Most of our knowledge of helical cytokine-like molecules in invertebrates relies on functional assays and similarities at the physicochemical level. It is hard to predict helical cytokines in invertebrates based on sequences from mammals and vertebrates, because of their long evolutionary divergence. In this article, we collected 12 kinds of fish cytokines and constructed their respective consensus sequences using hidden Markov models; then, the conserved domains region of each consensus sequence were further extracted by the SMART tool, and used as the query sequence for PSI-BLAST analysis in Drosophila melanogaster. After two filtering processes based on the properties of helical cytokines, we obtained one protein named CG14629, which shares 25% identities/46% positives to fish M17 cytokine in the half length of the N-terminus. Considering the homology between M17 and LIF/CNTF (leukemia inhibitory factor/ciliary neurotrophic factor), and the close relationship between Dome, the putative cytokine receptor in Drosophila cells, and LIFR/CNTFR (LIF receptor/CNTF receptor), the results suggest that CG14629 is a good candidate for the helical cytokine ortholog in D. melanogaster.
"Homologs of the proteins that associate with mammalian MBL have not been found in A. aegypti (Table S3), suggesting that the A. aegypti mosGCTL-1 may have different physiological functions than mammalian MBL. Invertebrates lack antibody-and interferon-based immune responses (Cheng et al., 2009). Since lectin expression is significantly upregulated by microbial infection , these molecules are presumed to participate in nonself recognition and pathogen resistance (Wilson et al., 1999; Tanji et al., 2006). "
[Show abstract][Hide abstract] ABSTRACT: West Nile virus (WNV) is the most common arthropod-borne flavivirus in the United States; however, the vector ligand(s) that participate in infection are not known. We now show that an Aedes aegypti C-type lectin, mosGCTL-1, is induced by WNV, interacts with WNV in a calcium-dependent manner, and facilitates infection in vivo and in vitro. A mosquito homolog of human CD45 in A. aegypti, designated mosPTP-1, recruits mosGCTL-1 to enable viral attachment to cells and to enhance viral entry. In vivo experiments show that mosGCTL-1 and mosPTP-1 function as part of the same pathway and are critical for WNV infection of mosquitoes. A similar phenomenon was also observed in Culex quinquefasciatus, a natural vector of WNV, further demonstrating that these genes participate in WNV infection. During the mosquito blood-feeding process, WNV infection was blocked in vivo with mosGCTL-1 antibodies. A molecular understanding of flaviviral-arthropod interactions may lead to strategies to control viral dissemination in nature.
[Show abstract][Hide abstract] ABSTRACT: The Cdk8 (cyclin-dependent kinase 8) module of Mediator integrates regulatory cues from transcription factors to RNA polymerase
II. It consists of four subunits where Med12 and Med13 link Cdk8 and cyclin C (CycC) to core Mediator. Here we have investigated
the contributions of the Cdk8 module subunits to transcriptional regulation using RNA interference in Drosophila cells. Genome-wide expression profiling demonstrated separation of Cdk8-CycC and Med12-Med13 profiles. However, transcriptional
regulation by Cdk8-CycC was dependent on Med12-Med13. This observation also revealed that Cdk8-CycC and Med12-Med13 often
have opposite transcriptional effects. Interestingly, Med12 and Med13 profiles overlapped significantly with that of the GATA
factor Serpent. Accordingly, mutational analyses indicated that GATA sites are required for Med12-Med13 regulation of Serpent-dependent
genes. Med12 and Med13 were also found to be required for Serpent-activated innate immunity genes in defense to bacterial
infection. The results reveal a novel role for the Cdk8 module in Serpent-dependent transcription and innate immunity.
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