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Anion exchanger 2 (AE2) is an electroneutral Na+-independent Cl-/HCO3- exchanger belongs to the SLC4 transporter family. The widely expressed AE2 participates in a variety of physiological processes, including transepithelial acid-base secretion and osteoclastogenesis. Both the transmembrane domains (TMDs) and the N-terminal cytoplasmic domain (NTD) are involved in regulation of AE2 activity. However, the regulatory mechanism remains unclear. Here, we report a 3.2 Å cryo-EM structure of the AE2 TMDs in complex with PIP2 and a 3.3 Å full-length mutant AE2 structure in the resting state without PIP2. We demonstrate that PIP2 at the TMD dimer interface is involved in the substrate exchange process. Mutation in the PIP2 binding site leads to the displacement of TM7 and further stabilizes the interaction between the TMD and the NTD. Reduced substrate transport activity and conformation similar to AE2 in acidic pH indicating the central contribution of PIP2 to the function of AE2. Anion exchanger 2 (AE2), a widely expressed Cl- /HCO3 - exchanger, participates in the regulation of intracellular pH. Here, the authors present the structures of AE2 and uncover the regulatory mechanism of PIP2. [ABSTRACT FROM AUTHOR]

Pyrroline-5-carboxylate reductase (PYCR), the last enzyme in proline synthesis that converts P5C into proline, was found promoting cancer growth and inhibiting apoptosis through multiple approaches, including regulating cell cycle and redox homeostasis, and promoting growth signaling pathways. Proline is abnormally up-regulated in multiple cancers and becomes one of the critical players in the reprogramming of cancer metabolism. As the last key enzymes in proline generation, PYCRs have been the subject of many investigations, and have been demonstrated to play an indispensable role in promoting tumorigenesis and cancer progression. In this article, we will thoroughly review the recent investigations on PYCRs in cancer development. [ABSTRACT FROM AUTHOR]

Background: Oesophageal cancer (EC) ranks high in both morbidity and mortality. A non-invasive and high-sensitivity diagnostic approach is necessary to improve the prognosis of EC patients.Methods: A total of 525 serum samples were subjected to lipidomic analysis. We combined serum lipidomics and machine-learning algorithms to select important metabolite features for the detection of oesophageal squamous cell carcinoma (ESCC), the major subtype of EC in developing countries. A diagnostic model using a panel of selected features was developed and evaluated. Integrative analyses of tissue transcriptome and serum lipidome were conducted to reveal the underlying mechanism of lipid dysregulation.Results: Our optimised diagnostic model with a panel of 12 lipid biomarkers together with age and gender reaches a sensitivity of 90.7%, 91.3% and 90.7% and an area under receiver-operating characteristic curve of 0.958, 0.966 and 0.818 in detecting ESCC for the training cohort, validation cohort and independent validation cohort, respectively. Integrative analysis revealed matched variation trend of genes encoding key enzymes in lipid metabolism.Conclusions: We have identified a panel of 12 lipid biomarkers for diagnostic modelling and potential mechanisms of lipid dysregulation in the serum of ESCC patients. This is a reliable, rapid and non-invasive tumour-diagnostic approach for clinical application. [ABSTRACT FROM AUTHOR]

Loss of Werner syndrome protein function causes Werner syndrome, characterized by increased genomic instability, elevated cancer susceptibility and premature aging. Although WRN is subject to acetylation, phosphorylation and sumoylation, the impact of these modifications on WRN's DNA metabolic function remains unclear. Here, we examined in further depth the relationship between WRN acetylation and its role in DNA metabolism, particularly in response to induced DNA damage. Our results demonstrate that endogenous WRN is acetylated somewhat under unperturbed conditions. However, levels of acetylated WRN significantly increase after treatment with certain DNA damaging agents or the replication inhibitor HU. Use of DNA repair-deficient cells or repair pathway inhibitors further increase levels of acetylated WRN, indicating that induced DNA lesions and their persistence are at least partly responsible for increased acetylation. Notably, acetylation of WRN correlates with inhibition of DNA synthesis, suggesting that replication blockage might underlie this effect. Moreover, WRN acetylation modulates its affinity for and activity on certain DNA structures, in a manner that may enhance its relative specificity for physiological substrates. Our results also show that acetylation and deacetylation of endogenous WRN is a dynamic process, with sirtuins and other histone deacetylases contributing to WRN deacetylation. These findings advance our understanding of the dynamics of WRN acetylation under unperturbed conditions and following DNA damage induction, linking this modification not only to DNA damage persistence but also potentially to replication stalling caused by specific DNA lesions. Our results are consistent with proposed metabolic roles for WRN and genomic instability phenotypes associated with WRN deficiency. [ABSTRACT FROM AUTHOR]

The p53 tumour suppressor is a short-lived protein that is maintained at low levels in normal cells by Mdm2-mediated ubiquitination and subsequent proteolysis. Stabilization of p53 is crucial for its tumour suppressor function. However, the precise mechanism by which ubiquitinated p53 levels are regulated in vivo is not completely understood. By mass spectrometry of affinity-purified p53-associated factors, we have identified herpesvirus-associated ubiquitin-specific protease (HAUSP) as a novel p53-interacting protein. HAUSP strongly stabilizes p53 even in the presence of excess Mdm2, and also induces p53-dependent cell growth repression and apoptosis. Significantly, HAUSP has an intrinsic enzymatic activity that specifically deubiquitinates p53 both in vitro and in vivo. In contrast, expression of a catalytically inactive point mutant of HAUSP in cells increases the levels of p53 ubiquitination and destabilizes p53. These findings reveal an important mechanism by which p53 can be stabilized by direct deubiquitination and also imply that HAUSP might function as a tumour suppressor in vivo through the stabilization of p53. [ABSTRACT FROM AUTHOR]

Shows that the deacetylation of the tumor suppressor and transcriptional factor p53 is mediated by a histone deacetylase-1 (HDAC1)-containing complex. Purification of a p53 target protein which has been identified as a component of the NuRD complex; Results, which show that deacetylation and functional interactions by the PID/MTA2-associated NuRD complex may represent an important pathway to regulate p53 function.

The PML gene of acute promyelocytic leukaemia (APL) encodes a growth- and tumour-suppresor protein that is essential for several apoptotic signals. The mechanisms by which PML exerts its pro-apoptotic function are still unknown. Here we show that PML acts as a transcriptional co-activator with p53. PML physically interacts with p53 bothin vitro andin vivo and co-localizes with p53 in the PML nuclear body (PML-NB). The co-activatory role of PML depends on its ability to localize in the PML-NB. p53-dependent, DNA-damage-induced apoptosis, transcriptional activation by p53, the DNA-binding ability of p53, and the induction of p53 target genes such asBax andp21 upon γ-irradiation are all impaired inPML(-/-)primary cells. These results define a new PML-dependent, p53-regulatory pathway for apoptosis and shed new light on the function of PML in tumour suppression. [ABSTRACT FROM AUTHOR]