Diabetes, Vol 31, Issue 2 185-188, Copyright © 1982 by American Diabetes Association
Alterations in the basement membrane (heparan sulfate) proteoglycan in diabetic mice
DH Rohrbach, JR Hassell, HK Kleinman and GR Martin
We have grown the EHS (Engelbreth-Holm, Swarm) tumor in normal and
genetically diabetic mice (db/db) and measured some components of basement
membrane produced in the tumor. These studies showed similar amounts of
total protein in control and diabetic tissue and similar patterns of
proteins on SDS gel electrophoresis of extracts of the tissue. Laminin, a
basement membrane specific glycoprotein utilized as an attachment factor by
epithelial cells, was present in increased amounts in diabetic tissue. In
contrast, the amount of BM-1 (heparan sulfate) proteoglycan was reduced.
Less 35S-sulfate was incorporated into this proteoglycan, and the
proteoglycan, but not its component glycosaminoglycans, was heterogeneous
in size. The data indicate that either the synthesis of proteoglycan was
decreased or its degradation was increased in diabetic tissue. Since the
heparan sulfate proteoglycan serves to block the passage of anionic
macromolecules through the basement membrane, decreased levels could
account for the increased porosity of diabetic basement membrane.
Compensatory synthesis of the basement membrane components to restore
normal permeability could account for the thickened basement membranes
observed in diabetes.