Neurotrophic and neurotoxic effects of amyloid beta protein: reversal by tachykinin neuropeptides

Article Abstract:

Amyloid beta protein (ABP) is a small protein which is the major component of the brain deposits that occur in Alzheimer's disease and Down syndrome. Although its structure and chemistry have been characterized, the role of ABP in normal biological function and in the development of Alzheimer's disease are unknown. Studies have suggested two opposite effects of ABP. One showed that a protein containing ABP was toxic to nerve cells grown in the laboratory, while the other showed that a protein structurally similar to ABP increased the survival of similar nerve cells. This study shows that ABP has both of these effects, neurotoxic and neurotrophic, depending on the age of the nerve cells and the dose of ABP. Low doses of ABP improved survival of immature cells, which have few characteristics of adult nerve cells. However, high levels of ABP were toxic to adult cells, which have differentiated, and the doses caused loss of nerve cell branches before cell death. The same small segment of the ABP protein was responsible for both of these effects. In addition, tachykinins, another group of nerve proteins, had similar activity. Tachykinin blockers mimicked ABP effects, which were reversed by the tachykinins. The study provides evidence for a functional role of ABP, and suggests that accumulation of high doses of ABP in the adult brain, as occurs in Alzheimer's disease, may lead to degeneration of nerves. The effects of tachykinins in reversing these effects may have significance in treatment strategies for Alzheimer's disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Alzheimer's disease, Tachykinins

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GTP hydrolysis in protein synthesis: two for Tu?

Article Abstract:

Researchers have used a new method to determine that the energy needed for protein synthesis is greater than the amount that most textbooks report. Evidence suggests that the stoichiometry of hydrolysis of GTP is greater than two.

Proteins, Protein synthesis, Stoichiometry

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Neuropeptides, adenylyl cyclase, and memory storage

Article Abstract:

Research on the cloned Drosophila memory gene amnesiac is providing insights into the role of neuropeptides in memory storage. Amnesiac encodes a peptide that is similar to mammalian adenylyl cyclase activating peptide.

Genetic aspects, Memory, Drosophila, Adenylate cyclase

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