Carotid body type I cells engage flavoprotein and Pin1 for oxygen sensing.

Carotid body (CB) type I cells sense the blood Po and generate a nervous signal for stimulating ventilation and circulation when blood oxygen levels decline. Three oxygen-sensing enzyme complexes may be used for this purpose: ) mitochondrial electron transport chain metabolism, ) heme oxygenase 2 (HO-2)-generating CO, and/or ) an NAD(P)H oxidase (NOX). We hypothesize that intracellular redox changes are the link between the sensor and nervous signals.

The presumed MTH1-inhibitor TH588 sensitizes colorectal carcinoma cells to ionizing radiation in hypoxia.

Background: The nudix family member enzyme MutT homologue-1 (MTH1) hydrolyses the oxidized nucleotides 8-oxo-dGTP and 2-hydroxy-dATP and thus prevents the incorporation of damaged nucleotides into nuclear and mitochondrial DNA. Therefore MTH1 was proposed to protect cancer cells from oxidative DNA lesions and subsequent cell death. We investigated whether the bona fide MTH1 inhibitor TH588 affects responses of cultured colorectal tumor cells to ionizing radiation (IR) in normoxia and in moderate or severe hypoxia.

Autophagy induced by ionizing radiation promotes cell death over survival in human colorectal cancer cells.

Autophagy is commonly described as a cell survival mechanism and has been implicated in chemo- and radioresistance of cancer cells. Whether ionizing radiation induced autophagy triggers tumor cell survival or cell death still remains unclear. In this study the autophagy related proteins Beclin1 and ATG7 were tested as potential targets to sensitize colorectal carcinoma cells to ionizing radiation under normoxic, hypoxic and starvation conditions.

PDI is an essential redox-sensitive activator of PERK during the unfolded protein response (UPR).

Endoplasmic reticulum (ER) stress leads to activation of the unfolded protein response (UPR) that results in transient suppression of protein translation to allow recovery but leads to cell death when stress cannot be resolved. Central to initiation of the UPR is the activation of the ER transmembrane kinase protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). Here we report that the thiol oxidoreductase ERp57 and protein disulfide isomerase-A1 (PDI), which belong to the same family of luminal ER oxidoreductases, have strikingly opposing roles in the regulation of PERK function.

Activating Akt1 mutations alter DNA double strand break repair and radiosensitivity.

The survival kinase Akt has clinical relevance to radioresistance. However, its contributions to the DNA damage response, DNA double strand break (DSB) repair and apoptosis remain poorly defined and often contradictory. We used a genetic approach to explore the consequences of genetic alterations of Akt1 for the cellular radiation response.