No abstract

The Q protein of bacteriophage lambda is a transcription antiterminator that modifies the elongation properties of E. coli RNA polymerase (RNAP). To do this, DNA-bound (lambda)Q must first engage a paused elongation complex. Here we show that this engagement of (lambda)Q with RNAP involves an interaction between (lambda)Q and sigma(70), demonstrating that sigma(70) can be a target of regulation during elongation. Furthermore, we provide evidence that this interaction between (lambda)Q and sigma(70) stabilizes a conformation of RNAP that requires the disengagement of a segment of sigma(70) from the core enzyme. Recent structure-based models posit that the transition from the initiation to the elongation phase of transcription involves the staged displacement of sigma(70) from the RNAP core. Our findings provide support for this proposal.

Background: Preoperative/Neoadjuvant treatment (NT) is increasingly used in unresectable pancreatic cancer (PDAC). However,~40% of patients cannot be resected after NT and reliable preoperative response evaluation is currently lacking. We investigated CA 19-9 levels and their dynamics during NT for prediction of resectability and survival.Methods: We screened our institution's database for patients who underwent exploration or resection after NT with gemcitabine-based therapy (GEM) or FOLFIRINOX (FOL). Pre-and post-NT CA 19-9, resection rate and survival were analyzed.Results: Of 318 patients 165 (51.9%) were resected and 153 (48.1%) received exploration. In the FOL group (n = 103; 32.4%), a post-NT CA 19-9 cutoff at 91.8 U/ml had a sensitivity of 75.0% and a specificity of 76.9% for completing resection with an AUC of 0.783 in the ROC analysis (95% CI: 0.692-0.874; p < 0.001. PPV: 84.2%, NPV: 65.2%). Resected patients above the cutoff did not benefit from resection. Post-NT CA 19-9 <91.8 U/ml (OR 11.63, p < 0.001) and CA 19-9 ratio of <0.4 (OR 5.77, p = 0.001) were independent predictors for resectability in FOL patients.Discussion: CA 19-9 levels after neoadjuvant treatment with FOLFIRINOX predict resectability and survival of PDAC more accurately than dynamic values and should be incorporated into response evaluation and surgical decision-making.

Pluripotent stem cells, including induced pluripotent and embryonic stem cells (ESCs), have less developed mitochondria than somatic cells and, therefore, rely more heavily on glycolysis for energy production. However, how mitochondrial homeostasis matches the demands of nuclear reprogramming and regulates pluripotency in ESCs is largely unknown. Here, we identified ATG3-dependent autophagy as an executor for both mitochondrial remodeling during somatic cell reprogramming and mitochondrial homeostasis regulation in ESCs. Dysfunctional autophagy by Atg3 deletion inhibited mitochondrial removal during pluripotency induction, resulting in decreased reprogramming efficiency and accumulation of abnormal mitochondria in established iPSCs. In Atg3 null mouse ESCs, accumulation of aberrant mitochondria was accompanied by enhanced ROS generation, defective ATP production and attenuated pluripotency gene expression, leading to abnormal self-renewal and differentiation. These defects were rescued by reacquisition of wild-type but not lipidation-deficient Atg3 expression. Taken together, our findings highlight a critical role of ATG3-dependent autophagy for mitochondrial homeostasis regulation in both pluripotency acquirement and maintenance.