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R M Perlmutter

Publications and source records attributed to R M Perlmutter.

At least 109 records · Page 6Linked to original sources
PubMed1988

Structure of the murine lck gene and its rearrangement in a murine lymphoma cell line.

The lck gene encodes a lymphocyte-specific protein-tyrosine kinase that is implicated in neoplastic transformation. We have determined the germ line organization of the murine lck gene and have isolated and characterized a rearranged lck allele in the murine lymphoma cell line LSTRA. The overall exon-intron organization of the normal lck gene is almost identical to that of avian c-src. In LSTRA DNA, an internally rearranged Moloney murine leukemia virus genome is interposed between two distinct promoters that normally generate lck transcripts differing only in 5' untranslated regions. The rearrangement appears to have been selected to permit splicing of transcripts that initiate from the Moloney virus promoter to an acceptor site located within the first exon 3' to the downstream promoter, thus generating an lck mRNA with a novel 5' untranslated region that may be more efficiently translated.

Animals↗
PubMed1987

Early restriction of the human antibody repertoire.

Diversification of the antibody repertoire in mammals results from a series of apparently random somatically propagated gene rearrangement and mutational events. Nevertheless, it is well known that the adult repertoire of antibody specificities is acquired in a developmentally programmed fashion. As previously shown, rearrangement of the gene segments encoding the heavy-chain variable regions (VH) of mouse antibodies is also developmentally ordered: the number of VH gene segments rearranged in B lymphocytes of fetal mice is small but increased progressively after birth. In this report, human fetal B-lineage cells were also shown to rearrange a highly restricted set of VH gene segments. In a sample of heavy-chain transcripts from a 130-day human fetus the most frequently expressed human VH element proved to be closely related to the VH element most frequently expressed in murine fetal B-lineage cells. These observations are important in understanding the development of immunocompetence.

Adult↗
PubMed1987

Molecular dissection of the murine antibody response to streptococcal group A carbohydrate.

Monoclonal antibodies (mAb) to streptococcal group A carbohydrate (GAC) are encoded by a minimum of two VH, four JH, four V kappa, three J kappa, one V lambda, and one J lambda gene segments. The IdX, IdI-1, and Id5 idiotypic determinants are expressed by anti-GAC mAb and are found on free kappa chains. Each pattern of these determinants is encoded by a distinct V kappa gene segment, apparently without the requirement for a particular J kappa, VH, or JH gene segment, or somatic mutation. In contrast, the binding site-associated idiotypic determinant IdI-3a does not correlate with any single V or J gene segment.

Animals↗
PubMed1987

Regulation of pp56lck during T-cell activation: functional implications for the src-like protein tyrosine kinases.

The lymphocyte-specific protein tyrosine kinase pp56lck, encoded by a member of the src gene family, is implicated in the control of T-cell growth and differentiation. Purified resting human T lymphocytes contain appreciable levels of lck mRNA and of pp56lck. Upon activation of these T cells, levels of lck mRNA and of pp56lck promptly decline. These reductions in lck mRNA and protein expression are closely correlated with the induction of lymphokine production. Both require identical stimuli and follow a similar time course of response. Down-regulation of lck expression, however, is not correlated with proliferation. Our results provide an example of regulation of a src-like protein tyrosine kinase in a normal fully differentiated cell population and suggest that modulation of lck RNA and protein expression is an important feature of the lymphocyte activation sequence leading to lymphokine production.

Adult↗
PubMed1987

A small multigene family encodes Gi signal-transduction proteins.

The guanine nucleotide-binding regulatory proteins known as G proteins are receptor-associated signal-transduction molecules that are implicated in the control of a variety of metabolic processes. Recent evidence suggests that G proteins may mediate B-lymphocyte responses to bacterial lipopolysaccharide and may also transduce signals from the T-cell antigen receptor. Since these receptors are uniquely expressed on lymphoid cells, we used molecular cloning strategies to ask whether lymphocytes contain specialized G-protein alpha subunits to assist in signal transduction. Comparison of our two deduced human alpha i amino acid sequences with those previously determined for bovine and rodent G proteins permits the identification of three closely related but distinct types of alpha i molecules that comprise a small multigene family. Using gene-specific probes, we found that both of our alpha i genes are expressed in most cell types but in differing ratios. Our data support the view that a modest repertoire of extremely closely related G proteins mediates the transduction of signals derived from multiple different receptor molecules.

Animals↗
PubMed1987

Novel protein-tyrosine kinase gene (hck) preferentially expressed in cells of hematopoietic origin.

Protein-tyrosine kinases are implicated in the control of cell growth by virtue of their frequent appearance as products of retroviral oncogenes and as components of growth factor receptors. Here we report the characterization of a novel human protein-tyrosine kinase gene (hck) that is primarily expressed in hematopoietic cells, particularly granulocytes. The hck gene encodes a 505-residue polypeptide that is closely related to pp56lck, a lymphocyte-specific protein-tyrosine kinase. The exon breakpoints of the hck gene, partially defined by using murine genomic clones, demonstrate that hck is a member of the src gene family and has been subjected to strong selection pressure during mammalian evolution. High-level expression of hck transcripts in granulocytes is especially provocative since these cells are terminally differentiated and typically survive in vivo for only a few hours. Thus the hck gene, like other members of the src gene family, appears to function primarily in cells with little growth potential.

Amino Acid Sequence↗
PubMed1986

Localization of a lymphocyte-specific protein tyrosine kinase gene (lck) at a site of frequent chromosomal abnormalities in human lymphomas.

The murine lck gene is closely related to a family of cellular protooncogenes and encodes a lymphocyte-specific, membrane-associated protein tyrosine kinase. We and others have demonstrated that the lck gene is rearranged and overexpressed in the murine lymphoma LSTRA, most likely as a result of the insertion of Moloney murine leukemia virus DNA immediately adjacent to the gene. We now report that the lck gene is located at the distal end of murine chromosome 4 and on human chromosome 1 at position 1p32-35 near a site of frequent structural abnormalities in human lymphomas and neuroblastomas. These results raise the possibility that structural alteration of the lck gene through chromosomal rearrangement may contribute to transformation in human malignant disease.

Animals↗
PubMed1985

Diversity in the germline antibody repertoire. Molecular evolution of the T15 VN gene family.

The T15 heavy chain variable region (VH) gene family in BALB/c mice includes four elements each greater than 88% homologous with the other. One of these elements, V1, encodes virtually all of the VH regions in BALB/c antiphosphorylcholine antibodies, while another element, V3, is a pseudogene and cannot be transcribed or translated. We have examined the structural features of this VH gene family in other mouse strains and, in particular, have cloned and sequenced the alleles of these gene segments present in B10.P mice. Each of the four B10.P sequences can be matched with its allelic counterpart in BALB/c mice. This represents the first successful analysis of allelism in antibody variable region gene segments. The V1B10.P allele, like its BALB/c counterpart, encodes most of the known phosphorylcholine binding heavy chains from C37BL/6 mice. Similarly, the V3B10.P gene segment is a pseudogene like V3BALB, although only two of four abnormalities present in the BALB/c allele are also present in the B10.P allele. Careful analysis of the specific substitutions observed in the T15 VH gene family suggests that environmental selection for functional combining regions contributes significantly to the pattern of variation in the germline antibody repertoire. In addition, evidence is presented supporting frequent gene conversion events in the divergence of antibody genes.

Alleles↗
PubMed1985

Ig heavy chain variable region gene complex of lupus mice exhibits normal restriction fragment length polymorphism.

B cell hyperactivity, hypergammaglobulinemia, and autoantibody expression, the hallmarks of systemic lupus erythematosus, might be associated with structural abnormalities within the Ig heavy chain variable region (Igh-V) gene complex. The Igh-V loci from several lupus-prone mouse strains, their ancestors, and other nonautoimmune mice were therefore analyzed by restriction fragment length polymorphisms with DNA probes corresponding to seven VH gene families. These seven families comprise the majority of the known polymorphic murine VH gene repertoire, including some involved in autoantibody generation. Our study showed that the Igh-V loci from lupus and haplotype-matched nonlupus mice resulted in essentially identical restriction fragment patterns, a finding which suggests that the Igh-V gene complex does not carry a primary defect responsible for autoimmune disease.

Animals↗
PubMed1985

Developmentally controlled expression of immunoglobulin VH genes.

Although antibody diversity arises mainly from apparently random combinatorial and somatic mutational mechanisms acting upon a limited number of germline antibody genes, the antibody repertoire develops in an ordered fashion during mammalian ontogeny. A series of early pre-B and B-lymphocyte cell lines were examined to determine whether an ordered rearrangement of gene families of the variable region of immunoglobulin heavy chains (VH) may be the basis for the programmed development of the antibody response. The results indicated that the VH repertoire of fetal B-lineage cells is largely restricted to the VH 7183 gene family and that subsequent recruitment of additional VH gene families occurs during neonatal development. These results have important implications in understanding the ontogeny of immune function.

Aging↗
PubMed1985

A lymphocyte-specific protein-tyrosine kinase gene is rearranged and overexpressed in the murine T cell lymphoma LSTRA.

Protein-tyrosine kinases are implicated in the control of normal and neoplastic cell growth. We have used molecular cloning strategies to characterize a lymphocyte-specific protein-tyrosine kinase gene distinct from but closely related to src and yes. This gene, encoded by a genetic locus defined here as lskT, is rearranged and overexpressed in the murine T cell lymphoma LSTRA. Thus alterations in the structure or expression of this protein-tyrosine kinase gene may in some cases mediate neoplastic transformation. In addition, transcription of the normal lskT gene is restricted to cells of lymphoid origin. We infer that the lskT-encoded protein-tyrosine kinase may aid in transducing proliferative or differentiative signals unique to lymphocytes.

Animals↗
PubMed1984

Multiple VH gene segments encode murine antistreptococcal antibodies.

Most mouse strains are able to mount a diverse antibody response against group A streptococcal carbohydrate (GAC). We have previously reported that murine anti-GAC antibodies are for the most part restricted to IgM and IgG3 subclasses. In addition, despite extensive heterogeneity in their isoelectric focusing patterns, greater than 50% of A/J anti-GAC antibodies share a common light chain defined by spectrotypic and idiotypic (VK1GAC) criteria. We have used protein and DNA sequencing strategies to examine the genetic basis of diversity in murine anti-GAC antibodies. In particular, we report that, (a) multiple, closely homologous VH gene segments contribute to the generation of anti-GAC antibodies, (b) a common framework sequence, related to the VK27 subgroup, probably defines VK1GAC, and (c) the A/J anti-GAC VH regions and BALB/c anti-inulin VH sequences are 95% homologous at the protein level and are likely encoded by overlapping VH gene families. Lastly, we discuss the genetic mechanisms that might permit the evolution of multiple, closely homologous germline VH gene segments in the context of highly divergent flanking region sequences.

Alleles↗
PubMed1984

Immunologic memory to phosphocholine. IV. Hybridomas representative of Group I (T15-like) and Group II (non-T15-like) antibodies utilize distinct VH genes.

The anti-phosphocholine (PC) memory response elicited in BALB/c mice by phosphocholine-keyhole limpet hemocyanin (PC-KLH) contains two groups of antibodies distinguished by their fine specificity for PC and p-nitrophenylphosphocholine (NPPC). Group I antibodies are inhibited by both PC and NPPC, while Group II antibodies are inhibited appreciably only by NPPC; only Group I antibodies are dominated by the T15 idiotype. Anti-PC hybridomas representative of the memory response to PC-KLH were produced to examine the variable region genes expressed by memory B cells. Two IgM hybridomas were of the Group I type, because they were inhibited by both PC and NPPC and they bound to the pneumococcus R36A. However, only one of these antibodies (PCM-2) expressed a T15 idiotope, while the other (PCM-1) did not express any of three T15 idiotopes. Despite its negative T15 idiotype profile, N-terminal amino acid sequencing of PCM-1 purified heavy chain and Southern blots of the hybridoma DNA indicated that it utilizes the T15 VH and JH1 genes. Three hybridomas, IgG1, IgM, and IgE, typical of Group II antibodies, were examined; these were negative for three T15 idiotopes and displayed measurable avidity only for NPPC in a PC-protein binding inhibition assay. These three hybridoma antibodies, like serum Group II IgG1, did not measurably bind to the bacterium R36A. The heavy chain amino termini of all three of these antibodies were inaccessible for Edman degradation. Southern blots of DNA from the IgG1 hybridoma revealed the T15 VH gene to be in the germ line configuration only and unassociated with any JH segment, indicating that this Group II antibody utilizes a VH gene different from the T15 family. These results signify that, whereas some diversity of the (anti-PC) memory response may be generated by somatic diversification of variable regions important in the primary response, a significant contribution to the overall heterogeneity of memory antibodies originates in the expression of additional variable region genes.

Amino Acid Sequence↗
PubMed1984

Immunologic memory to phosphocholine. V. Hybridomas representative of group II antibodies utilize V kappa 1-3 gene(s).

The anti-phosphocholine (PC) memory response of BALB/c mice to PC-KLH contains two groups of antibodies distinguished by fine specificity and by expression of the T15 idiotype that dominates Group I but not Group II anti-PC antibodies. The contribution of V kappa genes to this diversity was investigated by the analysis of L chains from PC-binding hybridoma proteins (PCBHP) representative of Group I and Group II. N-terminal amino acid sequence analysis was performed on the L chains of three independently derived Group II PCBHP up to residue 23 (PCG1-1) or 21 (aPC-111-1 and aPC-12-3). These three sequences differed from each other by only one or two residues, but differed by approximately 50% from the L chains of the Group I-like PC-binding myeloma proteins (PCBMP); the Group II sequences are closely related to V kappa 1-3. Isoelectric focusing analysis was also performed on the L chain of PCG1-1, as well as on L chains from PCBHP typical of Group I antibodies, and from an atypical PCBHP differing from Groups I and II in fine specificity. A Group I PCBHP and the atypical PCBHP expressed L chains related to V kappa 8 and V kappa 24, respectively. The L chains of another Group I PCBHP and of the Group II protein, PCG1-1, appeared different from those found in the PCBMP and from each other. The results indicate a more diverse expression of L chains in the memory anti-PC response than is represented by the PCBMP; both V kappa 8- and V kappa 24-derived L chains (and, presumably, somatic variants), as well as products of additional V kappa genes (V kappa 1-3), appear to be present in the anti-PC memory pool.

Amino Acid Sequence↗
PubMed1982

Streptococcal group A carbohydrate has properties of both a thymus-independent (TI-2) and a thymus-dependent antigen.

Streptococcal group A carbohydrate, which elicits mouse antibody of primarily the IgM and IgG3 isotypes, is relatively nonimmunogenic in nu/nu or xid mice, and thus appears to be a type of TD-2 antigen. The TD-2 antigens described previously have been proteins that elicit IgG antibody primarily of the IgG1 and IgG2 isotypes. Our findings indicate that TD-2 properties may also be a characteristic of at least some carbohydrate antigens that can elicit IgG antibody predominantly of the IgG3 class.

Animals↗
PubMed1979

Immunoglobulin subclass-specific immunodeficiency in mice with an X-linked B-lymphocyte defect.

CBA/N mice express an X-linked deficiency in their antibody response to many bacterial carbohydrates; we have shown recently that these antigens normally elicit antibody responses predominantly of the IgM and IgG3 isotypes. Here we demonstrate that mice, with the CBA/N phenotype have perferential deficiencies of IgM and IgG3 immunoglobulin expression, both when measured in serum and in cells secreting these isotypes, and that this deficiency is only partially corrected by polyclonal activation of B cells. This suggests that CBA/N mice may lack a subpopulation of B cells that contain most of the IgG3 precursors.

Animals↗