Mutations in the SLC3A1 Transporter Gene in Cystinuria

Cystinuria is an autosomal recessive disease characterized by the development of kidney stones. Guided by the identification of the SLC3A1 amino acid–transport gene on chromosome 2, we recently established genetic linkage of cystinuria to chromosome 2p in 17 families, without evidence for locus heterogeneity. Other authors have independently identified missense mutations in SLC3A1 in cystinuria patients. In this report we describe four additional cystinuria-associated mutations in this gene: a frameshift, a deletion, a transversion inducing a critical amino acid change, and a nonsense mutation. The latter stop codon was found in all of eight Ashkenazi Jewish carrier chromosomes examined. This report brings the number of disease-associated mutations in this gene to 10. We also assess the frequency of these mutations in our 17 cystinuria families.     

Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens.

Shewanella putrefaciens MR-1 can grow either aerobically or anaerobically at the expense of many different electron acceptors and is often found in abundance at redox interfaces in nature. Such redox interfaces are often characterized by very strong gradients of electron acceptors resulting from rapid microbial metabolism. The coincidence of S. putrefaciens abundance with environmental gradients prompted an examination of the ability of MR-1 to sense and respond to electron acceptor gradients in the laboratory. In these experiments, taxis to the majority of the electron acceptors that S. putrefaciens utilizes for anaerobic growth was seen. All anaerobic electron acceptor taxis was eliminated by the presence of oxygen, nitrate, nitrite, elemental sulfur, or dimethyl sulfoxide, even though taxis to the latter was very weak and nitrate and nitrite respiration was normal in the presence of dimethyl sulfoxide. Studies with respiratory mutants of MR-1 revealed that several electron acceptors that could not be used for anaerobic growth nevertheless elicited normal anaerobic taxis. Mutant M56, which was unable to respire nitrite, showed normal taxis to nitrite, as well as the inhibition of taxis to other electron acceptors by nitrite. These results indicate that electron acceptor taxis in S. putrefaciens does not conform to the paradigm established for Escherichia coli and several other bacteria. Carbon chemo-taxis was also unusual in this organism: of all carbon compounds tested, the only positive response observed was to formate under anaerobic conditions.     

Predisposition for cysteine substitutions in the immunoglobulin-like chain of FGFR2 in Crouzon syndrome

Four cases of Crouzon syndrome, one familial and three sporadic, were investigated for mutations in exon B of the fibroblast growth factor receptor 2 (FGFR2) gene. In the familial case, a mutation was found at codon 340 that exchanged tyrosine for histidine. Mutations at codon 342, detected in the three sporadic cases, replaced a cysteine by another amino acid. While three of the mutations have been described before, the fourth mutation, a CG transversion at codon 342 in one of the sporadic cases, has not been recognized previously. Compilation of all exon B mutations in Crouzon syndrome described to date revealed that 6 of the 8 sporadic and 2 of the 9 familial cases have mutations in codon 342. These mutations caused the substitution of cysteine for another amino acid. Given that a mutation in codon 342 was found in 8 out of 17 cases and that in 9 cases the mutation occurred at five additional positions, codon 342 of exon B of the FGFR2 gene may be predisposed to mutations in Crouzon syndrome.     

Mapping eight new polymorphisms in 11q13 in the vicinity of multiple endocrine neoplasia type 1: identification of a new distal recombinant

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder that predisposes affected individuals to neoplasms of the parathyroid glands, endocrine pancreas, anterior pituitary, and carcinoids. The MEN1 locus has been localized by family studies to 11q13, flanked by markers PGA and D11S97. Eight new polymorphisms located in three separate radiation-reduced somatic cell hybrid segregation groups were developed. The order of the new markers, within the context of previously described loci, was determined by linkage analysis on the Venezuelan reference pedigree. Four independent MEN1 families, consisting of 57 affected individuals, and 70 individuals at-risk for the disease were genotyped. Sixteen people inherited a chromosome that shows recombination between a linked marker and the disease. The nearest proximal and distal markers that show recombination with the disease are D11S822 and GSTP1, respectively, thereby narrowing the candidate region for MEN1 by 50% on the distal side. Using these loci in haplotype analysis, an accurate presymptomatic molecular diagnostic test has been developed. These new markers in 11q13 linked to MEN1 also facilitate the genetic and physical characterization of this very gene-rich region.     

Effects of lethal irradiation and cyclosporin A treatment on the growth and tumoricidal activity of a T cell clone potentially useful in cancer therapy

The TALL-104 cell line, originally derived from a patient with T cell leukemia, can be maintained indefinitely in culture in the presence of interleukin-2 (IL-2) and is endowed with a highly potent major-histocompatibilitycomplex (MHC)-non-restricted tumoricidal activity both in vitro and in animal models. The present study analyzes in detail the short- and long-term effects of irradiation and cyclosporin A (CsA) treatment on the growth and tumoricidal function of this T cell clone as compared to polyclonal lymphokine-activated killer (LAK) cell preparations from healthy donors. DNA and RNA syntheses by both TALL-104 and LAK cells were irreversibly arrested a few hours after irradiation with 40 Gy. However, 4-h⁵¹Cr-release assays, performed on different days (day 1 to day 7) after irradiation, showed that the cytotoxic efficiency of TALL-104 cells against hematopoietic and solid tumor targets was only modestly reduced, whereas that of LAK cells was severely inhibited. Moreover, the cytotoxic responses to recombinant human IL-2 and IL-12, measured 18 h after irradiation and cytokine addition, were normal in the case of TALL-104 cells but were abolished in the case of LAK cells. Co-culture of IL-2-or IL-12-preactivated TALL-104 cells with a tumor target for 5 days in the absence of cytokines resulted in a lower efficiency of lysis, as compared to the non-irradiated effectors, especially if the initial stimulus was IL-12. These findings suggest the requirement of multiple cytokine stimulation for optimal expression of tumoricidal activity by lethally irradiated TALL-104 cells. CsA, while abrogating TALL-104 cell proliferation at the low dose of 0.5 g/ml, inhibited their cytotoxic function marginally only at high doses (100 g/ml). By contrast, CsA reduced dose-dependently the cytotoxicity of LAK cells starting at very low doses (0.5 g/ml). CsA did not impair the ability of TALL-104 and LAK cells to produce interferon (IFN), tumor necrosis factor (TNF) , and granulocyte/macrophage-colony-stimulatory factor (GM-CSF) in response to IL-2, IL-12, or tumor targets. Irradiation reduced drastically IFN production by LAK, but not TALL-104 cells; release of TNF and GM-CSF by either type of effector was inhibited by 10%–50%, depending on the stimulus. The high resistance of the TALL-104 cells' tumoricidal function to irradiation and immunosuppressive drugs renders this immortal T cell clone a potentially safe and effective reagent for new adoptive-transfer approaches to cancer in MHC-incompatible recipients.     

Conformational analysis of bioactive peptides in reverse micelles as mimics of cell membrane environments

Summary Conformational preferences of secretin as a model peptide have been analyzed by CD and IR spectroscopy in reverse micelles of AOT/isooctane/water and compared to those in aqueous TFE, in SDS micelles and in DMPG vesicles. Among the systems examined, reverse micelles and phospholipid vesicles displayed almost identical conformational equilibria. Very high lipid-to-peptide ratios can be obtained in reverse micelles with full retention of optical transparency, even at millimolar peptide concentrations, thus indicating this system to be an interesting mimic of cell membrane environments for spectroscopic analysis of bioactive peptide conformations.Abbreviations TFE trifluoroethanol - SDS sodium dodecyl sulfate - DMPG dimyristoylphosphatidylglycerol - AOT bis(2-ethylhexyl)sulfosuccinate - CMC critical micellar concentration - VIP vasoactive intestinal peptide     

An investigation on the effect of oligomycin on state-4 respiration in isolated rat-liver mitochondria

The inhibitory action of oligomycin on State-4 respiration in rat-liver mitochondria has been investigated in detail with regard to the extent, mode and characteristics of the inhibition. The possibility that this effect may be due either to some damage of the mitochondrial preparation used or to the presence of heavy contaminations by microsomes has been excluded. It has been found that the concentration of specific binding sites is the same in State 4 as in State 3. The extent of the inhibition appears to be related to the ADP concentration, rather than to $\text{ATP}\text{ADP}$ ratios. The inhibition of this antibiotic on State-4 respiration does not depend on the experimental conditions used (i.e., choice of substrates or composition of the reaction medium). In agreement with these observations, it has been found that the membrane potential of State 4 is significantly increased when oligomycin is added. All these results provide further evidence to the conclusion that a large portion of State-4 respiration is linked to phosphorylation.     

Structural and functional properties of rat liver mitochondria in hexachlorobenzene induced experimental porphyria

A possible link between changes in iron and porphyrin content in liver mitochondria, from rats treated with either hexachlorobenzene, iron, or hexachlorobenzene plus iron, as a function of treatment time and their structural-functional properties, has been investigated. Normal oxidative phosphorylation in mitochondria from rats treated with iron has been shown. By contrast a significant and constant uncoupling of the phosphorylative process, fully reversed by albumin, in mitochondria from rats treated with hexachlorobenzene and hexachlorobenzene plus iron has been presented. A possible involvement of pentachlorophenol in causing these abnormalities has been proposed.     

The effect of alkaline pH on the cell growth of six different mammalian cells in tissue culture

The effect of high alkaline pH on the reinitiation of cell growth was studied in six different mammalian cells. We failed to confirm the observation of Zetterberg & Engström, Proc natl acad sci US 78 (1981) 4334 [17] and Exp cell res 144 (1983) 199 [18]. Treatment of quiescent cells at pH 9.5 did not stimulate cell growth when measured by total protein/flask or increase in cell number.     

Effects of aplysiatoxin and debromoaplysiatoxin on growth and differentiation of normal human bronchial epithelial cells

The effects of aplysiatoxin and debromoaplysiatoxin on the clonal growth rate, cross-linked envelope formation and plasminogen activator secretion of normal human bronchial epithelial cells were studied. Neither compound was mitogenic over a wide range of concentrations (10^–13 to 10^–7M). Both aplysiatoxin and debromoaplysiatoxin inhibited clonal growth rate with 50% inhibitory concentrations of 3 × 10^–11M and 10^–10M, respectively. Both compounds induced the formation of cross-linked envelopes and increased plasminogen activator secretion with equal potency. These data are similar to those previously obtained with 12-0-tetradecanoylphorbol-13-acetate and teleocidin B and suggest that aplysiatoxin and debromoaplysiatoxin induce terminal squamous differentiation in normal human bronchial epithelial cells.Abbreviations TPA 12-0-tetradecanoylphorbol-13-acetate - NHBE Normal Human bronchial epithelial - ID₅₀ 50% inhibitory concentration (dose) - PA Plasminogen activator - CLE Cross-linked envelope - LHC Laboratory of Human Carcinogenesis