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Biomedical subjects

V M Panin

Publications and source records attributed to V M Panin.

At least 19 recordsLinked to original sources
PubMed2000

Fringe is a glycosyltransferase that modifies Notch.

Notch receptors function in highly conserved intercellular signalling pathways that direct cell-fate decisions, proliferation and apoptosis in metazoans. Fringe proteins can positively and negatively modulate the ability of Notch ligands to activate the Notch receptor. Here we establish the biochemical mechanism of Fringe action. Drosophila and mammalian Fringe proteins possess a fucose-specific beta1,3 N-acetylglucosaminyltransferase activity that initiates elongation of O-linked fucose residues attached to epidermal growth factor-like sequence repeats of Notch. We obtained biological evidence that Fringe-dependent elongation of O-linked fucose on Notch modulates Notch signalling by using co-culture assays in mammalian cells and by expression of an enzymatically inactive Fringe mutant in Drosophila. The post-translational modification of Notch by Fringe represents a striking example of modulation of a signalling event by differential receptor glycosylation and identifies a mechanism that is likely to be relevant to other signalling pathways.

Animals↗
PubMed1998

Dorsal-ventral signaling in the Drosophila eye.

The development of the Drosophila eye has served as a model system for investigations of tissue patterning and cell-cell communication; however, early eye development has not been well understood. The results presented here indicate that specialized cells are established along the dorsal-ventral midline of the developing eye by Notch-mediated signaling between dorsal and ventral cells, and that Notch activation at the midline plays an essential role both in promoting the growth of the eye primordia and in regulating eye patterning. These observations imply that the developmental homology between Drosophila wings and vertebrate limbs extends to Drosophila eyes.

Animals↗
PubMed1998

Modulators of Notch signaling.

In addition to the core components of the Notch pathway, a number of proteins have been identified that exert positive or negative influences on Notch signaling. These include extracellular modulators, which may influence binding or activation of Notch by its ligands, cytoplasmic modulators, which presumably influence signal transduction steps after receptor activation, and nuclear modulators, which may influence the transcriptional activity of a Notch-CSL protein complex. Many of the cytoplasmic and nuclear modulators appear to bind directly to discrete domains within the intracellular domain of Notch. Genetic studies indicate that distinct modulators are deployed during distinct modes of Notch signaling.

Animals↗
PubMed1997

Fringe modulates Notch-ligand interactions.

The Notch family of transmembrane receptor proteins mediate developmental cell-fate decisions, and mutations in mammalian Notch genes have been implicated in leukaemia, breast cancer, stroke and dementia. During wing development in Drosophila, the Notch receptor is activated along the border between dorsal and ventral cells, leading to the specification of specialized cells that express Wingless (Wg) and organize wing growth and patterning. Three genes, fringe (fng), Serrate (Ser) and Delta (Dl), are involved in the cellular interactions leading to Notch activation. Ser and Dl encode transmembrane ligands for Notch, whereas fng encodes a pioneer protein. We have investigated the relationship between these genes by a combination of expression and coexpression studies in the Drosophila wing. We found that Ser and Dl maintain each other's expression by a positive feedback loop. fng is expressed specifically by dorsal cells and functions to position and restrict this feedback loop to the developing dorsal-ventral boundary. This is achieved by fng through a cell-autonomous mechanism that inhibits a cell's ability to respond to Serrate protein and potentiates its ability to respond to Delta protein.

Animals↗
PubMed1996

[Effect of specific nucleotide sequences on the transcription activity of long terminal repeats of avian retroviruses].

Influence of specific nucleotide sequences on the constitutive transcriptional activity of the Rous sarcoma long terminal repeats (LTR) was studied. The possible function of different elements of the transcriptional control region of the avian retroviral LTR was discussed on the basis of a comparative analysis of the effect of specific nucleotide insertions on LTR activity in vivo and in vitro.

Avian Sarcoma Viruses↗
PubMed1995

A relatively small 5' regulatory region of esterase S gene of Drosophila virilis determines the specific expression as revealed in transgenic experiments.

Expression of the esterase S gene of Drosophila virilis was studied in transgenic experiments. Truncated genomic copy of this gene including 400 bp of 5' regulatory region was integrated into the genome of Drosophila melanogaster. The products of the transferred gene were detected. It was found that strict temporal and tissue specificity of the esterase S gene expression is conserved in transformed flies. The results suggest that this specificity is evidently determined by the regulatory region of the esterase S gene and controlled by cis mechanism.

Animals↗
PubMed1995

The expression of esterase S gene of Drosophila virilis in Drosophila melanogaster.

Drosophila melanogaster was transformed with the esterase S gene from Drosophila virilis. This gene is strongly activated in ejaculatory bulbs of mature males of Drosophila virilis. The closely related gene from Drosophila melanogaster is activated in ejaculatory ducts. The tissue- and stage-specific expression of incomplete genomic copy of the esterase S gene integrated into the Drosophila melanogaster genome is the same as in Drosophila virilis. These data show that tissue and stage specificity is determined by relatively small 5' regulatory region of the esterase S gene. The comparison between deduced amino-acid sequences of the esterase S of Drosophila virilis and esterase 6 of Drosophila melanogaster was performed. These sequences revealed 50% homology.

Amino Acid Sequence↗
PubMed1993

A simple and reproducible method for analysis of chromatin condensation.

A method for examination of chromatin condensation with the help of gel electrophoresis in low-density agarose gels was suggested. This method provides a way for the degree of chromatin condensation to be estimated at different ionic conditions of the medium. It led to results which are in close agreement with the results of other traditional methods. Thus it was inferred that this method offers an alternative to the method of density-gradient ultracentrifugation for chromatin condensation study.

Animals↗
PubMed1993

Dynamics of unfolded nucleosomal fiber.

The "rigidity" of chromatin fiber solenoidal structure in different states of condensation was evaluated with the help of gel-electrophoresis. A new property of the unfolded nucleosomal fiber-the capacity to condense with temperature-was demonstrated. These results together with our previously obtained data (W.A. Krajewski et al., Mol. Gen. Genet. 230, pp. 442-448, 1991; W.A. Krajewski et al., Ibid. 231, pp. 17-22, 1991) testify that changes in DNA linking number of transcriptionally active minichromosomes arise in vivo from alteration of nucleosomal solenoid parameters (i.e. from supernucleosomal level of chromatin organization), rather than from core histone modifications only or from increased flexibility of DNA within nucleosomes.

Animals↗
PubMedDate not supplied

[Acetylation of histones in vitro causes chromatin decompactization].

It has been discovered that chemical acetylation of chromatin in vitro by acetyladenylate leads to decrease in the mobility of nucleosomal fiber fragments in agarose gel. Acetylation of HI-depleted chromatin does not produce this effect. Based on these results together with other available data, it is possible to conclude that acetylation causes decompactization of the chromatin fiber. A possible molecular mechanism of in vivo fiber decondensation and interaction of different chromatin compactization levels is discussed.

Acetylation↗