Periventricular Expression of Megalin in Adult Male Rat Brains and In-Vitro SHBG Binding to Cells Through Interaction with a Megalin Receptor
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Authors
Behr, Ian J.
Issue Date
2007
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Sex Hormone Binding Globulin (SHBG) carries androgens and estrogens
throughout the body to specific target cells. It was previously believed that SHBG
transported its cargo outside of target cells, and the hormones then diffused through the
membrane into the target cell. However, recent studies have suggested SHBG binds to a
cell surface receptor, and then SHBG and its associated hormone are internalized by the
cell. This paper studies the in vitro interaction of fluorescently-Iabeled SHBG with fetal
mouse hippochampal cells and fibroblast cells to determine how blocking one ofSHBG's
known receptors, megalin, affects SHBG. Immunohistochemistry in adult male rat brain
sections was performed to localize megalin using an antibody raised against itself. This
identified megalin in ependymal cells lining the lateral and third ventricles. In vitro
results showed fluorescently labeled SHBG (SHBG-Alexa-555™) bound to the outside of
HT22 mouse hippocampal cells and fibroblast NIH3 T3 cells after short treatment
periods; longer treatment times resulted in the appearance of granular fluorescence inside
these cells. Binding of SHBG was decreased when cells were treated with megalin
antibody before the addition of fluorescent SHBG; this suggests megalin bound by
antibody was unable to interact with SHBG as strongly. These studies suggest SHBG
binds to brain cells through the interaction with its cell surface receptor megalin, which
subsequently internalizes SHBG and its associated steroid hormone.
Description
iv, 20 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.