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K J Moore

Publications and source records attributed to K J Moore.

At least 55 records · Page 3Linked to original sources
PubMed1998

In vitro-differentiated embryonic stem cell macrophages: a model system for studying atherosclerosis-associated macrophage functions.

Monocytes/macrophages (Mo) appear to play a critical role in the initiation and progression of atherosclerotic lesions. In this study, we characterized in vitro-differentiated embryonic stem (ES) cell macrophages as a model system for studying atherosclerosis-associated Mo functions. Using immunofluorescence staining and Western analysis, we demonstrate that ES Mo express typical macrophage cell surface markers, as well as the known receptors for modified forms of low density lipoprotein (LDL), including the Mo scavenger receptors (SR-A type I and type II), CD36, and CD68. Differentiated ES Mo specifically bind and degrade 125I-labeled acetylated LDL with high affinity, and their incubation with acetylated LDL (15 microg/mL) for 48 hours produces characteristic "foamy" Mo, as visualized by oil red O staining. ES Mo also express matrix-degrading metalloproteinases (MMP-3, MMP-9), which have been implicated in collagen breakdown in the fibrous cap of atherosclerotic plaques, and secrete cytokines (tumor necrosis factor-alpha, interleukin-6) in response to inflammatory stimuli. Transfection experiments, using a green fluorescent protein reporter gene, driven by the myeloid-specific promoter, CD11b, demonstrated that ES Mo can also be used to study macrophage-restricted gene expression in vitro. Taken together, these data demonstrate that ES Mo exhibit many properties typical of arterial lesion macrophages. Its ease of genetic manipulation makes it an attractive system for investigations of macrophage functions in vitro.

Antigens, CD↗
PubMed1997

The physical and genetic map surrounding the Lyst gene on mouse chromosome 13.

During the recent cloning of the mouse Lyst gene we developed both a high-resolution genetic map and a complete YAC and BAC contig of the Lyst critical region on mouse Chromosome 13. We also report the mapping of the human homologue of the mouse Lyst gene (LYST) to 1q43. These data are consistent with LYST being the gene for the human Chediak-Higashi Syndrome and strengthen the synteny relationship between MMU13 and human 1q43.

Animals↗
PubMed1997

Theoretical and empirical issues for marker-assisted breeding of congenic mouse strains.

Congenic breeding strategies are becoming increasingly important as a greater number of complex trait linkages are identified. Traditionally, the development of a congenic strain has been a time-consuming endeavour, requiring ten generations of backcrosses. The recent advent of a dense molecular genetic map of the mouse permits methods that can reduce the time needed for congenic-strain production by 18-24 months. We present a theoretical evaluation of marker-assisted congenic production and provide the empirical data that support it. We present this 'speed congenic' method in a user-friendly manner to encourage other investigators to pursue this or similar methods of congenic production.

Animals↗
PubMed1997

Mutations in the Chediak-Higashi syndrome gene (CHS1) indicate requirement for the complete 3801 amino acid CHS protein.

Chediak-Higashi syndrome (CHS) is a rare, usually fatal, autosomal recessive disorder characterized by severe immunologic defects, reduced pigmentation, progressive neurologic dysfunction and a bleeding diathesis. The hallmark of CHS is giant organelles and giant granules in many different cell types, most likely the result of defective trafficking of specific organellar and granular proteins necessary for the normal genesis, structure or function of these cytoplasmic components. The CHS1 gene has recently been identified and shown to be homologous to the beige locus of the mouse; however, there has been disagreement as to the length of the functional CHS1 mRNA and protein. Here we report homozygous CHS1 gene mutations in two of the original probands we used to map the gene to 1q42-q44. One of these, a frameshift at codon 3197, supports our assertion that the functional CHS protein is a predicted 3801 amino acid polypeptide encoded by a 13.5 kb mRNA.

Chediak-Higashi Syndrome↗
PubMed1997

Relationships between in situ protein degradability and grass developmental morphology.

The objective of this research was to determine the relationships between the morphological development and in situ ruminally degradable protein (RDP), ruminally undegradable protein (RUP), and microbial protein of two cool season grasses (intermediate wheatgrass and smooth bromegrass) and two warm season grasses (switchgrass and big bluestem). The initial growth of grass tillers grown near Mead, Nebraska was clipped at ground level six times during the 1992 growing season and morphologically classified. Mean stage was calculated. Forage was ground to pass a 2-mm screen and was incubated in ruminally fistulated steers for 16 h. The RUP was adjusted for microbial protein and acid detergent insoluble N. The mean stage of cool season grasses was higher than that of warm season grasses throughout the growing season. The RDP decreased as plant maturity increased for all species. The RUP expressed as a percentage of crude protein for the cool season grasses was lower than that for warm season grasses. The RUP for intermediate wheatgrass, smooth bromegrass, and switchgrass remained constant across maturities, but RUP for big bluestem decreased as maturity increased. Microbial augmentation of RUP decreased as crude protein decreased in all species. The RUP corrected for acid detergent insoluble N and microbial protein was relatively constant across plant maturities. The quantification of RUP across a range of plant maturities provided information for incorporating RUP content of forage grasses into the diets of animals.

Analysis of Variance↗
PubMed1996

Multiple mouse chromosomal loci for dynein-based motility.

Dyneins are multisubunit mechanochemical enzymes capable of interacting with microtubules to generate force. Axonemal dyneins produce the motive force for ciliary and flagellar beating by inducing sliding between adjacent microtubules within the axoneme. Cytoplasmic dyneins translocate membranous organelles and chromosomes toward the minus ends of cytoplasmic microtubules. Dynactin is an accessory complex implicated in tethering cytoplasmic dynein to membranous organelles and mitotic kinetochores. In the studies described here, we have identified a number of new dynein genes and determined their mouse chromosomal locations by interspecific backcross analysis. We have also mapped several dynein and dynactin genes cloned previously. Our studies provide the first comprehensive attempt to map dynein and dynactin genes in mammals and provide a basis for the further analysis of dynein function in development and disease.

Amino Acid Sequence↗
PubMed1996

TNF-alpha enhances colony-stimulating factor-1-induced macrophage accumulation in autoimmune renal disease.

The lpr mutation on the MRL background accelerates autoimmune nephritis in which macrophage (M phi) accumulation is prominent. Renal disease is absent in other strains with lpr. TNF-alpha and CSF-1 are increased in the kidney of MRL-lpr mice with loss of renal function. We have established that CSF-1 can incite renal injury in mice with the lpr mutation, and M phi from the MRL strain hyper-respond to this growth factor. We hypothesized that TNF-alpha enhanced the M phi response to CSF-1 in MRL-lpr mice. We now report that TNF-alpha enhanced CSF-1-induced bone marrow M phi proliferation in MRL-lpr mice, and not in congenic MRL +/+, normal C3H +/+, and BALB/c, or another strain with lpr (C3H-lpr). Using a gene transfer approach to deliver CSF-1 together with TNF-alpha into the kidney, we evaluated the impact on renal injury. Tubular epithelial cells genetically modified to produce CSF-1 (CSF-1-TEC) and TNF-alpha (TNF-TEC) placed under the renal capsule caused a greater accumulation of M phi in the implant site than CSF-1-TECs alone in MRL-lpr, but not MRL +/+ mice. We noted in tissues adjacent but not distal to the implanted TECs, an increase in M phi in the interstitium and surrounding glomeruli of MRL-lpr but not MRL +/+ mice. This indicated that CSF-1 and TNF-alpha released by TECs were responsible for promoting renal pathology. Taken together, these data suggest that the simultaneous expression of TNF-alpha and CSF-1 in the MRL-lpr kidney fosters M phi accumulation. We speculate that the increase in M phi in the kidney in response to CSF-1 and TNF-alpha is responsible for the rapid tempo of autoimmune renal injury in MRL-lpr mice.

Adjuvants, Immunologic↗
PubMed1996

Enhanced response of macrophages to CSF-1 in autoimmune mice: a gene transfer strategy.

Mice with the MRL background have a genetic propensity for autoimmune lupus nephritis. The lpr mutation on the MRL, but not the C3H background, induces rapid and fatal renal injury in which macrophages (M phi) are prominent. We previously established that CSF-1 accompanies M phi accumulation in the kidney of MRL-lpr mice. Furthermore, CSF-1 introduced into the kidney incites renal injury in mice with the lpr mutation, but not congenic strains. Notably, CSF-1 induces more severe tissue injury in MRL-lpr than in C3H-lpr mice. We hypothesized that M phi from the MRL background respond more readily to CSF-1 than normal strains. We establish herein the following: 1) glomerular M phi and bone marrow M phi (BMM phi) from MRL-lpr mice proliferate similarly to CSF-1; 2) MRL BMM phi proliferate more vigorously to CSF-1 than normal strains (C3H, BALB/c) or another strain with lpr (C3H-lpr); and 3) modulation of CSF-1 receptor expression by CSF-1 is more rapid in MRL than C3H BMM phi. We used a gene transfer strategy to deliver CSF-1 into the kidney to evaluate M phi response to CSF-1. We genetically modified tubular epithelial cells to produce CSF-1 (CSF-1-TECs) and placed these cells with BMM phi under the renal capsule. CSF-1-TEC + BMM phi caused a greater accumulation of M phi in the implant site and interstitium of MRL +/+ than C3H +/+ mice. Furthermore, CSF-1-TEC + BMM phi caused a lesion consisting of M phi in MRL +/+ mice, extending from the implant into the adjacent cortex. We suggest that the response of MRL M phi to CSF-1 is responsible for the notable accumulation of M phi in the MRL-lpr kidney.

Animals↗
PubMed1996

ATPase activity of Escherichia coli Rep helicase is dramatically dependent on DNA ligation and protein oligomeric states.

The Escherichia coli Rep helicase catalyzes the unwinding of duplex DNA using the energy derived from ATP binding and hydrolysis. Rep functions as a dimer but assembles to its active dimeric form only on binding DNA. Each promoter of a dimer contains a DNA binding site that can bind either single-stranded (S) or duplex (D) DNA. The dimer can bind up to two oligodeoxynucleotides in five DNA-ligation states: two half-ligated states, P2S and P2D, and three fully-ligated states, P2S2, P2D2, and P2SD. We have previously shown that the relative stabilities of these ligation states are allosterically regulated by the binding and hydrolysis of ATP and have proposed an "active rolling" model for DNA unwinding where the enzyme cycles through a series of these ligation states in a process that is coupled to the catalytic cycle of ATP hydrolysis [Wong, I., & Lohman, T.M., (1992), Science 256, 350-355]. THe basal ATPase activity of Rep protein is stimulated by ss DNA binding and by protein dimerization. We have measured the steady-state ATPase activities of Rep bound to dT(pT)15 in each distinct ss DNA ligation state (PS, P2S, and P2S2) to compare with our previous measurements with unligated Rep monomer (P) [Moore, K.J.M., & Lohman, T.M. (1994) Biochemistry 33, 14550]. We find the ATPase activity of Rep is influenced dramatically by both dimerization and ss DNA ligation state, with the following kcat values for ATP hydrolysis increasing by over 4 orders of magnitude: 2.1 x 10(-3) s(-1) for P, 2.17 +/- 0.04 s(-1) for PS, 16.5 +/- 0.2 s(-1) for P2S, and 71 +/- 2.5 s(-1) for P2S2 (20 mM Tris-HCl, pH 7.5, 6mM NaCl, 5 mM MgCl2, 10% glycerol, 4 degrees C). The apparent KM's for ATP hydrolysis are 2.05 +/- 0.1 microM for PS and 2.7 +/- 0.2 microM for P2S. These widely different ATPase activities reflect the allosteric effects of DNA ligation and demonstrate that cooperative communication occurs between the ATP and DNA site of both subunits of the Rep dimer. These results further emphasize the need to explicitly consider the population distribution of oligomerization and DNA ligation states of the helicase when attempting to infer information about elementary processes such as helicase translocation based solely on macroscopic steady-state ATPase measurements.

Adenosine Triphosphatases↗
PubMed1996

Identification and characterization of the mouse obesity gene tubby: a member of a novel gene family.

The mutated gene responsible for the tubby obesity phenotype has been identified by positional cloning. A single base change within a splice donor site results in the incorrect retention of a single intron in the mature tub mRNA transcript. The consequence of this mutation is the substitution of the carboxy-terminal 44 amino acids with 24 intron-encoded amino acids. The normal transcript appears to be abundantly expressed in the hypothalamus, a region of the brain involved in body weight regulation. Variation in the relative abundance of alternative splice products is observed between inbred mouse strains and appears to correlate with an intron length polymorphism. This allele of tub is a candidate for a previously reported diet-induced obesity quantitative trait locus on mouse chromosome 7.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Kinetic mechanism of DNA binding and DNA-induced dimerization of the Escherichia coli Rep helicase.

The monomeric Escherichia coli Rep protein undergoes a DNA-induced dimerization upon binding either single-stranded (ss) or duplex DNA with the dimer being the active form of the Rep helicase. Using stopped-flow fluorescence, we have determined a minimal kinetic mechanism for this reaction in which Rep monomer (P) binds to ss oligodeoxynucleotides (dN(pN)15) (S) by a two-step mechanism to form PS*, which can then dimerize with P to form P2S as indicated: [reaction in text]. This minimal mechanism is supported by four independent studies in which the kinetics were monitored by changes in fluorescence intensity of three different probes: the intrinsic Rep tryptophan fluorescence, the fluorescence of d(T5(2-AP)T4(2-AP)T5), containing the fluorescent base, 2-aminopurine (2-AP), and dT(pT)15 labeled at its 3'-end with fluorescein (3'-F-dT(pT)15). Simultaneous (global) analysis of the time courses of d(T5(2-AP)T4(2-AP)T5) (100 nM) binding to a range of Rep monomer concentrations (25-400 nM) yields the following rate constants: k1 = (3.3 +/- 0.5) x 10(7) M-1 s-1; k-1 = 1.4 +/- 0.4 s-1; k2 = 2.7 +/- 0.9 s-1; k-2 = 0.21 +/- 0.06 s-1; k3 = (4.5 +/- 0.3) x 10(5) M-1 s-1; k-3 = 0.0027 +/- 0.0008 s-1 [20 mM Tris-HCl, pH 7.5, 6 mM NaCl, 5 mM MgCl2, 5 mM 2-mercaptoethanol, and 10% (v/v) glycerol, 4.0 degrees C]. This mechanism provides direct evidence that Rep monomers can bind ss DNA and that ss DNA binding induces a conformational change in the Rep monomer that is probably required for Rep dimerization. This conformational change is likely to be large and global since it is detected by all three fluorescence probes. The apparent bimolecular rate constant for Rep monomer binding to 3'-F-dT(pT)15 [k1(app) = (6.0 +/- 0.7) x 10(7) M-1 s-1] is slightly larger than measured with d(T5(2-AP)T4(2-AP)T5) binding. The apparent rate constant for dissociation of d(T5(2-AP)T4(2-AP)T5) (S) from the half-ligated Rep dimer, P2S, increases with increasing concentration of a nonfluorescent competitor ss DNA (d(T5-AT4AT5)) (C), indicating transient formation of a doubly ligated P2SC intermediate. However, the apparent bimolecular rate constant for binding of C to P2S is extremely slow (> or = 250 M-1 s-1), suggesting the occurrence of a multistep process before dissociation of ss DNA. In the absence of competitor DNA, dissociation of ss DNA from P2S occurs only after slow dissociation of the Rep dimer to form PS* + P. The implications of these results for Rep-catalyzed DNA unwinding are discussed.

Adenosine Triphosphatases↗
PubMed1996

Evidence that the diabetes gene encodes the leptin receptor: identification of a mutation in the leptin receptor gene in db/db mice.

OB-R is a high affinity receptor for leptin, an important circulating signal for the regulation of body weight. We identified an alternatively spliced transcript that encodes a form of mouse OB-R with a long intracellular domain. db/db mice also produce this alternatively spliced transcript, but with a 106 nt insertion that prematurely terminates the intracellular domain. We further identified G --> T point mutation in the genomic OB-R sequence in db/db mice. This mutation generates a donor splice site that converts the 106 nt region to a novel exon retained in the OB-R transcript. We predict that the long intracellular domain form of OB-R is crucial for initiating intracellular signal transduction, and as a corollary, the inability to produce this form of OB-R leads to the severe obese phenotype found in db/db mice.

Alternative Splicing↗
PubMed1996

Rapid in situ harvesting and cytogenetic analysis of perinatal tissue samples.

Thirty perinatal solid tissue samples were used in a pilot study to test the efficacy of collagenase disaggregation onto coverslips, open system culture under low O2 conditions, pre-harvest incubation in bromodeoxyuridine (BrdU) and colcemid, and in situ automated harvesting. Following the success of the pilot study, the new method was applied to a further 126 consecutive diagnostic samples making a total of 156. The method reduced average tissue culture times from 17 to 8.7 days (range 2-17), improved success rates from 76 to 88 per cent, and simultaneously increased the resolution of cytogenetic analysis.

Amnion↗
PubMed1996

Identification of the murine beige gene by YAC complementation and positional cloning.

The beige mutation is a murine autosomal recessive disorder, resulting in hypopigmentation, bleeding and immune cell dysfunction. The gene defective in beige is thought to be a homologue of the gene for the human disorder Chediak-Higashi syndrome. We have identified the murine beige gene by in vitro complementation and positional cloning, and confirmed its identification by defining mutations in two independent mutant alleles. The sequence of the beige gene message shows strong nucleotide homology to multiple human ESTs, one or more of which may be associated with the Chediak-Higashi syndrome gene. The amino acid sequence of the Beige protein revealed a novel protein with significant amino acid homology to orphan proteins identified in Saccharomyces cerevisiae, Caenorhabditis elegans and humans.

Amino Acid Sequence↗
PubMed1996

Identification and mutation analysis of the complete gene for Chediak-Higashi syndrome.

Chediak-Higashi syndrome (CHS) is a rare, autosomal recessive disorder characterized by hypopigmentation, severe immunologic deficiency with neutropenia and lack of natural killer (NK) cells, a bleeding tendency and neurologic abnormalities. Most patients die in childhood. The CHS hallmark is the occurrence of giant inclusion bodies and organelles in a variety of cell types, and protein sorting defects into these organelles. Similar abnormalities occur in the beige mouse, the proposed model for human CHS. Two groups have recently reported the identification of the beige gene, however the two cDNAs were not at all similar. Here we describe the sequence of a human cDNA homologous to mouse beige, identify pathologic mutations and clarify the discrepancies of the previous reports. Analysis of the CHS polypeptide demonstrates that its modular architecture is similar to the yeast vacuolar sorting protein, VPS15.

Adult↗