Critical Role for Cold Shock Protein YB-1 in Cytokinesis.

High levels of the cold shock protein Y-box-binding protein-1, YB-1, are tightly correlated with increased cell proliferation and progression. However, the precise mechanism by which YB-1 regulates proliferation is unknown. Here, we found that YB-1 depletion in several cancer cell lines and in immortalized fibroblasts resulted in cytokinesis failure and consequent multinucleation. Rescue experiments indicated that YB-1 was required for completion of cytokinesis. Using confocal imaging we found that YB-1 was essential for orchestrating the spatio-temporal distribution of the microtubules, ß-actin and the chromosome passenger complex (CPC) to define the cleavage plane. We show that phosphorylation at six serine residues was essential for cytokinesis, of which novel sites were identified using mass spectrometry. Using atomistic modelling we show how phosphorylation at multiple sites alters YB-1 conformation, allowing it to interact with protein partners. Our results establish phosphorylated YB-1 as a critical regulator of cytokinesis, defining precisely how YB-1 regulates cell division.

Dephosphorylation of YB-1 is Required for Nuclear Localisation During G2 Phase of the Cell Cycle.

Elevated levels of nuclear Y-box binding protein 1 (YB-1) are linked to poor prognosis in cancer. It has been proposed that entry into the nucleus requires specific proteasomal cleavage. However, evidence for cleavage is contradictory and high YB-1 levels are prognostic regardless of cellular location. Here, using confocal microscopy and mass spectrometry, we find no evidence of specific proteolytic cleavage. Doxorubicin treatment, and the resultant G2 arrest, leads to a significant increase in the number of cells where YB-1 is not found in the cytoplasm, suggesting that its cellular localisation is variable during the cell cycle. Live cell imaging reveals that the location of YB1 is linked to progression through the cell cycle. Primarily perinuclear during G1 and S phases, YB-1 enters the nucleus as cells transition through late G2/M and exits at the completion of mitosis. Atomistic modelling and molecular dynamics simulations show that dephosphorylation of YB1 at serine residues 102, 165 and 176 increases the accessibility of the nuclear localisation signal (NLS). We propose that this conformational change facilitates nuclear entry during late G2/M. Thus, the phosphorylation status of YB1 determines its cellular location.

Heparin-like Effect Associated With Risk of Bleeding, Sepsis, and Death in Patients With Severe Alcohol-Associated Hepatitis.

BACKGROUND & AIMS: Endogenous heparinoids or heparin-like effects (HLEs) can cause coagulation failure in patients with cirrhosis and sepsis. We performed a prospective study of the association between HLE and bleeding events, sepsis, and outcomes of patients with severe alcohol-associated hepatitis. METHODS: Our final analysis comprised 78 patients with severe alcohol-associated hepatitis (44.3 ± 11.7 years; all male; discriminant function >32) who presented without sepsis at a single center in India from August 2015 through August 2016. Blood samples were collected at days 0, 3, and 7 after presentation and assessed by a global coagulation assay; by SONOCLOT (global and heparinase treated); and in assays for factor VIII, von Willebrand factor, protein C, and antithrombin. Patients were followed for sepsis, bleeding and outcome. The primary outcome was association of HLE with survival 28 days after presentation. RESULTS: HLEs were observed in 32 patients (41%) at day 0, 27 patients (34.6%) at day 3, and 28 patients (35.9%) patients at day 7. Factors associated with mortality at day 0 were factor VIII activity >160% (hazard ratio [HR], 3.1; 95% CI, 1.4-9.5; P = .026), level of protein C <34% (HR, 0.7; 95% CI, 0.5-0.8; P = .037), antithrombin activity <28% (HR, 0.7; 95% CI, 0.3-1.1; P = .008) and international normalized ratio >2.6 (HR, 2.3; 95% CI, 1.8-9.7; P = .010). In multivariate analyses, only factor VIII activity (HR, 2.3; 95% CI, 1.6-7.8; P = .046), international normalized ratio (1.9; 95% CI, 1.2-4.3; P = .039), level of protein C (HR, 0.9; 95% CI, 0.7-1.1; P = .052) and model for end-stage liver disease score (HR, 3.2; 95% CI, 1.9-10.2; P = .042) were associated with mortality. Episodes of epistaxis, hemorrhoid bleeding, hemoperitoneum, and pulmonary hemorrhage occurred in 10.2%, 12.3%, 3.4%, and 4.5% of patients respectively. The presence of HLE at day 0 increased the risk of sepsis (HR, 2.5; 95% CI, 2.2-4.3; P = .002), bleeding (HR, 1.4; 95% CI, 1.2-5.3; P = .004) and death (HR, 1.2; 95% CI, 1.4-1.7; P = .044). CONCLUSIONS: In a prospective study of patients with severe alcohol-associated hepatitis, we associated HLE with coagulation abnormalities, risk of sepsis, and mortality. Clinicaltrials.govNCT02307409.

Drug-Induced Acute-on-Chronic Liver Failure in Asian Patients.

OBJECTIVES: Acute insults from viruses, infections, or alcohol are established causes of decompensation leading to acute-on-chronic liver failure (ACLF). Information regarding drugs as triggers of ACLF is lacking. We examined data regarding drugs producing ACLF and analyzed clinical features, laboratory characteristics, outcome, and predictors of mortality in patients with drug-induced ACLF. METHODS: We identified drugs as precipitants of ACLF among prospective cohort of patients with ACLF from the Asian Pacific Association of Study of Liver (APASL) ACLF Research Consortium (AARC) database. Drugs were considered precipitants after exclusion of known causes together with a temporal association between exposure and decompensation. Outcome was defined as death from decompensation. RESULTS: Of the 3,132 patients with ACLF, drugs were implicated as a cause in 329 (10.5%, mean age 47 years, 65% men) and other nondrug causes in 2,803 (89.5%) (group B). Complementary and alternative medications (71.7%) were the commonest insult, followed by combination antituberculosis therapy drugs (27.3%). Alcoholic liver disease (28.6%), cryptogenic liver disease (25.5%), and non-alcoholic steatohepatitis (NASH) (16.7%) were common causes of underlying liver diseases. Patients with drug-induced ACLF had jaundice (100%), ascites (88%), encephalopathy (46.5%), high Model for End-Stage Liver Disease (MELD) (30.2), and Child-Turcotte-Pugh score (12.1). The overall 90-day mortality was higher in drug-induced (46.5%) than in non-drug-induced ACLF (38.8%) (P = 0.007). The Cox regression model identified arterial lactate (P < 0.001) and total bilirubin (P = 0.008) as predictors of mortality. DISCUSSION: Drugs are important identifiable causes of ACLF in Asia-Pacific countries, predominantly from complementary and alternative medications, followed by antituberculosis drugs. Encephalopathy, bilirubin, blood urea, lactate, and international normalized ratio (INR) predict mortality in drug-induced ACLF.

Coagulation failure is associated with bleeding events and clinical outcome during systemic inflammatory response and sepsis in acute-on-chronic liver failure: An observational cohort study.

BACKGROUND: Patients with acute-on-chronic liver failure (ACLF) have coagulation failure in the setting of systemic inflammatory syndrome (SIRS), sepsis and extra-hepatic organ failures. METHODS: Consecutive ACLF patients without sepsis at baseline were assessed at days 0, 3 and 7 with thromboelastography (TEG) and specific assays (Factor VIII, von Willebrand factor [vWF], protein C and antithrombin III [ATIII]) and followed for development of sepsis, bleeding and outcome. RESULTS: Of 243 patients, 114 (63% ethanol related; mean age 44.3 ± 11.7 years; 90% male) were recruited. SIRS was noted in 39 (34.2%), 45 (39.5%) and 46 (40%) patients at days 0, 3 and 7 and sepsis in 28 (24%) and 52 (56.1%) patients at days 3 and 7 respectively. The 28- and 90-day survivals were 62% and 51% respectively. A hypocoagulable TEG at baseline was a predictor of bleeding (hazard ratio [HR] 2.1; CI 1.6-4.9; P = 0.050) and mortality (HR 1.9; CI 1.3-7.9; P = 0.043). ACLF patients had increased Factor VIII, vWF, tissue factor levels and tissue plasminogen activator (tPA) activity with reduced protein C and ATIII. Coagulation parameters like Coagulation Index (HR 2.1; CI 1.1-4.5; P = 0.044),clot lysis (HR 3.2; CI 1.9-3.4; P = 0.033), low protein C < 30% (HR 2.1; CI 1.5-2.8; P = 0.017), ATIII (HR 1.4; CI 1.7-3.1; P = 0.052) and tPA (HR 1.5; CI 1.1-2.4; P = 0.052) were predictors of mortality at day 28. Protein C activity <30% (HR 1.3; CI 1.0-2.9; P = 0.042) and tPA >20 ng/mL (HR 1.2; CI 1.1-2.1; P = 0.040) predicted mortality when adjusted for age, gender and baseline MELD. CONCLUSIONS: Dynamic coagulation derangements, measured by TEG, determine the likelihood of bleeding and mortality in ACLF.

PASSPORT-seq: A Novel High-Throughput Bioassay to Functionally Test Polymorphisms in Micro-RNA Target Sites.

Next-generation sequencing (NGS) studies have identified large numbers of genetic variants that are predicted to alter miRNA-mRNA interactions. We developed a novel high-throughput bioassay, PASSPORT-seq, that can functionally test in parallel 100s of these variants in miRNA binding sites (mirSNPs). The results are highly reproducible across both technical and biological replicates. The utility of the bioassay was demonstrated by testing 100 mirSNPs in HEK293, HepG2, and HeLa cells. The results of several of the variants were validated in all three cell lines using traditional individual luciferase assays. Fifty-five mirSNPs were functional in at least one of three cell lines (FDR ≤ 0.05); 11, 36, and 27 of them were functional in HEK293, HepG2, and HeLa cells, respectively. Only four of the variants were functional in all three cell lines, which demonstrates the cell-type specific effects of mirSNPs and the importance of testing the mirSNPs in multiple cell lines. Using PASSPORT-seq, we functionally tested 111 variants in the 3' UTR of 17 pharmacogenes that are predicted to alter miRNA regulation. Thirty-three of the variants tested were functional in at least one cell line.