Varying Selection Pressure for a Na+ Sensing Site in Epithelial Na+ Channel Subunits Reflect Divergent Roles in Na+ Homeostasis.

The epithelial Na+ channel (ENaC) emerged early in vertebrates and has played a role in Na+ and fluid homeostasis throughout vertebrate evolution. We previously showed that proteolytic activation of the channel evolved at the water-to-land transition of vertebrates. Sensitivity to extracellular Na+, known as Na+ self-inhibition, reduces ENaC function when Na+ concentrations are high and is a distinctive feature of the channel. A fourth ENaC subunit, δ, emerged in jawed fishes from an α subunit gene duplication. Here, we analyzed 849 α and δ subunit sequences and found that a key Asp in a postulated Na+ binding site was nearly always present in the α subunit, but frequently lost in the δ subunit (e.g. human). Analysis of site evolution and codon substitution rates provide evidence that the ancestral α subunit had the site and that purifying selection for the site relaxed in the δ subunit after its divergence from the α subunit, coinciding with a loss of δ subunit expression in renal tissues. We also show that the proposed Na+ binding site in the α subunit is a bona fide site by conferring novel function to channels comprising human δ subunits. Together, our findings provide evidence that ENaC Na+ self-inhibition improves fitness through its role in Na+ homeostasis in vertebrates.

SGLT2-independent effects of canagliflozin on NHE3 and mitochondrial complex I activity inhibit proximal tubule fluid transport and albumin uptake.

Beyond glycemic control, SGLT2 inhibitors (SGLT2is) have protective effects on cardiorenal function. Renoprotection has been suggested to involve inhibition of NHE3 leading to reduced ATP-dependent tubular workload and mitochondrial oxygen consumption. NHE3 activity is also important for regulation of endosomal pH, but the effects of SGLT2i on endocytosis are unknown. We used a highly differentiated cell culture model of proximal tubule (PT) cells to determine the direct effects of SGLT2i on Na+-dependent fluid transport and endocytic uptake in this nephron segment. Strikingly, canagliflozin but not empagliflozin reduced fluid transport across cell monolayers and dramatically inhibited endocytic uptake of albumin. These effects were independent of glucose and occurred at clinically relevant concentrations of drug. Canagliflozin acutely inhibited surface NHE3 activity, consistent with a direct effect, but did not affect endosomal pH or NHE3 phosphorylation. In addition, canagliflozin rapidly and selectively inhibited mitochondrial complex I activity. Inhibition of mitochondrial complex I by metformin recapitulated the effects of canagliflozin on endocytosis and fluid transport, whereas modulation of downstream effectors AMPK and mTOR did not. Mice given a single dose of canagliflozin excreted twice as much urine over 24 h compared with empagliflozin-treated mice despite similar water intake. We conclude that canagliflozin selectively suppresses Na+-dependent fluid transport and albumin uptake in PT cells via direct inhibition of NHE3 and of mitochondrial function upstream of the AMPK/mTOR axis. These additional targets of canagliflozin contribute significantly to reduced PT Na+-dependent fluid transport in vivo.NEW & NOTEWORTHY Reduced NHE3-mediated Na+ transport has been suggested to underlie the cardiorenal protection provided by SGLT2 inhibitors. We found that canagliflozin, but not empagliflozin, reduced NHE3-dependent fluid transport and endocytic uptake in cultured proximal tubule cells. These effects were independent of SGLT2 activity and resulted from inhibition of mitochondrial complex I and NHE3. Studies in mice are consistent with greater effects of canagliflozin versus empagliflozin on fluid transport. Our data suggest that these selective effects of canagliflozin contribute to reduced Na+-dependent transport in proximal tubule cells.

Bile acids regulate the epithelial Na+ channel in native tissues through direct binding at multiple sites.

Bile acids, originally known to emulsify dietary lipids, are now established signalling molecules that regulate physiological processes. Signalling targets several proteins that include the ion channels involved in regulating intestinal motility and bile viscosity. Studies show that bile acids regulate the epithelial sodium channel (ENaC) in cultured cell models and heterologous expression systems. ENaC plays both local and systemic roles in regulating extracellular fluids. Here we investigated whether bile acids regulate ENaC expressed in native tissues. We found that taurocholic acid and taurohyodeoxycholic acid regulated ENaC in both the distal nephron and distal colon. We also tested the hypothesis that regulation occurs through direct binding. Using photoaffinity labelling, we found evidence for specific binding to both the ß and γ subunits of the channel. In functional experiments, we found that the α subunit was sufficient for regulation. We also found that regulation by at least one bile acid was voltage-sensitive, suggesting that one binding site may be closely associated with the pore-forming helices of the channel. Our data provide evidence that bile acids regulate ENaC by binding to multiple sites to influence the open probability of the channel. KEY POINTS: Recent studies have shown that bile acids regulate the epithelial sodium channel (ENaC) in vitro. Here we investigated whether bile acids regulate ENaC in native tissues and whether bile acids directly bind the channel. We found that bile acids regulate ENaC expressed in the mouse cortical collecting duct and mouse colon by modulating open probability. Photoaffinity labelling experiments showed specific binding to the ß and γ subunits of the channel, while channels comprising only α subunits were sensitive to taurocholic acid in functional experiments using Xenopus oocytes. Taurocholic acid regulation of ENaC was voltage-dependent, providing evidence for binding to pore-forming helices. Our data indicate that bile acids are ENaC regulatory effectors that may have a role in the physiology and pathophysiology of several systems.

Validation of the predictive model for seizure recurrence after withdrawal of antiepileptic drugs.

PURPOSE: The purpose of this study was to validate the practicability of Lamberink's prediction model in risk assessment of antiepileptic drug (AED) withdrawal in a real, seizure-free population and to find a practical cutoff value to guide clinical withdrawal. METHODS: A group of seizure-free patients from West China Hospital was recruited. Each patient had been seizure-free for at least two years. The seizure recurrence risk among the patients was calculated by an online AED withdrawal risk calculator. The predictive ability of Lamberink's model was assessed by analyzing discrimination and calibration with receiver operating characteristic (ROC) curves and calibration plots, respectively. RESULTS: A total of 184 seizure-free patients received risk evaluation, all of whom were followed up for at least two years or had an earlier report of seizure relapse. Of these patients, 128 patients were followed up for at least five years or had an earlier report of relapse within five years. Sixty-two of 184 (33.7%) patients relapsed within two years, while 81 of 184 (44.0%) patients relapsed within five years after the start of AEDs' withdrawal. Cox regression analyses showed that seizure duration before remission and the age of seizure onset were independent predictors of relapse at two years. For predictors of recurrence at five years, seizure duration before remission, age at onset, and withdrawal were significant. For discrimination, ROC curve analysis showed that the area under the curve (AUC) for the seizure recurrence within two and five years was 0.605 (95% confidence interval [CI]: 0.518-0.692, p = 0.02) and 0.656 (95% CI: 0.563-0.749, p = 0.003), respectively. For calibration, it was poor in two-year prediction; the observed number was considerably lower than the predicted number. However, the calibration plot showed good calibration with the five-year prediction except for the second, fourth, and eighth deciles. With a cutoff two-year recurrence risk of 47%, the model had a sensitivity of 0.758 and a specificity of 0.410; the largest Youden index was 1.168. With a cutoff five-year recurrence risk of 77%, the model had a sensitivity of 0.358 and a specificity of 0.979; the largest Youden index was 1.337. CONCLUSIONS: Lamberink's prediction model has a general discrimination ability. The model overestimated the actual recurrence events when predicting the two-year recurrence risk, but it showed relatively good calibration with five-year prediction. The cutoff value found in this study may be used to guide patients and clinicians towards a decision regarding the withdrawal of AEDs. The model appears to be a useful tool for predicting seizure recurrence for the five-year recurrence risk.

Coordinating carbon and nitrogen metabolic signaling through the cyanobacterial global repressor NdhR.

The coordination of carbon and nitrogen metabolism is essential for bacteria to adapt to nutritional variations in the environment, but the underlying mechanism remains poorly understood. In autotrophic cyanobacteria, high CO2 levels favor the carboxylase activity of ribulose 1,5 bisphosphate carboxylase/oxygenase (RuBisCO) to produce 3-phosphoglycerate, whereas low CO2 levels promote the oxygenase activity of RuBisCO, leading to 2-phosphoglycolate (2-PG) production. Thus, the 2-PG level is reversely correlated with that of 2-oxoglutarate (2-OG), which accumulates under a high carbon/nitrogen ratio and acts as a nitrogen-starvation signal. The LysR-type transcriptional repressor NAD(P)H dehydrogenase regulator (NdhR) controls the expression of genes related to carbon metabolism. Based on genetic and biochemical studies, we report here that 2-PG is an inducer of NdhR, while 2-OG is a corepressor, as found previously. Furthermore, structural analyses indicate that binding of 2-OG at the interface between the two regulatory domains (RD) allows the NdhR tetramer to adopt a repressor conformation, whereas 2-PG binding to an intradomain cleft of each RD triggers drastic conformational changes leading to the dissociation of NdhR from its target DNA. We further confirmed the effect of 2-PG or 2-OG levels on the transcription of the NdhR regulon. Together with previous findings, we propose that NdhR can sense 2-OG from the Krebs cycle and 2-PG from photorespiration, two key metabolites that function together as indicators of intracellular carbon/nitrogen status, thus representing a fine sensor for the coordination of carbon and nitrogen metabolism in cyanobacteria.

[Inpatient Care Expenditure of Terminally Ill Patients in the Geriatric Ward of Peking Union Medical College Hospital].

Objective To describe the inpatient care expenditure of the terminally ill patients in the geriatric ward of Peking Union Medical College Hospital and facilitate future research on the economic outcomes of hospice and palliative care.Methods The histories of patients admitted to the Department of Geriatrics of Peking Union Medical College Hospital during 2018 were reviewed by trained doctors.According to the diagnosis and overall health state,terminally ill patients were selected and enrolled in the study.Demographics,health and disease information,prescriptions,and expenditure details were retrieved from the HIS system.Results In 2018,35 patients were terminally ill and eligible for hospice care,including 20 males and 15 females,with the average age of(78±8)years(59-91 years),the average age-adjusted Charlson Comorbidity Index of 10±3,and the median Barthel index of 40(10,70).These patients had malignant tumor(23 cases),heart failure(4 cases),end-stage renal disease(1 case),end-stage liver disease(2 cases),dementia(4 cases)and other severe diseases(3 cases).The patients received standard care within the scope of internal medicine and geriatrics.Finally,8 patients died during hospitalization,and 27 were discharged alive.The 35 patients had the median length of stay of 15(12,23)days,the median inpatient expenditure of CNY 21 500(13 800,37 600),and the median daily expenditure of CNY 1425(970,2503).The percentage of expenditure was(28.5±12.3)% for medication,(33.2±18.0)% for tests and examinations,and 11.5%(6.4%,15.8%)for accommodation and medical services.The medications for symptom control costed CNY(77±58)per day on average,accounting for(5.2±3.5)% of the total expenditure.Conclusions The inpatient expenditure for terminally ill patients in the tertiary grade A hospital was higher than that reported in community hospitals providing hospice care.In terms of expenditure constitution,the money spent on medications and tests/examinations were similar,and the percentage of expenditure on medications for symptom control was low.There is a need for further research on the economic impact of hospice and palliative care among terminally ill patients in China.

Murine epithelial sodium (Na+) channel regulation by biliary factors.

The epithelial sodium channel (ENaC) mediates Na+ transport in several epithelia, including the aldosterone-sensitive distal nephron, distal colon, and biliary epithelium. Numerous factors regulate ENaC activity, including extracellular ligands, post-translational modifications, and membrane-resident lipids. However, ENaC regulation by bile acids and conjugated bilirubin, metabolites that are abundant in the biliary tree and intestinal tract and are sometimes elevated in the urine of individuals with advanced liver disease, remains poorly understood. Here, using a Xenopus oocyte-based system to express and functionally study ENaC, we found that, depending on the bile acid used, bile acids both activate and inhibit mouse ENaC. Whether bile acids were activating or inhibiting was contingent on the position and orientation of specific bile acid moieties. For example, a hydroxyl group at the 12-position and facing the hydrophilic side (12α-OH) was activating. Taurine-conjugated bile acids, which have reduced membrane permeability, affected ENaC activity more strongly than did their more membrane-permeant unconjugated counterparts, suggesting that bile acids regulate ENaC extracellularly. Bile acid-dependent activation was enhanced by amino acid substitutions in ENaC that depress open probability and was precluded by proteolytic cleavage that increases open probability, consistent with an effect of bile acids on ENaC open probability. Bile acids also regulated ENaC in a cortical collecting duct cell line, mirroring the results in Xenopus oocytes. We also show that bilirubin conjugates activate ENaC. These results indicate that ENaC responds to compounds abundant in bile and that their ability to regulate this channel depends on the presence of specific functional groups.

Conserved cysteines in the finger domain of the epithelial Na+ channel α and γ subunits are proximal to the dynamic finger-thumb domain interface.

The epithelial Na+ channel (ENaC) is a member of the ENaC/degenerin family of ion channels. In the structure of a related family member, the "thumb" domain's base interacts with the pore, and its tip interacts with the divergent "finger" domain. Between the base and tip, the thumb domain is characterized by a conserved five-rung disulfide ladder holding together two anti-parallel α helices. The ENaC α and γ subunits' finger domains harbor autoinhibitory tracts that can be proteolytically liberated to activate the channel and also host an ENaC-specific pair of cysteines. Using a crosslinking approach, we show that one of the finger domain cysteines in the α subunit (αCys-263) and both of the finger domain cysteines in the γ subunit (γCys-213 and γCys-220) lie near the dynamic finger-thumb domain interface. Our data suggest that the αCys-256/αCys-263 pair is not disulfide-bonded. In contrast, we found that the γCys-213/γCys-220 pair is disulfide-bonded. Our data also suggest that the γ subunit lacks the terminal rung in the thumb domain disulfide ladder, suggesting asymmetry between the subunits. We also observed functional asymmetry between the α and γ subunit finger-thumb domain interfaces; crosslinks bridging the α subunit finger-thumb interface only inhibited ENaC currents, whereas crosslinks bridging the γ subunit finger-thumb interface activated or inhibited currents dependent on the length of the crosslinker. Our data suggest that reactive cysteines lie at the dynamic finger-thumb interfaces of the α and γ subunits and may play a yet undefined role in channel regulation.

Prognostic value of estrogen receptor-α and progesterone receptor in curatively resected colorectal cancer: a retrospective analysis with independent validations.

BACKGROUND: Prognostic assessment is crucial for optimal treatment. The aim of our study was to investigate the potential impact of estrogen receptor-α (ER-α) and progesterone receptor (PR) on the prognosis of colorectal cancer (CRC) patients who received curative resection. METHODS: Retrospective evaluation of two independent cohorts of CRC patients maintained prospectively in 2009-2010 (training set) (n = 148) and 2007-2009 (internal validation set) (n = 485). Furthermore, we used an external independent CRC cohort from The Cancer Genome Atlas (TCGA) (n = 511) for further validation. ER-α and PR expression as well as other potential prognostic factors were retrospectively evaluated in training set with respect to overall survival (OS), local relapse free survival (LRFS) and distant metastasis free survival (DMFS). The prognostic factors found in training set will be validated in two validation cohorts. RESULTS: On univariate analysis for the training set, OS, LRFS and DMFS were not associated with PR expression. While patients with ER-αexpression were found to have poor prognosis. In addition, multivariate analysis showed that ER-αexpression maintained significance with respect to OS (HR, 5.06; p = 0.002), LRFS (HR, 8.81; p = 0.002) and DMFS (HR, 8.07; p = 0.004). Similarly, ER-α expression showed prognostic significance with respect to OS with hazard ratios (HRs) of 1.572 (95% CI: 1.001-2.467, p = 0.049) and 1.624 (95% CI: 1.047-2.520, p = 0.031) for the internal and external validation cohort, respectively. CONCLUSION: ER-α expression was a biomarker of poor prognosis and it might inform treatment decision for high risk CRC patients. However, PR expression was not associated with survival outcomes.

A Meta-Analysis of Cardiovascular Events in Systemic Lupus Erythematosus.

Objective: To identify accurate occurrence and risk of cardiovascular (CV) events (stroke and myocardial infarction [MI]) in patients with systemic lupus erythematosus (SLE). Methods: Systemic literature search in PubMed and additional manual search were performed to obtain interested studies until March 31, 2018. The pooled incidences and risk of stroke and MI were calculated. Results: A total of 24 studies were included in this meta-analysis. For MI, a total of 1,516 SLE patients were reported to had MI (n = 96,154) over a mean follow-up of 9.98 years: incidence 2.0% (95% CI: 1.7-2.4%), i.e. 0.20/100 pyrs; in the five studies, 360 SLE patients (n = 18,943) and 817 controls had MI (n = 111,525), revealing that the risk of MI in SLE population was 3.04 times higher than in the general population (RR = 3.04, 95% CI: 1.81-5.11). For stroke, the incidence of 17 studies during the 10.09 follow-up period using random model was 4.4% (95% CI: 3.6-5.1%), i.e. 0.44/100 pyrs; in the 7 studies, 694 SLE patients (n = 22,594) and 4,034 controls had stroke (n = 255,023), indicating that the risk of MI in SLE population was 1.95 times higher than that in the general population (RR = 1.95, 95% CI: 1.52-2.53). Conclusion: Based on the findings from previous reports, our meta-analysis showed that patients with SLE have been at higher risk of CV events.

Wnt signaling pathway involvement in genotypic and phenotypic variations in Waardenburg syndrome type 2 with MITF mutations.

Mutation in the gene encoding microphthalmia-associated transcription factor (MITF) lead to Waardenburg syndrome 2 (WS2), an autosomal dominantly inherited syndrome with auditory-pigmentary abnormalities, which is clinically and genetically heterogeneous. Haploinsufficiency may be the underlying mechanism for WS2. However, the mechanisms explaining the genotypic and phenotypic variations in WS2 caused by MITF mutations are unclear. A previous study revealed that MITF interacts with LEF-1, an important factor in the Wnt signaling pathway, to regulate its own transcription through LEF-1-binding sites on the MITF promoter. In this study, four different WS2-associated MITF mutations (p.R217I, p.R217G, p.R255X, p.R217del) that are associated with highly variable clinical features were chosen. According to the results, LEF-1 can activate the expression of MITF on its own, but MITF proteins inhibited the activation. This inhibition weakens when the dosage of MITF is reduced. Except for p.R217I, p.R255X, p.R217G, and p.R217del lose the ability to activate TYR completely and do not inhibit the LEF-1-mediated activation of the MITF-M promoter, and the haploinsufficiency created by mutant MITF can be overcome; correspondingly, the mutants' associated phenotypes are less severe than that of p.R217I. The dominant negative of p.R217del made it have a second-most severe phenotype. This study's data imply that MITF has a negative feedback loop of regulation to stabilize MITF gene dosage that involves the Wnt signaling pathway and that the interaction of MITF mutants with this pathway drives the genotypic and phenotypic differences observed in Waardenburg syndrome type 2 associated with MITF mutations.

Chemokine CCL27 is a novel plasma biomarker for identification the nasopharyngeal carcinoma patients from the Epstein-Barr virus capsid antigen-specific IgA seropositive population.

BACKGROUND: To investigate the predictive value of chemokine CCL27 for identifying early stage nasopharyngeal carcinoma (NPC) patients within a population seropositive for Epstein-Barr virus (EBV) capsid antigen-specific IgA (VCA-IgA). METHODS: CCL27 in plasma samples from 104 NPC patients, 112 VCA-IgA-positive healthy donors, and 140 VCA-IgA-negative normal subjects was measured by ELISA. Expression of CCL27 in nasopharyngeal tissue from 20 VCA-IgA-positive healthy donors and 20 NPC patients was examined by immunohistochemical staining. RESULTS: Levels of CCL27 in the plasma of VCA-IgA-positive healthy donors (607.33 ± 218.81 pg/ml) were significantly higher than the levels in all NPC patients (437.09 ± 217.74, P = < 0.0001) and in the subset of patients with early stage NPC (463.85 ± 226.17, P = 0.0126). Plasma CCL27 levels were significantly lower in the VCA-IgA-negative normal subjects (358.22 ± 133.15 pg/ml) than in either the VCA-IgA-positive healthy donors (P < 0.0001) or the NPC patients (P = 0.0113). CCL27 protein was detected in 16 of 20 (80%) nasopharyngeal tissue samples from VCA-IgA-positive healthy donors and in 3 of 20 (15%) tumor tissue samples from NPC patients. There was no relationship between CCL27 levels and VCA-IgA titers or plasma EBV DNA content. Receiver operating characteristic (ROC) curves demonstrated that plasma CCL27 levels had a sensitivity of 67.00%, a specificity of 73.10%, and an area under the ROC of 0.725 (95% confidence interval [CI]: 0.657-0.793) for distinguishing between NPC patients and VCA-IgA-positive healthy donors. Further analysis showed that CCL27 levels could distinguish between early stage NPC patients and VCA-IgA-positive healthy donors with an area under the ROC of 0.712 (95% CI: 0.560-0.865), a sensitivity of 59.80%, and a specificity of 84.60%. CONCLUSIONS: Chemokine CCL27 could successfully identify NPC patients within a VCA-IgA-positive population.

Functional analysis of a SOX10 gene mutation associated with Waardenburg syndrome II.

Waardenburg syndrome (WS) is an autosomal dominant inherited non-syndromic type of hereditary hearing loss characterized by varying combinations of sensorineural hearing loss and abnormal pigmentation of the hair, skin, and inner ear. WS is classified into four subtypes (WS1-WS4) based on additional symptoms. WS2 is characterized by the absence of additional symptoms. Recently, we identified a SOX10 missense mutation c.422T > C (p.L141P) associated with WS2. We performed functional assays and found the mutant loses DNA-binding capacity, shows aberrant cytoplasmic and nuclear localization, and fails to interact with PAX3. Therefore, the mutant cannot transactivate the MITF promoter effectively, inhibiting melanin synthesis and leading to WS2. Our study confirmed haploinsufficiency as the underlying pathogenesis for WS2.

Two spatially and temporally distinct Ca2+ signals convey Arabidopsis thaliana responses to K+ deficiency.

In plants, potassium (K+ ) homeostasis is tightly regulated and established against a concentration gradient to the environment. Despite the identification of Ca2+ -regulated kinases as modulators of K+ channels, the immediate signaling and adaptation mechanisms of plants to low-K+ conditions are only partially understood. To assess the occurrence and role of Ca2+ signals in Arabidopsis thaliana roots, we employed ratiometric analyses of Ca2+ dynamics in plants expressing the Ca2+ reporter YC3.6 in combination with patch-clamp analyses of root cells and two-electrode voltage clamp (TEVC) analyses in Xenopus laevis oocytes. K+ deficiency triggers two successive and distinct Ca2+ signals in roots exhibiting spatial and temporal specificity. A transient primary Ca2+ signature arose within 1 min in the postmeristematic stelar tissue of the elongation zone, while a secondary Ca2+ response occurred after several hours as sustained Ca2+ elevation in defined tissues of the elongation and root hair differentiation zones. Patch-clamp and TEVC analyses revealed Ca2+ dependence of the activation of the K+ channel AKT1 by the CBL1-CIPK23 Ca2+ sensor-kinase complex. Together, these findings identify a critical role of cell group-specific Ca2+ signaling in low K+ responses and indicate an essential and direct role of Ca2+ signals for AKT1 K+ channel activation in roots.

AtKC1 and CIPK23 Synergistically Modulate AKT1-Mediated Low-Potassium Stress Responses in Arabidopsis.

In Arabidopsis (Arabidopsis thaliana), the Shaker K(+) channel AKT1 conducts K(+) uptake in root cells, and its activity is regulated by CBL1/9-CIPK23 complexes as well as by the AtKC1 channel subunit. CIPK23 and AtKC1 are both involved in the AKT1-mediated low-K(+) (LK) response; however, the relationship between them remains unclear. In this study, we screened suppressors of low-K(+) sensitive [lks1 (cipk23)] and isolated the suppressor of lks1 (sls1) mutant, which suppressed the leaf chlorosis phenotype of lks1 under LK conditions. Map-based cloning revealed a point mutation in AtKC1 of sls1 that led to an amino acid substitution (G322D) in the S6 region of AtKC1. The G322D substitution generated a gain-of-function mutation, AtKC1(D), that enhanced K(+) uptake capacity and LK tolerance in Arabidopsis. Structural prediction suggested that glycine-322 is highly conserved in K(+) channels and may function as the gating hinge of plant Shaker K(+) channels. Electrophysiological analyses revealed that, compared with wild-type AtKC1, AtKC1(D) showed enhanced inhibition of AKT1 activity and strongly reduced K(+) leakage through AKT1 under LK conditions. In addition, phenotype analysis revealed distinct phenotypes of lks1 and atkc1 mutants in different LK assays, but the lks1 atkc1 double mutant always showed a LK-sensitive phenotype similar to that of akt1 This study revealed a link between CIPK-mediated activation and AtKC1-mediated modification in AKT1 regulation. CIPK23 and AtKC1 exhibit distinct effects; however, they act synergistically and balance K(+) uptake/leakage to modulate AKT1-mediated LK responses in Arabidopsis.

Prognostic value of pretreatment serum alanine aminotransferase/aspartate aminotransferase (ALT/AST) ratio and gamma glutamyltransferase (GGT) in patients with esophageal squamous cell carcinoma.

BACKGROUND: The levels of liver function tests (LFTs) are often used to assess liver injury and non-liver disease-related mortality. In our study, the relationship between pretreatment serum LFTs and overall survival (OS) was evaluated in esophageal squamous cell carcinoma (ESCC) patients. METHODS: Our purpose was to investigate the prognostic value of the preoperative alanine aminotransferase/aspartate aminotransferase (ALT/AST) ratio and gamma glutamyltransferase (GGT) in ESCC patients. A retrospective study was performed in 447 patients with ESCC, and follow-up period was at least 60 months until death. The prognostic significance of serum LFTs were determined by univariate and multivariate Cox hazard models. RESULTS: LFTs including ALT, AST, LSR, GGT, TBA and LDH were analyzed. Serum LSR (HR: 0.592, 95% CI = 0.457-0.768, p < 0.001 and GGT (HR: 1.507, 95% CI = 1.163-1.953, p = 0.002) levels were indicated as significant predictors of OS. The 5-year OS among patients with higher LSR levels was longer compared with those patients with decreased LSR levels, not only in the whole cohort but also in the subgroups stratified by pathological stage (T1-T2 subgroup, T3-T4 subgroup, N0 subgroup and M0 subgroup). We also found that patients with a higher GGT might predict worse OS than patients with a normal GGT, not only in the whole cohort but also in the subgroups stratified by pathological stage (T3-T4 subgroup and N1-N2 subgroup). CONCLUSIONS: Both increased levels of LSR and decreased levels of GGT might predict shorter overall survival in ESCC patients. Our findings suggest that serum LSR and GGT levels could be used as a key predictor of survival in patients with ESCC.

Differential expression of fatty acid transporters and fatty acid synthesis-related genes in crop tissues of male and female pigeons (Columba livia domestica) during incubation and chick rearing.

1. The growth performance of squabs reared solely by male or female parent pigeons was measured, and the changes of lipid content of crop milk and the expression profiles of genes potentially involved in lipid accumulation by crop tissues of parent pigeons were evaluated during incubation and chick rearing. 2. Squabs increased in body weight during 25 d of rearing, whereas both male and female pigeons lost weight after finishing rearing chicks, and the weight loss of male pigeons was significantly greater than that of female parent pigeons. Lipid content of crop milk from both parent pigeons gradually decreased to the crude fat level in the formulated diet after 10 d (R10) of chick rearing. 3. The gene expression of fatty acid translocase (FAT/CD36), fatty acid-binding protein 5 (EFABP) and acyl-CoA-binding protein (ACBP) in male pigeon crop tissue were the greatest at 17 d (I17) of incubation. In female pigeons, FAT/CD36 expression was the highest at I14, and both EFABP and ACBP expression peaked at I14 and R7. The expression of acetyl-CoA carboxylase and fatty acid synthase in male pigeons reached the maximum level at R1, while they peaked at I14 and I17, respectively in female pigeons. The gene expression of peroxisome proliferators-activated receptor-gamma (PPARγ) was the greatest at I17 in the male, while it was at I14 in the female. However, no regular changing pattern was found in PPARα gene expression in male pigeons. 4. These results indicated that male and female pigeons may make different contributions in rearing squabs. The gene expression study suggested that fatty acids used in lipid biosynthesis of crop milk probably originated from both exogenous supply and de novo synthesis. The sex of the parent pigeon affected the lipid content of crop milk and the expression profiles of genes involved in fatty acid transportation and lipogenesis.

[Advances of mechanism research on procyanidin in prevention and treatment of type 2 diabetes mellitus].

Diabetes mellitus, a chronic disease, is characterized by high blood glucose that could induce various complications. Procyanidin, a kind of polyphenol compounds existing in many plants, have shown to be effective in preventing and treating type 2 diabetes mellitus as they may lower blood glucose, moderate insulin resistance and protect islet ß cells. This review focused on the research advances on the preventive and therapeutic application of procyanidin in promoting glucose absorption, protecting islet ß cells, modulating intestinal microbiota and regulating diabetic complications of type 2 diabetes mellitus, which should provide useful reference for subsequent studies.

Structural and enzymatic analyses of a glucosyltransferase Alr3699/HepE involved in Anabaena heterocyst envelop polysaccharide biosynthesis.

Formation of the heterocyst envelope polysaccharide (HEP) is a key process for cyanobacterial heterocyst differentiation. The maturation of HEP in Anabaena sp. strain PCC 7120 is controlled by a gene cluster termed HEP island in addition to an operon alr3698-alr3699, which encodes two putative proteins termed Alr3698/HepD and Alr3699/HepE. Here we report the crystal structures of HepE in the apo-form and three complex forms that bind to UDP-glucose (UDPG), UDP&glucose, and UDP, respectively. The overall structure of HepE displays a typical GT-B fold of glycosyltransferases, comprising two separate ß/α/ß Rossmann-fold domains that form an inter-domain substrate-binding crevice. Structural analyses combined with enzymatic assays indicate that HepE is a glucosyltransferase using UDPG as a sugar donor. Further site-directed mutageneses enable us to assign the key residues that stabilize the sugar donor and putative acceptor. Based on the comparative structural analyses, we propose a putative catalytic cycle of HepE, which undergoes "open-closed-open" conformational changes upon binding to the substrates and release of products. These findings provide structural and catalytic insights into the first enzyme involved in the HEP biosynthesis pathway.