Project description:Skin is usually exposed during human exposures to ionizing radiation, however there are few experiments that evaluate the radiation responsiveness of the cells of the epidermis (keratinocytes) and those of the dermis (fibroblasts) in the same studies. We evaluated the transcriptional responses of quiesent primary keratinocytes and fibroblasts from the same individual and compared them with quiescent keratinocytes and fibroblasts that were immortalized by human telomerase (hTert). The primary transcriptional responses to 10-500 cGy ionizing radiation were p53-mediated responses; however, we did identify distinct responses between the keratinocytes and the fibroblasts. Keywords: keratinocytes and fibroblasts - dose response to ionizing radiation
Project description:Investigation of ATM-dependent and dose-dependent, or -independent, responses were examined in human lymphoblast cells 6 hr following exposure to either 1 or 5 Gy ionizing radiation. Human lymphoblast cells from "apparently healthy" individuals and individuals with Ataxia telangiectasia were exposed to 1 Gy or 5 Gy ionizing radiation. Gene expression responses 6 hr following IR were examined. Untreated samples were hybridized together with their matched treated samples.
Project description:Investigation of ATM-dependent and dose-dependent, or -independent, responses were examined in human lymphoblast cells 6 hr following exposure to either 1 or 5 Gy ionizing radiation. Keywords: cDNA, dual-channel
Project description:Skin is usually exposed during human exposures to ionizing radiation, however there are few experiments that evaluate the radiation responsiveness of the cells of the epidermis (keratinocytes) and those of the dermis (fibroblasts) in the same studies. We evaluated the transcriptional responses of quiesent primary keratinocytes and fibroblasts from the same individual and compared them with quiescent keratinocytes and fibroblasts that were immortalized by human telomerase (hTert). The primary transcriptional responses to 10-500 cGy ionizing radiation were p53-mediated responses; however, we did identify distinct responses between the keratinocytes and the fibroblasts. Experiment Overall Design: Four cell types (primary keratinocytes, hTert immortalized keratinocytes, primary fibroblasts, hTert immortalized fibroblasts) grown to quiescence, treated with 0, 10, 100 or 500 cGy gamma irradiation, RNA collected at 4 hrs.
Project description:The relationships between profiles of global gene expression and DNA damage checkpoint functions were studied in cells from patients with ataxia telangiectasia (AT). Three telomerase-expressing AT fibroblast lines displayed the expected hypersensitivity to ionizing radiation (IR) and defects in DNA damage checkpoints. Profiles of global gene expression in AT cells were determined at 2, 6 and 24 h after treatment with 1.5 Gy IR or sham-treatment, and were compared to those previously recognized in normal human fibroblasts. Under basal conditions 160 genes or ESTs were differentially expressed in AT and normal fibroblasts, and these were associated by gene ontology with insulin-like growth factor binding and regulation of cell growth. Upon DNA damage, 1091 gene mRNAs were changed in at least two of the three AT cell lines. When compared with the 1811 genes changed in normal human fibroblasts after the same treatment, 715 were found in both AT and normal fibroblasts, including most genes categorized by gene ontology into cell cycle, cell growth and DNA damage response pathways. However, the IR-induced changes in these 715 genes in AT cells usually were delayed or attenuated in comparison to normal cells. The reduced change in DNA-damage-response genes and the attenuated repression of cell-cycle-regulated genes may account for the defects in cell cycle checkpoint function in AT cells. The observation of attenuated and not ablated checkpoint responses in AT cells supports a hypothesis that the ATM- and rad3-related checkpoint kinase ATR also responds to IR-induced DNA damage and complements ATM signaling. Keywords: ATM, cell cycle checkpoint, ionizing radiation, microarray
Project description:In this study we show that, in embryonic fibroblasts from mice on a high fat diet and treated with Forskolin, ionizing radiation exposure or both, phosphorylation of CREB-binding protein (CREB) by ATM (ataxia-telangiectasia-mutated) and casein kinases 1 and 2 (CK1 and CK2) on a cluster of five phosphorylation sites (the ATM/CK cluster) within the unstructured kinase-inducible domain (KID) provides an additional level of regulation through dynamic modulation of CREB DNA binding activity. Stoichiometric phosphorylation of the ATM/CK cluster in response to DNA damage inhibited cAMP-induced CREB target gene expression, CREB DNA binding activity, and CREB-CRTC2-DNA ternary complex formation proportional to the number of phosphate residues modified. Substoichiometric phosphorylation of the ATM/CK cluster promoted cAMP/Ca2+-regulated transcriptional coactivators (CRTCs) recruitment and CREB activation via an ATM-independent, PKA-dependent pathway. Mice expressing a non-phosphorylatable CREBS111A allele exhibited phenotypes consistent with CREB deregulation, including fasting hyperglycemia, susceptibility to diet-induced obesity, and reduced expression of gluconeogenic genes. Two genotypes: CREB+/+ (wild type) and CREBS111A (non-phosphorylatable CREB KID S111A mutant allele) each control treated, exposed to forskolin, ionizing radiation or both in triplicate and in two batches toataling 48 arrays