Autoimmunity: a diversity of diabetes

Article Abstract:

Insulin-dependent diabetes mellitus, also called type 1 diabetes, is now generally recognized to be an autoimmune disease. That is, the body's own immune system turns on and attacks the beta cells in the pancreas responsible for the manufacture and secretion of insulin. In the June 21, 1990 issue of Nature, three independent groups of researchers report results of experiments on non-obese diabetic mice which provide new insight into human diabetes as well. Class II HLA antigens of the major histocompatibility complex (MHC) play a key role in the recognition of antigens by T-cells. Research has shown that a member of this complex, the HLA-DQ molecule, plays a role in the development of diabetes in susceptible patients. The prevailing notion is that when this protein has an aspartic acid amino acid residue at position 57 of the protein chain, diabetes will not develop; any other amino acid in that spot may result in diabetes. A similar situation occurs in mice; the I-A molecule, homologous to the human HLA-DQ, has a serine in position 57 in genetically NOD (non-obese diabetic) mice. Using the techniques of molecular biology, researchers grew transgenic NOD mice possessing an additional I-A molecule, this one with an aspartic acid at the right spot. The mice did not develop diabetes, providing strong support for the belief that genetic variation in this molecule plays a critical role in the development of type 1 diabetes. Researchers were also able to provide protection against diabetes by restoring the normal expression of the I-E molecule to these mutant mice. The evidence suggests that the presence of the serine does not cause the diabetes, but rather that the aspartic acid is protective. To appreciate how a single amino acid can have such a dramatic effect, it is vital to remember the importance of the three-dimensional structure of the coiled and contorted protein molecule. Any change in an amino acid may change the forces within the molecule and result in a different shape; a different shape which produces a different function. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Diabetes, Diabetes mellitus, Genetic aspects, Autoimmune diseases, editorial, Histocompatibility antigens, HLA class II antigens

---

Deconstructing the MHC

Article Abstract:

The use of protein crystallography has yielded further information on the structure and immunological function of the major histocompatibility complex (MHC) molecules. Hwai-Chen Guo and colleagues, Michael L. Silver and colleagues and D.R. Madden and colleagues showed that the HLA-A68 and HLA-B27 MHC molecules are made up of a beta-structure capable of binding in the middle. This binding property explains how class I MHC molecules are both able to attach to any peptide and yet bind best to only certain peptides.

Usage, Major histocompatibility complex, Crystallography

---

Soaring costs in defence

Article Abstract:

A paper by the MHC sequencing consortium provides a complete nucleotide sequence of an HLA complex and a linear map ordering of each of the genes. Kaufam and colleagues have described two genes in the chick major histocompatibility complex (MHC), which specify proteins similar to the lectin-like receptors of mammalian NK cells.

Immunogenetics

Similar abstracts:

• Abstracts: Male density, female density and inter-sexual conflict in a stream-dwelling insect. Optimal diet theory: when does it work, and when and why does it fail
• Abstracts: Company accused over lab data 'theft'. Cashing in on the rich coast
• Abstracts: Fluctuation-induced diffusive instabilities. Friction and fracture. A new crack at friction
• Abstracts: Nucleation and growth of fibres and gel formation in sickle cell haemoglobin. Haemoglobin C protects against clinical Plasmodium falciparum malaria
• Abstracts: Effect of road traffic on two amphibian species of differing vagility. Effects of Road Fencing on Population Persistence

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.