Katholieke Universiteit Leuven

About: Katholieke Universiteit Leuven is a education organization based out in Leuven, Belgium. It is known for research contribution in the topics: Population & Transplantation. The organization has 61109 authors who have published 176584 publications receiving 6210872 citations.

Loss of microRNA cluster miR-29a/b-1 in sporadic Alzheimer's disease correlates with increased BACE1/beta-secretase expression.

Abstract: Although the role of APP and PSEN genes in genetic Alzheimer's disease (AD) cases is well established, fairly little is known about the molecular mechanisms affecting A generation in sporadic AD. Deficiency in A clearance is certainly a possibility, but increased expression of proteins like APP or BACE1/-secretase may also be associated with the disease. We therefore investigated changes in microRNA (miRNA) expression profiles of sporadic AD patients and found that several miRNAs potentially involved in the regulation of APP and BACE1 expression appeared to be decreased in diseased brain. We show here that miR-29a, -29b-1, and -9 can regulate BACE1 expression in vitro. The miR-29a/b-1 cluster was signifi- cantly (and AD-dementia-specific) decreased in AD patients dis- playing abnormally high BACE1 protein. Similar correlations be- tween expression of this cluster and BACE1 were found during brain development and in primary neuronal cultures. Finally, we provide evidence for a potential causal relationship between miR-29a/b-1 expression and A generation in a cell culture model. We propose that loss of specific miRNAs can contribute to in- creased BACE1 and A levels in sporadic AD. neurodegeneration amyloid noncoding RNA

Lectins as Plant Defense Proteins

Abstract: Many plant species contain carbohydrate-binding proteins, which are commonly referred to as either lectins or agglutinins. Generally speaking, lectins are proteins that bind reversibly to specific monoor oligosaccharides. Since the initial discovery of a hemagglutinating factor in castor bean extracts by Stillmark in 1888, several hundred of these proteins have been isolated and characterized in some detail with respect to their carbohydrate-binding specificity, molecular structure, and biochemical properties. Lectins from different plant species often differ with respect to their molecular structure and specificity. It is important, therefore, to realize that all plant lectins are artificially classified together solely on the basis of their ability to recognize and bind carbohydrates. Moreover, the question arises whether proteins with a completely different structure and sugar-binding specificity fulfill the same physiological role. No conclusive answer can be given to this question as yet, for the simple reason that the role of most plant lectins is not known with certainty. There is, however, growing evidence that most lectins play a role in the plant's defense against different kinds of plant-eating organisms. The idea that lectins may be involved in plant defense is not new. In an earlier review, Chrispeels and Raikhel (1991) critically assessed the defensive role of the phytohemagglutinin family and a number of chitin-binding proteins. During the last few years important progress has been made in the study of plant lectins in general and in the understanding of their effects on other organisms in particular. In this Update we summarize the recent developments that support the defensive role of plant lectins and, in addition, discuss earlier work in this field against the background of our present knowledge of this group of plant proteins.