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Biomedical subjects

D S Latchman

Publications and source records attributed to D S Latchman.

At least 235 records · Page 13Linked to original sources
PubMed1994

Serological and genetic characterization of a human monoclonal immunoglobulin G anti-DNA idiotype.

This study analyzed the distribution of an idiotype, B3-Id, in patients with active SLE, classified according to organ involvement, normal controls, and other autoimmune rheumatic diseases. A polyclonal anti-idiotype was raised by immunizing a rabbit with a monoclonal IgG anti-double-stranded (ds) DNA antibody, B3, generated from a patient with SLE who had active arthritis. The idiotype is present on the lambda chain and is at or near the binding site for double-stranded DNA. The lambda chain, which was characterized by nucleotide sequencing, was 90% homologous to the V lambda 2.1 germline, which is known to be involved in coding for nephritogenic anti-DNA antibodies carrying the 8.12 idiotype. There were four changes to positively charged amino acids, known to be involved in DNA binding, in the complementarity determining regions of B3 lambda chain compared with a non-DNA binding, 8.12 positive antibody, PV11. Only one change to a positively charged amino acid occurs in the heavy chain of B3, which is 93.5% homologous to VH-26. The B3-Id was present on IgG antibodies in the serum of 20% of patients with SLE but was not found in the normal controls. Within the SLE group, there is a statistically significant association of B3-Id on IgG in the arthritis group (42%) compared to the other manifestations (9%) (P < 0.001). In four B3-Id-positive SLE patients tested serially, the level of B3-Id reflected the arthritis disease activity more closely than the overall disease activity (P < 0.05). The B3-Id was also present on IgM antibodies in one third of patients with rheumatoid arthritis. This idiotype is the first to be derived from a human monoclonal anti-DNA antibody of the IgG class, the isotype associated with active disease. Sequence analysis shows that positively charged amino acids on the lambda chain may contribute to DNA binding.

Adult↗
PubMed1994

Identification and characterization of a new human DNA reactive monoclonal antibody and a common idiotype, WRI 176 Id beta.

We describe a human monoclonal antibody designated WRI 176 beta and a common idiotype that it carries. This antibody was derived from the spleen of a patient with SLE. WRI 176 is an IgM kappa monoclonal reacting with ssDNA, dsDNA, poly(dT) and it is likely that mAb WRI 176 beta is a representative of the so-called natural autoantibodies. The common Id designated WRI 176 Id beta is located on the heavy chain of the mAb WRI 176 beta molecule and appears to be located outside the binding site. Sequence analysis of the WRI 176 beta heavy chain showed it to be highly homologous (97.3%) with a germline gene 56PI derived from a human fetus. In a retrospective analysis, although 44% of SLE patients had raised levels of the WRI 176 beta no correlation was found with the activity of the disease. The idiotype was also expressed frequently in a range of autoimmune rheumatic and infectious diseases and in some healthy first-degree relatives of SLE patients.

Amino Acid Sequence↗
PubMed1994

The role of hsp90 in SLE.

The heat shock proteins are a group of evolutionarily conserved proteins with important physiological functions, whose synthesis is enhanced by elevated temperature or other stresses. A role for one or more of these proteins in human autoimmune disease has been extensively discussed. This review considers the evidence of a role for hsp90 in systemic lupus erythematosus (SLE) where overexpression of this protein, its surface localization and auto-antibodies to it have been observed in both human patients and in the MRL/lpr mouse model of SLE.

Animals↗
PubMed1994

Enhanced transcription of the gene encoding the SmN autoantigen in patients with systemic lupus erythematosus does not result in enhanced levels of the SmN protein.

The SmN, protein is closely related to the constitutively expressed SmB and SmB' autoantigens and can also act as a target for human autoimmune sera. In contrast to the single gene encoding SmB and SmB' which is expressed in all tissues, the distinct gene encoding SmN is expressed at high levels only in brain and heart tissue. We show that the SmN gene is transcribed at significantly elevated levels in peripheral blood mononuclear cells (PBMCs) from SLE patients compared to normal controls. In contrast no significant elevation in transcription of the genes encoding SmB/B' or the U1-associated 70kD RNP autoantigen is observed in these patients. The elevation in SmN gene transcription in patient PBMCs does not result however, in enhanced levels of the SmN protein in the PBMCs of these patients. The significance of transcriptional and post-transcriptional processes in regulating the expression in SLE patients of SmN and other autoantigens is discussed.

Adult↗
PubMed1994

Bcl-2 and Fas, molecules which influence apoptosis. A possible role in systemic lupus erythematosus?

Polyclonal B cell activation and the production of antibodies against a variety of autoantigens are features of systemic lupus erythematosus (SLE). Autoreactive B cells are found in healthy individuals but their numbers are probably regulated by cell death, after a few days, in the absence of proliferative stimuli. The process which achieves this regulation is known as apoptosis or programmed cell death. It has been postulated that in SLE patients dysfunction of apoptosis could result in the inappropriate longevity of autoreactive B cells, allowing autoantibody levels to reach pathogenic thresholds. This hypothesis has arisen as a result of studies revealing links between autoimmunity and two molecules which influence apoptosis. These are bcl-2 which enhances cell survival by inhibiting or delaying apoptosis and Fas, a cell surface molecule involved in the induction of apoptosis. Transgenic mice over expressing bcl-2 in their B cells showed polyclonal B cell expansion and their B cells showed extended survival in vitro. After a few months these mice developed an autoimmune syndrome resembling SLE. Mice that carry the lpr disorder have defects in the Fas gene. These mice, which do not express functional Fas molecules, suffer from an SLE-like autoimmune syndrome. Thus inappropriate expression of both bcl-2 and Fas can result in SLE-like autoimmune disease in mice. Research is now in progress to ascertain whether quantitative or functional abnormalities in these molecules exist in human SLE patients and contribute to the pathogenesis of the disease in some or all cases.

Animals↗
PubMed1994

The tissue specific elevation in synthesis of the 90 kDa heat shock protein precedes the onset of disease in lupus prone MRL/lpr mice.

OBJECTIVE: Expression of the 90 kDa heat shock protein (HSP 90) is elevated in the peripheral blood lymphocytes of a subset of patients with active systemic lupus erythematosus (SLE). We therefore wished to test whether this effect would also be observed in the lupus prone MRL/lpr mouse strain. METHODS: Levels of the individual HSP were measured by Western blotting in various tissues of MRL/lpr mice at different ages. RESULTS: Elevation of HSP 90 is observed in the spleen but not other tissues of MRL/lpr mice compared to Balb/c mice. The elevation in HSP 90 levels in the spleen is independent of the age of the MRL/lpr mice and precedes the development of autoimmune disease as measured by the appearance of high levels of antibodies to double and single stranded DNA. In contrast no alterations in the levels of HSP 73 and 65 are observed in MRL/lpr mice while elevated levels of HSP 72 are observed in several tissues of these mice and the level increases in an age dependent manner as the disease progresses. CONCLUSION: MRL/lpr mice show an age independent and tissue specific increase in HSP 90 levels which, as in human patients with SLE, is specific for this HSP.

Animals↗
PubMed1994

Elevation of the 90 kDa heat-shock protein in specific subsets of systemic lupus erythematosus.

We have previously shown that the 90 kDa heat-shock protein (hsp90) is notably elevated in lupus patients with active neuro-psychiatric (NP) and/or cardio-respiratory (CR) disease. This elevation is dependent upon enhanced transcription of the hsp90 beta gene. Serial studies have shown that changes in hsp90 levels have a high level of sensitivity for changes in activity of NP, CR, haematological and renal SLE. We now present evidence that overexpression of hsp90 in lupus patients is associated with the presence of the anti-phospholipid syndrome, and with the absence of the HLA allo-/haplotypes most commonly found in this particular cohort of patients. We conclude that the upregulation of hsp90 expression in SLE has a genetic basis, and that this may be directly involved in pathogenesis in subsets of patients with this disease.

Adolescent↗
PubMed1994

Regulation of viral and cellular gene expression in sensory neurons.

Herpes simplex virus (HSV) establishes latent infections of neuronal cells but replicates readily in other cell types. This effect is dependent upon the presence of the inhibitory cellular transcription factor Oct-2 in neuronal cells. This factor inhibits the viral immediate-early gene promoters by at least two distinct mechanisms. The significance of Oct-2 in regulating viral and cellular gene expression in sensory neurons is discussed.

Animals↗
PubMed1993

Transactivation of the human papilloma virus 16 octamer motif by the octamer binding protein Oct-2 requires both the N and C terminal activation domains.

The upstream regulatory region (URR) of the human papillomaviruses HPV16 and 18 contains a sequence with a seven out of eight base match to the consensus binding site for octamer binding transcription factors. This motif acts as a target for repression by the Oct-1 transcription factor and therefore inhibits promoter activity in non-cervical cells expressing only Oct-1. In contrast the HPV octamer motif activates promoter activity in cervical cells. Here we show that cervical cells express the activating form of the Oct-2 transcription factor, Oct 2.1 and that this factor can transactivate promoter activity via the HPV16 octamer. This effect is dependent upon both the N and C-terminal activation domains of Oct-2. The expression of specific octamer binding proteins such as Oct-2 in cervical cells thus allows the HPV16 motif to produce opposite effects on gene expression in cervical and non-cervical cells suggesting that it may play a role in the cervical specificity of URR driven gene expression.

Cervix Uteri↗
PubMed1993

The snRNP core protein SmB and tissue-specific SmN protein are differentially distributed between snRNP particles.

The SmN protein is a tissue specific component of the small nuclear ribonucleoprotein particle which is closely related to the ubiquitously expressed SmB protein but is expressed only in the brain and heart. To investigate the function of SmN, its localisation within different snRNP particles was investigated using a range of anti-snRNP monoclonal antibodies. SmN and SmB were found to exhibit different patterns of association with snRNP particles in two cell lines, ND7 and F9 which express SmN. In both cases, SmN was found to be present in the U-2 snRNP but was excluded from the U-1 snRNPs whereas SmB was present in both U-1 and U-2 snRNPs. Data from transfected 3T3 mouse fibroblasts cell lines artificially expressing a low level of SmN also confirm this observation. In contrast, SmN was found to be an integral component of both the U-1 and U-2 snRNPs in both 3T3 cells artificially expressing high levels of SmN and in adult rat brain which has a naturally high level of SmN expression. Taken together, the results suggest that the pre-U1 snRNP particle has a lower affinity for SmN than for SmB. Thus, SmN expressed at low levels incorporates into U2, but SmN expressed at high levels incorporates into both U1 and U2 snRNPs and replaces SmB. The significance of these effects is discussed in terms of the potential role played by SmN in constitutive and alternative splicing pathways in neuronal cells.

3T3 Cells↗
PubMed1993

A distal region of the CALC-1 gene is necessary for regulated alternative splicing.

The CALC-1 gene exhibits tissue specific alternative splicing with exons 1-4 being spliced to produce the calcitonin mRNA in thyroid C cells and exons 1-3 and 5-6 being joined to produce the CGRP mRNA in neuronal cells. Previous studies have identified an element in intron 3 within the alternatively spliced region which is critical for this effect to occur. We show here that deletion of sequences downstream of the alternatively spliced region also disrupts the tissue specific pattern of alternative splicing. The manner in which these sequences act is discussed.

Alternative Splicing↗
PubMed1993

Molecular cloning of a human neuronal nicotinic acetylcholine receptor beta 3-like subunit.

Three cDNA clones homologous to rat neuronal nicotinic receptors were identified in a human brain stem library by screening at low stringency with a mixture of rat alpha 5, beta 2 and beta 4 subunit probes. Positive clones were further analysed by hybridisation at higher stringency with individual rat nicotinic receptor probes. One positive clone was found to encode a protein that exhibited characteristic features of a member of the ligand-gated ion channel class of protein subunits, and showed 89% homology with a rat beta 3 neuronal nicotinic receptor subunit. Northern blots demonstrated the presence of a 1.7 kb transcript in RNA extracted from adult human Pons. This clone has therefore been designated the human beta 3 neuronal nicotinic receptor subunit.

Amino Acid Sequence↗
PubMed1993

Alternative splicing of the mRNA encoding the alpha subunits of the G(o) GTP-binding protein during brain development and in neuronal cell lines.

The RNA encoding the alpha subunit of the G(o) GTP-binding protein is alternatively spliced in some tissues to produce mRNAs encoding two distinct forms of the protein which differ at the carboxyl terminus. This alternative splicing process is observed at all stages during development of the rat brain and heart and in some but not all neuronal cell lines. These effects are discussed both in terms of the regulation of the alternative splicing event and the functional role(s) of the two forms of the protein which it produces.

3T3 Cells↗
PubMed1993

The octamer binding site in the HPV16 regulatory region produces opposite effects on gene expression in cervical and non-cervical cells.

The upstream regulatory region (URR) of the tumorigenic human papillomaviruses HPV 16 and 18 contains an octamer binding site which is located adjacent to a binding site for the ubiquitous transcription factor NFI. The octamer site binds both the constitutively expressed transcription factor Oct-1 and a novel cervical octamer binding protein. In contrast the URR of the non-tumorigenic viruses HPV6 and HPV11 lacks the octamer binding site although the adjacent NFI site is conserved. Inactivation of the octamer binding site results in a higher level of gene expression in cells which contain only Oct-1 and a lower level in cells containing the cervical octamer binding protein indicating that that whilst Oct-1 binding reduces promoter activity, the cervical protein increases it. In agreement with this, over-expression of Oct-1 reduces the level of gene activity directed by this region of the HPV 16/18 URR and inhibits its activation by NFI whilst having no effect on the corresponding region of the HPV 6/11 URR. The significance of these effects is discussed in terms of the cervical-specific activity of the HPV16/18 URR and its role in HPV-mediated transformation.

Base Sequence↗
PubMed1993

Human sperm-egg binding is inhibited by peptides corresponding to core region of an acrosomal serine protease inhibitor.

An antiserum, designated R4 and raised against denatured hamster acrosomes, was shown to localize specifically to the acrosomal region of hamster, rat, mouse, and human spermatozoa, and to inhibit both hamster and human sperm-oocyte binding in vitro. Following screening of a human testis lambda gt11 cDNA expression library with the antiserum R4, a series of cDNA clones were isolated. One (cDNA 134) was selected based on the ability of the beta-galactosidase fusion protein to inhibit human and hamster sperm-zona binding in vitro. The fusion protein was also shown to inhibit the penetration of zona-free hamster oocytes by human spermatozoa. Sequence analysis revealed that cDNA 134 coded for a portion of a serine protease inhibitor (serpin) closely related to plasma Protein C inhibitor. Sequencing of an additional cDNA clone (261) and Northern blot analysis confirmed that a Protein C inhibitor-like mRNA is synthesised in the human testis. Affinity-purified anti-134 antibody specifically localized to the acrosomal region of both hamster and human sperm. Synthetic peptides corresponding to the conserved core region responsible for the interaction of the serpin with its cognate protease also blocked human sperm-zona binding in vitro. The results suggest that this acrosomally located inhibitor plays an important role in the series of binding events that results in human fertilization.

Acrosome↗
PubMed1993

Expression of the SmN splicing protein is developmentally regulated in the rodent brain but not in the rodent heart.

The SmN protein is a tissue-specific splicing factor which is closely related to the ubiquitous SmB splicing protein but which is expressed only in the adult brain and heart. SmN is also detectable albeit at a low level in both the embryonic brain and heart. During heart development, SmN levels remain constant while during rodent brain development the levels of SmN rise such that SmN replaces SmB as the predominant protein in adult brain. This increase in SmN levels is dependent upon a corresponding increase in the SmN mRNA which is detectable by in situ hybridization within neurons in virtually all areas of the adult brain.

Animals↗