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41.
D R Marchington G M Hartshorne D Barlow J Poulton 《American journal of human genetics》1997,60(2):408
While mtDNA polymorphisms at single base positions are common, the overwhelming majority of the mitochondrial genomes within a single individual are usually identical. When there is a point-mutation difference between a mother and her offspring, there may be a complete switching of mtDNA type within a single generation. It is generally assumed that there is a genetic bottleneck whereby a single or small number of founder mtDNA(s) populate the organism, but it is not known at which stages the restriction/amplification of mtDNA subtype(s) occur, and this uncertainty impedes antenatal diagnosis for mtDNA disorders. Length polymorphisms in homopolymeric tracts have been demonstrated in the large noncoding region of mtDNA. We have developed a new method, T-PCR (trimmed PCR), to quantitate heteroplasmy for two of these tracts (D310 and D16189). D310 variation is sufficient to indicate clonal origins of tissues and single oocytes. Tissues from normal individuals often possessed more than one length variant (heteroplasmy). However, there was no difference in the pattern of the length variants between somatic tissues in any control individual when bulk samples were taken. Oocytes from normal women undergoing in vitro fertilization were frequently heteroplasmic for length variants, and in two cases the modal length of the D310 tract differed in individual oocytes from the same woman. These data suggest that a restriction/amplification event, which we attribute to clonal expansion of founder mtDNA(s), has occurred by the time oocytes are mature, although further segregation may occur at a later stage. In contrast to controls, the length distribution of the D310 tract varied between tissues in a patient with heteroplasmic mtDNA rearrangements, suggesting that these mutants influence segregation. These findings have important implications for the genetic counselling of patients with pathogenic mtDNA mutations. 相似文献
42.
43.
Partha Sinha Piia Aarnisalo Rhiannon Chubb Ingrid J. Poulton Jun Guo Gregory Nachtrab Takaharu Kimura Srilatha Swami Hamid Saeed Min Chen Lee S. Weinstein Ernestina Schipani Natalie A. Sims Henry M. Kronenberg Joy Y. Wu 《The Journal of biological chemistry》2016,291(4):1631-1642
Parathyroid hormone (PTH) is an important regulator of osteoblast function and is the only anabolic therapy currently approved for treatment of osteoporosis. The PTH receptor (PTH1R) is a G protein-coupled receptor that signals via multiple G proteins including Gsα. Mice expressing a constitutively active mutant PTH1R exhibited a dramatic increase in trabecular bone that was dependent upon expression of Gsα in the osteoblast lineage. Postnatal removal of Gsα in the osteoblast lineage (P-GsαOsxKO mice) yielded markedly reduced trabecular and cortical bone mass. Treatment with anabolic PTH(1–34) (80 μg/kg/day) for 4 weeks failed to increase trabecular bone volume or cortical thickness in male and female P-GsαOsxKO mice. Surprisingly, in both male and female mice, PTH administration significantly increased osteoblast numbers and bone formation rate in both control and P-GsαOsxKO mice. In mice that express a mutated PTH1R that activates adenylyl cyclase and protein kinase A (PKA) via Gsα but not phospholipase C via Gq/11 (D/D mice), PTH significantly enhanced bone formation, indicating that phospholipase C activation is not required for increased bone turnover in response to PTH. Therefore, although the anabolic effect of intermittent PTH treatment on trabecular bone volume is blunted by deletion of Gsα in osteoblasts, PTH can stimulate osteoblast differentiation and bone formation. Together these findings suggest that alternative signaling pathways beyond Gsα and Gq/11 act downstream of PTH on osteoblast differentiation. 相似文献
44.
波长514nm的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统,能用于研究突变的感应现象,并与从γ-线辐射源获得的结果进行了比较。
Abstract:Laser irradiation at wavelength 514 nm was used to study the effect of lasers in inducing chromosomal aberrations at mitosis.This study offers a new radiation system which could be used for the induction of mutations.Results are compared with those obtained from studies using γ-rays as irradiation source. 相似文献
45.
Sphingosine-1-phosphate, a sphingolipid metabolite, is involved in the mitogenic response of platelet-derived growth factor (PDGF) and is formed by activation of sphingosine kinase. We examined the effect of PDGF on sphingosine kinase activation in TRMP cells expressing wild-type or various mutant betaPDGF receptors. Sphingosine kinase was stimulated by PDGF in cells expressing wild-type receptors but not in cells expressing kinase-inactive receptors (R634). Cells expressing mutated PDGF receptors with phenylalanine substitutions at five major tyrosine phosphorylation sites 740/751/771/1009/1021 (F5 mutants), which are unable to associate with PLCgamma, phosphatidylinositol 3-kinase, Ras GTPase-activating protein, or protein tyrosine phosphatase SHP-2, not only failed to increase DNA synthesis in response to PDGF but also did not activate sphingosine kinase. Moreover, mutation of tyrosine-1021 of the PDGF receptor to phenylalanine, which impairs its association with PLCgamma, abrogated PDGF-induced activation of sphingosine kinase. In contrast, PDGF was still able to stimulate sphingosine kinase in cells expressing the PDGF receptor mutated at tyrosines 740/751 and 1009, responsible for binding of phosphatidylinositol 3-kinase and SHP-2, respectively. In agreement, PDGF did not stimulate sphingosine kinase activity in F5 receptor 'add-back' mutants in which association with the Ras GTPase-activating protein, phosphatidylinositol 3-kinase, or SHP-2 was individually restored. However, a mutant PDGF receptor that was able to bind PLCgamma (tyrosine-1021), but not other signaling proteins, restored sphingosine kinase sensitivity to PDGF. These data indicate that the tyrosine residue responsible for binding of PLCgamma is required for PDGF-induced activation of sphingosine kinase. Moreover, calcium mobilization downstream of PLCgamma, but not protein kinase C activation, appears to be required for stimulation of sphingosine kinase by PDGF.-Olivera, A., Edsall, J., Poulton, S., Kazlauskas, A., Spiegel, S. Platelet-derived growth factor-induced activation of sphingosine kinase requires phosphorylation of the PDGF receptor tyrosine residue responsible for binding of PLCgamma. 相似文献
46.
Multiple deficiencies underlie NK cell inactivity in lymphotoxin-alpha gene-targeted mice. 总被引:2,自引:0,他引:2
M J Smyth R W Johnstone E Cretney N M Haynes J D Sedgwick H Korner L D Poulton A G Baxter 《Journal of immunology (Baltimore, Md. : 1950)》1999,163(3):1350-1353
We have evaluated the NK cell antitumor activity in lymphotoxin (LT)-deficient mice. Both NK cell-mediated tumor rejection and protection from experimental metastases were significantly compromised in LT-alpha-deficient mice. Analysis of LT-alpha-deficient mice revealed that the absolute number of alphabetaTCR- NK1.1+ NK cells was reduced in bone marrow and thymus, but with overall proportional decreases in other hemopoietic organs. In addition, the antitumor potential of alphabetaTCR- NK1.1+ cells, as determined by their lytic capacity and perforin expression, was reduced 1.5- to 3-fold in LT-alpha-deficient mice, as compared with wild-type mice. Combined defects in NK cell development and effector function contribute to compromised NK cell antitumor function in LT-alpha-deficient mice. 相似文献
47.
Adam W Clarke Lynn Poulton Hoi Yi Wai Stuart A Walker Shanti David Victor Teresa Domagala Dragana Mraovic Danyal Butt Nina Shewmaker Philip Jennings Anthony G Doyle 《MABS-AUSTIN》2010,2(5):539-549
While current therapeutic antibodies bind to IL-12 and IL-23 and inhibit their binding to IL-12Rβ1, we describe a novel antibody, termed 6F6, that binds to IL-12 and IL-23 and inhibits the interaction of IL-12 and IL-23 with their cognate signaling receptors IL-12Rβ2 and IL23R. This antibody does not affect the natural inhibition of the IL-12/23 pathway by the antagonists monomeric IL-12p40 and IL-12p80 respectively, which suggests that a dual antagonist system is possible. We have mapped the epitope of 6F6 to domain 3 of the p40 chain common to IL-12 and IL-23 and demonstrate that an antibody bound to this epitope is sufficient to inhibit engagement of the signaling receptors. Antibodies with this unique mechanism of inhibition are potent inhibitors of IL-12 induced IFNγ production and IL-23 induced IL-17 production in vitro, and in an in vivo model of psoriasis, treatment with a humanized variant of this antibody, h6F6, reduced the inflammatory response, resulting in decreased epidermal hyperplasia. We believe that this new class of IL-12/23 neutralising antibodies has the potential to provide improved potency and efficacy as anti-inflammatory agents, particularly in diseases characterized by an overproduction of IL-12.Key words: IL-12, IL-23, IL-12p40, IL-12 receptor, IL-12Rβ1, IL-12Rβ2, IL-23R, antibody, TH17, TH1 相似文献
48.
De Jonghe S Van Overmeire I Poulton S Hendrix C Busson R Van Calenbergh S De Keukeleire D Spiegel S Herdewijn P 《Bioorganic & medicinal chemistry letters》1999,9(21):3175-3180
Short-chain sphinganine analogues 8, 9, 18, and 19, as well as 3-fluoro-sphingosine analogues 25 and 26 were synthesized. Their potential as sphingosine kinase inhibitors was investigated, in combination with previously synthesized sphingosine and fluorinated sphinganine analogues. 相似文献
49.
Poulton CJ Schot R Kia SK Jones M Verheijen FW Venselaar H de Wit MC de Graaff E Bertoli-Avella AM Mancini GM 《American journal of human genetics》2011,(2):519-276
We describe a syndrome of primary microcephaly with simplified gyral pattern in combination with severe infantile epileptic encephalopathy and early-onset permanent diabetes in two unrelated consanguineous families with at least three affected children. Linkage analysis revealed a region on chromosome 18 with a significant LOD score of 4.3. In this area, two homozygous nonconserved missense mutations in immediate early response 3 interacting protein 1 (IER3IP1) were found in patients from both families. IER3IP1 is highly expressed in the fetal brain cortex and fetal pancreas and is thought to be involved in endoplasmic reticulum stress response. We reported one of these families previously in a paper on Wolcott-Rallison syndrome (WRS). WRS is characterized by increased apoptotic cell death as part of an uncontrolled unfolded protein response. Increased apoptosis has been shown to be a cause of microcephaly in animal models. An autopsy specimen from one patient showed increased apoptosis in the cerebral cortex and pancreas beta cells, implicating premature cell death as the pathogenetic mechanism. Both patient fibroblasts and control fibroblasts treated with siRNA specific for IER3IP1 showed an increased susceptibility to apoptotic cell death under stress conditions in comparison to controls. This directly implicates IER3IP1 in the regulation of cell survival. Identification of IER3IP1 mutations sheds light on the mechanisms of brain development and on the pathogenesis of infantile epilepsy and early-onset permanent diabetes. 相似文献
50.
J. Poulton M. Hirano A. Spinazzola M. Arenas Hernandez C. Jardel A. Lombès B. Czermin R. Horvath J.W. Taanman A. Rotig M. Zeviani C. Fratter 《生物化学与生物物理学报:疾病的分子基础》2009,1792(12):1109-1112
These tables list both published and a number of unpublished mutations in genes associated with early onset defects in mitochondrial DNA (mtDNA) maintenance including C10orf2, SUCLG1, SUCLA2, TYMP, RRM2B, MPV17, DGUOK and TK2. The list should not be taken as evidence that any particular mutation is pathogenic. We have included genes known to cause mtDNA depletion, excluding POLG1, because of the existing database (http://tools.niehs.nih.gov/polg/). We have also excluded mutations in C10orf2 associated with dominant adult onset disorders. 相似文献