Atlantic salmon populations reveal adaptive divergence of immune related genes - a duplicated genome under selection
BMC GENOMICS
Authors: Kjaerner-Semb, Erik; Ayllon, Fernando; Furmanek, Tomasz; Wennevik, Vidar; Dahle, Geir; Niemela, Eero; Ozerov, Mikhail; Vaha, Juha-Pekka; Glover, Kevin A.; Rubin, Carl J.; Wargelius, Anna; Edvardsen, Rolf B.
Abstract
Background: Populations of Atlantic salmon display highly significant genetic differences with unresolved molecular basis. These differences may result from separate postglacial colonization patterns, diversifying natural selection and adaptation, or a combination. Adaptation could be influenced or even facilitated by the recent whole genome duplication in the salmonid lineage which resulted in a partly tetraploid species with duplicated genes and regions. Results: In order to elucidate the genes and genomic regions underlying the genetic differences, we conducted a genome wide association study using whole genome resequencing data from eight populations from Northern and Southern Norway. From a total of similar to 4.5 million sequencing-derived SNPs, more than 10 % showed significant differentiation between populations from these two regions and ten selective sweeps on chromosomes 5, 10, 11, 13-15, 21, 24 and 25 were identified. These comprised 59 genes, of which 15 had one or more differentiated missense mutation. Our analysis showed that most sweeps have paralogous regions in the partially tetraploid genome, each lacking the high number of significant SNPs found in the sweeps. The most significant sweep was found on Chr 25 and carried several missense mutations in the antiviral mx genes, suggesting that these populations have experienced differing viral pressures. Interestingly the second most significant sweep, found on Chr 5, contains two genes involved in the NF-KB pathway (nkap and nkrf), which is also a known pathogen target that controls a large number of processes in animals. Conclusion: Our results show that natural selection acting on immune related genes has contributed to genetic divergence between salmon populations in Norway. The differences between populations may have been facilitated by the plasticity of the salmon genome. The observed signatures of selection in duplicated genomic regions suggest that the recently duplicated genome has provided raw material for evolutionary adaptation.
Upregulation of miRNA-301a-3p promotes tumor progression in gastric cancer by suppressing NKRF and activating NF-kappa B signaling
INTERNATIONAL JOURNAL OF ONCOLOGY
Authors: Xu, Xiaodong; Xia, Yingjie; Ma, Jie; Li, Weijun; Niu, Nan; Li, Xiao; Tao, Houquan; Xu, Ji; He, Xujun
Abstract
MicroRNA-301a (miRNA/miR-301a) and nuclear factor (NF)-kappa B signaling play important roles in tumor invasion, migration and progression. However, the role of miRNA-301a-3p in human gastric cancer (GC), and specifically in the activation of NF-kappa B signaling, remains unclear. The aim of the present study was to investigate miRNA-301a-3p expression in GC progression and the molecular mechanisms as regards the regulation of NF-kappa B signaling. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect miRNA-301a-3p expression in GC and paired normal tissues. The association between the expression of miRNA-301a-3p and patient pathological parameters and the prognosis of GC was statistically analyzed using anin situhybridization (ISH) assay. An MTS assay and a Transwell assay were performed to evaluate the effects of miRNA-301a-3p on the proliferation, invasion and migration of GC cells. RT-qPCR and western blot analysis were used to analyze the association between miRNA-301a-3p and nuclear factor-kappa B repressing factor (NKRF) expression and the corresponding downstream NF-kappa B signaling molecules. A luciferase assay was used to verify the target effect of miRNA-301a-3p and NKRF. It was found that miRNA-301a-3p expression was significantly higher in 30 cases of primary GC compared with matched normal tissues. Additionally, the ISH assay indicated that the high expression of miRNA-301a-3p in GC was associated with tumor invasion depth, lymph node metastasis, lymph node invasion and tumor metastasis stage. Patients whose tumors had a higher miRNA-301a-3p expression level exhibited a poorer prognosis. Thein vitroassay indicated that miRNA-301a-3p affected the proliferative and invasive ability of GC cells by targeting the expression of NKRF, which then affected NF-kappa B signaling. Therefore, it was hypothesize that miRNA-301a-3p promotes GC progression and affects the prognosis of patients with GC by targeting NKRF, which in turn, directly influences NF-kappa B activation.