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The diagnosis of endometrial atypical hyperplasia/endometrioid intraepithelial neoplasia (AH/EIN) remains challenging and subjective in some cases, with variable histologic criteria and differences of opinion among gynecologic pathologists, potentially leading to under/overtreatment. There has been growing interest in the use of specific immunohistochemical markers as adjuncts in AH/EIN diagnosis. For example, the World Health Organization 2020 Classification specifies that loss of Pten, Pax2, or mismatch repair proteins are desirable diagnostic criteria. Other markers, most notably β-catenin and Arid1a, are also aberrantly expressed in some AH/EIN. However, the performance of some markers individually-and more importantly as a group-has not been rigorously explored, raising questions as to which marker(s) or combination(s) is the most effective in practice. Formalin-fixed paraffin-embedded tissue sections from AH/EIN cases (n=111) were analyzed by immunohistochemistry for 6 markers: Pax2, Pten, Mlh1, β-catenin, Arid1a, and p53. Aberrant expression was tabulated for each case and marker. An additional set of normal endometria (n=79) was also analyzed to define optimal diagnostic criteria for marker aberrance. The performance characteristics of each marker, the entire panel, and subsets thereof were quantitatively and statistically analyzed. In order of number of cases detected, the most frequently aberrant markers in AH/EIN were Pax2 (81.1% of cases), Pten (50.5%), β-catenin (47.7%), Arid1a (7.2%), Mlh1 (4.5%), and p53 (2.7%). The majority of cases showed aberrant expression of ≥2 markers. All 6 markers together identified 92.8% of cases. Arid1a, Mlh1, and p53 were robust and readily scored markers, but all cases showing aberrant expression of these 3 markers were also detected by Pax2, Pten, or β-catenin. A focused panel of only 3 markers (Pax2, Pten, and β-catenin) showed optimal performance characteristics as a diagnostic adjunct in the histopathologic diagnosis of AH/EIN. Use of this panel is practicable and robust, with at least 1 of the 3 markers being aberrant in 92.8% of AH/EIN.

Atherosclerosis (AS) is a chronic cardiovascular disease endangering human health and is one of the most common causes of myocardial infarction and stroke. Macrophage polarization plays a vital role in regulating plaque stability. As an important component of sunlight, ultraviolet B (UVB) has been proven to promote vitamin D and nitric oxide synthesis. This research used an AS model in ApoE−/− mice to study the effects of UVB on macrophage polarization and atherosclerotic plaque stability. In vitro, UVB irradiation increased arginase-I (Arg-I, M2 macrophage) and macrophage mannose receptor (CD206) expression, while the expression of inducible nitric oxide synthase (iNOS) (M1 macrophage) and CD86 was decreased. UVB promoted Akt phosphorylation in vitro. In vivo, UVB irradiation promoted the stabilization of atherosclerotic lesion plaques, while the phenotype of M2 macrophages increased. Our research provides new evidence for UVB in preventing and treating atherosclerosis.

Cancer is instigated by mutator phenotypes, including deficient mismatch repair and p53-associated chromosomal instability. More recently, a distinct class of cancers was identified with unusually high mutational loads due to heterozygous amino acid substitutions (most commonly P286R) in the proofreading domain of DNA polymerase ε, the leading strand replicase encoded by POLE. Immunotherapy has revolutionized cancer treatment, but new model systems are needed to recapitulate high mutational burdens characterizing human cancers and permit study of mechanisms underlying clinical responses. Here, we show that activation of a conditional LSL-Pole(P286R) allele in endometrium is sufficient to elicit in all animals endometrial cancers closely resembling their human counterparts, including very high mutational burden. Diverse investigations uncovered potentially novel aspects of Pole-driven tumorigenesis, including secondary p53 mutations associated with tetraploidy, and cooperation with defective mismatch repair through inactivation of Msh2. Most significantly, there were robust antitumor immune responses with increased T cell infiltrates, accelerated tumor growth following T cell depletion, and unfailing clinical regression following immune checkpoint therapy. This model predicts that human POLE-driven cancers will prove consistently responsive to immune checkpoint blockade. Furthermore, this is a robust and efficient approach to recapitulate in mice the high mutational burdens and immune responses characterizing human cancers.

Potassium and nitrogen are essential macronutrients for plant growth and have a positive impact on crop yield. Previous studies have indicated that the absorption and translocation of K+ and NO3 2 are correlated with each other in plants; however, the molecular mechanism that coordinates K+ and NO3 2 transport remains unknown. In this study, using a forward genetic approach, we isolated a low-K+-sensitive Arabidopsis thaliana mutant, lks2, that showed a leaf chlorosis phenotype under low-K+ conditions. LKS2 encodes the transporter NRT1.5/NPF7.3, a member of the NRT1/PTR (Nitrate Transporter 1/Peptide Transporter) family. The lks2/nrt1.5 mutants exhibit a remarkable defect in both K+ and NO3 2 translocation from root to shoot, especially under low-K+ conditions. This study demonstrates that LKS2 (NRT1.5) functions as a proton-coupled H+/K+ antiporter. Proton gradient can promote NRT1.5-mediated K+ release out of root parenchyma cells and facilitate K+ loading into the xylem. This study reveals that NRT1.5 plays a crucial role in K+ translocation from root to shoot and is also involved in the coordination of K+/NO3 2 distribution in plants

Cancer is characterized by increased mutation rate, and recent work has led to a deeper understanding of mutator phenotypes and underlying molecular mechanisms. Differences in the mutational landscape of individual cancers underlie key aspects of clinical behavior. For example, overall base substitution rate is the best predictor of immune therapy response. Most genetically engineered mouse models of cancer (GEMMs) reiterate a few driver events but fail to recapitulate the high mutational loads that are the ultimate cause of most human cancer, making GEMMs inadequate for many aspects of tumor behavior, such as immune responses. The highest base substitution rates in cancers (≥100/Mb) result from specific heterozygous single amino acid substitutions (usually P286R) in the proofreading domain of DNA polymerase epsilon (POLE), rendering POLE highly error prone. POLE mutations are most common in endometrial cancer but occur with lower incidence in a wide range of cancers. We hypothesized that GEMMs could be generated by recapitulating PoleP286R via conditional knockin. Previously, we showed that constitutive expression of PoleP286R throughout the body triggered malignancies of diverse lineages. Mice harboring LSL-PoleP286R and the endometrial BAC-Sprr2f-Cre developed endometrial cancers starting at 1 year. Endometrial cancers exhibited histologic features previously reported in human POLE tumors, and metastasized in all mice (p This abstract is also being presented as Poster A34. Citation Format: Hao-Dong Li, Changzheng Lu, He Zhang, Ileana C. Cuevas, Subhransu S. Sahoo, Yang-Xin Fu, Diego H. Castrillon. Polymerase-mediated ultramutagenesis: A new approach for modeling the high mutational load of human cancer [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr PR13.

Mutations underlie all cancers, and their identification and study are the foundation of cancer biology. We describe what we believe to be a novel approach to mutagenesis and cancer studies based on the DNA polymerase e (POLE) ultramutator phenotype recently described in human cancers, in which a single amino acid substitution (most commonly P286R) in the proofreading domain results in error-prone DNA replication. We engineered a conditional PoleP286R allele in mice. PoleP286R/+ embryonic fibroblasts exhibited a striking mutator phenotype and immortalized more efficiently. PoleP286R/+ mice were born at Mendelian ratios but rapidly developed lethal cancers of diverse lineages, yielding the most cancer-prone monoallelic model described to date, to our knowledge. Comprehensive whole-genome sequencing analyses showed that the cancers were driven by high base substitution rates in the range of human cancers, overcoming a major limitation of previous murine cancer models. These data establish polymerase-mediated ultramutagenesis as an efficient in vivo approach for the generation of diverse animal cancer models that recapitulate the high mutational loads inherent to human cancers.

Purpose: To compare cryopreserved human corneal endothelial cells (HCECs) grown in human serum-supplemented media (HS-SM) with cryopreserved HCECs grown in fetal bovine serum-supplemented media (FBS-SM). Methods: Three pairs of human corneas from donors aged 8, 28, and 31 years were obtained from the eye bank. From each pair, one cornea was used to start a HCEC culture using HS-SM; the other cornea was grown in FBS-SM. On reaching confluence, the six cell populations were frozen using 10% dimethyl sulfoxidecontaining medium. Thawed cells grown in HS-SM were compared with those grown in FBS-SM with respect to morphology, growth curves, immunohistochemistry, real time-reverse transcriptase polymerase chain reaction (RT-PCR) for endothelial cell markers, and detachment time. Results: No difference in morphology was observed for cells grown in the two media before or after cryopreservation. By growth curves, cell counts after thawing were similar in both media, with a slight trend toward higher cell counts in FBS-SM. Cells grown in both the media demonstrated a similar expression of endothelial cell markers when assessed by immunohistochemistry, although HCEC marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM as assessed by RT-PCR. With FBS-SM, there was a tendency of longer detachment time and lower cell passages. Conclusions: HS-SM was similar to FBS-SM for cryopreservation of cultured HCECs as assessed by analysis of cell morphology, proliferation, and protein expression, although marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM. Detachment time was longer with FBS-SM and in lower passages. RESUMO Objetivo: Comparar células endoteliais de córnea humana (HCECs) criopreservadas e cultivadas em meio suplementado com soro humano (HS-SM) com HCEC criopreservadas e cultivadas em meio suplementado com soro bovino fetal (FBS-SM). Métodos: Três pares de córneas humanas de doadores com 8, 28 e 31 anos de idade foram obtidos do banco de olhos e, de cada par, uma córnea foi utilizado para iniciar uma cultura com HS-SM e outra com FBS-SM. Ao atingir a confluência, as populações de células foram congeladas utilizando-se dimetil-sulfóxido 10% no respectivo meio de cultura. Após descongeladas, as células cultivadas em HS-SM foram comparados com as cultivadas em FBS-SM por meio de morfologia, curva de crescimento, imuno-histoquímica, reação em cadeia de Reação em cadeia da polimerase da transcrição reversa em tempo real (RT-PCR) para marcadores de células endoteliais e tempo de descolamento. Resultado: Não foram observadas diferenças morfológicas antes ou após a criopreservação. Curva de crescimento mostrou contagens celulares semelhantes em ambos os meios, com discreta tendência para um maior número em FBS-SM. As células cultivadas em ambos os meios mostraram expressão semelhante de marcadores celulares endoteliais quando avaliadas por imuno-histoquímica, embora a expressão genética de marcadores para HCEC tenha sido maior em HS-SM quando avaliado por RT-PCR. Houve uma tendência de maior tempo de descolamento com FBS-SM e passagens iniciais. Conclusões: HS-SM foi semelhante ao FBS-SM na criopreservação de HCEC cultivadas in vitro quando avaliadas por morfologia celular, proliferação celular e expressão proteica, embora a expressão genética de marcadores endoteliais tenha sido maior em células cultivadas em HS-SM quando comparadas a células cultivadas em FBS-SM. O tempo de descolamento foi maior quando utilizado FBS-SM e em passagens iniciais.

Potassium transporters play crucial roles in K(+) uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassium channel AtKC1, encoded by the AtLKT1 gene cloned from the Arabidopsis thaliana low-K(+) (LK)-tolerant mutant Atlkt1, significantly regulates AKT1-mediated K(+) uptake under LK conditions. Under LK conditions, the Atkc1 mutants maintained their root growth, whereas wild-type plants stopped their root growth. Lesion of AtKC1 significantly enhanced the tolerance of the Atkc1 mutants to LK stress and markedly increased K(+) uptake and K(+) accumulation in the Atkc1-mutant roots under LK conditions. Electrophysiological results showed that AtKC1 inhibited the AKT1-mediated inward K(+) currents and negatively shifted the voltage dependence of AKT1 channels. These results demonstrate that the 'silent' K(+) channel alpha-subunit AtKC1 negatively regulates the AKT1-mediated K(+) uptake in Arabidopsis roots and consequently alters the ratio of root-to-shoot under LK stress conditions.

Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein, molecular chaperone, and a component of the translocon. We discovered a novel interaction between the calnexin cytoplasmic domain and UBC9, a SUMOylation E2 ligase, which modified the calnexin cytoplasmic domain by the addition of SUMO. We demonstrated that calnexin interaction with the SUMOylation machinery modulates an interaction with protein tyrosine phosphatase 1B (PTP1B), an ER-associated protein tyrosine phosphatase involved in the negative regulation of insulin and leptin signaling. We showed that calnexin and PTP1B form UBC9-dependent complexes, revealing a previously unrecognized contribution of calnexin to the retention of PTP1B at the ER membrane. This work shows that the SUMOylation machinery links two ER proteins from divergent pathways to potentially affect cellular protein quality control and energy metabolism.

Background Calnexin, together with calreticulin, constitute the calnexin/calreticulin cycle. Calnexin is a type I endoplasmic reticulum integral membrane protein and molecular chaperone responsible for the folding and quality control of newly-synthesized (glyco)proteins. The endoplasmic reticulum luminal domain of calnexin is responsible for lectin-like activity and interaction with nascent polypeptide chains. The role of the C-terminal, cytoplasmic portion of calnexin is not clear. Methodology/Principal Findings Using yeast two hybrid screen and immunoprecipitation techniques, we showed that the Src homology 3-domain growth factor receptor-bound 2-like (Endophilin) interacting protein 1 (SGIP1), a neuronal specific regulator of endocytosis, forms complexes with the C-terminal cytoplasmic domain of calnexin. The calnexin cytoplasmic C-tail interacts with SGIP1 C-terminal domains containing the adaptor complexes medium subunit (Adap-Comp-Sub) region. Calnexin-deficient cells have enhanced clathrin-dependent endocytosis in neuronal cells and mouse neuronal system. This is reversed by expression of full length calnexin or calnexin C-tail. Conclusions/Significance We show that the effects of SGIP1 and calnexin C-tail on clathrin-dependent endocytosis are due to modulation of the internalization of the receptor-ligand complexes. Enhanced clathrin-dependent endocytosis in the absence of calnexin may contribute to the neurological phenotype of calnexin-deficient mice.

SummaryPotassium is an essential mineral element for plant growth and development. Although it is known that plants absorb and transport K+ through membrane transporters, it remains unclear how these transporters are regulated. Here we show that the protein kinase CIPK23, encoded by the LKS1 gene, regulates K+ uptake under low-K+ conditions. Lesion of LKS1 significantly reduced K+ uptake and caused leaf chlorosis and growth inhibition, whereas overexpression of LKS1 significantly enhanced K+ uptake and tolerance to low K+. We demonstrate that CIPK23 directly phosphorylates the K+ transporter AKT1 and further find that CIPK23 is activated by the binding of two calcineurin B-like proteins, CBL1 and CBL9. We propose a model in which the CBL1/9–CIPK23 pathway ensures activation of AKT1 and enhanced K+ uptake under low-K+ conditions.