Gene: Dmel\cact
cac, fs(2)ltoRN48, BG:DS02740.15
Please see the JBrowse view of Dmel\cact for information on other features
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Annotated transcripts do not represent all supported alternative splices within 5' UTR.
Low-frequency RNA-Seq exon junction(s) not annotated.
Gene model reviewed during 5.48
2.5, 2.1 (northern blot)
2.6, 2.2, 1.7 (northern blot)
500 (aa); 54 (kD)
500, 482 (aa); 53, 52 (kD)
Phosphorylated isoform A binds to dorsal (dl); inhibits dl translocation to the nucleus and therefore from binding to DNA. In vitro, interacts with IKKbeta. Interacts with cactin and kappa-B-Ras.
Activated IKKbeta phosphorylates cact.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\cact using the Feature Mapper tool.
Comment: maternally deposited
Comment: at puparium formation
Comment: 12 hr APF
Expression pattern inferred from unspecified enhancer trap line.
cact transcript is expressed in salivary glands at puparium formation at the end of the last larval ecdysone pulse, and at 12 hours APF at the end of the prepupal ecdyosne pulse.
Levels of the 2.1kb cact transcript decline rapidly after 4 hours of development.
The 2.5kb cact transcript appears at 2 hours and persists at low levels throughout development.
The 2.6kb cact transcript is present from about 4hr onwards.
The 1.7kb cact transcript is produced in unfertilized eggs and 0-4hr embryos.
Expression of cact is seen in the neuromuscular junction of wildtype fly when observed at 3 days post-eclosion, but is weaker at 60 days post-eclosion.
cact protein is diffusely distributed in the nucleus and cytoplasm of somatic muscles during the last hours of larval development, and though the first four hours of pupariation. cact protein is enriched in the subsynaptic reticulum of type I synaptic boutons. A similar distribution is observed in adult somatic muscles.
The level of cact protein in 0-3hr embyros of three genetic backgrounds was studied. One is dorsalventral signal constitutive (Tl8), one wild type, and one signal deficient (gd2). cact levels are lowest in the signal constitutive mutant, intermediate in wild type, and highest in signal deficient embryos. These differences are apparent as early as stage 2. Furthermore, cact protein is present in a dorsoventral gradient. High levels of protein are present in the dorsal cytoplasm where no intracellular signal transduction occurs and little protein is found in the ventral cytoplasm where signalling is strongest. In Tl8 and gd2 embryos, cact protein levels are uniformly low or high respectively.
GBrowse - Visual display of RNA-Seq signals
View Dmel\cact in GBrowse 22-49.7
Please Note FlyBase no longer curates genomic clone accessions so this list may not be complete
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
polyclonal
Source for identity of: cact CG5848
S2 cells treated with dsRNA generated against this gene show reduced phagocytosis of Candida albicans compared to untreated cells.
dsRNA made from templates generated with primers directed against this gene tested in RNAi screen for effects on Kc167 and S2R+ cell morphology.
cact acts in a cell-autonomous manner in the fat body.
cact is up-regulated in response to immune challenge.
Tl pathway is required for the nuclear import of dl in the immune response, but not required for the nuclear import of Dif. Cytoplasmic retention of both dl and Dif depends on cact protein. The two signalling pathways that target cact for degradation must discriminate between cact-dl and cact-Dif complexes.
The molecular evolution of the Rel/NF-κB and IκB proteins is studied in parallel. Phylogenetic analysis allows the structure of the putative ancestor genes to be defined and proposes and evolutionary model that clusters both families in a unique Rel/NF-κB/IκB superfamily.
Casein kinase II phosphorylates Ser468 (a residue in the PEST domain) of cact in vitro.
cact forms a concentration gradient inversely correlated to the nuclear translocation gradient of dl. Deletions of the N-terminus and C-terminus of cact reveal that two modes of degradation control cact activity: signal-induced degradation and signal-independent degradation, respectively. Genetic evidence indicates degradation of cact is required, but not sufficient, to translocate dl completely into the nucleus.
The embryonic regulatory pathway, comprising the gene products between spz and cact (Tl, tub and pll) but not the genes acting upstream or downstream (ea and dl), is involved in the induction of the Drs gene in adults. Mutations that affect the synthesis of antimicrobial peptides dramatically lower the resistance of flies to infection.
In cultured cells and embryos cact degradation is dependent on a pll mediated signal, mutation of a putative phosphorylation motif blocks signal responsiveness. In embryos there is a gradient of cact protein. In ventral regions cact is degraded allowing dl to translocate into the nuclei, in dorsal regions cact persists, retaining dl in the cytoplasm.
cact inhibits nuclear translocation of dl on the ventral side of the embryo by binding to and retaining dl in the cytoplasm. cact is rapidly degraded in response to signalling from the dorsal ventral pathway between spz and dl/cact, this signal-dependent degradation does not require the presence of dl but does require sequences in the amino terminus or ankyrin repeats of the cact protein. Disruption of the dl-cact complex is a secondary result of cact degradation. Signal independent degradation of free cact requires the carboxy terminal region of the protein that includes a PEST sequence.
Comparisons of early development to that in other insects have revealed conservation of some aspects of development, as well as differences that may explain variations in early patterning events.
P-elements transposing from a donor site at the cact gene were found to show nearly a three fold preference for transposition to a region of the homologous chromosome containing the cact locus and extending over two or three number divisions. This preferential transposition is likely to result from a physical proximity of homologous chromosomal regions in the nuclei of germline cells.
Studies of protein binding and their conformation suggests that the ankyrin repeats of cact fold together in helical bundles interconnected by diverged loops.
The cactus gene was cloned starting with a P{lacZ} insertion. Bacterially expressed cactus protein (which has sequence similarity to IκB) inhibits binding to DNA of dorsal protein in vitro. Antisense cactus RNA can phenocopy cactus mutations. Sense cactus RNA rescues its maternal effect mutant phenotype.
cact mutations have a ventralizing maternal effect that yield significantly increased axial ratios in pupae.
Mutations in maternal ventral class gene cact interact with RpII140wimp.
cact is a germline-dependent maternal-effect gene. Double mutant analysis of cactus and dorsal group genes demonstrate that cact and dl act downstream of all other dorsal group genes.
Mutations at the fs(2)ltoRN48 locus causes defects in midoogenesis.
Mutations in cact result in a maternal effect phenotype with defects during the early stages of gastrulation and defects in the dorsoventral axis; embryos derived from homozygous females are ventralised.
