UV radiation is an important etiologic factor for skin cancer, including melanoma. Constitutive pigmentation and the ability to tan are considered the main photoprotective mechanism against sun-induced carcinogenesis. Pigmentation in the skin is conferred by epidermal melanocytes that synthesize and transfer melanin to keratinocytes. Therefore, insuring the survival and genomic stability of epi...

Skin cancer is the most ubiquitous cancer type in the Caucasian population, and its incidence is increasing rapidly [1]. Transcribed proliferation-related genes in dermal stem cells are targets for the induction of ultraviolet light (UV)-induced mutations that drive carcinogenesis. We have recently found that transcription of a gene increases its mutability by UV in mammalian stem cells, sugges...

12-O-Tetnadecanoyl-phonbol-13-acetate (TPA) and phon bol were tested in Chinese hamster cells for their effects on mutagenesis (resistance to 6-thioguanine and to ouabain), DNA repair, and survival after ultraviolet (UV) irradiation. Recovery of 6-thioguanineand ouabain-resistant colonies was significantly increased by TPA treatment and, to a lessen extent, by phonbol in UV-innadiated cells. Mo...

In a search for mutants that affect genetic recombination, Clark and Margulies (1) discovered the recA gene in Escherichia coli, but subsequently recA mutants were found to be pleiotropic, affecting not only recombination but repair, mutagenesis, phage induction, and cell division (2). Not surprisingly, many years passed before the basis of this complex phenotype was understood. A milestone was...

UV radiation is an important etiologic factor for skin cancer, including melanoma. Constitutive pigmentation and the ability to tan are considered the main photoprotective mechanism against sun-induced carcinogenesis. Pigmentation in the skin is conferred by epidermal melanocytes that synthesize and transfer melanin to keratinocytes. Therefore, insuring the survival and genomic stability of epi...

Ultraviolet (UV) cone pigments can provide insights into the molecular evolution of vertebrate vision since they are nearer to ancestral pigments than the dim-light rod photoreceptor rhodopsin. While visible-absorbing pigments contain an 11-cis retinyl chromophore with a protonated Schiff-base (PSB11), UV pigments uniquely contain an unprotonated Schiff-base (USB11). Upon F86Y mutation in model...

The Escherichia coli UvrB protein possesses an amino acid sequence motif common to many ATPases. The role of this motif in UvrB has been investigated by site-directed mutagenesis. Three UvrB mutants, with amino acid replacements at lysine-45, failed to confer UV resistance when tested in the UV-sensitive strain N364 (delta uvrB), while five other mutants constructed near this region of UvrB con...

DNA excision repair modulates the mutagenic effect of many genotoxic agents. The recently observed strand specificity for removal of UV-induced cyclobutane dimers from actively transcribed genes in mammalian cells could influence the nature and distribution of mutations in a particular gene. To investigate this, we have analyzed UV-induced DNA repair and mutagenesis in the same gene, i.e. the h...