Diabetes, Vol 40, Issue 4 413-422, Copyright © 1991 by American Diabetes Association
Lilly lecture 1990. Molecular defects in diabetes mellitus
GI Bell
Howard Hughes Medical Institute, University of Chicago, IL 60637.
The application of molecular biology to problems in diabetes mellitus has
begun to reveal the underlying molecular defects contributing to the
development of hyperglycemia. Islet amyloid represents the most common
pathological lesion occurring in the islets of NIDDM subjects. The use of
both biochemistry and molecular biology has lead to the identification of
the major protein component of human islet amyloid and elucidation of the
structure of its precursor. This protein, termed islet amyloid polypeptide,
is related to two neuropeptides, calcitonin gene-related peptides 1 and 2,
and represents a new beta-cell secretory product whose normal physiological
function remains to be determined. The use of molecular biology has also
led to a better understanding of the molecular defects contributing to
insulin resistance. Characterization of the insulin-receptor gene in
patients with extreme forms of insulin resistance has resulted in the
identification of mutations that impair its function and lead to tissue
resistance to the action of insulin. Molecular biological approaches have
also led to a better understanding of the regulation of glucose transport.
They have revealed that there is a family of structurally related proteins
encoded by distinct genes and expressed in a tissue-specific manner that
are responsible for the transport of glucose across the plasma membrane.
Moreover, they have shown that specific depletion of the
glucose-transporter isoform that mediates insulin-stimulated glucose
transport is responsible for decreased transport activity in adipose tissue
in insulin-resistant states.