抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

It has been more than 10 years since it was first proposed that the neurodegeneration in Alzheimer9s disease (AD) may be caused by deposition of amyloid β-peptide (Aβ) in plaques in brain tissue. According to the amyloid hypothesis, accumulation of Aβ in the brain is the primary influence driving AD pathogenesis. The rest of the disease process, including formation of neurofibrillary tangles containing tau protein, is proposed to result from an imbalance between Aβ production and Aβ clearance.

/pdf/the-amyloid-hypothesis-of-alzheimer-s-disease-progress-and-211e4syver.pdf

The Amyloid Hypothesis of Alzheimer's Disease: Progress and Problems on the Road to Therapeutics

Rapid progress in deciphering the biological mechanism of Alzheimer's disease (AD) has arisen from the application of molecular and cell biology to this complex disorder of the limbic and association cortices. In turn, new insights into fundamental aspects of protein biology have resulted from research on the disease. This beneficial interplay between basic and applied cell biology is well illustrated by advances in understanding the genotype-to-phenotype relationships of familial Alzheimer's disease. All four genes definitively linked to inherited forms of the disease to date have been shown to increase the production and/or deposition of amyloid β-protein in the brain. In particular, evidence that the presenilin proteins, mutations in which cause the most aggressive form of inherited AD, lead to altered intramembranous cleavage of the β-amyloid precursor protein by the protease called γ-secretase has spurred progress toward novel therapeutics. The finding that presenilin itself may be the long-sought γ-...

Alzheimer's Disease: Genes, Proteins, and Therapy

Prospective Cohort Study

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes.

For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy.

Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

/pdf/guidelines-for-the-use-and-interpretation-of-assays-for-ijf2t30pbq.pdf

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

The A-beta 42/40 ratio is a driver of acute synaptotoxicity and LTP impairment

Background:A Disintegrin And Metalloprotease 10 (ADAM10) is an a-secretase that cleaves Amyloid Precursor Protein (APP) in the non-amyloidogenic pathway, thereby inhibiting amyloidogenic Ab production in Alzheimer’s disease (AD). Several studies address the deregulation of micro-RNAs (miRNAs) in a variety of human diseases, as well as in neurodegenerative processes. In this study we propose to explore and validate miRNAs that have directly or indirectly relations to the AD pathophysiology and ADAM10 gene expression. Methods: It is a comparative study, based on the assumptions of quantitative research. Biological samples were collected, analyzed and stored in a biorepository. Using MegaplexTM and MirWalk 2.0 database we analyzed data using RT-qPCR and relative expression of approximately 700 miRNAs in total blood, and validated 21 miRNAs in a sample of 21 AD subjects and 17 healthy elderly controls. Statistical association, regression and diagnostic accuracy tests were performed. The research project was approved by Brazil Ethics Platform (CAAE:02760312.0.0000.5504/112.543). Results: Mir-144-5p, miR-374 and miR-221 are downregulated in AD subjects compared to healthy controls, with moderate accuracy diagnosis (p<0.05). However, the association of selected miRNAs expression and Mini Mental State Examination (MMSE) was significantly better (p<0.0001) as a diagnostic tool compared to their expression

Mir-132: promoting adult neurogenesis in alzheimer’s disease

SUMMARY The Amyloid Precursor Protein (APP) and its homologues are transmembrane proteins required for various aspects of neuronal development and activity, whose molecular function is unknown. Specifically, it is unclear whether APP acts as a receptor, and if so what its ligand(s) may be. We show that APP binds the Wnt ligands Wnt3a and Wnt5a and that this binding regulates APP protein levels. Wnt3a binding promotes full length APP (flAPP) recycling and stability. In contrast, Wnt5a promotes APP targeting to lysosomal compartments and reduces flAPP levels. A conserved Cysteine Rich Domain (CRD) in the extracellular portion of APP is required for Wnt binding, and deletion of the CRD abrogates the effects of Wnts on flAPP levels and trafficking. Finally, loss of APP results in increased axonal and reduced dendritic growth of mouse embryonic primary cortical neurons. This phenotype can be cell-autonomously rescued by full length, but not CRD-deleted, APP.

https://biorxiv.org/content/10.1101/2021.01.18.426557v1.full.pdf

Bart De Strooper

Papers

The A-beta 42/40 ratio is a driver of acute synaptotoxicity and LTP impairment

Mir-132: promoting adult neurogenesis in alzheimer’s disease

The Amyloid Precursor Protein is a conserved Wnt receptor

P1-457: Neuronal differentiation of APP/APLP1/APLP2 triple knockout (tKO) embryonic stem (ES) cells

The Dementia UK Ecosystem: a call to action.