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Exercise-mediated wall shear stress increases mitochondrial biogenesis in vascular endothelium.

Kim B, Lee H, Kawata K, Park JY - PLoS ONE (2014)

Bottom Line: In this study, we sought to investigate the effect of fluid shear stress on mitochondrial biogenesis and mitochondrial respiratory function in endothelial cells (ECs) using in vitro and in vivo complementary studies.Also, shear-exposed cells showed diminished glycolysis and decreased mitochondrial membrane potential (ΔΨm).Our findings may suggest a novel mitochondrial pathway by which a chronic exercise may be beneficial for vascular function.

View Article: PubMed Central - PubMed

Affiliation: Department of Kinesiology, Temple University, Philadelphia, Pennsylvania, United States of America; Cardiovascular Research Center, Temple University, Philadelphia, Pennsylvania, United States of America.

ABSTRACT

Objective: Enhancing structural and functional integrity of mitochondria is an emerging therapeutic option against endothelial dysfunction. In this study, we sought to investigate the effect of fluid shear stress on mitochondrial biogenesis and mitochondrial respiratory function in endothelial cells (ECs) using in vitro and in vivo complementary studies.

Methods and results: Human aortic- or umbilical vein-derived ECs were exposed to laminar shear stress (20 dyne/cm2) for various durations using a cone-and-plate shear apparatus. We observed significant increases in the expression of key genes related to mitochondrial biogenesis and mitochondrial quality control as well as mtDNA content and mitochondrial mass under the shear stress conditions. Mitochondrial respiratory function was enhanced when cells were intermittently exposed to laminar shear stress for 72 hrs. Also, shear-exposed cells showed diminished glycolysis and decreased mitochondrial membrane potential (ΔΨm). Likewise, in in vivo experiments, mice that were subjected to a voluntary wheel running exercise for 5 weeks showed significantly higher mitochondrial content determined by en face staining in the conduit (greater and lesser curvature of the aortic arch and thoracic aorta) and muscle feed (femoral artery) arteries compared to the sedentary control mice. Interestingly, however, the mitochondrial biogenesis was not observed in the mesenteric artery. This region-specific adaptation is likely due to the differential blood flow redistribution during exercise in the different vessel beds.

Conclusion: Taken together, our findings suggest that exercise enhances mitochondrial biogenesis in vascular endothelium through a shear stress-dependent mechanism. Our findings may suggest a novel mitochondrial pathway by which a chronic exercise may be beneficial for vascular function.

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Related in: MedlinePlus

Increased mitochondrial biogenesis markers by LSS in HAECs.(a) An overview of LSS protocol used. HAECs were exposed to exercise-mimicking LSS at 20 dyne/cm2 for 48 hrs, and then, recovery (Rec) LSS at 5 dyne/cm2 was followed for another 24 hrs. (b) Effect of LSS on the mRNA and protein expression of mitochondrial biogenesis markers. mRNA expression of NRF-1, SCO1, SCO2, TFAM, and COX IV were assessed by real-time PCR and protein contents of PGC-1α, VDAC, and p53R2 were analyzed by western blot. (c) Effect of LSS on the mRNA expression of mitochondrial dynamics markers. mRNA expression of Mfn1, Mfn2, OPA1, Fis1, and Drp1 were assessed by real-time PCR. (d) Effect of LSS on mtDNA contents. Relative mtDNA contents are expressed as a ratio of COX I and II to 18s rRNA. (e) Effect of LSS on mitochondrial mass. Mitochondria were labeled with MitoTracker Green in live HAECs. Representative fluorescence micrographs under STT (left panel) and after 48 hrs of LSS at 20 dyne/cm2 (right panel) are shown. Bar  = 50 µm. The MitoTracker Green fluorescence intensities were analyzed using the Image J (NIH) software. All densitometry analyses values are shown as mean ± SE; * P<0.05 vs. STT; ** P<0.01 vs. STT.
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pone-0111409-g001: Increased mitochondrial biogenesis markers by LSS in HAECs.(a) An overview of LSS protocol used. HAECs were exposed to exercise-mimicking LSS at 20 dyne/cm2 for 48 hrs, and then, recovery (Rec) LSS at 5 dyne/cm2 was followed for another 24 hrs. (b) Effect of LSS on the mRNA and protein expression of mitochondrial biogenesis markers. mRNA expression of NRF-1, SCO1, SCO2, TFAM, and COX IV were assessed by real-time PCR and protein contents of PGC-1α, VDAC, and p53R2 were analyzed by western blot. (c) Effect of LSS on the mRNA expression of mitochondrial dynamics markers. mRNA expression of Mfn1, Mfn2, OPA1, Fis1, and Drp1 were assessed by real-time PCR. (d) Effect of LSS on mtDNA contents. Relative mtDNA contents are expressed as a ratio of COX I and II to 18s rRNA. (e) Effect of LSS on mitochondrial mass. Mitochondria were labeled with MitoTracker Green in live HAECs. Representative fluorescence micrographs under STT (left panel) and after 48 hrs of LSS at 20 dyne/cm2 (right panel) are shown. Bar  = 50 µm. The MitoTracker Green fluorescence intensities were analyzed using the Image J (NIH) software. All densitometry analyses values are shown as mean ± SE; * P<0.05 vs. STT; ** P<0.01 vs. STT.

Mentions: Human aortic ECs (HAECs) and human umbilical vein ECs (HUVECs) (Lonza) were cultured in EGM-2 and M199 medium supplemented with 20% fetal bovine serum and endothelial cell growth supplement, respectively. Cells were exposed to the arterial levels of LSS for various time points by using a cone-and-plate shear system once they reach at 100% confluency. Overview of the LSS protocol is outlined in figure 1A. All experiments with HAECs and HUVECs were conducted between the 3–7 passages.


Exercise-mediated wall shear stress increases mitochondrial biogenesis in vascular endothelium.

Kim B, Lee H, Kawata K, Park JY - PLoS ONE (2014)

Increased mitochondrial biogenesis markers by LSS in HAECs.(a) An overview of LSS protocol used. HAECs were exposed to exercise-mimicking LSS at 20 dyne/cm2 for 48 hrs, and then, recovery (Rec) LSS at 5 dyne/cm2 was followed for another 24 hrs. (b) Effect of LSS on the mRNA and protein expression of mitochondrial biogenesis markers. mRNA expression of NRF-1, SCO1, SCO2, TFAM, and COX IV were assessed by real-time PCR and protein contents of PGC-1α, VDAC, and p53R2 were analyzed by western blot. (c) Effect of LSS on the mRNA expression of mitochondrial dynamics markers. mRNA expression of Mfn1, Mfn2, OPA1, Fis1, and Drp1 were assessed by real-time PCR. (d) Effect of LSS on mtDNA contents. Relative mtDNA contents are expressed as a ratio of COX I and II to 18s rRNA. (e) Effect of LSS on mitochondrial mass. Mitochondria were labeled with MitoTracker Green in live HAECs. Representative fluorescence micrographs under STT (left panel) and after 48 hrs of LSS at 20 dyne/cm2 (right panel) are shown. Bar  = 50 µm. The MitoTracker Green fluorescence intensities were analyzed using the Image J (NIH) software. All densitometry analyses values are shown as mean ± SE; * P<0.05 vs. STT; ** P<0.01 vs. STT.
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pone-0111409-g001: Increased mitochondrial biogenesis markers by LSS in HAECs.(a) An overview of LSS protocol used. HAECs were exposed to exercise-mimicking LSS at 20 dyne/cm2 for 48 hrs, and then, recovery (Rec) LSS at 5 dyne/cm2 was followed for another 24 hrs. (b) Effect of LSS on the mRNA and protein expression of mitochondrial biogenesis markers. mRNA expression of NRF-1, SCO1, SCO2, TFAM, and COX IV were assessed by real-time PCR and protein contents of PGC-1α, VDAC, and p53R2 were analyzed by western blot. (c) Effect of LSS on the mRNA expression of mitochondrial dynamics markers. mRNA expression of Mfn1, Mfn2, OPA1, Fis1, and Drp1 were assessed by real-time PCR. (d) Effect of LSS on mtDNA contents. Relative mtDNA contents are expressed as a ratio of COX I and II to 18s rRNA. (e) Effect of LSS on mitochondrial mass. Mitochondria were labeled with MitoTracker Green in live HAECs. Representative fluorescence micrographs under STT (left panel) and after 48 hrs of LSS at 20 dyne/cm2 (right panel) are shown. Bar  = 50 µm. The MitoTracker Green fluorescence intensities were analyzed using the Image J (NIH) software. All densitometry analyses values are shown as mean ± SE; * P<0.05 vs. STT; ** P<0.01 vs. STT.
Mentions: Human aortic ECs (HAECs) and human umbilical vein ECs (HUVECs) (Lonza) were cultured in EGM-2 and M199 medium supplemented with 20% fetal bovine serum and endothelial cell growth supplement, respectively. Cells were exposed to the arterial levels of LSS for various time points by using a cone-and-plate shear system once they reach at 100% confluency. Overview of the LSS protocol is outlined in figure 1A. All experiments with HAECs and HUVECs were conducted between the 3–7 passages.

Bottom Line: In this study, we sought to investigate the effect of fluid shear stress on mitochondrial biogenesis and mitochondrial respiratory function in endothelial cells (ECs) using in vitro and in vivo complementary studies.Also, shear-exposed cells showed diminished glycolysis and decreased mitochondrial membrane potential (ΔΨm).Our findings may suggest a novel mitochondrial pathway by which a chronic exercise may be beneficial for vascular function.

View Article: PubMed Central - PubMed

Affiliation: Department of Kinesiology, Temple University, Philadelphia, Pennsylvania, United States of America; Cardiovascular Research Center, Temple University, Philadelphia, Pennsylvania, United States of America.

ABSTRACT

Objective: Enhancing structural and functional integrity of mitochondria is an emerging therapeutic option against endothelial dysfunction. In this study, we sought to investigate the effect of fluid shear stress on mitochondrial biogenesis and mitochondrial respiratory function in endothelial cells (ECs) using in vitro and in vivo complementary studies.

Methods and results: Human aortic- or umbilical vein-derived ECs were exposed to laminar shear stress (20 dyne/cm2) for various durations using a cone-and-plate shear apparatus. We observed significant increases in the expression of key genes related to mitochondrial biogenesis and mitochondrial quality control as well as mtDNA content and mitochondrial mass under the shear stress conditions. Mitochondrial respiratory function was enhanced when cells were intermittently exposed to laminar shear stress for 72 hrs. Also, shear-exposed cells showed diminished glycolysis and decreased mitochondrial membrane potential (ΔΨm). Likewise, in in vivo experiments, mice that were subjected to a voluntary wheel running exercise for 5 weeks showed significantly higher mitochondrial content determined by en face staining in the conduit (greater and lesser curvature of the aortic arch and thoracic aorta) and muscle feed (femoral artery) arteries compared to the sedentary control mice. Interestingly, however, the mitochondrial biogenesis was not observed in the mesenteric artery. This region-specific adaptation is likely due to the differential blood flow redistribution during exercise in the different vessel beds.

Conclusion: Taken together, our findings suggest that exercise enhances mitochondrial biogenesis in vascular endothelium through a shear stress-dependent mechanism. Our findings may suggest a novel mitochondrial pathway by which a chronic exercise may be beneficial for vascular function.

Show MeSH
Related in: MedlinePlus