Adjacent Genes Research Articles

Molecular Mechanisms Regulating the Columnar Tree Architecture in Apple

The columnar apple cultivar ‘McIntosh Wijcik’ was discovered as a spontaneous mutant from the top of a ‘McIntosh’ tree in the early 1960s. ‘McIntosh Wijcik’ exhibits the columnar growth phenotype: compact and sturdy growth, short internodes, and very few lateral shoots. Classical genetic analysis revealed that the columnar growth phenotype of ‘McIntosh Wijcik’ is controlled by a single dominant gene, Co. This review focuses on the advances made toward understanding the molecular mechanisms of columnar growth in the last decade. Molecular studies have shown that an 8.2 kb insertion in the intergenic region of the Co locus is responsible for the columnar growth phenotype of ‘McIntosh Wijcik’, implying that the insertion affects the expression patterns of adjacent genes. Among the candidate genes in the Co region, the expression pattern of MdDOX-Co, putatively encoding 2-oxoglutarate-dependent dioxygenase (DOX), was found to vary between columnar and non-columnar apples. Recent studies have found three functions of MdDOX-Co: facilitating bioactive gibberellin deficiency, increasing strigolactone levels, and positively regulating abscisic acid levels. Consequently, changes in these plant hormone levels caused by the ectopic expression of MdDOX-Co in the aerial organs of ‘McIntosh Wijcik’ can lead to dwarf trees with fewer lateral branches. These findings will contribute to the breeding and cultivation of new columnar apple cultivars with improved fruit quality.

DNA Methylome and LncRNAome Analysis Provide Insights Into Mechanisms of Genome-Dosage Effects in Autotetraploid Cassava.

Whole genome duplication (WGD) increases the dosage of all coding and non-coding genes, yet the molecular implications of genome-dosage effects remain elusive. In this study, we generated integrated maps of the methylomes and lncRNAomes for diploid and artificially generated autotetraploid cassava (Manihot esculenta Crantz). We found that transposable elements (TEs) suppressed adjacent protein coding gene (PCG)-expression levels, while TEs activated the expression of nearby long non-coding RNAs (lncRNAs) in the cassava genome. The hypermethylation of DNA transposons in mCG and mCHH sites may be an effective way to suppress the expression of nearby PCGs in autotetraploid cassava, resulting in similar expression levels for most of PCGs between autotetraploid and diploid cassava. In the autotetraploid, decreased methylation levels of retrotransposons at mCHG and mCHH sites contributed to reduced methylation of Gypsy-neighboring long intergenic non-coding RNAs, potentially preserving diploid-like expression patterns in the major of lncRNAs. Collectively, our study highlighted that WGD-induced DNA methylation variation in DNA transposons and retrotransposons may be as direct adaptive responses to dosage of all coding-genes and lncRNAs, respectively.

High temporal resolution RNA-seq time course data reveals widespread synchronous activation between mammalian lncRNAs and neighboring protein-coding genes.

The advent of massively parallel sequencing revealed extensive transcription beyond protein-coding genes, identifying tens of thousands of long noncoding RNAs (lncRNAs). Selected functional examples raised the possibility that lncRNAs, as a class, may maintain broad regulatory roles. Expression of lncRNAs is strongly linked with adjacent protein-coding gene expression, suggesting potential cis-regulatory functions. A more detailed understanding of these regulatory roles may be obtained through careful examination of the precise timing of lncRNA expression relative to adjacent protein-coding genes. Despite the diversity of reported lncRNA regulatory mechanisms, where causal cis-regulatory relationships exist, lncRNA transcription is expected to precede changes in target gene expression. Using a high temporal resolution RNA-seq time course, we profiled the expression dynamics of several thousand lncRNAs and protein-coding genes in synchronized, transitioning human cells. Our findings reveal that lncRNAs are expressed synchronously with adjacent protein-coding genes. Analysis of lipopolysaccharide-activated mouse dendritic cells revealed the same temporal relationship observed in transitioning human cells. Our findings suggest broad-scale cis-regulatory roles for lncRNAs are not common. The strong association between lncRNAs and adjacent genes may instead indicate an origin as transcriptional by-products from active protein-coding gene promoters and enhancers.

Chromatin interaction maps identify Wnt responsive cis-regulatory elements coordinating Paupar-Pax6 expression in neuronal cells.

Central nervous system-expressed long non-coding RNAs (lncRNAs) are often located in the genome close to protein coding genes involved in transcriptional control. Such lncRNA-protein coding gene pairs are frequently temporally and spatially co-expressed in the nervous system and are predicted to act together to regulate neuronal development and function. Although some of these lncRNAs also bind and modulate the activity of the encoded transcription factors, the regulatory mechanisms controlling co-expression of neighbouring lncRNA-protein coding genes remain unclear. Here, we used high resolution NG Capture-C to map the cis-regulatory interaction landscape of the key neuro-developmental Paupar-Pax6 lncRNA-mRNA locus. The results define chromatin architecture changes associated with high Paupar-Pax6 expression in neurons and identify both promoter selective as well as shared cis-regulatory-promoter interactions involved in regulating Paupar-Pax6 co-expression. We discovered that the TCF7L2 transcription factor, a regulator of chromatin architecture and major effector of the Wnt signalling pathway, binds to a subset of these candidate cis-regulatory elements to coordinate Paupar and Pax6 co-expression. We describe distinct roles for Paupar in Pax6 expression control and show that the Paupar DNA locus contains a TCF7L2 bound transcriptional silencer whilst the Paupar transcript can act as an activator of Pax6. Our work provides important insights into the chromatin interactions, signalling pathways and transcription factors controlling co-expression of adjacent lncRNAs and protein coding genes in the brain.

The Role of Vti1a in Biological Functions and Its Possible Role in Nervous System Disorders.

Vesicle transport through interaction with t-SNAREs 1A (Vti1a), a member of the N-ethylmaleimide-sensitive factor attachment protein receptor protein family, is involved in cell signaling as a vesicular protein and mediates vesicle trafficking. Vti1a appears to have specific roles in neurons, primarily by regulating upstream neurosecretory events that mediate exocytotic proteins and the availability of secretory organelles, as well as regulating spontaneous synaptic transmission and postsynaptic efficacy to control neurosecretion. Vti1a also has essential roles in neural development, autophagy, and unconventional extracellular transport of neurons. Studies have shown that Vti1a dysfunction plays critical roles in pathological mechanisms of Hepatic encephalopathy by influencing spontaneous neurotransmission. It also may have an unknown role in amyotrophic lateral sclerosis. A VTI1A variant is associated with the risk of glioma, and the fusion product of the VTI1A gene and the adjacent TCF7L2 gene is involved in glioma development. This review summarizes Vti1a functions in neurons and highlights the role of Vti1a in the several nervous system disorders.

Investigating Influenza Virus Polymerase Activity in Feline Cells Based on the Influenza Virus Minigenome Replication System Driven by the Feline RNA Polymerase I Promoter.

Emerging influenza virus poses a health threat to humans and animals. Domestic cats have recently been identified as a potential source of zoonotic influenza virus. The influenza virus minigenome replication system based on the ribonucleic acid (RNA) polymerase I (PolI) promoter is the most widely used tool for investigating polymerase activity. It could help determine host factors or viral proteins influencing influenza virus polymerase activity in vitro. However, influenza virus polymerase activity has never been studied in feline cells thus far. In the present study, the feline RNA PolI promoter was identified in the intergenic spacer regions between adjacent upstream 28S and downstream 18S rRNA genes in the cat (Felis catus) genome using bioinformatics strategies. The transcription initiation site of the feline RNA PolI promoter was predicted. The feline RNA PolI promoter was cloned from CRFK cells, and a promoter size of 250 bp contained a sequence with sufficient PolI promoter activity by a dual-luciferase reporter assay. The influenza virus minigenome replication system based on the feline RNA PolI promoter was then established. Using this system, the feline RNA PolI promoter was determined to have significantly higher transcriptional activity than the human and chicken RNA PolI promoters in feline cells, and equine (H3N8) influenza virus presented higher polymerase activity than human (H1N1) and canine (H3N2) influenza viruses. In addition, feline myxovirus resistance protein 1 (Mx1) and baloxavir were observed to inhibit influenza virus polymerase activity in vitro in a dose-dependent manner. Our study will help further investigations on the molecular mechanism of host adaptation and cross-species transmission of influenza virus in cats.

A transferred regulator that contributes to Xanthomonas oryzae pv. oryzicola oxidative stress adaptation and virulence by regulating the expression of cytochrome bd oxidase genes

Horizontal gene transfer (HGT) has been well documented as a driving force in the evolution of bacteria. It has been shown that a horizontally acquired gene, xoc_2868, involved in the global response against oxidative stress and pathogenicity of Xanthomonas oryzae pv. oryzicola strain BLS256. However, as a transcriptional factor (TF), the regulatory mechanism of XOC_2868 has not yet been revealed. Here, evolutionary analysis suggested XOC_2868 might be co-transferred with its physically proximate downstream genes from a Burkholderiaceae ancestor. Interestingly, RNA-seq data of wild-type (BLS256) and Δxoc_2868 strains under oxidative stress showed that XOC_2868 did not regulate the expression of its adjacent genes, but remarkably influenced the expression of several genes involved in the extracellular polysaccharide (EPS) production and xanthan biosynthesis. Chromatin immunoprecipitation-sequence (ChIP-seq) combined with transcriptome analysis revealed that XOC_2868 directly regulates a cydAB operon, encoding two subunits of cytochrome bd oxidase and involved in redox balance. Consistent with Δxoc_2868 strain, cydA- and cydAB-knockout mutants also showed a higher sensitivity to H2O2 along with a reduced bacterial virulence compared with the wild-type strain. Overall, our findings raise the possibility of regulatory circuit evolution shaped by HGT and driven by selection and reveal a novel regulatory pathway that regulates the expression of cytochrome bd oxidase and thus contributes to the virulence of BLS256.

Deciphering Chemical Mediators Regulating Specialized Metabolism in a Symbiotic Cyanobacterium.

Genomes of cyanobacteria feature a variety of cryptic biosynthetic pathways for complex natural products, but the peculiarities limiting the discovery and exploitation of the metabolic dark matter are not well understood. Here we describe the discovery of two cell density‐dependent chemical mediators, nostoclide and nostovalerolactone, in the symbiotic model strain Nostoc punctiforme, and demonstrate their pronounced impact on the regulation of specialized metabolism. Through transcriptional, bioinformatic and labeling studies we assigned two adjacent biosynthetic gene clusters to the biosynthesis of the two polyketide mediators. Our findings provide insight into the orchestration of specialized metabolite production and give lessons for the genomic mining and high‐titer production of cyanobacterial bioactive compounds.

Identification of A‐B, a Novel Chimeric RNA in Colorectal Cancer

Colorectal cancer (CRC) is the third leading cause of cancer‐related deaths worldwide, affecting more than one hundred thousand men and women in the United States every year. With the incidence of early‐onset (<50 years old) CRC increasing at an alarming rate, there is an urgent and unmet need for early biomarker discovery and the identification of novel therapeutic targets in CRC. Chimeric RNAs and their protein products are well‐established as ideal biomarkers and drug targets for malignant cancers, including BCR‐ABL in chronic myelogenous leukemia and EML4‐ALK in lung cancer. Using RNA‐seq data from The Cancer Genome Atlas (TCGA) database, we have identified a chimeric RNA, denoted as A‐B, present in 45.2% of CRC samples and just 17.6% of adjacent normal margin tissue, but absent in non‐cancer colon tissues. We determined that this chimeric RNA results from cis‐splicing between adjacent genes (cis‐SAGe), and includes a splice variant of the 5’ gene, altering the reading frame of the 3’ gene. This chimeric RNA encodes a novel transmembrane protein, with the alternate reading frame on the extracellular surface, making it an ideal target for antibody therapeutics. After generating an antibody to the chimeric protein and validating its use in immunoblotting, immunoprecipitation, and immunohistochemistry, we found this novel protein is present in patient CRC samples in a distinct, punctate pattern. Overexpression of this chimeric RNA resulted in increased cell proliferation, while siRNA mediated knockdown led to a reduction in cell proliferation. We are currently investigating the function of this chimeric RNA and its biomarker potential in clinical CRC samples.

CRISPRi and KO screens reveal integrated cis- and trans-regulation of the CD28, CTLA4, and ICOS locus in primary human T cells

Abstract Costimulation is essential for complete T cell activation, requiring the coordinated expression of various surface proteins including those encoded by CD28 family members CD28, CTLA4, and ICOS. Interestingly, these three genes lie adjacently in a topologically-associating domain (TAD) and are believed to have arisen through duplications of CD28, though they have evolved opposing functions and exhibit expression differences across cell states and T cell subsets. We hypothesized that distinct cis- and trans-regulatory circuits emerged to uniquely govern the expression of each gene. Therefore, we tiled CRISPR interference (CRISPRi) across the 1.44Mb TAD in primary human conventional (Tconv) and regulatory T (Treg) cells to functionally profile cis-regulatory elements (CREs) controlling expression of CD28, CTLA4, and ICOS. We find that inhibiting the transcriptional start site of one gene (but not gene KO) enhances the expression of an adjacent gene, potentially due to redirection of shared CREs to the un-inhibited promoter. Moreover, we find distinct CREs responsible for constitutive expression of CTLA4 in Treg cells but stimulation-responsiveness in Tconv cells. We also find evidence of a single CRE that negatively regulates CD28 at baseline but positively regulates CTLA4 upon restimulation. Lastly, we characterize mechanisms of CRE control by identifying upstream regulators of target genes via CRISPR knockout screening. Our work nominates ZNF217, a zinc finger protein with no known function in human T cells, as a novel negative regulator altering chromatin accessibility in the locus. Here, we present a framework for functional characterization of regulatory modules controlling loci of interest in primary human CD4+ T cells. CM is supported by NIAID F30 AI157167-01 and is a UCSF ImmunoX Computational Immunology Fellow. ZS is supported by the Parker Institute for Cancer Immunology scholarship. RS was supported by fellowships of the Austrian Exchange Service and the Austrian Society of Laboratory Medicine. C.J.Y. and AM are Chan Zuckerberg Biohub Investigators and members of the PICI. C.J.Y. is further supported by the National Institutes of Health (NIH) grant nos. R01AR071522, R01AI136972 and R01HG011239. AM is supported by National Institute of Diabetes and Digestive and Kidney Diseases DP3DK111914-01 (AM) Simons Foundation (AM) Burroughs Wellcome Fund, Career Award for Medical Scientists (AM) The Cancer Research Institute (CRI) Lloyd J. Old STAR grant (AM) Parker Institute for Cancer Immunotherapy, PICI (AM) Innovative Genomics Institute (IGI) National Institutes of Health grant P30 DK063720 (Parnassus Flow Cytometry Core, AM) National Institutes of Health grant S10 1S10OD021822-01 (Parnassus Flow Cytometry Core, AM) Investigator at the Chan Zuckerberg Biohub (AM) Gifts from Brook Byers, Barbara Bakar, Karen Jordan, Elena Radutzky

Active endogenous retroviral elements in human pluripotent stem cells play a role in regulating host gene expression

Human endogenous retroviruses, also called LTR elements, can be bound by transcription factors and marked by different histone modifications in different biological contexts. Recently, individual LTR or certain subclasses of LTRs such as LTR7/HERVH and LTR5_Hs/HERVK families have been identified as cis-regulatory elements. However, there are still many LTR elements with unknown functions. Here, we dissected the landscape of histone modifications and regulatory map of LTRs by integrating 98 ChIP-seq data in human embryonic stem cells (ESCs), and annotated the active LTRs enriching enhancer/promoter-related histone marks. Notably, we found that MER57E3 functionally acted as proximal regulatory element to activate respective ZNF gene. Additionally, HERVK transcript could mainly function in nucleus to activate the adjacent genes. Since LTR5_Hs/LTR5 was bound by many early embryo-specific transcription factors, we further investigated the expression dynamics in different pluripotent states. LTR5_Hs/LTR5/HERVK exhibited higher expression level in naïve ESCs and extended pluripotent stem cells (EPSCs). Functionally, the LTR5_Hs/LTR5 with high activity could serve as a distal enhancer to regulate the host genes. Ultimately, our study not only provides a comprehensive regulatory map of LTRs in human ESCs, but also explores the regulatory models of MER57E3 and LTR5_Hs/LTR5 in host genome.

Genome-wide screening for genes involved in the epigenetic basis of fragile X syndrome.

SummaryFragile X syndrome (FXS), the most prevalent heritable form of intellectual disability, is caused by the transcriptional silencing of the FMR1 gene. The epigenetic factors responsible for FMR1 inactivation are largely unknown. Here, we initially demonstrated the feasibility of FMR1 reactivation by targeting a single epigenetic factor, DNMT1. Next, we established a model system for FMR1 silencing using a construct containing the FXS-related mutation upstream to a reporter gene. This construct was methylated in vitro and introduced into a genome-wide loss-of-function (LOF) library established in haploid human pluripotent stem cells (PSCs), allowing the identification of genes whose functional loss reversed the methylation-induced silencing of the FMR1 reporter. Selected candidate genes were further analyzed in haploid- and FXS-patient-derived PSCs, highlighting the epigenetic and metabolic pathways involved in FMR1 regulation. Our work sheds light on the mechanisms responsible for CGG-expansion-mediated FMR1 inactivation and offers novel targets for therapeutic FMR1 reactivation.

Validation of reliable safe harbor locus for efficient porcine transgenesis.

Transgenic technology is now widely used in biomedical and agricultural fields. Transgenesis is commonly achieved through random integration which might cause some uncertain consequences. The site-specific integration could avoid this disadvantage. This study aimed to screen and validate the best safe harbor (SH) locus for efficient porcine transgenesis. First, the cells carrying the EGFP reporter construct at four different SH loci (ROSA26, AAVS1, H11 and COL1A1) were achieved through CRSIPR/Cas9-mediated HDR. At the COL1A1 and ROSA26 loci, a higher mRNA and protein expression of EGFP was detected, and it was correlated with a lower level of DNA methylation of the EGFP promoter, hEF1α. A decreased H3K27me3 modification of the hEF1α promoter at the COL1A1 locus was also detected. For the safety of transgenesis at different SH locus, we found that transgenesis could relatively alter the expression of the adjacent endogenous genes, but the influence was limited. We also did not observe any off-target cleavage for the selected sgRNAs of the COL1A1 and ROSA26 loci. In conclusion, the COL1A1 and ROSA26 were confirmed to be the best two SH loci with the COL1A1 being more competitive for porcine transgenesis. This work would greatly facilitate porcine genome engineering and transgenic pig production.

Pathogen-induced biosynthetic pathways encode defense-related molecules in bread wheat

Wheat is a widely grown food crop that suffers major yield losses due to attack by pests and pathogens. A better understanding of biotic stress responses in wheat is thus of major importance. The recently assembled bread wheat genome coupled with extensive transcriptomic resources provides unprecedented new opportunities to investigate responses to pathogen challenge. Here, we analyze gene coexpression networks to identify modules showing consistent induction in response to pathogen exposure. Within the top pathogen-induced modules, we identify multiple clusters of physically adjacent genes that correspond to six pathogen-induced biosynthetic pathways that share a common regulatory network. Functional analysis reveals that these pathways, all of which are encoded by biosynthetic gene clusters, produce various different classes of compounds—namely, flavonoids, diterpenes, and triterpenes, including the defense-related compound ellarinacin. Through comparative genomics, we also identify associations with the known rice phytoalexins momilactones, as well as with a defense-related gene cluster in the grass model plant Brachypodium distachyon. Our results significantly advance the understanding of chemical defenses in wheat and open up avenues for enhancing disease resistance in this agriculturally important crop. They also exemplify the power of transcriptional networks to discover the biosynthesis of chemical defenses in plants with large, complex genomes.

Novel Indel Variation of NPC1 Gene Associates With Risk of Sudden Cardiac Death

Background and Aims: Sudden cardiac death (SCD) was defined as an unexpected death from cardiac causes during a very short duration. It has been reported that Niemann-Pick type C1 (NPC1) gene mutations might be related to cardiovascular diseases. The purpose of the study is to investigate whether common genetic variants of NPC1 is involved in SCD susceptibility. Methods: Based on a candidate-gene-based approach and systematic screening strategy, this study analyzed an 8-bp insertion/deletion polymorphism (rs150703258) within downstream of NPC1 for the association with SCD risk in Chinese populations using 158 SCD cases and 524 controls. The association of rs150703258 and SCD susceptibility was analyzed using logistic regression. Genotype-phenotype correlation analysis was performed using public database including 1000G, expression quantitative trait loci (eQTL), and further validated by human heart tissues using PCR. Dual-luciferase assay was used to explore the potential regulatory role of rs150703258. Gene expression profiling interactive analysis and transcription factors prediction were performed. Results: Logistic regression analysis exhibited that the deletion allele of rs150703258 significantly increased the risk of SCD [odds ratio (OR) = 1.329; 95% confidence interval (95%CI):1.03–1.72; p = 0.0289]. Genotype-phenotype correlation analysis showed that the risk allele was significantly associated with higher expression of NPC1 at mRNA and protein expressions level in human heart tissues. eQTL analysis showed NPC1 and C18orf8 (an adjacent gene to NPC1) are both related to rs150703258 and have higher expression level in the samples with deletion allele. Dual-luciferase activity assays indicate a significant regulatory role for rs150703258. Gene expression profiling interactive analysis revealed that NPC1 and C18orf8 seemed to be co-regulated in human blood, arteries and heart tissues. In silico analysis showed that the rs150703258 deletion variant may create transcription factor binding sites. In addition, a rare 12-bp allele (4-bp longer than the insertion allele) of rs150703258 was discovered in the current cohort. Conclusion: In summary, our study revealed that rs150703258 might contribute to SCD susceptibility by regulating NPC1 and C18orf8 expression. This indel may be a potential marker for risk stratification and molecular diagnosis of SCD. Validations in different ethnic groups with larger sample size and mechanism explorations are warranted to confirm our findings.

Oct4 dependent chromatin activation is required for chicken primordial germ cell migration.

Primordial germ cells (PGCs) are the undifferentiated progenitors of the gametes. Unlike the poor maintenance of cultured mammalian PGCs, the avian PGCs can be expanded in vitro indefinitely while preserving pluripotency and germline competence. In mammals, the Oct4 is the master transcription factor that ensures the stemness of pluripotent cells such as PGCs, but the specific function of Oct4 in chicken PGCs remains unclear. As expected, the loss of Oct4 in chicken PGCs reduced the expression of key pluripotency factors and promoted the genes involved in endoderm and ectoderm differentiation. Furthermore, the global active chromatin was reduced as shown by the depletion of the H3K27ac upon Oct4 suppression. Interestingly, the de-activated chromatin caused the down-regulation of adjacent genes which are mostly known regulators of cell junction, chemotaxis and cell migration. Consequently, the Oct4-deficient PGCs show impaired cell migration and could not colonize the gonads when re-introduced into the bloodstream of the embryo. We propose that, in addition to maintaining pluripotency, the Oct4 mediated chromatin activation is dictating chicken PGC migration.

Carriage of CdtB Encoding Campylobacter spp., Salmonella enterica, and Yersinia entercolitica in Patients with Gastroenteritis and Irritable Bowel Syndrome.

Cytolethal distending toxin (Cdt) is one of the bacterial toxins that present in a variety of gram-negative human pathogens, such as E. coli, Salmonella spp., and Campylobacter spp. CDT is composed of three subunits encoded by three adjacent genes, including cdtA, cdtB, and cdtC. cdtB has been shown to have toxic activity and cause DNA damage in host cells. Despite its presence in different bacterial species, the role of CdtB in acute and chronic infections, such as gastroenteritis and irritable bowel syndrome (IBS), is unclear. To analyze this correlation, we studied the prevalence of cdtB among different enteropathogenic bacteria in patients with gastroenteritis and IBS compared with healthy people. In this cross-sectional descriptive study, 230 stool samples were collected from patients with gastroenteritis, IBS, and healthy people. The presence of CdtB encoding bacteria, including Escherichia coli, Campylobacter spp., Yersinia entercolitica, Providencia alkalifacience, and Salmonella enterica, was examined by polymerase chain reaction using genus-specific primers. Out of 230 stool samples, CdtB encoding Campylobacter spp. were found in 34.6% (52/150), 6.25% (5/80), and 4% (2/50) of the patients with gastroenteritis, IBS, and the control group, respectively. Carriage of CdtB encoding Salmonella enterica was characterized among 5.3% (8/150) of the patients with gastroenteritis and 17.5% (14/80) of the IBS patients. Although none of the patients carried CdtB encoding E. coli and Providencia spp., cdtB of Y. enterocolitica was detected in one of the patients with gastroenteritis (0.6%). Statistical analysis showed significant correlation between infection with CdtB encoding Campylobacter spp. and IBS-D subtype. Nosignificant correlation was found between infection with CdtB encoding bacteria and other clinical and demographic data. Our results confirmed a relatively higher frequency of CdtB encoding bacteria in the intestine of patients with gastroenteritis and those with IBS compared with healthy individuals. Regarding the frequency of CdtB encoding Salmonella and Campylobacter bacteria, it was proposed that infection with these enteropathogens could be considered a risk factor for the development or progression of IBS among Iranian patients. Further studies are needed to establish this involvement.

FOXC1 Binds Enhancers and Promotes Cisplatin Resistance in Bladder Cancer

Simple SummaryIn bladder cancer, cisplatin remains the front-line therapy, but drug resistance is common. Previously, we showed that cancer cells can spontaneously convert to an aggressive drug-resistant phenotype without mutational events. In the current work, we explored the epigenetic mechanism behind the conversion to the drug-resistant phenotype. We discovered that drug-resistant cells have differentially accessible enhancers, which are bound by FOXC1, a transcription factor that is overexpressed in these cells. Accordingly, FOXC1 knockout significantly attenuates the emergence of the drug-resistant phenotype and reduces cell survival upon cisplatin treatment. These findings suggest that FOXC1 binding at accessible enhancers promotes cisplatin drug resistance in bladder cancer cells. Therefore, FOXC1 targeting may be a new therapeutic avenue to mitigate cisplatin resistance and improve treatment efficacy in bladder cancer.Chemotherapy resistance is traditionally attributed to DNA mutations that confer a survival advantage under drug selection pressure. However, in bladder cancer and other malignancies, we and others have previously reported that cancer cells can convert spontaneously to an aggressive drug-resistant phenotype without prior drug selection or mutational events. In the current work, we explored possible epigenetic mechanisms behind this phenotypic plasticity. Using Hoechst dye exclusion and flow cytometry, we isolated the aggressive drug-resistant cells and analyzed their chromatin accessibility at regulatory elements. Compared to the rest of the cancer cell population, the aggressive drug-resistant cells exhibited enhancer accessibility changes. In particular, we found that differentially accessible enhancers were enriched for the FOXC1 transcription factor motif, and that FOXC1 was the most significantly overexpressed gene in aggressive drug-resistant cells. ChIP-seq analysis revealed that differentially accessible enhancers in aggressive drug-resistant cells had a higher FOXC1 binding, which regulated the expression of adjacent cancer-relevant genes like ABCB1 and ID3. Accordingly, cisplatin treatment of bladder cancer cells led to an increased FOXC1 expression, which mediated cell survival and conversion to a drug-resistant phenotype. Collectively, these findings suggest that FOXC1 contributes to phenotypic plasticity by binding enhancers and promoting a mutation-independent shift towards cisplatin resistance in bladder cancer.

Differential environmental and genomic architectures shape the natural diversity for trichome patterning and morphology in different Arabidopsis organs.

Despite the adaptive and taxonomic relevance of the natural diversity for trichome patterning and morphology, the molecular and evolutionary mechanisms underlying these traits remain mostly unknown, particularly in organs other than leaves. In this study, we address the ecological, genetic and molecular bases of the natural variation for trichome patterning and branching in multiple organs of Arabidopsis (Arabidopsis thaliana). To this end, we characterized a collection of 191 accessions and carried out environmental and genome‐wide association (GWA) analyses. Trichome amount in different organs correlated negatively with precipitation in distinct seasons, thus suggesting a precise fit between trichome patterning and climate throughout the Arabidopsis life cycle. In addition, GWA analyses showed small overlapping between the genes associated with different organs, indicating partly independent genetic bases for vegetative and reproductive phases. These analyses identified a complex locus on chromosome 2, where two adjacent MYB genes (ETC2 and TCL1) displayed differential effects on trichome patterning in several organs. Furthermore, analyses of transgenic lines carrying different natural alleles demonstrated that TCL1 accounts for the variation for trichome patterning in all organs, and for stem trichome branching. By contrast, two other MYB genes (TRY and GL1), mainly showed effects on trichome patterning or branching, respectively.

Cross-species conservation of a transposase-linked element enables genetic sexing of commercial populations of Russian sturgeon (Acipenser gueldenstaedtii).

SummaryAll‐female culture of sturgeon is essential for efficient caviar production. However, Russian sturgeon (Acipenser gueldenstaedtii) does not exhibit external sexual dimorphism, and therefore, commercial farms apply gonadal endoscopy or ultrasound at the earliest age of 4–5 years to separate the sexes, with ~90% accuracy. Recently, a dominant genomic marker (AllWSEX2) has been found with association to femaleness in sturgeons. We developed a duplex PCR (dAllWSEX2) with the adjacent bmp7 gene as an internal control, to validate an effective PCR. Robust amplification of control fragments was observed for all samples of our commercial A. gueldenstaedtii stock (n = 337). The dAllWSEX2 assay was significantly associated with sex (n = 43, p < 1.6 × 10−8), yet four (18%) of the endoscopy‐determined females were genetic males. To examine whether some females display a male genetic profile, we tested 96 egg‐producing females, which were all verified as genetic females, indicating that the observed mismatches may be attributed to wrong sexing by endoscopy. Application of dAllWSEX2 on 100 7‐month‐old fish showed no sex‐dependent differences in body weight, indicating that weighing is not an applicable tool for sorting females at a young age. Sanger sequencing of the bmp7 fragment revealed octaploidy and sex‐independent variation, suggesting that the critical sex‐determining region harboring AllWSEX2 is small. In keeping with a model of a single‐ploidy encoding female determination, AllWSEX2 showed no variation despite being a transposase‐linked repetitive element. Cross‐species conservation of AllWSEX2, and absence of annotated sex‐determination genes in this region suggests that, in sturgeons, the sex‐determining mechanism is different from mechanisms identified in other fish.