ABSTRACT
The nematode Caenorhabditis elegans contains a single ancestral p53 family member, cep-1, which is required to activate apoptosis of germ cells in response to DNA damage. To understand how the cep-1/p53 pathway is regulated in response to genotoxic stress, we performed an RNA interference screen and identified the neddylation pathway and components of an SCF (Skp1/cullin/F-box) E3 ubiquitin ligase as negative regulators of cep-1-dependent germ cell apoptosis. Here, we show that the cullin gene cul-1, the Skp1-related gene skr-1, and the ring box genes rbx-1 and rpm-1 all negatively regulate cep-1-dependent germ cell apoptosis in response to the DNA-alkylating agent N-ethyl-N-nitrosourea (ENU). We also identified the F-box protein FSN-1, previously shown to form an SCF ligase that regulates synapse development, as a negative regulator of cep-1-dependent germline apoptosis. The hypersensitivity of fsn-1 mutants to ENU-induced germline apoptosis was completely suppressed by a cep-1 loss-of-function allele. We further provide evidence that the transcriptional activity, phosphorylation status, and levels of endogenous CEP-1 are higher in fsn-1 mutants compared with wild-type animals after ENU treatment. Our results uncover a novel role for the SCF(FSN-1) E3 ubiquitin ligase in the regulation of cep-1-dependent germ cell apoptosis.
Subject(s)
Apoptosis , Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans Proteins/physiology , Caenorhabditis elegans/metabolism , F-Box Proteins/physiology , Germ Cells/metabolism , SKP Cullin F-Box Protein Ligases/physiology , Tumor Suppressor Protein p53/metabolism , Animals , Caenorhabditis elegans/cytology , Caenorhabditis elegans/enzymology , Caenorhabditis elegans Proteins/genetics , DNA Damage , F-Box Proteins/genetics , Germ Cells/cytology , Germ Cells/enzymology , Mutation , NEDD8 Protein , RNA Interference , SKP Cullin F-Box Protein Ligases/genetics , Signal Transduction , Transcription, Genetic , Ubiquitins/metabolismABSTRACT
The optical system configuration and design of a dot matrix holographic printer that can create image grating pixels of variable size, arbitrary pitch, and discretionary angle on a photoresist plate are presented. With the capability to vary spot size, grating orientation, and grating pitch on the fly, this newly developed holographic printer can apply a prespecified color at each specific viewing angle. Diffractive images with various visual effects and the wide color range that are possible by use of this system are examined in detail.
