Biology Reference
In-Depth Information
VEGF
Vascular endothelial growth factor
GGOH
Geranylgeraniol
TAUT
Taurine transporter
7.1
Introduction
Taurine (2-aminoethanesulfonic acid) is the most abundant free amino acid in the
retina (12 mM in rat) where its concentration is 100 times greater than that in the
serum (100-300 mM) (Jacobsen and Smith
1968
; Pasantes-Morales et al.
1972
;
Ando et al.
2012
). In the retina, taurine deficiency causes a retinal abnormality and
visual impairment in humans and rodents (Geggel et al.
1985
; Heller-Stilb et al.
2002
). The taurine supply to the retina from the circulating blood is mediated by the
taurine transporter TAUT in retinal capillary endothelial cells (inner blood-retinal
barrier, iBRB) and retinal pigment epithelial cells (outer BRB) (Törnquist and Alm
1986
; El-Sherbeny et al.
2004
; Tomi et al.
2007
). Diabetic retinopathy (DR) remains
a prevalent complication of diabetes and one of the leading causes of blindness
among working-age adults (Frank
2004
). Elevated glucose is believed to contribute
to loss of microvascular barrier integrity (Frank
1984,
2004
) . Especially, vascular
endothelial growth factor (VEGF) can trigger many of the retinal vascular changes
caused by diabetes, including leukocyte adhesion to retinal capillaries and vascular
leakage (Miyamoto et al.
2000
). Accordingly, transport activity of taurine may be
also changed at the iBRB under high glucose condition, and this change could
intensely affect the neuroprotective effect of taurine by influencing taurine concen-
tration in the retina. Therefore, the purpose of this study is to clarify the regulation
of taurine transport activity by high glucose concentration and the effect of VEGF
inhibitors, bisphosphonates, in taurine transport under high glucose condition using
TR-iBRB cell lines as an in vitro model of iBRB.
7.2
Methods
7.2.1
Cell Culture
The TR-iBRB cells were grown routinely in rat tail collagen type 1-coated tissue
culture dishes (Iwaki, Tokyo, Japan) at 33°C and cultured in a humidified atmo-
sphere of 5% CO
2
/air. The cells were cultured in Dulbecco's modified Eagle's
medium (DMEM; Invitrogen, Grand Island, NY, USA) supplemented with 10%
fetal bovine serum (FBS; Invitrogen, Grand Island, NY, USA), 15 m g/L endothelial
cell growth factor (Roche, Mannheim, Germany), and 100 U/mL penicillin and
100 mg/mL streptomycin (Invitrogen, Grand Island, NY, USA).
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