low Mild PMF PMF Uncoupling e e Local[O 2 ] Proton motive force Brand Model e? TBARS b a b Control MMI T 3 Thyroid treatment

Oxidative Phosphorylation

Oxidative Phosphorylation Electron Transport Chain (overview) The NADH and FADH 2, formed during glycolysis, β- oxidation and the TCA cycle, give up their electrons to reduce molecular O 2 to H 2 O. Electron transfer occurs through