RESUMEN
The NFAT gene encodes the only homolog in Drosophila of the five human Nuclear Factors of Activated T-cells, NFAT1-5. Its rel homology domain is most similar to that of NFAT5, and like the latter it lacks conserved AP1 and calcineurin binding sites. Two promoters give rise to alternative transcripts that are ubiquitously expressed in several different tissues. We generated mutants for each transcript, as well as a mutant that lacks all functional NFAT expression. Only the null mutant generated a visible phenotype, indicating that the two transcripts are redundant. The mutants are sensitive to high salt diet and have enlarged anal pads in hypotonic solution, suggesting that NFAT, like mammalian NFAT5, is regulating the osmotic balance. A phylogenetic reconstruction puts the Drosophila gene near the root of the NFAT tree, indicating that regulation of tonicity may be an ancestral function of the NFAT family.
Asunto(s)
Adaptación Fisiológica , Drosophila/fisiología , Factores de Transcripción NFATC/fisiología , Cloruro de Sodio/metabolismo , Animales , Drosophila/genética , Drosophila/metabolismo , Calor , Larva/metabolismo , Melaninas/metabolismo , Mutación , Factores de Transcripción NFATC/genética , Factores de Transcripción NFATC/metabolismoRESUMEN
A new genetic study has shown that the phagocytic ability of Drosophila blood cells, the hemocytes, may be important for the further induction of an antibacterial response in other tissues.
Asunto(s)
Presentación de Antígeno/fisiología , Drosophila/inmunología , Cuerpo Adiposo/fisiología , Hemocitos/fisiología , Fagocitosis/fisiología , AnimalesRESUMEN
The peptidoglycan recognition protein PGRP-LC is a major activator of the imd/Relish pathway in the Drosophila immune response. Three transcripts are generated by alternative splicing of the complex PGRP-LC gene. The encoded transmembrane proteins share an identical intracellular part, but each has a separate extracellular PGRP-domain: x, y, or a. Here we show that two of these isoforms play unique roles in the response to different microorganisms. Using RNA interference in Drosophila mbn-2 cells, we found that PGRP-LCx is the only isoform required to mediate signals from Gram-positive bacteria and purified bacterial peptidoglycan. By contrast, the recognition of Gram-negative bacteria and bacterial lipopolysaccharide requires both PGRP-LCa and LCx. The third isoform, LCy, is expressed at lower levels and may be partially redundant. Two additional PGRP domains in the gene cluster, z and w, are both included in a single transcript of a separate gene, PGRP-LF. Suppression of this transcript does not block the response to any of the microorganisms tested.