RESUMO
Protein synthesis in response to neuronal activity, known as activity-dependent translation, is critical for synaptic plasticity and memory formation. However, the signaling cascades that couple neuronal activity to the translational events remains elusive. In this study, we identified the role of calmodulin (CaM), a conserved Ca2+-binding protein, in rRNA biogenesis in neurons. We found the CaM-regulated rRNA synthesis is Ca2+-dependent and necessary for nascent protein synthesis and axon growth in hippocampal neurons. Mechanistically, CaM interacts with nucleolar DDX21 in a Ca2+-dependent manner to regulate nascent rRNA transcription within nucleoli. We further found CaM alters the conformation of DDX21 to liberate the DDX21-sequestered RPA194, the catalytic subunit of RNA polymerase I, to facilitate transcription of rDNA. Using high-throughput screening, we identified the small molecules Batefenterol and Indacaterol that attenuate the CaM-DDX21 interaction and suppress nascent rRNA synthesis and axon growth in hippocampal neurons. These results unveiled the previously unrecognized role of CaM as a messenger to link the activity-induced Ca2+ influx to the nucleolar events essential for protein synthesis. We thus identified the ability of CaM to transmit information to the nucleoli of neurons in response to stimulation.Significance statement Protein synthesis in response to neuronal activity, known as activity-dependent translation, is critical for synaptic plasticity and long-term memory formation. In this study, we identify the novel role of calmodulin (CaM), a highly conserved Ca2+-binding protein, which is well-known by regulating myriad vital biological processes, in activity-dependent translation by regulating rRNA synthesis in neurons. We find that CaM can shuttle into the nucleolus upon depolarization and modulate the activity-induced de novo rRNA biogenesis, which is associated with ribosome assembly and protein synthesis in neurons. Mechanistically, CaM interacts with DDX21, an RNA helicase directly associated with Pol I subunit, to regulate the transcription of rDNA. Our study demonstrates CaM as a messenger linking neuronal activity to ribosome-dependent protein biosynthesis.
RESUMO
Purpose: This study aimed to investigate the relationship between peripheral blood indices and the efficacy and prognosis of advanced esophageal squamous cell carcinoma (ESCC) patients treated with camrelizumab. Patients and Methods: We retrospectively analyzed 64 patients who received camrelizumab for advanced ESCC at the Second People's Hospital of Lianyungang City between July 2020 and June 2022. The study included examination of the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the systemic inflammation index (SII), the lymph-to-monocytes ratio (LMR), the absolute lymphocyte count (ALC), and lactate dehydrogenase (LDH). We used multivariate logistic regression analysis to explore the link existing between peripheral blood and the efficacy of treatment. Determination of potential prognostic factors for Progression-free survival (PFS) and Overall survival (OS) using Cox regression analysis. The nomogram model was developed based on the results of the Cox multivariate analysis. Patients were divided into three groups according to the reduction in LDH and LDL levels before treatment, and the Kaplan-Meier survival curves for the three groups were compared and ROC curves for LDH combined with PLR were plotted. Results: Lower LDH (OR=6.237, 95% CI: 1.625-23.944) were independently associated with disease control rates(DCR). LDH was independently correlated with PFS (HR: 0.227 95% CI: 0.099-0.517). LDH and PLR were independently linked to OS. The C index of the nomogram model is 0.819, indicating good predictive performance. Kaplan-Meier Survival Curve suggested better OS in patients with reduced pretreatment LDH and PLR. The area under the ROC curve showed that the LDH index combined with the PLR index predicts patient survival better than the index alone. Conclusion: LDH combined with PLR predicted prognosis in patients with ESCC treated with camrelizumab.