RISC-y Memories

Insights into the Interplay between KIR Gene Frequencies and Chronic HBV Infection in Burkina Faso

Background/Objective

Hepatitis B virus (HBV) infection is the leading risk factor for cirrhosis and hepatocellular carcinoma (HCC). The objective of this investigation was to assess the association between “Killer Cell Immunoglobulin-Like Receptor” (KIR) gene frequencies and chronic HBV infection.

Methods

Chronic HBV carriers and healthy patients were selected for this study. The viral load for HBV were performed, and SSP-PCR was used to characterize the frequencies of KIR genes.

Results

The study suggested that inhibitory genes KIR2DL2 (crude OR = 2.82; p < 0.001), KIR2DL3 (crude OR = 2.49; p < 0.001) and activator gene KIR2DS2 (crude OR = 3.95; p< 0.001) might be associated with chronic stages of HBV infection. Conversely the inhibitory genes KIR3DL1 (crude OR = 0.49; p = 0.0018) and KIR3DL2 (crude OR = 0.41; p = 0.005), the activator gene KIR2DS1 (crude OR = 0.48; p = 0.014) and the pseudo gene KIR2DP1 (crude OR = 0.49; p = 0.008) could be associated with immunity against HBV infection. Chronic HBV patients who are carriers for the KIR3DL3 gene (crude OR = 8; p = 0.048) were positive for HBeAg and patients who carried the KIR3DL2 gene (crude OR = 3.21; p = 0.012) had a high HBV viral load compared to the rest of the study population.

Conclusion

Our data showed evidence of a correlation between the risk of developing chronic HBV infection and certain KIR gene frequencies and also show that KIR3DL1, KIR3DL2, KIR2DS1 might confer a protective status against chronic HBV infection.

Common chromosomal fragile sites (CFS) may be involved in normal and traumatic cognitive stress memory consolidation and altered nervous system immunity

Previous reports of specific patterns of increased fragility at common chromosomal fragile sites (CFS) found in association with certain neurobehavioural disorders did not attract attention at the time due to a shift towards molecular approaches to delineate neuropsychiatric disorder candidate genes. Links with miRNA, altered methylation and the origin of copy number variation indicate that CFS region characteristics may be part of chromatinomic mechanisms that are increasingly linked with neuroplasticity and memory. Current reports of large-scale double-stranded DNA breaks in differentiating neurons and evidence of ongoing DNA demethylation of specific gene promoters in adult hippocampus may shed new light on the dynamic epigenetic changes that are increasingly appreciated as contributing to long-term memory consolidation. The expression of immune recombination activating genes in key stress-induced memory regions suggests the adoption by the brain of this ancient pattern recognition and memory system to establish a structural basis for long-term memory through controlled chromosomal breakage at highly specific genomic regions. It is furthermore considered that these mechanisms for management of epigenetic information related to stress memory could be linked, in some instances, with the transfer of the somatically acquired information to the germline. Here, rearranged sequences can be subjected to further selection and possible eventual retrotranscription to become part of the more stable coding machinery if proven to be crucial for survival and reproduction. While linkage of cognitive memory with stress and fear circuitry and memory establishment through structural DNA modification is proposed as a normal process, inappropriate activation of immune-like genomic rearrangement processes through traumatic stress memory may have the potential to lead to undesirable activation of neuro-inflammatory processes. These theories could have a significant impact on the interpretation of risks posed by heredity and the environment and the search for neuropsychiatric candidate genes.

Spinal adenosine A2a receptor activation elicits long-lasting phrenic motor facilitation

Acute intermittent hypoxia elicits a form of spinal, brain-derived neurotrophic factor (BDNF)-dependent respiratory plasticity known as phrenic long-term facilitation. Ligands that activate G(s)-protein-coupled receptors, such as the adenosine 2a receptor, mimic the effects of neurotrophins in vitro by transactivating their high-affinity receptor tyrosine kinases, the Trk receptors. Thus, we hypothesized that A2a receptor agonists would elicit phrenic long-term facilitation by mimicking the effects of BDNF on TrkB receptors. Here we demonstrate that spinal A2a receptor agonists transactivate TrkB receptors in the rat cervical spinal cord near phrenic motoneurons, thus inducing long-lasting (hours) phrenic motor facilitation. A2a receptor activation increased phosphorylation and new synthesis of an immature TrkB protein, induced TrkB signaling through Akt, and strengthened synaptic pathways to phrenic motoneurons. RNA interference targeting TrkB mRNA demonstrated that new TrkB protein synthesis is necessary for A2a-induced phrenic motor facilitation. A2a receptor activation also increased breathing in unanesthetized rats, and improved breathing in rats with cervical spinal injuries. Thus, small, highly permeable drugs (such as adenosine receptor agonists) that transactivate TrkB receptors may provide an effective therapeutic strategy in the treatment of patients with ventilatory control disorders, such as obstructive sleep apnea, or respiratory insufficiency after spinal injury or during neurodegenerative diseases.

Control and regulation of the cellular responses to cold shock: the responses in yeast and mammalian systems

Although the cold-shock response has now been studied in a number of different organisms for several decades, it is only in the last few years that we have begun to understand the molecular mechanisms that govern adaptation to cold stress. Notably, all organisms from prokaryotes to plants and higher eukaryotes respond to cold shock in a comparatively similar manner. The general response of cells to cold stress is the elite and rapid overexpression of a small group of proteins, the so-called CSPs (cold-shock proteins). The most well characterized CSP is CspA, the major CSP expressed in Escherichia coli upon temperature downshift. More recently, a number of reports have shown that exposing yeast or mammalian cells to sub-physiological temperatures (<30 or <37 degrees C respectively) invokes a co-ordinated cellular response involving modulation of transcription, translation, metabolism, the cell cycle and the cell cytoskeleton. In the present review, we summarize the regulation and role of cold-shock genes and proteins in the adaptive response upon decreased temperature with particular reference to yeast and in vitro cultured mammalian cells. Finally, we present an integrated model for the co-ordinated responses required to maintain the viability and integrity of mammalian cells upon mild hypothermic cold shock.