Trithorax and dCBP acting in a complex to maintain expression of a homeotic gene.

Trithorax (Trx) is a member of the trithorax group (trxG) of epigenetic regulators, which is required to maintain active states of Hox gene expression during development. We have purified from Drosophila embryos a trithorax acetylation complex (TAC1) that contains Trx, dCBP, and Sbf1. Like CBP, TAC1 acetylates core histones in nucleosomes, suggesting that this activity may be important for epigenetic maintenance of gene activity. dCBP and Sbf1 associate with specific sites on salivary gland polytene chromosomes, colocalizing with many Trx binding sites. One of these is the site of the Hox gene Ultrabithorax (Ubx). Mutations in either trx or the gene encoding dCBP reduce expression of the endogenous Ubx gene as well as of transgenes driven by the bxd regulatory region of Ubx. Thus Trx, dCBP, and Sbf1 are closely linked, physically and functionally, in the maintenance of Hox gene expression.

Association between angiotensin-converting enzyme and Alzheimer disease.

BACKGROUND: Angiotensin-converting enzyme has been reported to show altered activity in patients with neurologic diseases. An insertion-deletion polymorphism in ACE has recently been linked to heart disease, cerebrovascular disease, and AD. OBJECTIVE: To determine whether the angiotensin-converting enzyme (ACE) is associated with risk of Alzheimer disease (AD). METHODS: We investigated the ACE polymorphism as a potential risk factor for AD in 151 patients with AD and 206 ethnically matched controls from Russia and in 236 patients with AD and 169 controls from North America by means of allele association methods and logistic regression. RESULTS: None of the ACE genotypes was associated with increased susceptibility to AD in the total sample or in subsets stratified by apolipoprotein E gene (APOE) epsilon4 status. However, the D allele was more frequent among AD cases between ages 66 and 70 years compared with controls in both the Russian (P = .02) and North American (P = .001) datasets. In this age group, the effect of D (odds ratio, 11.2; 95% confidence interval, 2.9-44.0) appeared to be independent of and equal or greater in magnitude to the effect of APOE epsilon4 (odds ratio, 7.8; 95% confidence interval, 3.5-7.4). CONCLUSIONS: Our results suggest that APOE and ACE genotypes may be independent risk factors for late-onset AD, but the ACE association needs to be confirmed in independent samples in which the time and extent of vascular cofactors can be assessed.

Trithorax and ASH1 interact directly and associate with the trithorax group-responsive bxd region of the Ultrabithorax promoter.

Trithorax (TRX) and ASH1 belong to the trithorax group (trxG) of transcriptional activator proteins, which maintains homeotic gene expression during Drosophila development. TRX and ASH1 are localized on chromosomes and share several homologous domains with other chromatin-associated proteins, including a highly conserved SET domain and PHD fingers. Based on genetic interactions between trx and ash1 and our previous observation that association of the TRX protein with polytene chromosomes is ash1 dependent, we investigated the possibility of a physical linkage between the two proteins. We found that the endogenous TRX and ASH1 proteins coimmunoprecipitate from embryonic extracts and colocalize on salivary gland polytene chromosomes. Furthermore, we demonstrated that TRX and ASH1 bind in vivo to a relatively small (4 kb) bxd subregion of the homeotic gene Ultrabithorax (Ubx), which contains several trx response elements. Analysis of the effects of ash1 mutations on the activity of this regulatory region indicates that it also contains ash1 response element(s). This suggests that ASH1 and TRX act on Ubx in relatively close proximity to each other. Finally, TRX and ASH1 appear to interact directly through their conserved SET domains, based on binding assays in vitro and in yeast and on coimmunoprecipitation assays with embryo extracts. Collectively, these results suggest that TRX and ASH1 are components that interact either within trxG protein complexes or between complexes that act in close proximity on regulatory DNA to maintain Ubx transcription.

Trithorax- and Polycomb-group response elements within an Ultrabithorax transcription maintenance unit consist of closely situated but separable sequences.

In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each approximately 400 bp) contain both TRX- and Polycomb-group response elements (TREs and PREs) and that in the context of the endogenous Ultrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (approximately 90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group gene pleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators.

[Association analysis of polymorphism in angiotensin-converting enzyme gene in ischemic stroke]. / Analiz assotsiatsii polimorfizma v gene angiotenzinprevrashchaiushchego fermenta pri ishemicheskom insul'te.

Family and twins study demonstrated that genetic factors may be involved in stroke. Previously, insertion/deletion (I/D) Alu-polymorphism in the angiotensin-converting enzyme (ACE) gene has been suggested as a risk factor for some cardiovascular diseases. There fore, cardiovascular factors are well-known risk factors for ischemic stroke. We selected patients with ischemic stroke and with no evidence for arterial hypertension and carried out ACE polymorphism analysis. Association study of I/D polymorphism in group of these patients (52 individuals) and 80 control persons from the same population of Russian descent demonstrated no evidence for statistically significant differences in frequencies of I/D alleles or II/DD/ID genotypes between these groups. Thus, it suggests that ACE I/D polymorphism alone is not risk factor for stroke in non-hypertension patients. We cannot, however, exclude possible interaction between ACE-D/D genotype and sex.

[Role of the lawc(p1) mutation in the regulation of the white locus expression in Drosophila]. / Rol' mutatsii lawc(p1) v reguliatsii ékspressii lokusa white u drozofily.

The lawcp1 mutation of the leg-arista-wing complex (lawc) gene alters expression of three proneural loci: achaete, scute, and cut. In combination with the product of the zeste (z) gene, the product of the lawc gene regulates expression of the white (w) gene. The -w B3 mutation was genetically analyzed in compounds with various z and w mutations and dominant mutations modifying the z-w interaction. The results showed that lawcp1 can enhance the transvection effect. The lawc gene was assumed to regulate expression of the white locus at the level of chromatin condensation.

[Cloning of the gene leg-arista-wing complex and analysis of its mutant derivatives in Drosophila]. / Klonirovanie gena leg-arista-wing complex i analiz ego mutantnykh proizvodnykh u drozofily.

Insertion of a double copy of P element was shown to be the cause of the lawcp1 mutation. Mapping and cloning of a DNA fragment bearing the lawc locus was carried out. New alleles of this gene were characterized.

[Genetic analysis of the lawc(p1) mutation in combination with different alleles of AS-C genes in Drosophila]. / Geneticheskii analiz mutatsii lawc(p1) v ee kombinatsiiakh s razlichnymi alleliami genov AS-C u Drosophila.

Phenotypic expression of mutations within the leg-aristal-wing complex (lawc) locus involves alteration of the number and location of macrochaetae. In Drosophila, development of macrochaetae depends on products of the two proneural genes, achaete (ac) and scute (sc), constituents of the approximately 90-kb ac-sc gene complex (AS-C). Untranscribed regions of AS-C involve enhancer-like cis-elements that are responsible for the local combination of some factors specifically determining expression of the ac-sc genes in larval imaginal discs of Drosophila. In the present work, the frequency of appearance of additional macrochaetae was tested to analyze phenotypic exhibition of the temperature-sensitive lawcp1 allele. This mutation was also genetically analyzed in combination with various AS-C alleles involving alterations of transcribed or cis-regulatory regions of this gene complex. A hypothesis that the lawc gene encodes a factor determining the specific expression of the ac-sc genes is discussed.

[Differential characteristics of the temperature-sensitive period of the lawcp1 mutation on the basis of macrochaetae overexpression in Drosophila]. / Differentsial'naia kharkateristika temperaturochuvstvitel'nogo perioda mutatsii lawcpa po priznaku superékspressii makrokhet u drozofily.

Temperature-sensitive periods (TSPs) of lawcpl mutations were studied via the frequencies of arising of extras macrochaetae for each macrochaetae type separately. TSPs for the formation of extras macrochaetae of original classes were unevenly distributed within larval instars II and III. It was found that macrochaetae of different types differed from one another in their temperature sensitivity. The TSP of development of macrochaetae belonging to new ectopic classes was multiphase, with the first phase at larval instar II, and the second phase, at the prepupal to early pupal stage. It is assumed that in Drosophila, the products of the lawc gene participate, along with other genes, in the development of the nervous system through regulation of ac-sc expression, both in proneural clusters and outside them.

[Determination of a temperature-sensitive period of the new mutation lawc(P1) in Drosophila melanogaster]. / Opredelenie temperaturochuvstvitel'nogo perioda novoi mutatsii lawc(P1) u Drosophila melanogaster.

Determination of the period of temperature sensitivity in the temperature-sensitive allele of the regulatory lawc(P1) mutation was performed. Homeotic transformation of arista into tarsus, frequency of leg deformation, and bristle superexpression were examined. The sensitive periods were detected using reciprocal changes of cultivation temperature from 28 to 17 degrees C and from 17 to 28 degrees C. The temperature-sensitive period (TSP) for arista transformation was shown to manifest polyphasic expression and sexual dimorphism. In females, it occurred in late third instar larvae (the first phase) and prepupae (the second stage); in males, it includes the whole period from the late third instar larva upto and including prepupa. TSP for the frequency of deformed legs was polyphasic and took place during the third larval instar (the first phase) and prepupa stage (the second one). TSP for bristle superexpression occurred during a single interval from the late third larval instar until the early prepupa stage. The products of the lawc gene are assumed to play a role both in the cell proliferation in the legs of antennal and imaginal discs and in the control of bristle expression at the final stages of Drosophila ontogeny.

[Complex instability in the system of hobo and stalker mobile element interaction in Drosophila melanogaster]. / Mnozhestvennaia nestabil'nost' v sisteme vzaimodeistviia mobil'nykh élementov hobo i stalker u Drosophila melanogaster.

A number of mutations in different Drosophila loci resulted from the relationship between hobo and stalker mobile elements. In this investigation an insertion from the parential white mutation-waG-was cloned. And the Doc element, that is the reason of the mutation, is not moving in the observed instability system. But transpositions of the copia-like elements (e.g. mdg1, 2, 3 and copia) were shown in this system. A cases of chromosomal rearrangements and abnormal recombination in compound with transpositions of different mobile elements were found. Thus, the system of instability could be explained in terms of universal mechanism which involved both transpositions and recombinations phenomena.

[Participation of mobile element hobo in transposition events in the long-term instability system of Drosophila melanogaster]. / Uchastie mobil'nogo élementa hobo v transpozitsionnykh sobytiiakh v sisteme linii prodlennoi nestabil'nosti u Drosophila melanogaster.

The lines with an active hobo elements as well as those without any hobo fragments were hybridized with the y2sc1waG line. This resulted in the appearance of a number of mutations at the white, miniature, and some other loci. The authors analysed, in which way the hobo transposable elements take part in mutagenesis in these crosses. Most of the white mutants obtained were analysed and transpositions of hobo and Stalker elements were demonstrated. Both independent and simultaneous transpositions were found. It was shown by means of the Southern blot analysis that additional hobo or Stalker insertion into or close to the parental unknown waG insertion resulted in mutant white phenotype's shift toward both extreme and partial reversion. Possible participation in mutagenesis of other mobile elements is also under debate.