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PubMed2000

Identification of two novel zinc finger modules and nuclear localization signal in rat spermatidal protein TP2 by site-directed mutagenesis.

Spermatidal protein TP2, which appears transiently during stages 12-16 of mammalian spermiogenesis, is a DNA condensing zinc metalloprotein with a preference to GC-rich DNA. We have carried out a detailed site-directed mutagenesis analysis of rat spermatidal protein TP2 to delineate the amino acid residues involved in coordination with two atoms of zinc. Two zinc fingers modules have been identified involving 4 histidine and 4 cysteine residues, respectively. The modular structure of the two zinc fingers identified in TP2 define a new class of zinc finger proteins that do not fall into any of the known classes of zinc fingers. Transfection experiments with COS-7 cells using wild type and the two zinc finger pocket mutants have shown that TP2 preferentially localizes to nucleolus. The nuclear localization signal in TP2 was identified to be (87)GKVSKRKAV(95) present in the C-terminal third of TP2 as a part of an extended NoLS sequence.

Amino Acid Sequence↗
PubMed2004

The zinc finger motif of Escherichia coli RecQ is implicated in both DNA binding and protein folding.

The RecQ family of DNA helicases has been shown to be important for the maintenance of genomic integrity. Mutations in human RecQ genes lead to genomic instability and cancer. Several RecQ family of helicases contain a putative zinc finger motif of the C4 type at the C terminus that has been identified in the crystalline structure of RecQ helicase from Escherichia coli. To better understand the role of this motif in helicase from E. coli, we constructed a series of single mutations altering the conserved cysteines as well as other highly conserved residues. All of the resulting mutant proteins exhibited a high level of susceptibility to degradation, making functional analysis impossible. In contrast, a double mutant protein in which both cysteine residues Cys397 and Cys400 in the zinc finger motif were replaced by asparagine residues was purified to homogeneity. Slight local conformational changes were detected, but the rest of the mutant protein has a well defined tertiary structure. Furthermore, the mutant enzyme displayed ATP binding affinity similar to the wild-type enzyme but was severely impaired in DNA binding and in subsequent ATPase and helicase activities. These results revealed that the zinc finger binding motif is involved in maintaining the integrity of the whole protein as well as DNA binding. We also showed that the zinc atom is not essential to enzymatic activity.

Adenosine Triphosphatases↗
PubMed1994

Inhibitory effects of zinc on magnesium balance and magnesium absorption in man.

OBJECTIVE: Both zinc (Zn) and magnesium (Mg) are widely used as nutritional supplements and the possibility was considered that Zn may interfere with the absorption of Mg, similar to previously reported results [1,2] obtained with the same dose of supplemental Zn on the absorption of calcium (Ca). METHODS: Mg absorption studies and metabolic balances of Mg and of Zn were carried out in three groups of adult males in a metabolic research unit during the intake of supplemental doses of 142 mg Zn as Zn sulfate (ZnSO4) during Ca intakes of 230, 500 and 800 mg/day. RESULTS: The Zn intake of 142 mg/day decreased the Mg balance and Mg absorption only during the 500 mg Ca intake compared to control values. However, the overall effect of the high Zn intake of the three groups combined, regardless of the Ca intake, was a highly significant decrease of Mg absorption and of the Mg balance. CONCLUSION: Zn supplements of 142 mg/day decreased Mg absorption and the Mg balance significantly during all Ca intakes for the three groups combined.

Calcium↗
PubMed1984

Effects of iron, tin, and copper on zinc absorption in humans.

Zinc absorption as measured by body retention of [65Zn]zinc chloride or a turkey test meal extrinsically labeled with 65Zn was determined in human subjects by whole body counting after 7 days. Average 65Zn absorption from zinc chloride in persons with a high iron-absorbing capacity was similar to persons with a low capacity to absorb iron. Inorganic iron, 920 mumol (51 mg), or HB iron, 480 mumol (26 mg), inhibited 65Zn absorption from 92 mumol (6 mg) of zinc chloride. When 610 mumol of iron (34 mg) was added to a turkey test meal containing 61 mumol of zinc (4 mg), 65Zn absorption was not inhibited. Tin, 306 mumol (36 mg), given with zinc chloride or turkey test meals (61 mumol, 4 mg, of Zn) significantly reduced 65Zn absorption. Copper, 79 mumol (5 mg), had no significant effect on the 65Zn absorption from 7.9 mumol (0.5 mg) of zinc chloride. In summary, the capacity to absorb iron did not influence 65Zn absorption, but both inorganic iron and heme-iron inhibited 65Zn absorption from zinc chloride. Inorganic iron had no effect, however, on 65Zn absorption from the turkey test meal. Tin in a large dose also inhibited 65Zn absorption from both zinc chloride and the turkey test meal.

Adolescent↗
PubMed1986

Intestinal transport of zinc and folic acid: a mutual inhibitory effect.

Recent observations suggest an inverse relationship between folic acid intake and zinc nutriture and indicate an interaction between folic acid and zinc at the intestinal level. To define that interaction, we designed in vivo and in vitro transport studies in which folic acid transport in the presence of zinc, as well as zinc transport in the presence of folic acid was examined. These studies show that zinc transport is significantly decreased when folate is present in the intestinal lumen. Similarly folic acid transport is significantly decreased with the presence of zinc. To determine whether this intestinal inhibition is secondary to zinc and folate-forming complexes, charcoal-binding studies were performed. These studies indicate that zinc and folate from complexes at pH 2.0, but that at pH 6.0, these complexes dissolve. Therefore, our studies suggest that under normal physiological conditions a mutual inhibition between folate and zinc exists at the site of intestinal transport.

Animals↗
PubMed1982

Zinc sensitivity of Trichomonas vaginalis: in vitro studies and clinical implications.

The high zinc concentration (2.3-15.3 mM) in human prostatic secretions may be an important defense of the male lower urinary tract against infection by Trichomonas vaginalis. Trichomonads were rapidly killed by zinc salts at concentrations similar to those in prostatic fluid of normal men. There was some variation in the zinc sensitivity of 15 clinical isolates of T. vaginalis (minimal inhibitory concentration, 0.8-6.4 mM). A time-kill technique showed subtle differences in the kinetics of zinc killing of trichomonad strains. It was possible to select relatively zinc-resistant substrains of T. vaginalis from a zinc-sensitive population. Zinc resistance was a stable characteristic after multiple passages of substrains in growth medium without supplemental zinc. Variations in the zinc sensitivity of infecting T. vaginalis strains or in the zinc content of host prostatic secretions may be significant determinants of the natural history of T. vaginalis infection in men.

Animals↗
PubMed1982

Influence of intraluminal constituents on zinc absorption by isolated, vascularly perfused rat intestine.

An isolated, vascularly perfused rat intestine system was utilized to compare the influence of a variety of potential zinc-binding compounds on zinc absorption. Citric acid, cysteine, reduced glutathione, histidine, methionine, picolinic acid and tryptophan were added to the lumen perfusate at 110 microM. Two lumen perfusate pH values (4.2 and 6.6) were compared. The influence of EDTA at pH 6.6 was also investigated as was the influence of citric acid, histidine, picolinic acid and tryptophan additions to the lumen perfusate at 550 microM. Of the substances tested only EDTA significantly enhanced the transfer of zinc from the lumen to the portal circulation. These results suggest these potential zinc chelators, exclusive of EDTA, do not promote zinc absorption by the intestine in this system.

Amino Acids↗
PubMed1987

Effect of zinc source and picolinic acid on 65Zn uptake in an in vitro continuous-flow perfusion system for pig and poultry intestinal segments.

Twenty weanling pigs and fourteen 9-wk-old broiler chickens were used in three continuous-flow in vitro perfusion experiments using noneverted intestinal sacs to 1) determine differences in 65Zn absorption due to location within the intestinal tract, 2) evaluate 65Zn uptake from ZnCl2 and Zn-methionine (ZnMet) with or without added picolinic acid (PA) in pig intestinal sacs and 3) evaluate 65Zn uptake from ZnCl2 and ZnMet in chicken intestinal sacs. No differences in 65Zn uptake due to gut segment position were observed in the pigs. A Zn source x PA interaction was observed for 65Zn uptake into the pig gut tissue and for 65Zn uptake to the serosal side of the gut sacs. Total 65Zn absorption in the pig gut sacs from the two Zn sources was not different, but the addition of a 5 M ratio of PA to Zn depressed 65Zn absorption. No differences were observed in total 65Zn absorption or 65Zn uptake in poultry gut sac tissue. There was, however, greater uptake of 65Zn from ZnCl2 to the serosal side of the sacs than from ZnMet. The data indicate that 65Zn from ZnCl2 and ZnMet is similar in total absorption and that the addition of PA depresses Zn uptake.

Animals↗
PubMed1993

Regulation of hsp70 synthesis induced by cupric sulfate and zinc sulfate in thermotolerant HeLa cells.

Upon exposure to the heavy metals copper and zinc, a large amount of 70,000-Da heat shock protein (hsp70) was synthesized in normal, non-thermotolerant (NT) HeLa cells, whereas only a little increase of hsp70 synthesis was observed in thermotolerant (TT) cells. To determine the inhibition mechanism of hsp70 induction in the TT cells, we first analyzed the hsp70 mRNA of these cells. Hsp70 mRNA in the NT cells increased immediately after exposure to these metals. In TT cells, however, the increase of hsp70 mRNA was delayed, even though it eventually increased to a similar or slightly lower level compared with NT cells. Further analysis of the activation of heat shock transcription factor (HSF) showed that a significant activation of HSF was observed immediately after exposure to these metals in the NT cells, whereas the activation of HSF was initially repressed in the TT cells. Thus, the decreased induction of hsp70 synthesis observed in the TT cells seemed to be due to the reduced translation of hsp70 mRNA and also in part to the reduced activation of HSF. Furthermore, by the gel mobility shift assay using anti-hsp70 antibody, the association of copper- and zinc-activated HSF with hsp70 was observed in both NT and TT cells. The amount of HSF-hsp70 complex was prominent in TT cells, in which the hsp70 content was 5 to 10 times higher than that in the NT cells. These findings strongly suggest that the activity of HSF is negatively regulated by hsp70 in the TT cells.

Base Sequence↗
PubMed1996

Case report: successful treatment with cimetidine and zinc sulphate in chronic mucocutaneous candidiasis.

The authors evaluated the clinical efficacy of a treatment with cimetidine and zinc sulphate in a patient with chronic mucocutaneous candidiasis. Cimetidine was given at a dose of 400 mg three times daily; zinc sulphate at a dose of 200 mg daily, then adjusted to maintain blood zinc levels at the upper normal range. This treatment lasted 16 months. An impressive and significant reduction of the infectious events and an increased CD4 (helper/inducer) cell counts were observed. The authors conclude that this combined immunopotentiating treatment is safe and inexpensive to treat immunodeficiency disorders.

Adjuvants, Immunologic↗
PubMed1994

Specific binding of herpes simplex virus type 1 (HSV-1) strain HSZP to host cell surface can provoke interference with early shutoff of host protein synthesis induced by HSV-1 strain KOS.

The HSZP strain of herpes simplex virus type 1 (HSV-1) is defective with respect to the early shutoff of host protein synthesis but is effective at interfering with the early shutoff function of the HSV-1 KOS strain, even when heat-inactivated or neutralized by antibody. The interference was not due to exclusion of strain KOS by HSZP at the level of adsorption or penetration. The component responsible for the interference is an integral part of HSZP virions. Strain HSZP inactivated with zinc ions failed to interfere with the early shutoff function of the superinfecting strain KOS. The same effect was also found with strain HSZP purified from cells treated with 2-deoxy-D-glucose. This finding supports the idea that a specific interaction between HSZP virions and the cell surface can be responsible for the interference phenomenon.

Animals↗
PubMed1995

Over-expressed ZF5 gene product, a c-myc-binding protein related to GL1-Kruppel protein, has a growth-suppressive activity in mouse cell lines.

ZF5 encodes a zinc finger protein, which contains five C2H2-type zinc fingers showing homology with the zinc finger of the Kruppel family, and binds to two sites in the mouse c-myc promoter. We report the effect of over-expression of ZF5 on cell growth. ZnCl2 treatment suppressed the growth of a mouse fibroblast cell line (L cells) transfected with the wild-type ZF5 gene driven by the metallothionein promoter. Cells transfected with the wild-type ZF5 gene formed colonies two- to fivefold less efficiently than those transfected with the mutant ZF5 gene in P19, NIH3T3, 3T3-L1 and L cells. Over-expression of ZF5 did not cause c-myc down-regulation or arrest of the cell cycle, but increased the DNA content.

3T3 Cells↗
PubMed1994

Short report: zinc sulphate supplementation corrects abnormal erythrocyte membrane long-chain fatty acid composition in patients with Crohn's disease.

Patients with Crohn's disease may become zinc-deficient and, in such patients, an altered metabolism of radiolabelled long-chain fatty acids has been reported. We have investigated the possible reversal by zinc supplementation of altered long-chain fatty acid profiles of red cells in Crohn's disease. Twenty patients with long-standing Crohn's disease in clinical remission received 200 mg of zinc sulphate daily for 6 weeks. Phospholipid fatty acid profiles of washed red cells were analysed before and after zinc treatment and compared to those of 20 unsupplemented healthy controls. Plasma zinc levels in Crohn's were 72 +/- 8 micrograms/dL before zinc treatment and increased to 114 +/- 10 micrograms/dl after the therapy. Prior to zinc supplementation, the percentage of palmitic, stearic and oleic acids was significantly higher in Crohn's disease, while linoleic, arachidonic and n-3 fatty acids were reduced in Crohn's disease compared to healthy controls. Zinc supplementation abolished these pre-treatment differences in red-cell long-chain fatty acid profiles but did not affect plasma fatty acid values. Further studies are needed to clarify whether these fatty acid changes can be related to the clinical course of the disease.

Adult↗
PubMed1996

Trichohyalin expression in skin tumors: retrieval of trichohyalin antigenicity in tissues by microwave irradiation.

BACKGROUND: The antitrichohyalin antibody AE 15 is effective for identifying the cell lineage that undergoes the pathway of inner root sheath-type differentiation. Unfortunately, the AE 15 does not react with trichohyalin in tissue that is formalin-fixed and embedded in paraffin according to routine procedures. METHODS: We attempted to retrieve the trichohyalin antigenicity in formalin-fixed, paraffin-embedded biopsy specimens that included normal skin as well as skin tumors such as trichofolliculoma and pilotricoma. RESULTS: We found that the use of a metal solution in combination with microwave oven heating improves the trichohyalin immunoreactivity substantially. Further, trichohyalin was found to be expressed not only in the secondary hair structure in trichofolliculoma but also in a certain cell lineage that differentiates to squamoid cells in pilomatricoma. CONCLUSIONS: Our findings established that surgical specimens processed under routine procedures can be successfully investigated with AE 15 using the microwave irradiation method. Studies of epidermal diseases expressing trichohyalin should provide valuable insights into our understanding the functional significance of trichohyalin during abnormal keratinization.

Adjuvants, Immunologic↗
PubMed1995

Transient zinc deficiency in a breast-fed premature infant.

Symptomatic zinc deficiency developed in a breast-fed premature male infant of 31 weeks gestation. At 13 weeks of age he presented with diarrhoea, irritability and an eruption identical to acrodermatitis enteropathica. Breast milk zinc concentrations were low. His course was complicated by milk protein intolerance. After 7 weeks, zinc supplementation was ceased without recurrence of disease.

Acrodermatitis↗
PubMedDate not supplied

Wilson's disease: resolution of MRI lesions following long-term oral zinc therapy.

A 28-year-old man with Wilson's disease developed neurological deterioration after a low-dose of d-penicillamine treatment for 2 weeks. He showed an akinetic rigid syndrome with generalized dystonia. Brain magnetic resonance images (MRI) on T2 and proton weighted images showed an increased signal intensity over the thalamus, basal ganglia and brainstem, especially the midbrain and pons. After treatment had been changed to zinc sulphate, the akinetic-rigid syndrome and dystonia were improved slowly in the following 4 years. Serial MRI studies showed a gradual resolution of the lesions. His current neurological status was almost normal except for dysarthria and mild intention tremor.

Administration, Oral↗
PubMed1994

The effect of mouthrinses containing zinc and triclosan on plaque accumulation and development of gingivitis in a 3-week clinical test.

Experimental mouthrinses containing 0.4% zinc sulphate and 0.15% triclosan were compared with a chlorhexidine and a negative control mouthrinse in a 3-week clinical trial. The zinc/triclosan mouthrinses 1 and 2 differed in their ethanol and humectant contents used to deliver the triclosan. The experimental protocol employed the partial mouth gingivitis design, whereby participants wear a toothshield during toothbrushing. Gingival health at baseline was established by professional cleaning, oral hygiene instruction and effective toothbrushing 3 x per day during a pre-experimental period of 2 weeks. The mouthrinses were subsequently used 2x daily following normal toothbrushing during 3 weeks. The pre-experimental oral hygiene phase very effectively reduced plaque levels and gingival bleeding. During the rinsing period, in the absence of mechanical removal of plaque from the protected teeth, gingival bleeding rose to above the prestudy level in the negative control group. The increments (change from baseline to 21 days) of plaque and bleeding scores for the zinc/triclosan mouthrinse 1 were significantly lower than those in the negative control group. As expected, plaque and gingivitis scores were lowest in the group that rinsed with chlorhexidine. The results extend previous observations on the efficacy of the zinc/triclosan system to maintain gingival health.

Adult↗