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E H Leiter

Publications and source records attributed to E H Leiter.

At least 19 recordsLinked to original sources
PubMed2005

mt-Nd2 Allele of the ALR/Lt mouse confers resistance against both chemically induced and autoimmune diabetes.

AIMS/HYPOTHESIS: ALR/Lt, a mouse strain with strong resistance to type 1 diabetes, is closely related to autoimmune type 1 diabetes-prone NOD/Lt mice. ALR pancreatic beta cells are resistant to the beta cell toxin alloxan, combinations of cytotoxic cytokines, and diabetogenic NOD T-cell lines. Reciprocal F1 hybrids between either ALR and NOD or ALR and NON/Lt, showed that alloxan resistance was transmitted to F1 progeny only when ALR was the maternal parent. Here we show that the mitochondrial genome (mtDNA) of ALR mice contributes resistance to diabetes. METHODS: When F1 progeny from reciprocal outcrosses between ALR and NOD were backcrossed to NOD, a four-fold lower frequency of spontaneous type 1 diabetes development occurred when ALR contributed the mtDNA. Because of the apparent interaction between nuclear and mtDNA, the mitochondrial genomes were sequenced. RESULTS: An ALR-specific sequence variation in the mt-Nd2 gene producing a leucine to methionine substitution at amino acid residue 276 in the NADH dehydrogenase 2 was discovered. An isoleucine to valine mutation in the mt-Co3 gene encoding COX3 distinguished ALR and NOD from NON and ALS. All four strains were distinguished by variation in a mt-encoded arginyl tRNA polyadenine tract. Shared alleles of mt-Co3 and mt-Tr comparing NOD and ALR allowed for exclusion of these two genes as candidates, implicating the mt-Nd2 variation as a potential ALR-derived type 1 diabetes protective gene. CONCLUSIONS/INTERPRETATION: The unusual resistance of ALR mice to both ROS-mediated and autoimmune type 1 diabete stresses reflects an interaction between the nuclear and mt genomes. The latter contribution is most likely via a single nucleotide polymorphism in mt-Nd2.

Animals↗
PubMed2005

Conditioning the genome identifies additional diabetes resistance loci in Type I diabetes resistant NOR/Lt mice.

While sharing the H2g7 MHC and many other important Type I diabetes susceptibility (Idd) genes with NOD mice, the NOR strain remains disease free due to resistance alleles within the approximately 12% portion of their genome that is of C57BLKS/J origin. Previous F2 segregation analyses indicated multiple genes within the 'Idd13' locus on Chromosome 2 provide the primary component of NOR diabetes resistance. However, it was clear other genes also contribute to NOR diabetes resistance, but were difficult to detect in the original segregation analyses because they were relatively weak compared to the strong Idd13 protection component. To identify these further genetic components of diabetes resistance, we performed a new F2 segregation analyses in which NOD mice were outcrossed to a 'genome-conditioned' NOR stock in which a large component of Idd13-mediated resistance was replaced with NOD alleles. These F2 segregation studies combined with subsequent congenic analyses confirmed the presence of additional NOR resistance genes on Chr. 1 and Chr. 4, and also potentially on Chr. 11. These findings emphasize the value for diabetes gene discovery of stratifying not only MHC loci conferring the highest relative risk but also as many as possible of the non-MHC loci presumed to contribute significantly.

Alleles↗
PubMed2002

Mice with targeted gene disruptions or gene insertions for diabetes research: problems, pitfalls, and potential solutions.

The mouse has been a favoured organism for molecular manipulation in studies seeking to establish the genetic bases and pathophysiologic mechanisms underlying both Type I (insulin-dependent) and Type II (non-insulin-dependent) diabetes mellitus. Gene targeting and transgenesis are the two powerful molecular technologies used in these endeavours. Interpretation of results generated from such studies, either entailing an altered phenotype or the absence of a phenotypic change, is not always simple. This review focuses on certain complications inherent in the methodologies, and outlines steps that can be taken to distinguish effects of the genetic manipulation from unexpected contributions from the genetic background.

Animals↗
PubMed2001

A major quantitative trait locus on chromosome 3 controls colitis severity in IL-10-deficient mice.

Colitic lesions are much more severe in C3H/HeJBir (C3H) than C57BL/6J (B6) mice after 10 backcrosses of a disrupted interleukin-10 (Il10) gene. This study identified cytokine deficiency-induced colitis susceptibility (Cdcs) modifiers by using quantitative trait locus (QTL) analysis. A segregating F(2) population (n = 408) of IL-10-deficient mice was genotyped and necropsied at 6 weeks of age. A major C3H-derived colitogenic QTL (Cdcs1) on chromosome (Chr.) 3 contributed to lesions in both cecum [logarithm of odds ratio (LOD) = 14.6)] and colon (LOD = 26.5) as well as colitis-related phenotypes such as spleen/body weight ratio, mesenteric lymph node/body weight ratio, and secretory IgA levels. Evidence for other C3H QTL on Chr. 1 (Cdcs2) and Chr. 2 (Cdcs3) was obtained. Cdcs1 interacted epistatically or contributed additively with loci on other chromosomes. The resistant B6 background also contributed colitogenic QTL: Cdcs4 (Chr. 8), Cdcs5 (Chr. 17, MHC), and Cdcs6 (Chr. 18). Epistatic interactions between B6 QTL on Chr. 8 and 18 contributing to cecum hyperplasia were particularly striking. In conclusion, a colitogenic susceptibility QTL on Chr. 3 has been shown to exacerbate colitis in combination with modifiers contributed from both parental genomes. The complex nature of interactions among loci in this mouse model system, coupled with separate deleterious contributions from both parental strains, illustrates why detection of human inflammatory bowel disease linkages has proven to be so difficult. A human ortholog of the Chr. 3 QTL, if one exists, would map to Chr. 4q or 1p.

Animals↗
PubMed2001

Structure, chromosomal localization, and expression of the gene for mouse ecto-mono(ADP-ribosyl)transferase ART5.

Mono(ADP-ribosyl)transferases regulate the function of target proteins by attaching ADP-ribose to specific amino acid residues in their target proteins. The purpose of this study was to determine the structure, chromosomal localization, and expression profile of the gene for mouse ecto-ADP-ribosyltransferase ART5. Southern blot analyses indicate that Art5 is a single copy gene which maps to mouse chromosome 7 at offset 49.6 cM in close proximity to the Art1, Art2a and Art2b genes. Northern blot and RT-PCR analyses demonstrate prominent expression of Art5 in testis, and lower levels in cardiac and skeletal muscle. Sequence analyses reveal that the Art5 gene encompasses six exons spanning 8 kb of genomic DNA. The 5' end of the Art5 gene overlaps with that of the Art1 gene. A single long exon encodes the predicted ART5 catalytic domain. Separate exons encode the N-terminal leader peptide and a hydrophilic C-terminal extension. Sequencing of RT-PCR products and ESTs identified six splice variants. The deduced amino acid sequence of ART5 shows 87% sequence identity to its orthologue from the human, and 37 and 32% identity to its murine paralogues ART1 and ART2. Unlike ART1 and ART2, ART5 lacks a glycosylphosphatidylinositol-anchor signal sequence and is predicted to be a secretory enzyme. This prediction was confirmed by transfecting an Art5 cDNA expression construct into Sf9 insect cells. The secreted epitope-tagged ART5 protein resembled rat ART2 in exhibiting potent NAD-glycohydrolase activity. This study provides important experimental tools to further elucidate the function of ART5.

ADP Ribose Transferases↗
PubMed2001

Inhibition of autoimmune diabetes in nonobese diabetic mice by transgenic restoration of H2-E MHC class II expression: additive, but unequal, involvement of multiple APC subtypes.

Transgenic restoration of normally absent H2-E MHC class II molecules on APC dominantly inhibits T cell-mediated autoimmune diabetes (IDDM) in nonobese diabetic (NOD) mice. We analyzed the minimal requirements for transgenic H2-E expression on APC subtypes (B lymphocytes vs macrophages/dendritic cells (DC)) to inhibit IDDM. This issue was addressed through the use of NOD stocks transgenically expressing high levels of H2-E and/or made genetically deficient in B lymphocytes in a series of genetic intercross and bone marrow/lymphocyte chimera experiments. Standard (H2-E(null)) NOD B lymphocytes exert a pathogenic function(s) necessary for IDDM. However, IDDM was inhibited in mixed chimeras where H2-E was solely expressed on all B lymphocytes. Interestingly, this resistance was abrogated when even a minority of standard NOD H2-E(null) B lymphocytes were also present. In contrast, in NOD chimeras where H2-E expression was solely limited to approximately half the macrophages/DC, an active immunoregulatory process was induced that inhibited IDDM. Introduction of a disrupted IL-4 gene into the NOD-H2-E transgenic stock demonstrated that induction of this Th2 cytokine does not represent the IDDM protective immunoregulatory process mediated by H2-E expression. In conclusion, high numbers of multiple subtypes of APC must express H2-E MHC class II molecules to additively inhibit IDDM in NOD mice. This raises a high threshold for success in future intervention protocols designed to inhibit IDDM by introduction of putatively protective MHC molecules into hemopoietic precursors of APC.

Animals↗
PubMed2001

Unusual resistance of ALR/Lt mouse beta cells to autoimmune destruction: role for beta cell-expressed resistance determinants.

Genetic analysis of autoimmune insulin-dependent diabetes mellitus (IDDM) has focused on genes controlling immune functions, with little investigation of innate susceptibility determinants expressed at the level of target beta cells. The Alloxan (AL) Resistant (R) Leiter (Lt) mouse strain, closely related to the IDDM-prone nonobese diabetic (NOD)/Lt strain, demonstrates the importance of such determinants. ALR mice are unusual in their high constitutive expression of molecules associated with dissipation of free-radical stress systemically and at the beta-cell level. ALR islets were found to be remarkably resistant to two different combinations of beta-cytotoxic cytokines (IL-1beta, tumor necrosis factor alpha, and IFN-gamma) that destroyed islets from the related NOD and alloxan-susceptible strains. The close MHC relatedness between the NOD and ALR strains (H2-Kd and H2-Ag7 identical) allowed us to examine whether ALR islet cells could survive autoimmune destruction by NOD-derived Kd-restricted diabetogenic cytotoxic T lymphocyte clones (AI4 and the insulin-reactive G9C8 clones). Both clones killed islet cells from all Kd-expressing strains except ALR. ALR resistance to diabetogenic immune systems was determined in vivo by means of adoptive transfer of the G9C8 clone or by chimerizing lethally irradiated ALR or reciprocal (ALR x NOD)F1 recipients with NOD bone marrow. In all in vivo systems, ALR and F1 female recipients of NOD marrow remained IDDM free; in contrast, all of the NOD recipients became diabetic. In conclusion, the ALR mouse presents a unique opportunity to identify dominant IDDM resistance determinants expressed at the beta cell level.

Adoptive Transfer↗
PubMed2000

Metalloprotease-mediated shedding of enzymatically active mouse ecto-ADP-ribosyltransferase ART2.2 upon T cell activation.

T cells proteolytically shed the ectodomains of several cell surface proteins and, thereby, can alter their responsiveness and can release soluble intercellular regulators. ART2.2 is a GPI-anchored ecto-ADP-ribosyltransferase (ART) related to ADP-ribosylating bacterial toxins. ART2.2 is expressed exclusively by mature T cells. Here we show that ART2.2 is shed from the cell surface in enzymatically active form upon activation of T cells. Shedding of ART2.2 resembles that of L-selectin (CD62L) in dose response, kinetics of release, and sensitivity to the metalloprotease inhibitor Immunex Compound 3, suggesting that ART2.2, like CD62L, is cleaved by TNF-alpha-converting enzyme or by another metalloprotease. ART2.2 shed from activated T cells migrates slightly faster in SDS-PAGE analyses than does ART2.2 released upon cleavage of the GPI anchor. This indicates that shedding of ART2.2 is mediated by proteolytic cleavage close to its membrane anchor. Shed ART2.2 is enzymatically active and ADP-ribosylates several substrates in vitro. Thus, shedding of ART2.2 releases a potential intercellular regulator. Finally, using a new FACS assay for monitoring ADP-ribosylation of cell surface proteins, we demonstrate that shedding of ART2.2 correlates with a reduced sensitivity of T cell surface proteins to ADP-ribosylation. Our findings suggest that by shedding ART2.2 the activated T cell not only releases a potential intercellular regulator but also may alter its responsiveness to immune regulation by ART2.2-mediated ADP-ribosylation of cell surface proteins.

ADP Ribose Transferases↗
PubMed2000

Heritable susceptibility for colitis in mice induced by IL-10 deficiency.

Severity of inflammatory bowel disease in IL-10 gene-targeted mice is in part determined by genetic background. In the current study, a targeted IL-10 gene was transferred into the C3H/HeJBir substrain, known to exhibit high T-cell and B-cell responses to enteric flora, and to be highly sensitive to colitigenic stress. IL-10-deficient C3H/HeJBir mice developed early onset colitis in contrast to IL-10-deficient C57BL/6J congenic mice. Histopathologic analysis of disease in C3H/HeJBir.Il10-/- and C57BL/6J.Il10-/- mice showed significant differences at all ages studied. Hybrids of these congenic strains (F1.Il10-/-) were produced to study the mode of inheritance as well as subphenotypes that correlated with histopathology. Lesions in F1 mice were intermediate between parental strains. C3H-contributed subphenotypes that correlated best with histopathology were peripheral blood granulocyte percentage, serum amyloid A concentration, spleen weight/body weight ratio, and mesenteric lymph node weight/ body weight ratio. Neither enhanced humoral immunity (secretory IgA, anti-Escherichia coli cellular membrane Ig) characteristic of C3H/HeJBir, nor T-cell percentages in peripheral blood correlated as well. This study represents a necessary step in elucidating murine genetic modifiers controlling colitis sensitivity.

Animals↗
PubMed2000

Mouse FcgammaRI: identification and functional characterization of five new alleles.

The mouse Fcgr1 gene encoding the high-affinity IgG receptor (FcgammaRI) exists as two known alleles, FcgammaRI-BALB and FcgammaRI-NOD, and these alleles exhibit functional differences. To determine whether other alleles exist in mouse strains, Fcgr1 coding regions from 35 strains of mice were sequenced and a further five alleles were identified. The FcgammaRI-BALB and NOD alleles are now designated the "a" and "d" alleles, respectively. Analysis of the five new alleles revealed that although no polymorphisms were observed in the two leader exons, nucleotide and subsequent amino acid changes were observed in the exons encoding the extracellular domains, and transmembrane and cytoplasmic tail. The cDNA of the seven alleles (a-g) were isolated and transiently transfected into COS cells, and IgG-binding studies were performed. Receptors encoded by four of the five new alleles (b, c, f, g) bound IgG2a with high affinity, displaying IgG binding characteristics similar to the a allele (previously FcgammaRI-BALB). The d allele (previously FcgammaRI-NOD) and the e allele [derived from Mus spretus (SPRET/Ei)] encoded receptors which showed broader specificity by binding monomeric IgG2a, IgG2b, and IgG3.

Alleles↗
PubMed2000

Maternal environment and genotype interact to establish diabesity in mice.

Obesity, a major risk factor for type II diabetes, is becoming more prevalent in Western populations consuming high calorie diets while expending less energy both at the workplace and at home. Most human obesity, and probably most type II diabetes as well, reflects polygenic rather than monogenic inheritance. We have genetically dissected a polygenic mouse model of obesity-driven type II diabetes by outcrossing the obese, diabetes-prone, NZO (New Zealand Obese)/HlLt strain to the relatively lean NON (Nonobese Nondiabetic)/Lt strain, and then reciprocally backcrossing obese F1 mice to the lean NON/Lt parental strain. A continuous distribution of body weights was observed in a population of 203 first backcross males. The 22% of first backcross males developing overt diabetes showed highest peripubertal weight gains and earliest development of hyperinsulinemia. We report a complex diabetes-predisposing ("diabesity") QTL (Quantitative Trait Loci) on chromosome 1 contributing significant main effects to increases in body weight, plasma insulin, and plasma glucose. NZO contributed QTL with significant main effects on adiposity parameters on chromosomes 12 and 5. A NON QTL on chromosome 14 interacted epistatically with the NZO obesity QTL on chromosome 12 to increase adiposity. Although the main effect of the diabetogenic QTL on chromosome 1 was on rapid growth rather than adiposity, it interacted epistatically with the obesity QTL on chromosome 12 to increase plasma glucose levels. Additional complex epistatic interactions eliciting significant increases in body weight and/or plasma glucose were found between the NZO-contributed QTL on chromosome 1 and other NZO-contributed QTL on chromosomes 15 and 17, as well as with an NON-contributed QTL on chromosome 2. We further show that certain of these intergenic interactions are predicated on, or enhanced by, the maternal postparturitional environment. We show by cross-fostering experiments that the maternal environmental influence in part is because of the presence of early obesity-inducing factors in the milk of obese F1 dams. We also discuss a strategy for using recombinant congenic strains to separate and reassemble interacting QTL for future study.

Animals↗
PubMed2000

Reevaluation of the major histocompatibility complex genes of the NOD-progenitor CTS/Shi strain.

The common Kd and/or Db alleles of NOD mice contribute to the development of autoimmune diabetes, but their respective contributions are unresolved. The major histocompatibility complex (MHC) of the CTS/Shi mouse, originally designated as H2ct, shares MHC class II region identity with the H2g7 haplotype of NOD mice. However, CTS mice were reported to express distinct but undefined MHC class I gene products. Because diabetes frequency was reduced 56% in females of a NOD stock congenic for H2ct, this partial resistance may have derived from the MHC class I allelic differences. In the present report, we use a combination of serologic analysis and sequencing of MHC class I cDNAs to establish that NOD/Lt and CTS/Shi share a common H2-Kd allele but differ at the H2-D end of the MHC complex. The H2-D allele of CTS/Shi was identified as the rare H2-Ddx recently described in ALR/Lt, another NOD-related strain. These results in mouse model systems show that multiple MHC genes confer diabetes resistance and suggest that at least one of the protective MHC or MHC-linked genes in CTS mice may be at the H2-D end of the complex.

Alleles↗
PubMed1999

A new monoclonal antibody detects a developmentally regulated mouse ecto-ADP-ribosyltransferase on T cells: subset distribution, inbred strain variation, and modulation upon T cell activation.

ADP-ribosylation of membrane proteins on mouse T cells by ecto-ADP-ribosyltransferase(s) (ARTs) can down-regulate proliferation and function. The lack of mAbs against mouse ARTs has heretofore prevented analysis of ART expression on T cell subsets. Using gene gun technology, we immunized a Wistar rat with an Art2b expression vector and produced a novel mAb, Nika102, specific for ART2.2, the Art2b gene product. We show that ART2.2 is expressed as a GPI-anchored protein on the surface of mature T cells. Inbred strain-dependent differences in ART2.2 expression levels were observed. C57BL/6J and C57BLKS/J express the Ag at high level, with up to 70% of CD4+ and up to 95% of CD8+ peripheral T cells expressing ART2.2. CBA/J and DBA/2J represent strains with lowest expression levels. T cell-deficient mice and NZW/LacJ mice with a defective structural gene for this enzyme were ART2.2 negative. In the thymus, ART2.2 expression is restricted to subpopulations of mature cells. During postnatal ontogeny, increasing percentages of T cells express ART2.2, reaching a peak at 6-8 wk of age. Interestingly, ART2.2 and CD25 are reciprocally expressed: activation-induced up-regulation of CD25 is accompanied by loss of ART2.2 from the cell surface. Nika102 thus defines a new differentiation/activation marker of thymic and postthymic T cells in the mouse and should be useful for further elucidating the function of the ART2.2 cell surface enzyme.

ADP Ribose Transferases↗
PubMed1999

Genetic analysis of susceptibility to dextran sulfate sodium-induced colitis in mice.

The genetic basis for differential sensitivity of inbred mice to inflammatory bowel disease induced by dextran sulfate sodium (DSS) is unknown. Susceptible C3H/HeJ were outcrossed to partially resistant C57BL/6J mice. F2 and N2 progeny were phenotyped by evaluating histopathologic lesions in large intestine detected 16 days after a 5-day period of feeding 3.5% DSS. Screening for DSS colitis (Dssc) loci revealed quantitative trait loci (QTL) on Chr 5 (Dssc1) and Chr 2 (Dssc2). These traits contributed additively, explaining 17.5% of the variation in total colonic lesions. Additional QTL on Chr 18 and 1 that collectively explained 11% of the variation in total colon lesions were indicated. In the cecum, only a putative QTL on Chr 11 was associated with pathology (lesion severity) in the cecum. Reduced DSS susceptibility was observed in congenic stocks in which the highly susceptible NOD/Lt strain carried putative resistance alleles from either B6 on Chr 2 or from the highly resistant NON/Lt strain on Chr 9. We conclude that multiple genes control susceptibility to DSS colitis in mice. Possible Dssc candidate genes are discussed in terms of current knowledge of inflammatory bowel disease susceptibility loci in humans.

Animals↗
PubMed1999

Genotypic and phenotypic characterization of six new recombinant congenic strains derived from NOD/Shi and CBA/J genomes.

Recombinant Congenic Strains (RCS) are useful for dissecting complex polygenic traits. Here, we describe genetic and phenotypic characterization of six new RCS generated from outcrosses between NOD/Shi and CBA/LsLt, followed by sib mating of first backcross progeny (to CBA) for 20 generations, whereupon genetic and phenotypic analysis commenced. Four of the RCS were selected on the basis of residual heterozygosity present at F20 in one of the three original RCS. Contrary to expectations for RCS developed at first backcross, all derived at least 50% of the polymorphic markers typed from the NOD parental strain. Development of autoimmune insulin-dependent diabetes mellitus (IDDM) in NOD is a strain-specific characteristic. The major genetic component predisposing NOD mice to IDDM, their H2(g7) haplotype, was present in all RCS. Nevertheless, the presence of variable amounts of CBA genome at non-MHC loci conferred complete resistance in all RCS to spontaneous IDDM development, and rendered them strongly resistant to cyclophosphamide-induced IDDM. Although the RCS more resemble NOD in regard to certain strain-specific characteristics, such as prolificacy, an immunologic phenotype that was significantly reduced when compared to both parental strains was the number of peripheral CD8(+) T cells. Given the genetic characterization presented, these new RCS should prove valuable to investigators interested in studying genes controlling differential susceptibilities distinguishing the NOD and CBA inbred strain backgrounds.

Animals↗