Interactions of polymorphisms in different clock genes associated with circadian phenotypes in humans

Several studies have shown that mutations and polymorphisms in clock genes are associated with abnormal circadian parameters in humans and also with more subtle non-pathological phenotypes like chronotypes. However, there have been conflicting results, and none of these studies analyzed the combined effects of more than one clock gene. Up to date, association studies in humans have focused on the analysis of only one clock gene per study. Since these genes encode proteins that physically interact with each other, combinations of polymorphisms in different clock genes could have a synergistic or an inhibitory effect upon circadian phenotypes. In the present study, we analyzed the combined effects of four polymorphisms in four clock genes (Per2, Per3, Clock and Bmal1) in people with extreme diurnal preferences (morning or evening). We found that a specific combination of polymorphisms in these genes is more frequent in people who have a morning preference for activity and there is a different combination in individuals with an evening preference for activity. Taken together, these results show that it is possible to detect clock gene interactions associated with human circadian phenotypes and bring an innovative idea of building a clock gene variation map that may be applied to human circadian biology

Characterization of global transcription profile of normal and HPV-immortalized keratinocytes and their response to TNF treatment

<p>Abstract</p> <p>Background</p> <p>Persistent infection by high risk HPV types (e.g. HPV-16, -18, -31, and -45) is the main risk factor for development of cervical intraepithelial neoplasia and cervical cancer. Tumor necrosis factor (TNF) is a key mediator of epithelial cell inflammatory response and exerts a potent cytostatic effect on normal or HPV16, but not on HPV18 immortalized keratinocytes. Moreover, several cervical carcinoma-derived cell lines are resistant to TNF anti-proliferative effect suggesting that the acquisition of TNF-resistance may constitute an important step in HPV-mediated carcinogenesis. In the present study, we compared the gene expression profiles of normal and HPV16 or 18 immortalized human keratinocytes before and after treatment with TNF for 3 or 60 hours.</p> <p>Methods</p> <p>In this study, we determined the transcriptional changes 3 and 60 hours after TNF treatment of normal, HPV16 and HPV18 immortalized keratinocytes by microarray analysis. The expression pattern of two genes observed by microarray was confirmed by Northern Blot. NF-κB activation was also determined by electrophoretic mobility shift assay (EMSA) using specific oligonucleotides and nuclear protein extracts.</p> <p>Results</p> <p>We observed the differential expression of a common set of genes in two TNF-sensitive cell lines that differs from those modulated in TNF-resistant ones. This information was used to define genes whose differential expression could be associated with the differential response to TNF, such as: <it>KLK7 </it>(<it>kallikrein 7</it>), <it>SOD2 </it>(<it>superoxide dismutase 2</it>), <it>100P </it>(<it>S100 calcium binding protein P</it>), <it>PI3 </it>(<it>protease inhibitor 3, skin-derived</it>), <it>CSTA </it>(<it>cystatin A</it>), <it>RARRES1 </it>(<it>retinoic acid receptor responder 1</it>), and <it>LXN </it>(<it>latexin</it>). The differential expression of the <it>KLK7 </it>and <it>SOD2 </it>transcripts was confirmed by Northern blot. Moreover, we observed that <it>SOD2 </it>expression correlates with the differential NF-κB activation exhibited by TNF-sensitive and TNF-resistant cells.</p> <p>Conclusion</p> <p>This is the first in depth analysis of the differential effect of TNF on normal and HPV16 or HPV18 immortalized keratinocytes. Our findings may be useful for the identification of genes involved in TNF resistance acquisition and candidate genes which deregulated expression may be associated with cervical disease establishment and/or progression.</p