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S V Desiderio

Publications and source records attributed to S V Desiderio.

7 recordsLinked to original sources
PubMed1992

itk, a T-cell-specific tyrosine kinase gene inducible by interleukin 2.

T lymphocytes are activated by interactions with antigens, lymphokines, and cell adhesion molecules. Tyrosine phosphorylation has been implicated as important in signaling through each of these pathways, but except for p56lck, a member of the Src family that associates with CD4 and CD8, the protein-tyrosine kinases involved have not been defined. We describe here a tyrosine kinase gene that we have designated itk (for IL-2-inducible T-cell kinase). The itk gene specifies a 72-kDa protein-tyrosine kinase that is related to members of the Src family but lacks two features characteristic of Src kinases: an N-terminal myristoylation consensus sequence and a regulatory tyrosine residue near the C terminus. Analysis of mouse tissues and cell lines indicates that itk is specifically expressed in the T-cell lineage, suggesting that the tyrosine kinase encoded by itk functions in a signal transduction pathway unique to T lymphocytes. On addition of IL-2 to responsive T cells, itk RNA increases in parallel with that of IL-2R alpha, implicating itk in T-cell activation.

Base Sequence↗
PubMed1992

Recognition of angiotensin II: antibodies at different levels of an idiotypic network are superimposable.

Genetic and sequence information are reported for an angiotensin II-reactive antibody (Ab1, MAb 110) and an anti--anti-idiotypic antibody (Ab3, MAb 131) that have identical antigen binding properties and that are related by an anti-idiotypic antibody (Ab2-beta) that satisfies accepted biochemical criteria for an internal image-bearing antibody. The sequences of the variable regions of the Ab3 and of the Ab1 are nearly identical, even though the Ab1 is an antibody to a peptide and the Ab3 is an antibody to a globular protein. Significantly, amino acid residues that make critical contacts with antigen in the crystal structure of the Ab3-antigen complex are highly conserved in Ab1, suggesting that the epitopes of the Ab2-beta recognized by the Ab3 do indeed resemble the bound structure of the antigen.

Amino Acid Sequence↗
PubMed1992

Structure and developmental regulation of the B-lymphoid tyrosine kinase gene blk.

The murine blk gene, which encodes a B-lymphoid-specific tyrosine kinase of the Src family (p55blk), contains 13 exons that span more than 30 kilobases of DNA on chromosome 14. In the first three exons, which encode the 5'-untranslated region and N-terminal amino acid sequence unique to p55blk, the blk gene differs from other members of the src family; in the last 10 exons, the organization of the blk gene is similar to that of other src genes. By primer extension and S1 nuclease protection analyses, we show that blk transcripts initiate from four major sites at the 5'-flank of blk; two sites predominate. The resulting transcripts differ only in the lengths of their 5'-untranslated sequences and encode identical proteins. None of the transcriptional start sites are preceded by consensus TATA elements, AT-rich elements, or extensive GC-rich regions. Expression of blk is regulated during B-cell development: blk RNA is expressed in all pro-B-, pre-B-, and mature B-cell lines examined, but is absent from plasma cell lines. Immunolocalization of p55blk in normal mouse spleen supports these observations: staining is restricted to lymphocytes and is concentrated in regions rich in B-cells; plasma cells and stromal cells are not stained with anti-Blk antibodies. Assays for RNA synthesis in isolated nuclei indicate that the lineage and developmental stage specificities of blk expression are regulated at least in part by changes in its rate of transcription.

Amino Acid Sequence↗
PubMed1992

B-cell activation.

Extraordinary progress has been made in refining our understanding of the B-cell antigen receptor complex, the role of protein-tyrosine phosphorylation as the key intermediary in immunoglobulin signal transduction, and in identifying candidate effectors of immunoglobulin-mediated signaling. In addition, the properties of a new group of G proteins may rekindle interest in older observations implicating such molecules as important in B-cell activation.

Amino Acid Sequence↗
PubMed1991

Repression of immunoglobulin enhancers by the helix-loop-helix protein Id: implications for B-lymphoid-cell development.

It has been proposed that the helix-loop-helix (HLH) protein Id serves as a general antagonist of cell differentiation by inhibiting bHLH (HLH with an adjacent stretch of basic amino acids) proteins specifically required for developmental programs (such as MyoD). We show here that ectopic expression of Id represses in vivo activity of the bHLH protein E2-5 (encoded by the E2A gene) and of both the immunoglobulin heavy-chain (IgH) and kappa-light-chain gene enhancers to which E2-5 binds. Id does not affect the activity of the bHLH-zip protein, TFE3, which also binds these enhancers. We examined a large panel of B-cell lines that represent different stages of lymphoid development and found only two that express Id mRNA. The cell lines Ba/F3 and LyD9 have been categorized previously as early B-lymphoid-cell progenitors. Unlike their more mature B-lymphoid-cell counterparts, Ba/F3 and LyD9 cells do not express I mu sterile transcripts, which are indicative of IgH enhancer activity. Moreover, Ba/F3-derived nuclear extracts lack E2-box-binding activity, indicating the absence of free bHLH proteins, and transfected Ba/F3 cells fail to support the activity of the IgH enhancer. Hence, expression of Id correlates inversely with bHLH protein activity and enhancer function in vivo. These results suggest that Id may play a role early in B-lymphoid-cell development to regulate transcription of the IgH locus.

3T3 Cells↗
PubMed1991

Coordination of immunoglobulin DJH transcription and D-to-JH rearrangement by promoter-enhancer approximation.

The genes that encode the variable regions of immunoglobulin (Ig) heavy chains are encoded by three DNA segments: VH, D, and JH. During B-cell development these segments are brought together by a pair of site-specific DNA rearrangements. The first of these joins a D segment to a JH segment; the second brings a VH segment in apposition to a DJH unit. B-cell precursors that have undergone D-to-JH joining express transcripts that initiate at the 5' flanks of rearranged D segments (DJH transcription). In this study we have examined the coordination of D-to-JH rearrangement and DJH transcription. The B-lymphoid progenitor cell line HAFTL-1 cell clone, joining of distal D segments (DSP2 and DFL16) to JH is accompanied by an increase in the steady-state level of transcripts initiating 5' of the D coding region. Steady-state transcription of a DSP2 gene segment was undetectable prior to rearrangement and was observed to increase at least 20-fold upon joining to JH. In contrast, transcription from the 5' flank of DQ52, which lies within 700 bp of the JH cluster, was detected prior to rearrangement and did not increase significantly after rearrangement. The 5' flank of a DSP2 segment was found to support expression of a heterologous gene upon transfection into B progenitor cell lines. Expression from this DSP2 promoter was at least 30-fold higher in the presence of the Ig heavy-chain enhancer, in either orientation, than in its absence. A DNA fragment spanning the interval from -165 to +19 bp relative to the major DSP2 transcriptional start site retained enhancer-dependent promoter activity. These observations imply that activation of DSP12JH and DFL16JH transcription is coordinated with D-to-JH rearrangement by approximation of enhancer-dependent D promoter elements to the Ig heavy-chain enhancer. This interpretation is consistent with our observation that the DQ52 segment, which is closely linked to the JH cluster, is transcribed both before and after rearrangement.

Animals↗