Mitochondrie et muscle lisse. Vladimir Veksler

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1 Mitochondrie et muscle lisse Vladimir Veksler

2 Main mitochonrial functions Energy production

3 ATP consumption rate in smooth and striated muscle smooth muscle striated (cardiac) muscle at rest 30 µmol/min/g at maximal stress µmol ATP/min/g smooth muscle energetics

4 Main mitochonrial functions Oxygen probe Cell proliferation Apoptosis ROS production H2 O2, O2. - Ca2+ K+ Ionic homeostasis K+, Ca++ Synthesis of steroid hormones Energy production ATP, PCr Thermogenesis UCP

5 Depolarization of the mitochondrial membrane potential inhibits IP3-evoked Ca 2+ release Microcirculation Volume 20, Issue 4, pages , 10 MAY 2013 DOI: /micc l#micc12039-fig-0004

Volume 20, Issue 4, pages 317-329, 10 MAY 2013 DOI: 10.1111/micc.

6 Depolarization of the mitochondrial membrane potential with CCCP inhibits Ca 2+ release from an IP 3 R cluster Microcirculation Volume 20, Issue 4, pages , 10 MAY 2013 DOI: /micc

7 Role of mitochondria in hypoxic pulmonary vasoconstriction Hypoxia Mitochondrion is an oxygen sensor Mitochondria ROS production modulation Vascular smooth muscle contraction

proliferation and resistance to apoptosis of pulmonary arterial smooth muscle cells (PASMCs) Two

8 Pulmonary arterial hypertension (PAH) Severe and progressive vascular disease that frequently leads to right heart failure and premature death Common hallmark: vascular remodeling, due to excessive proliferation and resistance to apoptosis of pulmonary arterial smooth muscle cells (PASMCs) Two mitochondrial mechanisms seem to be involved: 1 - mitochondrial dynamics 2 mitochondrial biogenesis (PGC-1α)

9 Mitochondrial fission: DRP1

10 Mitochondrial fusion: mitofusins Fusion proteins TM: transmembrane HR heptad repeat (coiled coil)

OPA1 (in pink) anchored to the inner membrane (IM) could controls its dynamic in coordination with the dynamic outer

11 OPA1: protein responsible for autosomal dominant optic atrophy Mfn2 Olichon et al., 2006 OPA1 Cyt C Possible roles for OPA1. OPA1 (in pink) anchored to the inner membrane (IM) could controls its dynamic in coordination with the dynamic outer membrane (OM) by interacting either directly or indirectly with Mfn2 (in grey). Oligomerized OPA1 could structure the cristae or could control the cristae junction opening, sequestering cytochrome c (in green) in intra-cristae compartment.

12 Excessive fission in human pulmonary arterial hypertension (PAH) pulmonary artery smooth muscle cells Marsboom et al., 2012

13 Dynamin-related protein-1 (DRP1) inhibition reduces proliferation of smooth muscle cells Marsboom et al., 2012

14 Therapeutic benefit of mitochondrial fission inhibition by Mdivi-1 in the chronic hypoxia model pulmonary artery acceleration time tricuspid annular plane systolic excursion Marsboom et al., 2012

15 MFN2 Down-regulation Increases Proliferation in Normal PASMC Ryan et al., 2013

16 Mitofusin-2 (MFN2) overexpression reduces mitochondrial fragmentation and proliferation in pulmonary arterial smooth muscle Ryan et al., 2013

Expression of mitochondrial fusogenic proteins in human pulmonary artery

, 2013 MFN1/Citrate synthase ratio 2,4 2,0 1,6 1,2 0,8 0,4 0,0 Control

OPA1-100 KDa OPA1-80 kda Control ipah OPA1 (80)/Citrate synthase ratio

17 Expression of mitochondrial fusogenic proteins in human pulmonary artery smooth muscle cells Ryan et al., 2013 MFN1/Citrate synthase ratio 2,4 2,0 1,6 1,2 0,8 0,4 0,0 Control ipah MFN2/Citrate synthase ratio 2,0 1,5 1,0 0,5 0,0 Control * ipah CS OPA1-100 KDa OPA1-80 kda Control ipah OPA1 (80)/Citrate synthase ratio 3,0 2,4 1,8 1,2 0,6 ** OPA1 (100)/Citrate synthase ratio 1,6 1,2 0,8 0,4 * β-actin 0,0 Control ipah 0,0 Control ipah

incorporation (cpm) 3000 2500 2000 1500 1000 500 0 Control ipah Scrambl-Seq OPA1-SiRNA Scrambl-Seq OPA1-SiRNA ** * Basal

18 OPA1 downregulation dramatically decreases pulmonary artery smooth muscle cell proliferation and increases apoptosis OPA1 mrna levels (2 -(Ct gene of interest Ct r18s) 1 0,8 0,6 0,4 0,2 0 ** Scramble-Seq controls IPAH OPA1-SiRNA [ 3 H]thymidine incorporation (cpm) Control ipah Scrambl-Seq OPA1-SiRNA Scrambl-Seq OPA1-SiRNA ** * Basal FCS (5%) C 80 Control ipah Apoptotic cells (%) * 0 Basal scrambl-seq OPA1-siRNA Basal scrambl-seq OPA1-siRNA Basal H2O2

19 OPA1-deficient mice have neither hypoxia-induced pulmonary artery hypertension nor right ventricle hypertrophy 30 NS NS *** *** *** 40 NS NS *** *** *** RVSP (mmhg) RV/(LV+S), % OPA1 0 +/+ +/- +/+ +/- 0 OPA1 +/+ +/- +/+ +/- Normoxia Hypoxia Normoxia Hypoxia Pulmonary Vessels (%) Normoxic OPA1 (+/+) mice Normoxic OPA1 (+/-) mice Hypoxic OPA1 (+/+) mice Hypoxic OPA1 (+/-) mice NM PM FM NM non muscular PM partially muscular FM fully muscular

20 Proliferating smooth muscle cells have downregulated PGC-1α PGC1α vehicle PDGF Energy depletion Redox alterations tubulin Relative band density 1,4 1,2 1 0,8 0,6 0,4 0,2 * vehicle PDGF Phosphorylation interplay Deacetylation 0 PGC-1alpha Mitochondrial biogenesis Metabolic fitness

21 Effects of SIRT1 downregulation on human PASMC proliferation CNTR PASMCs scramble sisirt1 SIRT1 β actin rd 1 0,16 BrdU incorporation assay Relative absorbance (A450nm) 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 * CNTR PASMCs scramble sisirt1 SIRT1 downregulation favours human PASMC proliferation.

22 Effects of STAC-3 on human PAH PASMC proliferation SIRT1 activator 3 (stac-3) WST-1 assay BrdU assay Relative absorbance (A440nm-A690nm) 1,4 1,2 1 0,8 0,6 0,4 0,2 0 * PAH PASMCs Reletive absorbance (A450nm) 1,4 1,2 1 0,8 0,6 0,4 0,2 0 * PAH PASMC vehicle stac-3 10µM SIRT1 activation by 10 µm stac-3 strongly inhibits human PAH PASMC proliferation.

23 Putative mechanisms of sirtuin1-dependent inhibition of smooth muscle proliferation mitochondrial antioxidant activity Sirtuin1 activation PGC-1α deacetylation (activation) mitochondrial biogenesis inhibition of smooth muscle cell hyperproliferation mitochondrial fragmentation?

24 Take home message Abnormal pulmonary artery vascular smooth muscle proliferation is associated with alterations in expression of proteins involved in mitochondrial dynamics and apoptosis (DRP-1, mitofusin, OPA-1, PGC-1α). Correction of these proteins (DRP-1 and OPA1 down-regulation; mitofusin and PGC-1α up-regulation) could be a therapeutic target in pulmonary artery hypertension.

25 Participants U-769 INSERM Châtenay- Malabry, France Giada ZURLO Frédéric JOUBERT Christophe LEMAIRE Matthieu RUIZ Anne GARNIER Renée VENTURA-CLAPIER U-999 INSERM, Hospital Marie- Lannelongue, Le Plessis-Robinson, France Mohamed IZIKKI Saadia EDDAHIBI Tartu University Estonia Allen KAASIK Johannes-Gutenberg Universität Mainz Germany Marcel ALAVI

Supplementary Figure 1.

Supplementary Figure 1. Characterisation of IHG-1 overexpressing and knockdown cell lines. (A) Total cellular RNA was prepared from HeLa cells stably overexpressing IHG-1 or mts-ihg-1. IHG-1 mrna was quantified