Homologous recombination (HR) and nonhomologous end-joining (NHEJ) are mechanistically distinct DNA repair pathways that contribute substantially to double-strand break (DSB) repair in mammalian cells. We have combined mutations in factors from both repair pathways, the HR protein Rad54 and the DNA-end-binding factor Ku80, which has a role in NHEJ. Rad54 −/− Ku80−/− mice were severely compromised in their survival, such that fewer double mutants were born than expected, and only a small proportion of those born reached adulthood. However, double-mutant mice died at lower frequency from tumors than Ku80 single mutant mice, likely as a result of rapid demise at a young age from other causes. When challenged with an exogenous DNA damaging agent, ionizing radiation, double-mutant mice were exquisitely sensitive to low doses. Tissues and cells from double-mutant mice also showed indications of spontaneous DNA damage. Testes from some Rad54 −/− Ku80−/− mice displayed enhanced apoptosis and reduced sperm production, and embryonic fibroblasts from Rad54 −/− Ku80−/− animals accumulated foci of ␥-H2AX, a marker for DSBs. The substantially increased DNA damage response in the double mutants implies a cooperation of the two DSB repair pathways for survival and genomic integrity in the animal.[Keywords: DNA double-strand break; homologous recombination; nonhomologous end-joining; Ku80, Rad54] Supplemental material is available at http://www.genesdev.org.

The production of reactive oxygen species (ROS) is a ubiquitous defense response in plants. Adapted pathogens evolved mechanisms to counteract the deleterious effects of host-derived ROS and promote infection. How plant pathogens regulate this elaborate response against ROS burst remains unclear. Using the rice blast fungus Magnaporthe oryzae, we uncovered a self-balancing circuit controlling response to ROS in planta and virulence. During infection, ROS induces phosphorylation of the high osmolarity glycerol pathway kinase MoOsm1 and its nuclear translocation. There, MoOsm1 phosphorylates transcription factor MoAtf1 and dissociates MoAtf1-MoTup1 complex. This releases MoTup1-mediated transcriptional repression on oxidoreduction-pathway genes and activates the transcription of MoPtp1/2 protein phosphatases. In turn, MoPtp1/2 dephosphorylate MoOsm1, restoring the circuit to its initial state. Balanced interactions among proteins centered on MoOsm1 provide a means to counter host-derived ROS. Our findings thereby reveal new insights into how M. oryzae utilizes a phosphor-regulatory circuitry to face plant immunity during infection.

No abstract

With the US Food and Drug Administration (FDA) approval of four CD19-and one BCMA-targeted chimeric antigen receptor (CAR) therapy for B cell malignancies, CAR T cell therapy has finally reached the status of a medicinal product. The successful manufacturing of autologous CAR T cell products is a key requirement for this promising treatment modality. By analyzing the composition of 214 apheresis products from 210 subjects across eight disease indications, we found that high CD14 + cell content poses a challenge for manufacturing CAR T cells, especially in patients with non-Hodgkin's lymphoma and multiple myeloma caused by the non-specific phagocytosis of the magnetic beads used to activate CD3 + T cells. We demonstrated that monocyte depletion via rapid plastic surface adhesion significantly reduces the CD14 + monocyte content in the apheresis products and simultaneously boosts the CD3 + content. We established a 40% CD14 + threshold for the stratification of apheresis products across nine clinical trials and demonstrated the effectiveness of this procedure by comparing manufacturing runs in two phase 1 clinical trials. Our study suggests that CD14 + content should be monitored in apheresis products, and that the manufacturing of CAR T cells should incorporate a step that lessens the CD14 + cell content in apheresis products containing more than 40% to maximize the production success.

No abstract