Biomedical subjects

A Voronova

Publications and source records attributed to A Voronova.

6 recordsLinked to original sources

PubMed1999

Direct interaction in T-cells between thetaPKC and the tyrosine kinase p59fyn.

The protein kinase C (PKC) family has been clearly implicated in T-cell activation as have several nonreceptor protein-tyrosine kinases associated with the T-cell receptor, including p59fyn. This report demonstrates that thetaPKC and p59fyn specifically interact in vitro, in the yeast two-hybrid system, and in T-cells. Further indications of direct interaction are that p59fyn potentiates thetaPKC catalytic activity and that thetaPKC is a substrate for tyrosine phosphorylation by p59fyn. This interaction may account for the localization of thetaPKC following T-cell activation, pharmacological disruption of which results in specific cell-signaling defects. The demonstration of a physical interaction between a PKC and a protein-tyrosine kinase expands the class of PKC-anchoring proteins (receptors for activated C kinases (RACKs)) and demonstrates a direct connection between these two major T-cell-signaling pathways.

Antibodies↗

PubMed1991

Functional activity of myogenic HLH proteins requires hetero-oligomerization with E12/E47-like proteins in vivo.

In this report we provide four lines of evidence indicating that E12/E47-like proteins interact in vivo with the myogenic HLH proteins MyoD and myogenin. First, cotransfection of MyoD and E47 in COS cells indicates that these factors synergistically enhance transcription of a reporter gene containing an oligomerized MyoD-binding site. Second, mobility-shift assays of muscle cell nuclear extracts, "double shifted" with specific antisera, have identified complexes binding to the MEF1 site that contain either MyoD or myogenin in association with E12/E47-like proteins. Third, association with E47 alters the phosphorylation state of MyoD. Fourth, C3H10T1/2 cells expressing antisense E2A transcripts contain low levels of E2A gene products and display less terminal muscle differentiation when infected with retroviral MyoD or when challenged to differentiate with 5-azacytidine treatment. In addition we demonstrate that MyoD, in conjunction with E12/E47-like proteins, is functioning as a regulatory nodal point for activation of several other downstream muscle regulators.

Adenovirus Early Proteins↗

PubMed1991

Helix-loop-helix transcription factor E47 activates germ-line immunoglobulin heavy-chain gene transcription and rearrangement in a pre-T-cell line.

E47 is a helix-loop-helix transcription factor that binds to sites in the immunoglobulin heavy-chain and kappa light-chain gene enhancers. Other proteins of this type are involved in cell-type determination. A possible role for E47 in B-cell development was tested by overexpressing a cDNA encoding E47 in the pre-T-cell line 2017. We found a dramatic activation of a germ-line heavy-chain gene transcript in these stable transfectants and an equally large induction of immunoglobulin D-to-J rearrangement, the first recognized step in B-cell development. Germ-line kappa light-chain gene transcription and rearrangement were unaffected, but transcription of the recombination-activating genes RAG-1 and RAG-2 and the lymphoid-specific transcription factor Oct-2 was increased. These T cells did not transcribe their rearranged DJ alleles, however, and failed to progress to the next stage of heavy-chain gene assembly, V-to-DJ rearrangement. Because transcription factor E47 can induce pre-T cells to carry out events of B-cell differentiation, it may be a crucial determinant of the earliest stages of B-cell development.

Animals↗

PubMed1991

B-cell- and myocyte-specific E2-box-binding factors contain E12/E47-like subunits.

Recent studies have identified a family of DNA-binding proteins that share a common DNA-binding and dimerization domain with the potential to form a helix-loop-helix (HLH) structure. Various HLH proteins can form heterodimers that bind to a common DNA sequence, termed the E2-box. We demonstrate here that E2-box-binding B-cell- and myocyte-specific nuclear factors contain subunits which are identical or closely related to ubiquitously expressed (E12/E47) HLH proteins. These biochemical function for E12/E47-like molecules in mammalian differentiation, similar to the genetically defined function of daughterless in Drosophila development.

Animals↗

PubMed1990

Mutations that disrupt DNA binding and dimer formation in the E47 helix-loop-helix protein map to distinct domains.

A common DNA binding and dimerization domain containing an apparent "helix-loop-helix" (HLH) structure was recognized recently in a number of regulatory proteins, including the E47 and E12 proteins that bind to the kappa E2 motif in immunoglobulin kappa gene enhancer. The effect of site-directed mutagenesis on E47 protein multimerization and DNA binding was examined. Mutations in either putative helix domain disrupted protein dimerization and DNA binding. No DNA binding was observed when mutations were introduced in the basic region, but these mutants were able to dimerize. These basic region mutants were not able to bind to DNA as heterodimers with the wild-type E47 proteins, demonstrating that two functional basic regions are required for binding to DNA. Therefore the basic region mutants are "transdominant."

Amino Acid Sequence↗

PubMed1984

Construction and expression of a recombinant DNA gene encoding a polyomavirus middle-size tumor antigen with the carboxyl terminus of the vesicular stomatitis virus glycoprotein G.

We constructed a molecular clone encoding the N-terminal 379 amino acids of the polyomavirus middle-size tumor antigen, followed by the C-terminal 60 amino acids of the vesicular stomatitis virus glycoprotein G. This hybrid gene contained the coding region for the C-terminal hydrophobic membrane-spanning domain of the G protein in place of the C-terminal hydrophobic domain of the middle-size tumor antigen. The hybrid gene was expressed in COS-1 cells under the control of the simian virus 40 late promoter. The hybrid protein was located in cell membranes and was associated with a tyrosine-specific protein kinase activity, as was the middle-size tumor antigen. Plasmids encoding the hybrid protein failed to transform mouse NIH 3T3 or rat F2408 cells.

Antigens, Neoplasm↗