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Background: Transposable elements (TEs) are common and often present with high copy numbers in cellular genomes. Unlike in cellular organisms, TEs were previously thought to be either rare or absent in viruses. Almost all reported TEs display only one or two copies per viral genome. In addition, the discovery of pandoraviruses with genomes up to 2.5-Mb emphasizes the need for biologists to rethink the fundamental nature of the relationship between viruses and cellular life., Results: Herein, we performed the first comprehensive analysis of miniature inverted-repeat transposable elements (MITEs) in the 5170 viral genomes for which sequences are currently available. Four hundred and fifty one copies of ten miniature inverted-repeat transposable elements (MITEs) were found and each MITE had reached relatively large copy numbers (some up to 90) in viruses. Eight MITEs belonging to two DNA superfamilies ( hobo/Activator/Tam3 and Chapaev-Mirage-CACTA ) were for the first time identified in viruses, further expanding the organismal range of these two superfamilies. TEs may play important roles in shaping the evolution of pandoravirus genomes, which were here found to be very rich in MITEs. We also show that putative autonomous partners of seven MITEs are present in the genomes of viral hosts, suggesting that viruses may borrow the transpositional machinery of their cellular hosts' autonomous elements to spread MITEs and colonize their own genomes. The presence of seven similar MITEs in viral hosts, suggesting horizontal transfers (HTs) as the major mechanism for MITEs propagation., Conclusions: Our discovery highlights that TEs contribute to shape genome evolution of pandoraviruses. We concluded that as for cellular organisms, TEs are part of the pandoraviruses' diverse mobilome., Competing Interests: Not applicableNot applicableThe authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Background: Currently, some studies have demonstrated that miR-34a could serve as a suppressor of several cancers including hepatocellular carcinoma (HCC). Previously, we discovered that miR-34a was downregulated in HCC and involved in the tumorigenesis and progression of HCC; however, the mechanism remains unclear. The purpose of this study was to estimate the expression of miR-34a in HCC by applying the microarray profiles and analyzing the predicted targets of miR-34a and their related biological pathways of HCC., Methods: Gene expression omnibus (GEO) datasets were conducted to identify the difference of miR-34a expression between HCC and corresponding normal tissues and to explore its relationship with HCC clinicopathologic features. The natural language processing (NLP), gene ontology (GO), pathway and network analyses were performed to analyze the genes associated with the carcinogenesis and progression of HCC and the targets of miR-34a predicted in silico. In addition, the integrative analysis was performed to explore the targets of miR-34a which were also relevant to HCC., Results: The analysis of GEO datasets demonstrated that miR-34a was downregulated in HCC tissues, and no heterogeneity was observed (Std. Mean Difference(SMD) = 0.63, 95% confidence intervals(95%CI):[0.38, 0.88], P < 0.00001; P heterogeneity  = 0.08 I 2  = 41%). However, no association was found between the expression value of miR-34a and any clinicopathologic characteristics. In the NLP analysis of HCC, we obtained 25 significant HCC-associated signaling pathways. Besides, we explored 1000 miR-34a-related genes and 5 significant signaling pathways in which CCND1 and Bcl-2 served as necessary hub genes. In the integrative analysis, we found 61 hub genes and 5 significant pathways, including cell cycle, cytokine-cytokine receptor interaction, notching pathway, p53 pathway and focal adhesion, which proposed the relevant functions of miR-34a in HCC., Conclusion: Our results may lead researchers to understand the molecular mechanism of miR-34a in the diagnosis, prognosis and therapy of HCC. Therefore, the interaction between miR-34a and its targets may promise better prediction and treatment for HCC. And the experiments in vivo and vitro will be conducted by our group to identify the specific mechanism of miR-34a in the progress and deterioration of HCC.

Background: Studies have been reported that cyclin-dependent kinase5 (CDK5) was associated with the development of several cancers. However, the relationship between CDK5 level and clinicopathological factors is still poorly understood in cervical diseases. The aim of the current study was to investigate the expression of CDK5 and its clinical significance in variant cervical lesions., Methods: Immunohistochemistry (IHC) was used to detect CDK5 expression in 54 cases of chronic cervicitis, 42 cases of condyloma acuminate (CA), 38 cases of carcinoma in situ, and 360 cases of cervical cancers [adenocarcinoma, n = 63; squamous cell carcinoma (SCC), n = 263; adenosquamous carcinoma, n = 34]. The clinicopathological characteristics in relation to CDK5 were examined by Pearson's Chi-square test., Results: The positive rates of CDK5 were 27.8, 31.0, 50, 54.0, 58.8, and 62.7 % in chronic cervicitis, CA, carcinoma in situ, adenocarcinoma, adenosquamous carcinoma and SCC, respectively. Statistically analysis showed that CDK5 expression in cervical cancer tissues was higher than non-cervical cancer tissues (inflammation and CA) (P < 0.001). The overexpression of CDK5 was significantly correlated with lymph node metastasis (r = 0.317; P < 0.001), histological type (r = 0.198; P < 0.001), FIGO stage (r = 0.358; P < 0.001), TNM stage (r = 0.329; P < 0.001) and pathological grade (r = 0.259; P < 0.001) in cervical lesions evaluated by Pearson's Chi-square test. Furthermore, the positive relationships were found between CDK5 and lymph node metastasis (P < 0.001), FIGO stage (P < 0.001), TNM stage (P < 0.001) and pathological grade (P < 0.001) in SCC. CDK5 was positively interrelated to TNM stage (P = 0.017) in adenosquamous carcinoma., Conclusions: CDK5 may play a vital role in the development of cervical cancer, which may be a marker for the diagnosis, therapy and prognosis of cervical cancer.

Background: Horizontal transfer (HT) of transposable elements (TEs) into a new genome is considered as an important force to drive genome variation and biological innovation. However, most of the HT of DNA transposons previously described occurred between closely related species or insects., Results: In this study, we carried out a detailed analysis of four DNA transposons, which were found in the first sequenced twisted-wing parasite, Mengenilla moldrzyki. Through the homology-based strategy, these transposons were also identified in other insects, freshwater planarian, hydrozoans, and bats. The phylogenetic distribution of these transposons was discontinuous, and they showed extremely high sequence identities (>87%) over their entire length in spite of their hosts diverging more than 300 million years ago (Mya). Additionally, phylogenies and comparisons of transposons versus orthologous gene identities demonstrated that these transposons have transferred into their hosts by independent HTs., Conclusions: Here, we provided the first documented example of HT of CACTA transposons, which have been so far extensively studied in plants. Our results demonstrated that bats had continuously acquired new DNA elements via HT. This implies that predation on a large quantity of insects might increase bat exposure to HT. In addition, parasite-host interaction might facilitate exchanging of their genetic materials.