[Abstract Title]. - Society for Neuroscience

provide a molecular link between CNS angiogenesis and BBB formation, two processes
previously thought to be independent
Disclosures: R. Daneman , None; D. Agalliu, None; L. Zhou, None; B.A. Barres, None.
Poster
287. Blood Brain Barrier and CSF
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 287.3/QQ57
Topic: E.09.c. Blood brain barrier
Support: NIH GRANT RO-1 NS41405
Title: Transferrin mediated transport of iron across rat brain microvascular endothelial cells: an
EM study
Authors: M. E. KLINGER 1 , K. DEVRAJ 1 , J. R. CONNOR 2 , A. CARRUTHERS 3 , *I. A.
SIMPSON 1 ;
1 Neural & Behav Sci., 2 Neurosurg., Coll Med, Penn State Univ., Hershey, PA; 3 Biochem. and
Mol. Pharmacol., Univ. of Massachusetts Med. Sch., Worcester, MA
Abstract: Iron is an essential element for neural cell survival and is involved in numerous
catalytic reactions and regulatory processes, such as ATP production, myelin and dopamine
synthesis. The initial uptake of iron at the blood-brain barrier (BBB) is mediated by the
transferrin receptor in the luminal membrane, which upon binding two molecules of transferrin
with two molecules of Fe to each, undergoes endocytosis and the iron transferrin complex is
internalized. The subsequent fate of the receptor, transferrin and Fe within the endothelial cell
then becomes controversial. In this study, we have monitored the distribution of the transferrin
receptors in the luminial, abluminal, and intracellular membranes of brain miscrovascular
endothelial cells in control and Belgrade rats by immunogold electron microscopy. The receptor
was detected using a mouse monoclonal antibody (Zymed) and visualized with silver enhanced
1.4 nm gold- labeled goat anti-mouse Fab fragments. In control cells, the ratio of receptors
between luminal: abluminal: intracellular (L:A:I) is 1:1.2:3.6. The Belgrade rat has autosomal
recessive hypochromic microcystic anemia associated with a mutation in the metal ion
transporter DMT-1, which results in a decreased uptake of iron from the gut and impaired release
of iron from the endocytic vesicles in most other cells. Western blotting of the brain
miscrovascular endothelial cells from control and Belgrade rats revealed a 50% increase in total
transferrin receptors in Belgrade rat cells. The EM study demonstrated an L:A:I ratio of 1:1.6:3.4
in Belgrade rats indicating that the predominant increase in receptors occurs at the abluminal