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

A new aspect of cell membrane structure is presented, based on the dynamic clustering of sphingolipids and cholesterol to form rafts that move within the fluid bilayer. It is proposed that these rafts function as platforms for the attachment of proteins when membranes are moved around inside the cell and during signal transduction.

Functional rafts in cell membranes

Cell signaling by receptor-tyrosine kinases

Signal transduction is initiated by complex protein-protein interactions between ligands, receptors and kinases, to name only a few. It is now becoming clear that lipid micro-environments on the cell surface -- known as lipid rafts -- also take part in this process. Lipid rafts containing a given set of proteins can change their size and composition in response to intra- or extracellular stimuli. This favours specific protein-protein interactions, resulting in the activation of signalling cascades.

/pdf/lipid-rafts-and-signal-transduction-2pg659jt8g.pdf

Lipid rafts and signal transduction

http://www.ipg.org.br/Rosa_Rademakers_Neuron%20tese%20integra.pdf

Expanded GGGGCC hexanucleotide repeat in noncoding region of C9ORF72 causes chromosome 9p-linked FTD and ALS

We use the Semliki Forest Virus (SFV) as a tool for protein expression in primary cultures of rat hippocampal neurons. These cells develop in vitro into polarized neurons that can be infected with recombinant SFV with an efficiency of 60 - 80%. SFV-driven protein expression is detectable within 3-4 hours postinfection, at which time the newly-synthesized proteins are mainly present in the cell soma. By 6 to 8 hours postinfection foreign proteins are detectable in the neurites. Protein expression can continue for up to 48 hours. However, after 8 - 10 hours infected neurons start to suffer from cytopathic effects as evidenced by a change in morphology and detachment from the coverslip. The infection does not seem to affect the polarized distribution of proteins. Upon overexpression of rab8, a somatodendritic distribution is observed, similar to that of the endogenous protein. Therefore, the SFV expression system is suitable for short-term expression of proteins and can be used successfully to study the polarized distribution of heterologous proteins expressed in cultured hippocampal neurons.

Semliki Forest virus as a tool for protein expression in cultured rat hippocampal neurons.

Aspartylglucosaminidase (AGA: E.C. 3.5.1.26) is a lysosomal amidase that hydrolyzes the N-acetylglucosamine-asparagine linkage as one of the final steps in the breakdown of glycoproteins. Deficiency of this enzyme results in aspartylglucosaminuria (AGU), an inherited lysosomal storage disease. In an attempt to establish the tissue-specific expression of AGA in normal individuals and in AGU patients, we adapted biochemical and immunohistochemical techniques to analyze AGA polypeptides in human cells and tissues. The biochemical analysis revealed the existence of alpha- and beta-subunit structures of AGA in all tissues. Immunohistochemical staining demonstrated a cell specificity in the distribution of AGA: immunoreactivity was strongest in hepatocytes, pyramidal cells in the cerebral cortex, and proximal tubule cells in the kidney. In tissues from AGU patients, AGA immunoreactivity could be detected in hepatocytes and in proximal tubule cells but not in the pyramidal cells. The regulation of the expression of AGA was approached by analyzing the transcript levels and the methylation of the AGA gene. Both heavy methylation of the AGA gene and the constant level of AGA mRNA were typical of a "house-hold" type of enzyme that can be found in small quantities in all tissues. This was in contrast to the variability of the amount of AGA polypeptides observed in different cells and tissues, suggesting that the expression of AGA is regulated not at the transcriptional but rather at the translational level.

Expression of aspartylglucosaminidase in human tissues from normal individuals and aspartylglucosaminuria patients.

Huntington disease (HD) is found at exceptionally low frequency in the Finnish population. In this population, linkage disequilibrium was earlier established with markers from the D4S10 and D4S43 loci. We now report a continuation to the restriction fragment length polymorphism haplotype analysis, in combination with a genealogical study of all the Finnish HD families. When the HD pedigrees were systematically traced to the 18th century, only one consanguinity was found, and a high percentage (28%) of the families had foreign ancestors. The majority of the Finnish ancestors were localized to border regions or trade centers of the country following the old postal routes. The observed high risk haplotypes formed with markers from the D4S10 and D4S43 loci were evenly distributed among the HD families in different geographical locations. Consequently, the HD gene(s) has most probably arrived in Finland on several occasions via foreign immigrants during the last few centuries.

Huntington disease in Finland: a molecular and genealogical study

The Finnish disease heritage refers to rare hereditary diseases that occur in the Finnish population in a relatively larger proportion than in other populations. The genes underlying all of the 36 diseases of the disease heritage have been identified. Together with her group and collaborators, Leena Palotie identified 15 of these, and this review includes the description of some of these achievements. As a result of the so-called founder effect, one predominant mutation underlying these diseases occurs in our population, facilitating the diagnostics of these diseases in our country.

Finnish disease heritage

Objective Heat Shock Proteins (HSPs) maintain cellular homeostasis under stress. HSP70 represents a major stress-inducible family member and has been identified as a druggable target in inherited cholesterol-sphingolipid storage diseases. We investigated if HSP70 modulates cholesterol accumulation in more common conditions related to atherogenesis. Methods We studied the effects of recombinant HSP70 in cholesterol-laden primary macrophages from human blood donors and pharmacological HSP70 upregulation in high-cholesterol diet fed zebrafish. Results Recombinant HSP70 facilitated cholesterol removal from primary human macrophage foam cells. RNA sequencing revealed that HSP70 induced a robust transcriptional re-programming, including upregulation of key targets of liver X receptors (LXR), master regulators of whole-body cholesterol removal. Mechanistically, HSP70 interacted with the macrophage LXRalpha promoter, increased LXRalpha and its target mRNAs, and led to elevated levels of key proteins facilitating cholesterol efflux, including ATP-binding cassette transporters A1 and G1. Pharmacological augmentation of endogenous HSP70 in high-cholesterol diet fed zebrafish activated LXR and its target mRNAs and reduced cholesterol storage at the whole organism level. Conclusion These data demonstrate that HSP70 exerts a cholesterol lowering effect in primary human cells and animals and uncover a nuclear action of HSP70 in mediating cross-talk between HSP and LXR transcriptional regulation.

Elina Ikonen

Papers

Semliki Forest virus as a tool for protein expression in cultured rat hippocampal neurons.

Expression of aspartylglucosaminidase in human tissues from normal individuals and aspartylglucosaminuria patients.

Huntington disease in Finland: a molecular and genealogical study

Finnish disease heritage

HSP70 induces liver X receptor pathway activation and cholesterol reduction in vitro and in vivo