Glen B. Zamansky

Disruption of cytoplasmic microtubules by ultraviolet radiation

Ultraviolet (UV) irradiation of cultured human skin fibroblasts causes the disassembly of their microtubules. Using indirect immunofluorescence microscopy, we have now investigated whether damage to the microtubule precursor pool may contribute to the disruption of microtubules. Exposure to polychromatic UV radiation inhibits the reassembly of microtubules during cellular recovery from cold treatment. In addition, the ability of taxol to promote microtubule polymerization and bundling is inhibited in UV-irradiated cells. However, UV irradiation of taxol-pretreated cells or in situ detergent-extracted microtubules fails to disrupt the microtubule network. These data suggest that damage to dimeric tubulin, or another soluble factor(s) required for polymerization, contributes to the disassembly of microtubules in UV-irradiated human skin fibroblasts.

Disruption of keratin intermediate filaments by ultraviolet radiation in cultured human keratinocytes.

Abstract— Fluorescence microscopy has been utilized to investigate the effects of UV irradiation on the organization of keratin intermediate filaments in normal human epidermal keratinocytes. Sun lamp irradiation induced the condensation of keratin intermediate filaments into the perinuclear region and inhibited the reorganization of keratin filaments normally induced by Ca2+. Exposure to UVC appeared to disrupt keratin filaments similarly, whereas UVA had no discernible effect.

Varying sensitivity of human skin fibroblasts to polychromatic ultraviolet light

The inactivation of normal and xeroderma pigmentosum cells has been compared following exposure to environmentally relevant wavelengths of ultraviolet light or to the more commonly investigated 254-nm ultraviolet light. The sensitivity of xeroderma pigmentosum cells to polychromatic long-wavelength ultraviolet light was greatly lower than that observed using 254-nm light. Such variations in the relative sensitivities of normal and xeroderma pigmentosum cells support the likelihood that the lesions which contribute to cellular alterations induced by solar wavelengths of ultraviolet light are different from those which predominate at 254 nm.

Ultraviolet Radiation Induces Cytoskeletal Damage in Human Cells

Solar ultraviolet (UV) radiation is the major cause of skin cancer and contributes to the deterioration of dermal connective tissue associated with aging. It is therefore important to identify the UV induced lesions which alter normal cellular functions. Although genetic damage may be an important initiating factor in the carcinogenic process, epigenetic phenomena are also likely to play a role in the development of neoplasia. Current evidence indicates that lesions other than pyrimidine dimers are involved in the carcinogenic, mutagenic and lethal effects of UV radiation which reaches the earth’s surface (Zamansky, 1986 and references therein). Although investigators continue to seek additional DNA lesions which may contribute to these pathogenic phenomena, the importance of UV induced alterations of other cellular components must also be considered.

Recovery from UV-induced potentially lethal damage in systemic lupus erythematosus skin fibroblasts.

The repair of ultraviolet light-induced potentially lethal damage was investigated in density-inhibited skin fibroblast cell strains derived from patients with systemic lupus erythematosus. The effect of exposure to polychromatic ultraviolet light composed of environmentally relevant wavelengths or to the more commonly studied, short wavelength (254 nm) ultraviolet light was studied. Systemic lupus erythematosus cells, which are hypersensitive to ultraviolet light under growth promoting conditions, were able to repair potentially lethal damage as well as normal cells.

Microtubule disassembly induced by sensitizing halogenated nitrobenzene derivatives.

The potency of certain halogenated nitrobenzene derivatives to induce allergic contact dermatitis has been demonstrated in guinea-pigs and in man. As the first step towards understanding the mechanisms of cellular injury induced by these sensitizers, we have studied by fluorescence microscopy the effects of 13 halogenated (nitro)benzene derivatives on microtubule organization in mouse 3T3 fibroblasts and human AG1522 skin fibroblasts. Untreated cells have numerous microtubules distributed in a network fashion throughout the cytoplasm and extending to the cell periphery. Exposing cells for 3 hr to micromolar doses of halogenated nitrobenzene derivatives, which induce allergic contact dermatitis in guinea-pigs and man, resulted in a dose-dependent disassembly of microtubules. In contrast, incubation with 10-70 times higher doses of seven halogenated (nitro)benzene derivatives that do not sensitize guinea-pigs or man, had no discernible effect on microtubule organization of both cell types under identical assay conditions. Thus, for the 13 halogenated (nitro)benzene derivatives tested in this study, a 100% positive correlation exists between the sensitizing capacity as determined by in vivo tests on guinea-pigs and man (Landsteiner and Jacobs, 1936) and the ability to cause microtubule disassembly in cultured cells. These results may provide the basis for developing an in vitro screening assay for identifying other potential halogenated nitrobenzene sensitizers. In addition, these studies represent a new approach to investigating the mechanisms of contact sensitivity induced by simple chemicals.