Biology subjects

Bai, D.

Publications and source records attributed to Bai, D..

4 recordsLinked to original sources

bioRxiv2021

Essential role for Ggct in erythrocyte antioxidant defense

GGCT encodes {gamma}-glutamyl cyclotransferase enzyme activity, and its expression is up-regulated in various human cancers. {gamma}-glutamyl cyclotransferase enzyme activity was originally purified from human red blood cells (RBCs), however physiological function of GGCT in RBCs is still not clear. Here we reported that Ggct deletion in mouse leads to splenomegaly and progressive anemia phenotypes, due to elevated oxidative damage and shortened life span of Ggct-/- RBCs. Ggct-/- RBCs have increased reactive oxygen species (ROS), and are more sensitive to H2O2 induced damage compared to control RBCs. Glutathione (GSH) and GSH synthesis precursor L-cysteine are decreased in Ggct-/- RBCs. Our study suggests a critical function of Ggct in RBC redox balance and life span maintenance through regulating GSH metabolism.

genetics↗

bioRxiv2021

A novel Wnt/beta-catenin signaling driven adipocyte population that is required for beiging

Wnt/{beta}-catenin signaling has been well established as a potent inhibitor of adipogenesis. Here, we identified a population of adipocytes that exhibit persistent activity of Wnt/{beta}-catenin signaling, as revealed by the Tcf/Lef-Gfp reporter allele, in embryonic and adult mouse fat depots, named as Wnt+ adipocytes. We showed that the {beta}-catenin-mediated signaling activation in these cells is Wnt ligand- and receptor-independent but relies on AKT/mTOR pathway and is essential for cell survival. Such adipocytes are distinct from classical ones in transcriptomic and genomic signatures and can be induced from various sources of mesenchymal stromal cells including human cells. Genetic lineage-tracing and targeted cell ablation studies revealed that these adipocytes convert into beige adipocytes directly and are also required for beige fat recruitment under thermal challenge, demonstrating both cell autonomous and non-cell autonomous roles in adaptive thermogenesis. Furthermore, mice bearing targeted ablation of these adipocytes exhibited glucose intolerance, while mice receiving exogenously supplied such cells manifested enhanced glucose utilization. Our studies uncover a unique adipocyte population in regulating beiging in adipose tissues and systemic glucose homeostasis.

physiology↗

bioRxiv2020

Connexin 46 and connexin 50 gap junction channel open stability and unitary conductance are shaped by structural and dynamic features of their N-terminal domains

The connexins form intercellular communication channels, known as gap junctions (GJs), that facilitate diverse physiological roles in vertebrate species, ranging from electrical coupling and long-range chemical signaling, to coordinating development and nutrient exchange. GJs formed by different connexins are expressed throughout the body and harbor unique channel properties that have not been fully defined mechanistically. Recent structural studies have implicated the amino-terminal (NT) domain as contributing to isoform-specific functional differences that exist between the lens connexins, Cx50 and Cx46. To better understand the structural and functional differences in the two closely related, yet functionally distinct GJs, we constructed models corresponding to CryoEM-based structures of the wildtype Cx50 and Cx46 GJs, NT domain swapped chimeras (Cx46-50NT and Cx50-46NT), and point variants at the 9th residue (Cx46-R9N and Cx50-N9R) for comparative MD simulation and electrophysiology studies. All of these constructs formed functional GJ channels, except Cx46-50NT, which correlated with increased dynamical behavior (instability) of the NT domain observed by MD simulation. Single channel conductance (γj) also correlated well with free-energy landscapes predicted by MD, where γj of Cx46-R9N was increased from Cx46 and the γjs of Cx50-46NT and Cx50-N9R was decreased from Cx50, but to a surprisingly greater degree. Additionally, we observed significant effects on transjunctional voltage-dependent gating (Vj-gating) and open-state dwell times induced by the designed NT domain variants. Together, these studies indicate that the NT domains of Cx46 and Cx50 play an important role in defining channel properties related to open-state stability and single channel conductance.Competing Interest StatementThe authors have declared no competing interest.AbbreviationsGJgap junctionGjgap junctional coupling conductanceγjsingle gap junction channel conductanceIjmacroscopic transjunctional currentijsingle gap junction channel currentCx46sheep connexin 46Cx50sheep connexin 50Vjtransjunctional voltageMDmolecular dynamicsr.m.s.d.root mean square deviationr.m.s.f.root mean square fluctuationPMFpotential of mean forceView Full Text

biophysics↗

bioRxiv2019

Clinicopathological characteristics and survival of lymphoepithelial carcinoma of the oral cavity and pharynx: a population-based study

Lymphoepithelial carcinoma (LEC) of the oral cavity and pharynx is uncommon, and the characteristics and survival remains unclear. The present study aims to describe the clinicopathological characteristics and determine the factors associated with survival of this uncommon cancer. A population-based study was carried out to investigate clinical characteristics and prognosis of LEC of the oral cavity and pharynx using the data from Surveillance, Epidemiology and End Results (SEER) database between 1988 and 2013. The propensity-matched analysis was conducted for prognostic analysis, and a prognostic nomogram was also constructed. Totally, 1025 patients with LEC of the oral cavity and pharynx were identified, including 769 nasopharyngeal LEC patients and 256 non-nasopharyngeal LEC patients. The median OS of all LEC patients was 232.0m (95% CI 169.0-258.0). The 1-, 5-, 10- and 20-year survival rates were 92.9%, 72.9%, 59.3%, and 46.8%, respectively. Surgery could significantly prolong the survival time of LEC patients (P<0.01, mOS: 190m vs. 255m). Radiotherapy, as well as radiotherapy after surgery, could prolong the mOS (P<0.01 for both). The survival analysis demonstrated that old age (>60 years), lymph node (N3) and distant metastases were independent factors for poor survival, whereas radiotherapy and surgery were independent factors for favorable survival. No significant differences in survival time between nasopharyngeal LEC and non-nasopharyngeal LEC patients were observed. The prognostic nomogram was established base on five independent prognostic factors (C-index=0.70; 95% CI 0.66-0.74). In conclusion, LEC of the oral cavity and pharynx is a rare disease, and old age, lymph node and distant metastases, surgery and radiotherapy were significantly associated with prognosis. The prognostic nomogram could be used to make individual predictions of OS.

genetics↗