A direct interaction between survivin and myosin II is required for cytokinesis.

An acto-myosin contractile ring, which forms after anaphase onset and is highly regulated in time and space, mediates cytokinesis, the final step of mitosis. The chromosomal passenger complex (CPC), composed of Aurora-B kinase, INCENP, borealin and survivin (also known as BIRC5), regulates various processes during mitosis, including cytokinesis. It is not understood, however, how CPC regulates cytokinesis. We show that survivin binds to non-muscle myosin II (NMII), regulating its filament assembly. Survivin and NMII interact mainly in telophase, and Cdk1 regulates their interaction in a mitotic-phase-specific manner, revealing the mechanism for the specific timing of survivin-NMII interaction during mitosis. The survivin-NMII interaction is indispensable for cytokinesis, and its disruption leads to multiple mitotic defects. We further show that only the survivin homodimer binds to NMII, attesting to the biological importance for survivin homodimerization. We suggest a novel function for survivin in regulating the spatio-temporal formation of the acto-NMII contractile ring during cytokinesis and we elucidate the role of Cdk1 in regulating this process.This article has an associated First Person interview with the first author of the paper.

High resolution characterization of myosin IIC protein tailpiece and its effect on filament assembly.

The motor protein nonmuscle myosin II (NMII) must undergo dynamic oligomerization into filaments to perform its cellular functions. A small nonhelical region at the tail of the long coiled-coil region (tailpiece) is a common feature of all dynamically assembling myosin II proteins. This tailpiece is a key regulatory domain affecting NMII filament assembly properties and is subject to phosphorylation in vivo. We previously demonstrated that the positively charged region of the tailpiece binds to assembly-incompetent NMII-C fragments, inducing filament assembly. In the current study, we investigated the molecular mechanisms by which the tailpiece regulates NMII-C self-assembly. Using alanine scan, we found that specific positive and aromatic residues within the positively charged region of the tailpiece are important for inducing NMII-C filament assembly and for filament elongation. Combining peptide arrays with deletion studies allowed us to identify the tailpiece binding sites in the coiled-coil rod. Elucidation of the mechanism by which the tailpiece induces filament assembly permitted us further investigation into the role of tailpiece phosphorylation. Sedimentation and CD spectroscopy identified that phosphorylation of Thr(1957) or Thr(1960) inhibited the ability of the tailpiece to bind the coiled-coil rod and to induce NMII-C filament formation. This study provides molecular insight into the role of specific residues within the NMII-C tailpiece that are responsible for shifting the oligomeric equilibrium of NMII-C toward filament assembly and determining its morphology.

Human Gut Microbiota in Cardiovascular Disease.

The gut ecosystem, termed microbiota, is composed of bacteria, archaea, viruses, protozoa, and fungi and is estimated to outnumber human cells. Microbiota can affect the host by multiple mechanisms, including the synthesis of metabolites and toxins, modulating inflammation and interaction with other organisms. Advances in understanding commensal organisms' effect on human conditions have also elucidated the importance of this community for cardiovascular disease (CVD). This effect is driven by both direct CV effects and conditions known to increase CV risk, such as obesity, diabetes mellitus (DM), hypertension, and renal and liver diseases. Cardioactive metabolites, such as trimethylamine N -oxide (TMAO), short-chain fatty acids (SCFA), lipopolysaccharides, bile acids, and uremic toxins, can affect atherosclerosis, platelet activation, and inflammation, resulting in increased CV incidence. Interestingly, this interaction is bidirectional with microbiota affected by multiple host conditions including diet, bile acid secretion, and multiple diseases affecting the gut barrier. This interdependence makes manipulating microbiota an attractive option to reduce CV risk. Indeed, evolving data suggest that the benefits observed from low red meat and Mediterranean diet consumption can be explained, at least partially, by the changes that these diets may have on the gut microbiota. In this article, we depict the current epidemiological and mechanistic understanding of the role of microbiota and CVD. Finally, we discuss the potential therapeutic approaches aimed at manipulating gut microbiota to improve CV outcomes. © 2024 American Physiological Society. Compr Physiol 14:5449-5490, 2024.

Reprogramming of the MHC-I and its regulation by NFκB in human-induced pluripotent stem cells.

The immunogenicity of human pluripotent stem cells plays a major role in their potential use in the clinic. We show that, during their reprogramming, human-induced pluripotent stem (iPS) cells downregulate expression of human leukocyte antigen (HLA)-A/B/C and ß2 microglobulin (ß2M), the two components of major histocompatibility complex-I (MHC-I). MHC-I expression in iPS cells can be restored by differentiation or treatment with interferon-gamma (IFNγ). To analyze the molecular mechanisms that regulate the expression of the MHC-I molecules in human iPS cells, we searched for correlation between the expression of HLA-A/B/C and ß2M and the expression of transcription factors that bind to the promoter of these genes. Our results show a significant positive correlation between MHC-I expression and expression of the nuclear factors, nuclear factor kappa B 1 (NFκB1) and RelA, at the levels of RNA, protein and was confirmed by chromatin binding. Concordantly, we detected robust levels of NFκB1 and RelA proteins in the nucleus of somatic cells but not in the iPS cell derived from them. Overexpression of NFκB1 and RelA in undifferentiated pluripotent stem cells led to induction in expression of MHC-I, whereas silencing NFκB1 and RelA by small hairpin RNA decreased the expression of ß2M after IFNγ treatment. Our data point to the critical role of NFκB proteins in regulating the MHC-I expression in human pluripotent stem cells.

Exploring the Mechanisms Underlying the Cardiotoxic Effects of Immune Checkpoint Inhibitor Therapies.

Adaptive immune response modulation has taken a central position in cancer therapy in recent decades. Treatment with immune checkpoint inhibitors (ICIs) is now indicated in many cancer types with exceptional results. The two major inhibitory pathways involved are cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and programmed cell death protein 1 (PD-1). Unfortunately, immune activation is not tumor-specific, and as a result, most patients will experience some form of adverse reaction. Most immune-related adverse events (IRAEs) involve the skin and gastrointestinal (GI) tract; however, any organ can be involved. Cardiotoxicity ranges from arrhythmias to life-threatening myocarditis with very high mortality rates. To date, most treatments of ICI cardiotoxicity include immune suppression, which is also not cardiac-specific and may result in hampering of tumor clearance. Understanding the mechanisms behind immune activation in the heart is crucial for the development of specific treatments. Histological data and other models have shown mainly CD4 and CD8 infiltration during ICI-induced cardiotoxicity. Inhibition of CTLA4 seems to result in the proliferation of more diverse T0cell populations, some of which with autoantigen recognition. Inhibition of PD-1 interaction with PD ligand 1/2 (PD-L1/PD-L2) results in release from inhibition of exhausted self-recognizing T cells. However, CTLA4, PD-1, and their ligands are expressed on a wide range of cells, indicating a much more intricate mechanism. This is further complicated by the identification of multiple co-stimulatory and co-inhibitory signals, as well as the association of myocarditis with antibody-driven myasthenia gravis and myositis IRAEs. In this review, we focus on the recent advances in unraveling the complexity of the mechanisms driving ICI cardiotoxicity and discuss novel therapeutic strategies for directly targeting specific underlying mechanisms to reduce IRAEs and improve outcomes.

The positively charged region of the myosin IIC non-helical tailpiece promotes filament assembly.

The motor protein, non-muscle myosin II (NMII), must undergo dynamic oligomerization into filaments to participate in cellular processes such as cell migration and cytokinesis. A small non-helical region at the tail of the long coiled-coil region (tailpiece) is a common feature of all dynamically assembling myosin II proteins. In this study, we investigated the role of the tailpiece in NMII-C self-assembly. We show that the tailpiece is natively unfolded, as seen by circular dichroism and NMR experiments, and is divided into two regions of opposite charge. The positively charged region (Tailpiece(1946-1967)) starts at residue 1946 and is extended by seven amino acids at its N terminus from the traditional coiled-coil ending proline (Tailpiece(1953-1967)). Pull-down and sedimentation assays showed that the positive Tailpiece(1946-1967) binds to assembly incompetent NMII-C fragments inducing filament assembly. The negative region, residues 1968-2000, is responsible for NMII paracrystal morphology as determined by chimeras in which the negative region was swapped between the NMII isoforms. Mixing the positive and negative peptides had no effect on the ability of the positive peptide to bind and induce filament assembly. This study provides molecular insight into the role of the structurally disordered tailpiece of NMII-C in shifting the oligomeric equilibrium of NMII-C toward filament assembly and determining its morphology.

Carbon and chlorine isotope ratios of chlorinated ethenes migrating through a thick unsaturated zone of a sandy aquifer.

Compound-specific isotope analysis (CSIA) can potentially be used to relate vapor phase contamination by volatile organic compounds (VOCs) to their subsurface sources. This field and modeling study investigated how isotope ratios evolve during migration of gaseous chlorinated ethenes across a 18 m thick unsaturated zone of a sandy coastal plain aquifer. At the site, high concentrations of tetrachloroethene (PCE up to 380 µg/L), trichloroethene (TCE up to 31,600 µg/L), and cis-1,2-dichloroethene (cDCE up to 680 µg/L) were detected in groundwater. Chlorinated ethene concentrations were highest at the water table and steadily decreased upward toward the land surface and downward below the water table. Although isotopologues have different diffusion coefficients, constant carbon and chlorine isotope ratios were observed throughout the unsaturated zone, which corresponded to the isotope ratios measured at the water table. In the saturated zone, TCE became increasingly depleted along a concentration gradient, possibly due to isotope fractionation associated with aqueous phase diffusion. These results indicate that carbon and chlorine isotopes can be used to link vapor phase contamination to their source even if extensive migration of the vapors occurs. However, the numerical model revealed that constant isotope ratios are only expected for systems close to steady state.

Myosin II tailpiece determines its paracrystal structure, filament assembly properties, and cellular localization.

Non muscle myosin II (NMII) is a major motor protein present in all cell types. The three known vertebrate NMII isoforms share high sequence homology but play different cellular roles. The main difference in sequence resides in the C-terminal non-helical tailpiece (tailpiece). In this study we demonstrate that the tailpiece is crucial for proper filament size, overcoming the intrinsic properties of the coiled-coil rod. Furthermore, we show that the tailpiece by itself determines the NMII filament structure in an isoform-specific manner, thus providing a possible mechanism by which each NMII isoform carries out its unique cellular functions. We further show that the tailpiece determines the cellular localization of NMII-A and NMII-B and is important for NMII-C role in focal adhesion complexes. We mapped NMII-C sites phosphorylated by protein kinase C and casein kinase II and showed that these phosphorylations affect its solubility properties and cellular localization. Thus phosphorylation fine-tunes the tailpiece effects on the coiled-coil rod, enabling dynamic regulation of NMII-C assembly. We thus show that the small tailpiece of NMII is a distinct domain playing a role in isoform-specific filament assembly and cellular functions.

Derivation and molecular characterization of pancreatic differentiated MODY1-iPSCs.

Maturity onset diabetes of the young (MODY) is a hereditary form of diabetes mellitus presenting at childhood or adolescence, which eventually leads to pancreatic ß-cells dysfunction. The underlying genetic basis of MODY disorders is haploinsufficiency, where loss-of-function mutations in a single allele cause the diabetic phenotype in heterozygous patients. MODY1 is a type of MODY disorder resulting from a mutation in the transcription factor hepatocyte nuclear factor 4 alpha (HNF4α). In order to establish a human based model to study MODY1, we generated patient-derived induced pluripotent stem cells (iPSCs). Differentiation of these pluripotent cells towards the pancreatic lineage enabled to evaluate the effects of the MODY1 mutation and its impact on endodermal and pancreatic cells. Analyzing the gene expression profiles of differentiated MODY1 cells, revealed the outcome of HNF4α haploinsufficiency on its targets. This molecular analysis suggests that the differential expression of HNF4α target genes in MODY1 is affected by the number of HNF4α binding sites, their distance from the transcription start site, and the number of other transcription factor binding sites. These features may help explain the molecular manifestations of haploinsufficiency in MODY1 disease.

Puddles - A trigger for heterogeneous chemical influx into the unsaturated zone.

Spatial heterogeneity in the chemical concentration of interstitial water in the vadose zone was previously observed under apparently homogeneous surface conditions on two leveled fields sprinkler irrigated with treated sewage effluents on the phreatic Coastal Plain aquifer of Israel. This phenomenon greatly hampers the monitoring of groundwater quality. In this study we report on the presence of puddles of different size and shape that were sporadically observed in these fields. Temporal variability noted in the concentration of treated sewage effluents components in the puddles were considered to be related to evapotranspiration and degradation. For example: increases in the electrical conductivity (up to 1.32 mS/cm), and in the concentrations of chloride (up to 521 mg/L), dissolved organic carbon (up to 28.4 mg/L), and carbamazepine (up to 780 ng/L) and decreases in the concentrations of nitrate (up to 20.1mg/L) and caffeine (3,396 ng/L). Variable trends in concentration were observed for sulfamethoxazole, venlafaxine, 10-hydroxy-10,11-dihydrocarbamazepine and o-desmethylvenlafaxine. The presence of puddles was not necessarily related to areas with high irrigation water input. It is postulated that the continuous chemical variability in the puddles, whose location and size are also variable, determine a heterogeneous influx of solutes into the soil and subsequently into the vadose zone.

Differentiation of human parthenogenetic pluripotent stem cells reveals multiple tissue- and isoform-specific imprinted transcripts.

Parental imprinting results in monoallelic parent-of-origin-dependent gene expression. However, many imprinted genes identified by differential methylation do not exhibit complete monoallelic expression. Previous studies demonstrated complex tissue-dependent expression patterns for some imprinted genes. Still, the complete magnitude of this phenomenon remains largely unknown. By differentiating human parthenogenetic induced pluripotent stem cells into different cell types and combining DNA methylation with a 5' RNA sequencing methodology, we were able to identify tissue- and isoform-dependent imprinted genes in a genome-wide manner. We demonstrate that nearly half of all imprinted genes express both biallelic and monoallelic isoforms that are controlled by tissue-specific alternative promoters. This study provides a global analysis of tissue-specific imprinting in humans and suggests that alternative promoters are central in the regulation of imprinted genes.

Sex-dependent gene expression in human pluripotent stem cells.

Males and females have a variety of sexually dimorphic traits, most of which result from hormonal differences. However, differences between male and female embryos initiate very early in development, before hormonal influence begins, suggesting the presence of genetically driven sexual dimorphisms. By comparing the gene expression profiles of male and X-inactivated female human pluripotent stem cells, we detected Y-chromosome-driven effects. We discovered that the sex-determining gene SRY is expressed in human male pluripotent stem cells and is induced by reprogramming. In addition, we detected more than 200 differentially expressed autosomal genes in male and female embryonic stem cells. Some of these genes are involved in steroid metabolism pathways and lead to sex-dependent differentiation in response to the estrogen precursor estrone. Thus, we propose that the presence of the Y chromosome and specifically SRY may drive sex-specific differences in the growth and differentiation of pluripotent stem cells.

Identification of novel imprinted differentially methylated regions by global analysis of human-parthenogenetic-induced pluripotent stem cells.

Parental imprinting is an epigenetic phenomenon by which genes are expressed in a monoallelic fashion, according to their parent of origin. DNA methylation is considered the hallmark mechanism regulating parental imprinting. To identify imprinted differentially methylated regions (DMRs), we compared the DNA methylation status between multiple normal and parthenogenetic human pluripotent stem cells (PSCs) by performing reduced representation bisulfite sequencing. Our analysis identified over 20 previously unknown imprinted DMRs in addition to the known DMRs. These include DMRs in loci associated with human disorders, and a class of intergenic DMRs that do not seem to be related to gene expression. Furthermore, the study showed some DMRs to be unstable, liable to differentiation or reprogramming. A comprehensive comparison between mouse and human DMRs identified almost half of the imprinted DMRs to be species specific. Taken together, our data map novel DMRs in the human genome, their evolutionary conservation, and relation to gene expression.

Genomic stability in reprogramming.

The genetic stability of induced pluripotent stem (iPS) cells has a significant impact on their potential use in regenerative medicine and basic research. Analysis of the genomic integrity of iPS cells suggests a tendency to develop aberrations ranging from whole chromosome trisomies to single nucleotide mutations. Furthermore, fluctuations in telomere elongation and changes in mitochondrial DNA are also observed. Some mutations may already exist in the founder cells or result from prolonged culturing, however, many of the mutations occur during the reprogramming event. Thus, great care should be given to the initial characterization and subsequent culturing of new iPS cell lines in order to avoid the use of potentially aberrant cells.

Rationales behind irrationality of decision making in groundwater quality management.

This issue paper presents how certain policies regarding management of groundwater quality lead to unexpected and undesirable results, despite being backed by seemingly reasonable assumptions. This happened in part because the so-called reasonable decisions were not based on an integrative and quantitative methodology. The policies surveyed here are: (1) implementation of a program for aquifer restoration to pristine conditions followed, after failure, by leaving it to natural attenuation; (2) the "Forget About The Aquifer" (FATA) approach, while ignoring possible damage that contaminated groundwater can inflict on the other environmental systems; (3) groundwater recharge in municipal areas while neglecting the presence of contaminants in the unsaturated zone and conditions exerted by upper impervious surfaces; (4) the Soil Aquifer Treatment (SAT) practice considering aquifers to be "filters of infinite capacity"; and (5) focusing on well contamination vs. aquifer contamination to conveniently defer grappling with the problem of the aquifer as a whole. Possible reasons for the failure of these seemingly rational policies are: (1) the characteristic times of processes associated with groundwater that are usually orders of magnitude greater than the residence times of decision makers in their managerial position; (2) proliferation of improperly trained "groundwater experts" or policymakers with sectoral agendas alongside legitimate differences of opinion among groundwater scientists; (3) the neglect of the cyclic nature of natural phenomena; and (4) ignoring future long-term costs because of immediate costs.

Steady-state homogeneous approximations of vertical velocity from EC profiles.

Electrical conductivity (EC) logs were obtained by both open-borehole logging and passive multilevel sampling (MLS) in an observation borehole penetrating the Coastal Aquifer in Tel Aviv, Israel. Homogeneous vertical velocities for a 70-m thick subaquifer were approximated from each profile using a steady-state advection-diffusion model. The open-borehole log led to an overestimation of the steady-state upward advective flux of deep brines (vertical velocity of 0.95 cm/yr as compared to 0.07 cm/yr for the MLS profile). The combination of depth-dependent data and the suggested simple modeling approach comprises a method for assessing the vertical location of salinity sources and the nature of salt transport from them (i.e., advective vs. diffusive). However, in this case, the easily obtained open-borehole logs should not be used for collecting depth-dependent data.

Glyphosate transport through weathered granite soils under irrigated and non-irrigated conditions--Barcelona, Spain.

The transport of Glyphosate ([N-phosphonomethyl] glycine), AMPA (aminomethylphosphonic acid, CH(6)NO(3)P), and Bromide (Br(-)) has been studied, in the Mediterranean Maresme area of Spain, north of Barcelona, where groundwater is located at a depth of 5.5m. The unsaturated zone of weathered - granite soils was characterized in adjacent irrigated and non-irrigated experimental plots where 11 and 10 boreholes were drilled, respectively. At the non irrigated plot, the first half of the period was affected by a persistent and intense rainfall. After 69 days of application residues of Glyphosate up to 73.6 microgg(-1) were detected till a depth of 0.5m under irrigated conditions, AMPA, analyzed only in the irrigated plot was detected till a depth of 0.5m. According to the retardation coefficient of Glyphosate as compared to that of Br(-) for the topsoil and subsoil (80 and 83, respectively) and the maximum observed migration depth of Br(-) (2.9 m) Glyphosate and AMPA should have been detected till a depth of 0.05 m only. Such migration could be related to the low content of organic matter and clays in the soils; recharge generated by irrigation and heavy rain, and possible preferential solute transport and/or colloidal mediated transport.

Simultaneous counter-flow of chlorinated volatile organic compounds across the saturated-unsaturated interface region of an aquifer.

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated-unsaturated interface region (SUIR; depth of approximately 18m) of a sandy phreatic aquifer were measured in two monitoring wells located 25m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.

Sulfamethoxazole contamination of a deep phreatic aquifer.

Groundwater samples were obtained from the water table region of a phreatic aquifer (unsaturated zone depth up to 28 m) under land irrigated with wastewater effluents for about 5 decades and a relatively deep pumping well (109 m), used as a drinking water source till 2007, located downstream (1300 m) of wastewater effluent and sludge infiltration facilities. Sulfamethoxazole (SMX) concentrations in secondary effluents varied between 90 and 150 ng/L. SMX was extracted using SPE and was analyzed by HPLC-MS/MS. SMX (maximum concentration of 37 ng/L) was detected in the water table region, in two monitoring wells, after an unsaturated zone transport period of about 16 years. The maximum SMX concentration detected in the pumping well was of 20 ng/L. These results question wastewater effluent disposal strategies including the suitability of irrigation with effluents on the replenishment area of an aquifer supplying drinking water.