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Int J Physiol Pathophysiol Pharmacol 2011;3(3):210-222.

Original Article
Cystathionine β-synthase gene dose dependent vascular remodeling in murine
model of hyperhomocysteinemia

Neetu Tyagi, Natia Qipshidze, Utpal Sen, Walter Rodriguez, Alexander Ovechkin, Suresh C. Tyagi

Department of Physiology and Biophysics, University of Louisville School of Medicine, Louisville, Kentucky, USA.

Received July 29, 2011; accepted August 15, 2011; Epub September 6, 2010; Published September 30, 2011

Abstract: Although children born with severe homocystinurea (i.e. cystathionine beta synthase homozygote knockout, CBS-/-) develop
deleterious vascular complications with structural malformation and do not live past teenage, the heterozygote (CBS-/+) lives with
apparently normal phenotype. Interestingly, this differential role of CBS expression in vascular remodeling is unclear. Peroxisome
proliferator activated receptor gamma (PPARgamma) is nuclear transcription factor that mitigates vascular complications. The
hypothesis was that homocysteine (Hcy) decreased thioredoxin (Trx), peroxiredoxin (Prx), increased NADPH oxidase (NOX1),
mitochondrial nitric oxide synthase (mtNOS) activity and reactive oxygen species (ROS) in mitochondria in a CBS gene dose-dependent
manner. ROS transduced matrix metalloproteinase (MMP) activation causing thickening (fibrosis) of the basement membrane,
rendering ineffective endothelial nitric oxide synthase (eNOS) and promoted endothelial-smooth muscle disconnection/uncoupling by
antagonizing PPARgamma. Wild type (WT-CBS+/+), CBS-/+ and CBS -/- mice were treated with or without ciglitazone (CZ, a
PPARgamma agonist) in food at birth. Aortic nuclear PPARgamma expression was measured by EMSA. Aortic mtNOS activity and ROS
production was measured using NO- and H2O2-electrodes, respectively.  Aorta was analyzed for Trx, Prx, by Western blot, and PCR.
MMP activity was by in situ zymography. Aortic function was measured in tissue myobath. The results suggested 90% morbidity in CBS-
/- allele at 12 wks. However, treatment with the PPARgamma agonist, CZ significantly reduced the morbidity to 20%. In addition, CZ
restored the PPARgamma activity in CBS-/+ and -/- mice to normal levels. The oxidative stress was alleviated by CZ treatment. In situ
labeling with mito-tracker suggests co-localization of ROS with mitochondrial mitophagy. The mtNOS activity was increased in HHcy
compared to WT. The data support the notion that Hcy decreases redoxins, increases mtNOS activity and ROS/oxidase in mitochondrial
mitophagy in a gene dose-dependent manner of CBS. ROS transduces MMP activation, rendering ineffective eNOS and promotes
endothelial-smooth muscle disconnection/uncoupling by antagonizing PPARgamma. We suggest that the children born with severe
homocystineurea may do better if treated with PPARgamma agonist. (IJPPP1107007).

Keywords: Aorta stiffness, MMP, TIMP, ROS, mitochondrial nitric oxide, thioredoxin, NOX1, peroxiredoxin, endothelial function, PPAR,
endothelin, hypertension

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Address all correspondence to:
Suresh C Tyagi, PhD,
Department of Physiology & Biophysics,   
University of Louisville School of Medicine,
500 South Preston Street,
Louisville, KY 40202, USA.
Phone: 502-852-3381, Fax: 502-852-6239,
E-mail: s0tyag01@louisville.edu