Role of Sulfur In Skin

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J Nutr. 2006 Mar;136(3 Suppl):750S-754S. Related Articles, Links
Source: Aged garlic extract improves homocysteine-induced endothelial dysfunction in macro- and microcirculation.

Weiss N, Ide N, Abahji T, Nill L, Keller C, Hoffmann U.

Department of Metabolic Diseases, Medical Policlinic, City Campus, University of Munich Medical Center, Munich, Germany. norbert.weiss@med.uni-muenchen.de

Endothelial dysfunction caused by increases in vascular oxidant stress that decrease bioavailable nitric oxide (NO) plays a critical role in the vascular pathobiology of hyperhomocysteinemia. Boosting cellular glutathione levels or increasing the activity of cellular glutathione peroxidase can compensate for homocysteine's effects on endothelial function. Aged garlic extract (AGE) contains water- and oil-soluble sulfur compounds that modify the intracellular thiol and redox state, minimize intracellular oxidant stress, and stimulate NO generation in endothelial cells and animals. We performed a placebo-controlled, blinded, crossover trial to examine whether AGE reduces macro- and microvascular endothelial dysfunction during acute hyperhomocysteinemia induced by an oral methionine challenge in healthy subjects. Acute hyperhomocysteinemia leads to a significant decrease in flow-mediated vasodilation of the brachial artery as determined by vascular ultrasound, indicative of macrovascular endothelial dysfunction. In addition, acute hyperhomocysteinemia leads to a decrease in acetylcholine-stimulated skin perfusion as measured by laser-Doppler flowmetry. This indicates microvascular endothelial dysfunction, which is presumably a result of impairment of the endothelium-derived hyperpolarizing factor pathway. Pretreatment with AGE for 6 wk significantly diminished the adverse effects of acute hyperhomocysteinemia in both vascular territories. We conclude that AGE may at least partly prevent a decrease in bioavailable NO and endothelium-derived hyperpolarizing factor during acute hyperhomocysteinemia. This pilot study warrants further investigations on the effects of AGE on endothelial dysfunction in patients with other cardiovascular risk factors or established vascular disease and on the clinical outcome of patients with cardiovascular disease.

PMID: 16484556 [PubMed - indexed for MEDLINE]

Yakugaku Zasshi. 2006 Apr;126(4):297-300. Related Articles, Links: [Effect of orally administered chondrosine on uptake of 35S sulfate into rat cartilage]

[Article in Japanese]

Kusano S, Igarashi N, Sakai S, Toida T.

Fuji-Sangyou Co., Ltd., Marugame City, Japan.

Chondroitin sulfate is widely distributed in animal tissues and possibly plays an important role in different types of metabolic reactions as well as protecting joints, the internal wall of blood vessels, skin, bone, etc. In cartilage, glycosaminoglycans have a protective function; in particular, chondroitin sulfate stabilizes fibrous and cellular elements of the connective tissue and, at the same time, lubricates and protects the membranes in joints. Recently, chondroitin sulfate has been used as a nutraceutical for the treatment of joint diseases such as osteoarthritis, although acidic and large molecules such as chondroitin sulfate might not be able to be absorbed through digestive apparatus such as the intestine. In this study, we investigated the effects of orally administered chondrosine derived from shark chondroitin sulfate on the uptake of inorganic (35)S sulfate into rat cartilage and found that chondrosine stimulates the incorporation of (35)S sulfate into cartilage compared with intact chondroitin sulfate.

PMID: 16596020 [PubMed - indexed for MEDLINE]

J Appl Toxicol. 2006 May-Jun;26(3):239-46. Related Articles, Links: Preferential expression of matrix metalloproteinase-9 in mouse skin after sulfur mustard exposure.

Shakarjian MP, Bhatt P, Gordon MK, Chang YC, Casbohm SL, Rudge TL, Kiser RC, Sabourin CL, Casillas RP, Ohman-Strickland P, Riley DJ, Gerecke DR.

Department of Medicine, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ 08854-5635, USA.

Matrix metalloproteinases (MMPs), a class of enzymes responsible for the degradation of extracellular matrix proteins, play important roles in inflammatory and immune responses. In skin, MMP-2 (gelatinase A) and MMP-9 (gelatinase B) are normally inactive but can be expressed during tissue injury. Both degrade collagen IV and other critical components of the basement membrane zone that separates the epidermis from the dermis. The expression of MMP-2 and -9 was studied in sulfur mustard (SM)-exposed ear skin from mice to determine their role in tissue vesicant injury. Punch biopsies of mouse ears were collected between 6 and 168 h after exposure to 97.5 mM (0.08 mg) SM diluted in CH(2)Cl(2). They were examined histologically and assayed for MMP-2 and -9 expression by gelatinase activity assays, real-time reverse transcriptase-polymerase chain reaction and Western blot analysis. A time-related increase in overall gelatinase activity was observed in SM-treated ears. At 168 h after SM exposure, the relative levels of MMP-9 mRNA were increased 27-fold and MMP-9 protein 9-fold when compared with the control (CH(2)Cl(2) treated) ears. In contrast, there were no observable increases in the MMP-2 mRNA or protein levels between treated and control ears. These observations suggest the differential expression of MMP-2 and -9 during the cutaneous response to SM injury and suggest a role for MMP-9 in SM-induced injury. Copyright 2006 John Wiley & Sons, Ltd.

PMID: 16489579 [PubMed - in process]

Arch Gerontol Geriatr. 2006 May-Jun;42(3):289-306. Epub 2006 Jan 26. Related Articles, Links: Menopause: a review on the role of oxygen stress and favorable effects of dietary antioxidants.

Miquel J, Ramirez-Bosca A, Ramirez-Bosca JV, Alperi JD.

Department of Biotechnology, University of Alicante, San Vicente, Ap. 99, E-03080 Alicante, Spain.

Menopause is often accompanied by hot flashes and degenerative processes such as arteriosclerosis and atrophic changes of the skin that suggest an acceleration of aging triggered by estrogen lack. Therefore, hormone replacement therapy (HRT) has been considered the most suitable treatment for the above symptoms and processes. However, because of the possible serious side effects of HRT (especially the increased risk of thrombo-embolic accidents and breast cancer) there is a growing demand for alternative treatments of the symptoms and pathological processes associated with menopause. In agreement with the above, we review research that supports the concept that oxygen stress contributes to menopause and that some of its physiopathological effects may be prevented and/or treated improving the antioxidant defense of menopausic and postmenopausic women. Accordingly, a selection of micronutrients may be useful as a dietary supplement for protection against the decline of physiological functions caused by age-related oxygen stress. Since aging is accompanied by a progressive oxidation of the physiological sulfur pool, we emphasize the role of the vitamins B that help to maintain the GSH/GSSG ratio in its normal reduced state. Nutritional supplements should also include the key antioxidant vitamins C and E, as well as beta-carotene and the mineral micronutrients found in the oxygen radical-detoxifying enzymes glutathione peroxidase and superoxide dismutase. Moreover, the reviewed data suport the concept that other antioxidants such as lipoic acid and the precursors of glutathione thioproline (TP) and l-2-oxothiazolidine-4-carboxylic acid (OTC), as well as the soy isoflavones and the "coantioxidants" of an hydroalcoholic extract of Curcuma longa may help to prevent antioxidant deficiency with resulting protection of mitochondria against premature oxidative damage with loss of ATP synthesis and especialized cellular functions. Therefore, the administration under medical advice of synergistic combinations of some of the above mentioned antioxidants in the diet as well as topically (for skin protection) may have favorable effects on the health and quality of life of women, especially of those who cannot be treated with HR, suffer high levels of oxygen stress, and do not consume a healthy diet that includes five daily rations of fresh fruit and vegetables.

PMID: 16442644 [PubMed - in process]

Drug Chem Toxicol. 2005;28(1):105-16. Related Articles, Links: A convenient fluorometric method to study sulfur mustard-induced apoptosis in human epidermal keratinocytes monolayer microplate culture.

Ray R, Hauck S, Kramer R, Benton B.

Biochemical Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010-5400, USA. radharaman.ray@apg.amedd.army.mil

Sulfur mustard [SM; bis-(2-chloroethyl) sulfide], which causes skin blistering or vesication [(1991). Histo- and cytopathology of acute epithelial lesions. In: Papirmeister, B., Feister, A. J., Robinson, S. I., Ford, R. D., eds. Medical Defense Against Mustard Gas: Toxic Mechanisms and Pharmacological Implications. Boca Raton: CRC Press, pp. 43-78.], is a chemical warfare agent as well as a potential terrorism agent. SM-induced skin blistering is believed to be due to epidermal-dermal detachment as a result of epidermal basal cell death via apoptosis and/or necrosis. Regarding the role of apoptosis in SM pathology in animal skin, the results obtained in several laboratories, including ours, suggest the following: 1) cell death due to SM begins via apoptosis that proceeds to necrosis via an apoptotic-necrotic continuum and 2) inhibiting apoptosis decreases SM-induced microvesication in vivo. To study the mechanisms of SM-induced apoptosis and its prevention in vitro, we have established a convenient fluorometric apoptosis assay using monolayer human epidermal keratinocytes (HEK) adaptable for multiwell plates (24-, 96-, or 384-well) and high-throughput applications. This assay allows replication and multiple types of experimental manipulation in sister cultures so that the apoptotic mechanisms and the effects of test compounds can be compared statistically. SM affects diverse cellular mechanisms, including endoplasmic reticulum (ER) Ca2+ homeostasis, mitochondrial functions, energy metabolism, and death receptors, each of which can independently trigger apoptosis. However, the biochemical pathway in any of these apoptotic mechanisms is characterized by a pathway-specific sequence of caspases, among which caspase-3 is a key member. Therefore, we exposed 80-90% confluent HEK cultures to SM and monitored apoptosis by measuring the fluorescence generated due to hydrolysis of a fluorogenic caspase-3 substrate (acetyl- or benzyl oxycarbonyl-Asp-Glu-Val-Asp-fluorochrome, also designated as AC-or Z-DEVD- fluorochrome) added to the assay medium. Fluorescence was measured using a plate reader. We used two types of substrates, one (Sigma-Aldrich, CASP-3-F) required cell disruption and the other (Beckman-Coulter CellProbe HT Caspase-3/7 Whole Cell Assay Kit) was cell permeable. The latter substrate was useful in experiments such as determining the time-course of apoptosis immediately following SM exposure without disruption (e.g., due to cell processing). In SM-exposed HEK, fluorescence generated from the fluorogenic caspase-3 substrate hydrolysis increased in a time (0-24 h) and concentration (0.05, 0.1, 0.15, 0.2, 0.3, 0.5 mM) dependent manner. SM caused maximum fluorescence at about 0.5 mM. However, at 2 mM SM, fluorescence decreased compared with 0.5 mM, which remains to be explained. Following 0.3 mM SM exposure, which is considered to be the in vitro equivalent of a vesicating dose in vivo (Smith, W. J., Sanders, K. M., Ruddle, S. E., Gross, C. L. (1993). Cytometric analysis of DNA changes induced by sulfur mustard. J. Toxicol.-Cut. Ocular Toxicol. 12(4):337-347.), a small fluorescence increase was observed at 6 to 8 h, which was markedly higher at 12 h. At 24 h, all SM concentrations increased fluorescence. Fluorescence increase due to SM was prevented 100% by a caspase-3-specific peptide inhibitor AC-DEVD-CHO (acetyl-Asp-Glu-Val-Asp-aldehyde, 0.1 mM), but less effectively by a general caspase inhibitor Z-VAD-FMK (benzyl oxycarbonyl-Val-Ala-Asp-fluoromethylketone, 0.01 mM), indicating that the fluorescence increase was due to caspase-3-mediated apoptosis. These results suggest potential applications of this method to study apoptosis mechanisms involving caspase-3 substrates and possibly those involving other caspase substrates.

PMID: 15720039 [PubMed - indexed for MEDLINE]

Toxicol Appl Pharmacol. 2003 Dec 1;193(2):228-36. Related Articles, Links: Sulfur mustard induces the formation of keratin aggregates in human epidermal keratinocytes.

Dillman JF 3rd, McGary KL, Schlager JJ.

Applied Pharmacology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. James.Dillman@apg.amedd.army.mil

The vesicant sulfur mustard is an alkylating agent that has the capacity to cross-link biological molecules. We are interested in identifying specific proteins that are altered upon sulfur mustard exposure. Keratins are particularly important for the structural integrity of skin, and several genetically inherited blistering diseases have been linked to mutations in keratin 5 and keratin 14. We examined whether sulfur mustard exposure alters keratin biochemistry in cultured human epidermal keratinocytes. Western blotting with specific monoclonal antibodies revealed the formation of stable high-molecular-weight "aggregates" containing keratin 14 and/or keratin 5. These aggregates begin to form within 15 min after sulfur mustard exposure. These aggregates display a complex gel electrophoresis pattern between approximately 100 and approximately 200 kDa. Purification and analysis of these aggregates by one- and two-dimensional gel electrophoresis and mass spectrometry confirmed the presence of keratin 14 and keratin 5 and indicate that at least some of the aggregates are composed of keratin 14-keratin 14, keratin 14-keratin 5, or keratin 5-keratin 5 dimers. These studies demonstrate that sulfur mustard induces keratin aggregation in keratinocytes and support further investigation into the role of keratin aggregation in sulfur mustard-induced vesication.

PMID: 14644625 [PubMed - indexed for MEDLINE]

3. HEALTH EFFECTS
3.1 INTRODUCTION
The primary purpose of this chapter is to provide public health officials, physicians, toxicologists, and
other interested individuals and groups with an overall perspective on the toxicology of sulfur mustard. It
contains descriptions and evaluations of toxicological studies and epidemiological investigations and
provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.
A glossary and list of acronyms, abbreviations, and symbols can be found at the end of this profile.
Sulfur mustard [bis(2-chloroethyl)sulfide; C4H8Cl2S; CASRN: 505-60-2] or as it is commonly called,
‘mustard gas’, is one of a class of vesicant chemical warfare agents with the ability to form vesicles or
blisters on exposed skin.

Sulfur mustard is a component of the H-series blister agents including undistilled sulfur mustard (H; sulfur mustard with 20–30% impurities, also known as Levinstein mustard), distilled sulfur mustard (HD or HS; approximately 96% pure), a mustard-lewisite mixture (HL), an HD/agent T mixture (HT; a mixture of HD and nonvolatile agent T), and an HD/agent Q mixture (HQ; a
mixture of HD and nonvolatile agent Q; agent Q is also known as sesqui-mustard) (Gates and Moore
1946).

Mustard agents, including sulfur mustard, are regulated under the Chemical Weapons Convention
(CWC) (USCWCR1999). Three classes of chemicals are monitored under the CWC (1993), with sulfur
mustard grouped in the highest risk class, "Schedule 1." Information about mustard agents other than
sulfur mustard, such as nitrogen mustards, thickened mustard, or the mixtures listed above are not
discussed in this document.
Sulfur mustard is actually a clear, colorless, oily liquid. As a warfare or terrorist agent, sulfur mustard has
been dispersed by spraying or by explosive blasts producing a vapor, aerosol, and/or liquid droplets,
earning the chemical the name ‘mustard gas.’ Persons involved in the transport or disposal of sulfur
mustard may be exposed occupationally. It is also possible that workers involved in plastics
manufacturing may be exposed to mustard agents inadvertently, resulting from process contamination
with sulfur or nitrogen impurities, as occurred in a vinyl chloride monomer manufacturing facility in
Plaquemine, Louisiana in 1996 (Johnson 1998). Spouses, children, and others may be exposed if workers
SULFUR MUSTARD 22
3. HEALTH EFFECTS
unknowingly bring the mustard agents out of the factory on their skin or clothing. Both liquid and vapor
forms readily penetrate ordinary clothing.
Sulfur mustard is slightly soluble in water, but both the liquid and vapor forms are readily soluble in
alcohol, gasoline, kerosene, oils, fats, and organic solvents. Sulfur mustard is environmentally persistent.
Evaporation in air increases with increasing temperatures, but at temperatures below 58 °F (14 °C), it
freezes while retaining its vesicant properties. Both liquid and vapor forms readily penetrate ordinary
clothing. The effects of sulfur mustard poisoning may be local, systemic, or both, depending on
environmental conditions, exposed organs, and extent and duration of exposure. Because of the high lipid
solubility, sulfur mustard quickly penetrates the lipid cell membrane. Although sulfur mustard may be
lethal, it is more likely to cause extensive incapacitating injuries to the eyes, skin, and respiratory tract of
exposed persons. Alkylation reactions (replacement of a hydrogen atom in an organic compound by an
alkyl group [CnH2n+1]) of sulfur mustard with tissue are rapid and irreversible; however, there is a latency
period before effects become apparent. Eye and cutaneous lesions do not become apparent for 30 minutes
to several hours after exposure. Burns caused by sulfur mustard may require long healing periods. Local
effects are manifested at concentrations/doses far lower than those that produce systemic effects (NRC 1997)

Main Entry: ves·i·ca·tion
Pronunciation: "ves-&-'kA-sh&n
Function: noun
1 : BLISTER
2 : an instance or the process of blistering

Source: Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.

Hepatobiliary Pancreat Dis Int. 2003 May;2(2):270-3. Related Articles, Links: Detection of distribution of copper inside and outside of lysosomes in cultured hepatolenticular degeneration fibroblasts by electron probe X-ray microanalysis.

Liu W, Li JY, Jin J, Zuo J.

Department of Medical Genetics, School of Medicine, Fudan University, Shanghai 200032, China.

OBJECTIVE: To observe the distribution of copper in the subcellular structure for the understanding of primary pathogenesis of hepatolenticular degeneration (HLD). METHODS: Skin fibroblasts taken from HLD patients were cultured as an in vitro model of HLD, and the control cells taken from healthy volunteers were cultured in the same way. The distribution of copper inside and outside of lysosomes in fibroblasts was detected by quantitative electron probe X-ray microanalysis. The relationship between the subcellular location of copper and the genotype of the patients, and relationship between the distribution of copper and the course of the disease were analyzed. RESULTS: The content of Cu2+inside lysosomes of HLD cells (14.6+/-2.1 mmol/kg) and of heterozygote cells (11.6+/-0.6 mmol/kg) was higher than that of normal cells (4.5+/-1.2 mmol/kg) (P<0.01). The content of Cu2+outside lysosomes of HLD cells (17.5+/-4.2 mmol/kg) and of heterozygote cells (12.0+/-0.9 mmol/kg) was higher than that of normal cells (4.7+/-1.2 mmol/kg) (P<0.01). The distribution of copper in the subcellular structure was correlated with disease courses of HLD patients. With the progression of the disease, more copper was deposited in lysosomes (r=0.85, P<0.01). The content of copper in the diffused cytoplasmic compartment in HLD cells was correlated with that of sulfur (r=0.86, P<0.05), but not in heterozygote and normal cells. CONCLUSIONS: In the early stage of HLD, copper is accumulated outside lysosome, which is paralleled with increase of metallothionein-like proteins (copper and sulfur-binding proteins). With the development of the disease, more copper is deposited inside lysosome than outside lysosome. We conclude that the up-regulation expression of copper and sulfur-binding proteins and copper accumulation in lysosomes may play an important role in lowering the ATP7B gene mutation-induced toxic effects of free copper on the cell.

PMID: 14599982 [PubMed - indexed for MEDLINE]

J Struct Biol. 2003 Jul;143(1):85-93. Related Articles, Links: Nucleation and growth of macrofibrils in trichocyte (hard-alpha) keratins.

Bruce Fraser RD, Rogers GE, Parry DA.

Molecular Biosciences, University of Adelaide 5005, Australia.

The intermediate filaments (IF) in trichocyte (hard-alpha) keratin form ordered aggregates that are infiltrated by sulfur-rich and tyrosine-rich proteins during fiber development to give a filament-matrix texture, which is stabilized in the later stages by the formation of disulfide linkages. Two polymorphic forms of macrofibril are found in the cortical cells of fine Merino wool. In the first the packing of the IF in the macrofibril is quasi-hexagonal whilst in the second the IF are packed in cylindrical sheets around a central core. In hairs the second type generally predominate. In the present contribution specific models for the mechanisms of nucleation and growth are developed for the two types of macrofibril and their applicability tested by analyzing transmission electron micrographs of wool and hair. Evidence is presented which supports the idea that sheet formation plays an important role in both types of macrofibril assembly and it is suggested that differing intersheet interactions are responsible for the differences between the ortho- and para-types. It is shown that the increase in IF tilt with radius in the ortho-type can be related to the surface lattice of the IF as determined from X-ray diffraction studies. Two possible types of intersheet interaction in the ortho-type are discussed, the first leading to an increase of around 0.5 degrees in IF tilt per layer and the second leading to a much larger tilt of 9.4 degrees per layer. A crude estimate based on the decrease in visibility of the IF with increasing radius in cross-section yielded a value of 0.35 degrees -0.7 degrees.

PMID: 12892729 [PubMed - indexed for MEDLINE]

J Cosmet Sci. 2001 Sep-Oct;52(5):265-80. Related Articles, Links: Elucidating penetration pathways into the hair fiber using novel microscopic techniques.

Gummer CL.

Proctor & Gamble Technical Centres, Ltd, Egham, Surrey, UK.

Much controversy exists regarding the route of penetration of molecules into hair fibers. In brief, there are two schools of thought. The first argument is that molecules enter the hair fiber via the cell membrane complex (cmc) of the cuticle and then diffuse throughout the cortex via both the intercellular cement and the bulk of individual cortical cells. The second approach concludes that entry to the fiber is via the endocuticle and other non-keratinous parts of the fiber. In the latter case the cmc is definitely not considered to have a role in the penetration of molecules into the fiber. The tools available for studying penetration into the fiber, e.g., light and electron microscopy, mean that it is usually only possible to extract static information from a dynamic process. Similarly, great care is needed in the interpretation of images produced by the various techniques. Where a molecule is seen to end up does not always indicate how it got there! In these studies I have used novel derivations of conventional electron microscopic techniques, combined with early photographic chemistry, to elucidate further the pathways of penetration into the hair fiber. From these studies one can conclude that both arguments describing penetration into the fiber are complementary, valid, and highly relevant. The techniques allow one to visualize material within the cell membrane complex of the cuticle. In addition, these studies show that the high-sulphur proteins of the cuticle, usually considered as highly cross-linked and inaccessible, are easily penetrated. Therefore, all of the structures within a hair fiber should be considered as penetration routes into the hair fiber for the delivery of industrial and cosmetic materials, even though they may not form continuous pathways throughout the hair. The hair should be viewed as a structure composed of a number of compartments of differing capacity, chemistry, and accessibility, rather than as continuous pathways from the surface to the center of the fiber.

PMID: 11599503 [PubMed - indexed for MEDLINE]

Photochem Photobiol. 2000 Dec;72(6):746-52. Related Articles, Links: Inactivation of iron responsive element-binding capacity and aconitase function of iron regulatory protein-1 of skin cells by ultraviolet A.

Giordani A, Martin ME, Beaumont C, Santus R, Morliere P.

Museum National d'Histoire Naturelle, Laboratoire de Photobiologie, Paris, France.

The ultraviolet-A (UVA) component of sunlight produces in cutaneous cells a highly toxic oxidative stress mediated by redox cycling reactions of Fe ions. A tight regulation of cell iron uptake and storage by iron regulatory proteins (IRP) of keratinocytes and fibroblasts avoids these damaging reactions. We report here that about 40 J/cm2 of UVA are required to inactivate half of the binding capacity of apo-IRP-1 to iron responsive elements (IRE) of RNA whereas 15 J/cm2 already inhibit half of the holo-IRP-1 aconitase activity. No increase in the holo-IRP-1 activity is observed during the apo-IRP-1 photoinactivation suggesting that UVA does not trigger a shift between these two forms. As opposed to holo-IRP-1, which contains a 4Fe-4S cluster, apo-IRP-1 has no UVA chromophore. Thus it should be inactivated indirectly by reactive oxygen species generated by the UVA-induced endogenous photo-oxidative stress. The apo-IRP-1 photoinactivation is weakly prevented by the lipophilic oxyradical scavenger vitamin E but not by the hydrophilic azide anion, a singlet oxygen quencher or by diethyldithiocarbamate, a superoxide dismutase inhibitor. However, full protection against photoinactivation of the apo form is observed after incubation with N-acetylcysteine but the latter only partially protects the aconitase function of the holo-IRP-1 from photoinactivation. The marked difference in the kinetics of photoinactivation of the apo and holo forms, the light dose-independent effect of the sulfhydril group reagent, 2-mercaptoethanol and the partial protection brought by the ferric ion complexing agent desferrioxamine suggest that the photochemistry of the 4Fe-4S cluster of the holo form plays little, if any, role in the photoinactivation of the apo-IRP-1/IRE interaction. It is concluded that the apo/holo equilibrium is irreversibly destroyed by UVA irradiation.

PMID: 11140262 [PubMed - indexed for MEDLINE]

J Cell Biol. 2000 Dec 25;151(7):1459-68. Related Articles, Links: In vitro assembly and structure of trichocyte keratin intermediate filaments: a novel role for stabilization by disulfide bonding.

Wang H, Parry DA, Jones LN, Idler WW, Marekov LN, Steinert PM.

Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

Intermediate filaments (IF) have been recognized as ubiquitous components of the cytoskeletons of eukaryotic cells for 25 yr. Historically, the first IF proteins to be characterized were those from wool in the 1960s, when they were defined as low sulfur keratins derived from "microfibrils." These proteins are now known as the type Ia/type IIa trichocyte keratins that constitute keratin IF of several hardened epithelial cell types. However, to date, of the entire class of >40 IF proteins, the trichocyte keratins remain the only ones for which efficient in vitro assembly remains unavailable. In this paper, we describe the assembly of expressed mouse type Ia and type IIa trichocyte keratins into IF in high yield. In cross-linking experiments, we document that the alignments of molecules within reduced trichocyte IF are the same as in type Ib/IIb cytokeratins. However, when oxidized in vitro, several intermolecular disulfide bonds form and the molecular alignments rearrange into the pattern shown earlier by x-ray diffraction analyses of intact wool. We suggest the realignments occur because the disulfide bonds confer substantially increased stability to trichocyte keratin IF. Our data suggest a novel role for disulfide bond cross linking in stabilization of these IF and the tissues containing them.

PMID: 11134075 [PubMed - indexed for MEDLINE]

Source

Source

Blood. 2000 Aug 15;96(4):1545-9. Related Articles, Links: Mutations in the iron-sulfur cluster ligands of the human ferrochelatase lead to erythropoietic protoporphyria.

Schneider-Yin X, Gouya L, Dorsey M, Rufenacht U, Deybach JC, Ferreira GC.

Zentrallabor, Stadtspital Triemli, Zurich, Switzerland.

Ferrochelatase (FECH; EC 4.99.1.1) catalyzes the terminal step of the heme biosynthetic pathway. Defects in the human FECH gene may lead to erythropoietic protoporphyria (EPP), a rare inherited disorder characterized by diminished FECH activity with protoporphyrin overproduction and subsequent skin photosensitivity and in rare cases liver failure. Inheritance of EPP appeared to be autosomal dominant with possible modulation by low expression of the wild-type FECH allele. Animal FECHs have been demonstrated to be [2Fe-2S] cluster-containing proteins. Although enzymatic activity and stability of the protein appear to be dependent on the presence of the [2Fe-2S] cluster, the physiologic role of the iron-sulfur center remains to be unequivocally established. Three of the 4 [2Fe-2S] cluster-coordinating cysteines (ie, C403, C406, and C411 in the human enzyme) are located within the C-terminal domain. In this study 5 new mutations are identified in patients with EPP. Three of the point mutations, in 3 patients, resulted in FECH variants with 2 of the [2Fe-2S] cluster cysteines substituted with tyrosine, serine, and glycine (ie, C406Y, C406S, and C411G) and with undetectable enzymatic activity. Further, one of the patients exhibited a triple point mutation (T(1224)-->A, C(1225)-->T, and T(1231)-->G) leading to the N408K/P409S/C411G variant. This finding is entirely novel and has not been reported in EPP. The mutations of the codons for 2 of the [2Fe-2S] cluster ligands in patients with EPP supports the importance of the iron-sulfur center for the proper functioning of mammalian FECH and, in at least humans, its absence has a direct clinical impact. (Blood. 2000;96:1545-1549)

PMID: 10942404 [PubMed - indexed for MEDLINE]

Glycoconj J. 1999 Aug;16(8):457-63. Related Articles, Links: Sulfated sialic acid-polymers inhibit the cytotoxic action of bee and snake venom.

Oda Y, Kinoshita M, Hamada K, Nakayama K, Ohta Y, Yamaguchi S, Tsukada Y, Kawai Y, Kakehi K.

Faculty of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan. y_oda@phar.kindai.ac.jp

Colominic acid is an alpha2,8-linked sialic acid polymer produced by Escherichia coli. We found that synthetic sulfated-colominic acids (SC) remarkably inhibited the cytotoxicity of bee and snake venom toward mouse fibroblast cells, but colominic acids showed no inhibition themselves, indicating the important role of sulfate groups in the inhibitory activity of SC. Other sulfated carbohydrates such as chondroitin sulfates, heparin and heparan sulfate showed no inhibition. SC also exhibited potent inhibition of melittin, a highly basic peptide, which is a major cytotoxic component of bee venom. SC did not inhibit phospholipase A2 activity in bee venom. This suggests that the inhibition of bee and snake venom by SC is due to inhibition of melittin and cardiotoxin, which is a cytolytic peptide in snake venom, respectively. SC with a higher sulfur content and a larger molecular mass showed more potent activity. The interaction between SC and melittin basically seems an ionic one, however, the conformation of SC is also likely important. For the binding of SC to melittin leading loss of its cytotoxic activity, the sulfate groups of SC must be properly arranged to interact with lysine and arginine residues of melittin molecules, which play an important role in the cytolytic activity. A higher molecular mass of SC substituted with more sulfate groups is required for more obvious inhibition of the cytotoxic activity.

PMID: 10737330 [PubMed - indexed for MEDLINE]

Proc Natl Acad Sci U S A. 1999 Jun 8;96(12):6751-6. Related Articles, Links: Ultraviolet A radiation induces immediate release of iron in human primary skin fibroblasts: the role of ferritin.

Pourzand C, Watkin RD, Brown JE, Tyrrell RM.

Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, United Kingdom.

In mammalian cells, the level of the iron-storage protein ferritin (Ft) is tightly controlled by the iron-regulatory protein-1 (IRP-1) at the posttranscriptional level. This regulation prevents iron acting as a catalyst in reactions between reactive oxygen species and biomolecules. The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a source of oxidative stress to skin via generation of reactive oxygen species. We report here that the exposure of human primary skin fibroblasts, FEK4, to UVA radiation causes an immediate release of "free" iron in the cells via proteolysis of Ft. Within minutes of exposure to a range of doses of UVA at natural exposure levels, the binding activity of IRP-1, as well as Ft levels, decreases in a dose-dependent manner. This decrease coincides with a significant leakage of the lysosomal components into the cytosol. Stabilization of Ft molecules occurs only when cells are pretreated with lysosomal protease inhibitors after UVA treatment. We propose that the oxidative damage to lysosomes that leads to Ft degradation and the consequent rapid release of potentially harmful "free" iron to the cytosol might be a major factor in UVA-induced damage to the skin.

PMID: 10359784 [PubMed - indexed for MEDLINE]

Acta Derm Venereol. 1998 Sep;78(5):337-42. Related Articles, Links: The effects of fibroblast growth factors 1 and 2 on fibre growth of wool follicles in culture.

Bond JJ, Wynn PC, Moore GP.

University of Sydney, Department of Animal Science, Camden, Australia.

The effects of fibroblast growth factor-1 (FGF-1) and FGF-