Identification of microRNAs expressed in two mosquito vectors, Aedes albopictus and Culex quinquefasciatus

BMC Genomics, Feb 2010

Background MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression in a variety of organisms, including insects, vertebrates, and plants. miRNAs play important roles in cell development and differentiation as well as in the cellular response to stress and infection. To date, there are limited reports of miRNA identification in mosquitoes, insects that act as essential vectors for the transmission of many human pathogens, including flaviviruses. West Nile virus (WNV) and dengue virus, members of the Flaviviridae family, are primarily transmitted by Aedes and Culex mosquitoes. Using high-throughput deep sequencing, we examined the miRNA repertoire in Ae. albopictus cells and Cx. quinquefasciatus mosquitoes. Results We identified a total of 65 miRNAs in the Ae. albopictus C7/10 cell line and 77 miRNAs in Cx. quinquefasciatus mosquitoes, the majority of which are conserved in other insects such as Drosophila melanogaster and Anopheles gambiae. The most highly expressed miRNA in both mosquito species was miR-184, a miRNA conserved from insects to vertebrates. Several previously reported Anopheles miRNAs, including miR-1890 and miR-1891, were also found in Culex and Aedes, and appear to be restricted to mosquitoes. We identified seven novel miRNAs, arising from nine different precursors, in C7/10 cells and Cx. quinquefasciatus mosquitoes, two of which have predicted orthologs in An. gambiae. Several of these novel miRNAs reside within a ~350 nt long cluster present in both Aedes and Culex. miRNA expression was confirmed by primer extension analysis. To determine whether flavivirus infection affects miRNA expression, we infected female Culex mosquitoes with WNV. Two miRNAs, miR-92 and miR-989, showed significant changes in expression levels following WNV infection. Conclusions Aedes and Culex mosquitoes are important flavivirus vectors. Recent advances in both mosquito genomics and high-throughput sequencing technologies enabled us to interrogate the miRNA profile in these two species. Here, we provide evidence for over 60 conserved and seven novel mosquito miRNAs, expanding upon our current understanding of insect miRNAs. Undoubtedly, some of the miRNAs identified will have roles not only in mosquito development, but also in mediating viral infection in the mosquito host.

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Identification of microRNAs expressed in two mosquito vectors, Aedes albopictus and Culex quinquefasciatus

BMC Genomics Identification of microRNAs expressed in two mosquito vectors, Aedes albopictus and Culex quinquefasciatus Rebecca L Skalsky 0 Dana L Vanlandingham 1 Frank Scholle 2 Stephen Higgs 1 Bryan R Cullen 0 0 Department of Molecular Genetics and Microbiology and Center for Virology, Duke University Medical Center , Durham, NC 27710 , USA 1 Department of Pathology and Department of Microbiology and Immunology, University of Texas Medical Branch , Galveston, TX , USA 2 Department of Microbiology, North Carolina State University , Raleigh, NC 27695 , USA Background: MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression in a variety of organisms, including insects, vertebrates, and plants. miRNAs play important roles in cell development and differentiation as well as in the cellular response to stress and infection. To date, there are limited reports of miRNA identification in mosquitoes, insects that act as essential vectors for the transmission of many human pathogens, including flaviviruses. West Nile virus (WNV) and dengue virus, members of the Flaviviridae family, are primarily transmitted by Aedes and Culex mosquitoes. Using high-throughput deep sequencing, we examined the miRNA repertoire in Ae. albopictus cells and Cx. quinquefasciatus mosquitoes. Results: We identified a total of 65 miRNAs in the Ae. albopictus C7/10 cell line and 77 miRNAs in Cx. quinquefasciatus mosquitoes, the majority of which are conserved in other insects such as Drosophila melanogaster and Anopheles gambiae. The most highly expressed miRNA in both mosquito species was miR-184, a miRNA conserved from insects to vertebrates. Several previously reported Anopheles miRNAs, including miR-1890 and miR1891, were also found in Culex and Aedes, and appear to be restricted to mosquitoes. We identified seven novel miRNAs, arising from nine different precursors, in C7/10 cells and Cx. quinquefasciatus mosquitoes, two of which have predicted orthologs in An. gambiae. Several of these novel miRNAs reside within a ~350 nt long cluster present in both Aedes and Culex. miRNA expression was confirmed by primer extension analysis. To determine whether flavivirus infection affects miRNA expression, we infected female Culex mosquitoes with WNV. Two miRNAs, miR-92 and miR-989, showed significant changes in expression levels following WNV infection. Conclusions: Aedes and Culex mosquitoes are important flavivirus vectors. Recent advances in both mosquito genomics and high-throughput sequencing technologies enabled us to interrogate the miRNA profile in these two species. Here, we provide evidence for over 60 conserved and seven novel mosquito miRNAs, expanding upon our current understanding of insect miRNAs. Undoubtedly, some of the miRNAs identified will have roles not only in mosquito development, but also in mediating viral infection in the mosquito host. - Background Culex and Aedes mosquitoes are members of the Culicinae subfamily that vector positive-sense RNA viruses from the family Flaviviridae. Many flaviviruses, such as West Nile virus (WNV), dengue virus (DENV), and yellow fever virus (YFV), are highly pathogenic in humans and pose an important health problem worldwide [1]. Each year, an estimated 50 million human cases of dengue fever occur due to infection with DENV. Since the introduction of WNV to the United States in 1999, over 28,000 cases have been reported to the CDC, with approximately 3,000 cases annually http://CDC.gov. Culex mosquitoes are primarily responsible for the transmission of WNV to humans (reviewed in [2]), although WNV has also been isolated from Aedes albopictus in the eastern United States (reviewed in [3]). Virus transmission from Cx. quinquefasciatus occurs as early as five days following an infectious blood meal [4], and virus can persist as long as four weeks in the midguts and salivary glands of infected mosquitoes [5,6]. Both Culex and Aedes mosquitoes are prevalent in tropical and subtropical regions around the world. Recently, Ae. albopictus has emerged as a major vector for Chikungunya virus, an alphavirus, in regions bordering the western Indian Ocean [7,8]. Ae. albopictus is also considered a secondary vector for dengue virus serotypes 1-4 (DENV1-4) and YFV, which are predominantly transmitted to humans by a mosquito from the same genus, Ae. aegypti. Ae. albopictus can potentially vector at least 22 known arboviruses (reviewed in [3]). Of the over 3,000 mosquito species worldwide, microRNAs (miRNAs) have so far only been described in two species of African malaria mosquitoes, Anopheles gambiae and Anopheles stephensi, using direct cloning and computational methods. Over 55 miRNAs have been described for Anopheles mosquitoes, at least 49 of which have orthologs in Drosophila melanogaster and other insects [9-12]. The functions of these miRNAs in mosquitoes, and the identities of their mRNA targets, are not yet known. miRNAs are a class of small, non-c (...truncated)


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Rebecca L Skalsky, Dana L Vanlandingham, Frank Scholle, Stephen Higgs, Bryan R Cullen. Identification of microRNAs expressed in two mosquito vectors, Aedes albopictus and Culex quinquefasciatus, BMC Genomics, 2010, pp. 119, 11, DOI: 10.1186/1471-2164-11-119