PubMed Health⌕ Search

Biomedical subjects

B Kuzin

Publications and source records attributed to B Kuzin.

9 recordsLinked to original sources
PubMed2001

The Drosophila nitric-oxide synthase gene (dNOS) encodes a family of proteins that can modulate NOS activity by acting as dominant negative regulators.

Nitric oxide (NO) is involved in organ development, synaptogenesis, and response to hypoxia in Drosophila. We cloned and analyzed the only gene in the fly genome that encodes Drosophila nitric-oxide synthase (dNOS). It consists of 19 exons and is dispersed over 34 kilobases of genomic DNA. Alternative transcription start sites and alternative splice sites are used to generate a remarkable variety of mRNAs from the dNOS gene. We identified eight new transcripts that are widely expressed throughout Drosophila development and encode a family of DNOS-related proteins. Alternative splicing affects both the 5'-untranslated region and the coding region of the dNOS primary transcript. Most of the splicing alterations in the coding region of the gene lead to premature termination of the open reading frame. As a result, none of the alternative transcripts encode an enzymatically active protein. However, some of these shorter DNOS protein products can effectively inhibit enzymatic activity of the full-length DNOS1 protein when co-expressed in mammalian cells, thus acting as dominant negative regulators of NO synthesis. Using immunoprecipitation, we demonstrate that these short DNOS protein isoforms can form heterodimers with DNOS1, pointing to a physical basis for the dominant negative effect. Our results suggest a novel regulatory function for the family of proteins encoded by the Drosophila NOS gene.

Alternative Splicing↗
PubMed2000

Nitric oxide interacts with the retinoblastoma pathway to control eye development in Drosophila.

Animal organ development requires that tissue patterning and differentiation is tightly coordinated with cell multiplication and cell cycle progression. Several variations of the cell cycle program are used by Drosophila cells at different stages during development [1] [2]. In imaginal discs of developing larvae, cell cycle progression is controlled by a modified version of the well-characterized mammalian retinoblastoma (Rb) pathway [3] [4], which integrates signals from multiple effectors ranging from growth factors and receptors to small signaling molecules. Nitric oxide (NO), a multifunctional second messenger [5], can reversibly suppress DNA synthesis and cell division [6] [7]. In developing flies, the antiproliferative action of NO is essential for regulating the balance between cell proliferation and differentiation and, ultimately, the shape and size of adult structures in the fly [8] [9] [10]. The mechanisms of the antiproliferative activity of NO in developing organisms are not known, however. We used transgenic flies expressing the Drosophila nitric oxide synthase gene (dNOS1) and/or genes encoding components of the cell cycle regulatory pathways (the Rb-like protein RBF and the E2F transcription factor complex components dE2F and dDP) combined with NOS inhibitors to address this issue. We found that manipulations of endogenous or transgenic NOS activity during imaginal disc development can enhance or suppress the effects of RBF and E2F on development of the eye. Our data suggest a role for NO in the developing imaginal eye disc via interaction with the Rb pathway.

Animals↗
PubMed1999

Nitric oxide and Drosophila development.

Mechanisms controlling the transition of precursor cells from proliferation to differentiation during organism development determine the distinct anatomical features of tissues and organs. NO may mediate such a transition since it can suppress DNA synthesis and cell proliferation. Inhibition of NOS activity in the imaginal discs of Drosophila larvae results in hypertrophy of tissues and organs of the adult fly, whereas ectopic overexpression of NOS has the reciprocal, hypotrophic, effect. Furthermore, NO production is crucial for the establishment of ordered neuronal connections in the visual system of the fly, indicating that NO affects the acquisition of the differentiated phenotype by the neural tissue. Increasing evidence points to a broad role that NO may play in animal development by acting as an essential negative regulator of precursor cell proliferation during tissue and organ morphogenesis.

Animals↗
PubMed1997

Interaction between spineless-aristapedia gene and genes from Antennapedia and bithorax complexes of Drosophila melanogaster.

Mutations in the spineless-aristapedia (ssa) gene of Drosophila melanogaster are pleiotropic, and their classical manifestations include a reduction in size of all bristles (spineless phenotype), transformation of distal parts of antennae into tarsal segments of the mesothoracic leg (aristapedia phenotype), and, in extreme alleles, fusion of tarsal segments on all six legs and the transformed aristaes. We isolated a new allele, which is a severe loss-of-function mutation and, in addition to the above-mentioned features, is characterized by amplification of sex combs on the first leg. This phenotype can be caused by a change in the expression of the Sex combs reduced (Scr) gene of the ANTP-C. Identification of this phenotype, together with observed variations in the extent of the fusion of tarsal segments in the legs of different segments, raised the possibility that ssa interacts with homeotic genes controlling the identity of segments. This possibility was tested in genetical experiments using flies with loss-of-function mutations in several homeotic genes and flies transformed by heat shock-driven homeotic genes. Analysis of adult phenotypes of different ssa alleles in the background of under-, over-, or ectopic expression of some genes of BX-C and ANT-C suggests that the ssa product is required to prevent the effect of the homeotic gene products in the distal segments of the appendages.

Alleles↗
PubMed1996

Nitric oxide regulates cell proliferation during Drosophila development.

Cell division and subsequent programmed cell death in imaginal discs of Drosophila larvae determine the final size of organs and structures of the adult fly. We show here that nitric oxide (NO) is involved in controlling the size of body structures during Drosophila development. We have found that NO synthase (NOS) is expressed at high levels in developing imaginal discs. Inhibition of NOS in larvae causes hypertrophy of organs and their segments in adult flies, whereas ectopic expression of NOS in larvae has the opposite effect. Blocking apoptosis in eye imaginal discs unmasks surplus cell proliferation and results in an increase in the number of ommatidia and component cells of individual ommatidia. These results argue that NO acts as an antiproliferative agent during Drosophila development, controlling the balance between cell proliferation and cell differentiation.

Animals↗
PubMed1994

The Drosophila trithorax gene encodes a chromosomal protein and directly regulates the region-specific homeotic gene fork head.

The activity of the Drosophila gene trithorax is required to maintain the proper spatial pattern of expression of multiple homeotic genes of the Bithorax and Antennapedia complexes, trithorax encodes two large protein isoforms of > 400 kD. We have detected its products at 16 discrete sites on larval salivary gland polytene chromosomes, 12 of which colocalize with binding sites of several Polycomb group proteins. The intensity of trithorax protein binding is strongly decreased in larvae carrying mutations in another trithorax group gene ash-1, and in the Polycomb group gene pco/E(z). A strong trithorax binding site was found at the cytological location of the fork head gene, a region-specific homeotic gene not located within a homeotic complex. Further analysis showed that trithorax protein binds at ectopic sites carrying fork head sequences in transformed lines. Trithorax binding occurs within an 8.4-kb regulatory region that directs fork head expression in several embryonic tissues including salivary glands. Consistently, expression of endogenous fork head RNA is greatly reduced in trithorax mutant embryos and in larval tissues. These results show that trithorax maintains expression of target genes by interaction with their regulatory regions and that this interaction depends on the presence of at least some of the other trithorax and Polycomb group proteins.

Animals↗