BackgroundUbiquitination is a basic post-translational modification for cellular homeostasis, and members of the conjugating enzyme (E2) family are the key components of the ubiquitin–proteasome system. However, the role of E2 family in colorectal cancer (CRC) is largely unknown. Our study aimed to investigate the role of Ube2v1, one of the ubiquitin-conjugating E2 enzyme variant proteins (Ube2v) but without the conserved cysteine residue required for the catalytic activity of E2s, in CRC.MethodsImmunohistochemistry and real-time RT-PCR were used to study the expressions of Ube2v1 at protein and mRNA levels in CRC, respectively. Western blotting and immunofluorescence, transmission electron microscopy, and in vivo rescue experiments were used to study the functional effects of Ube2v1 on autophagy and EMT program. Quantitative mass spectrometry, immunoprecipitation, ubiquitination assay, western blotting, and real-time RT-PCR were used to analyze the effects of Ube2v1 on histone H4 lysine 16 acetylation, interaction with Sirt1, ubiquitination of Sirt1, and autophagy-related gene expression.ResultsUbe2v1 was elevated in CRC samples, and its increased expression was correlated with poorer survival of CRC patients. Ube2v1 promoted migration and invasion of CRC cells in vitro and tumor growth and metastasis of CRC cells in vivo. Interestingly, Ube2v1suppressed autophagy program and promoted epithelial mesenchymal transition (EMT) and metastasis of CRC cells in an autophagy-dependent pattern in vitro and in vivo. Moreover, both rapamycin and trehalose attenuated the enhanced Ube2v1-mediated lung metastasis by inducing the autophagy pathway in an orthotropic mouse xenograft model of lung metastasis. Mechanistically, Ube2v1 promoted Ubc13-mediated ubiquitination and degradation of Sirt1 and inhibited histone H4 lysine 16 acetylation, and finally epigenetically suppressed autophagy gene expression in CRC.ConclusionsOur study functionally links Ube2v1, an E2 member in the ubiquitin–proteasome system, to autophagy program, thereby shedding light on developing Ube2v1 targeted therapy for CRC patients.Electronic supplementary materialThe online version of this article (10.1186/s13045-018-0638-9) contains supplementary material, which is available to authorized users.

The pathogenesis and key functional molecules involved in inflammatory bowel disease (IBD) including Crohn's disease (CD) and ulcerative colitis (UC) remain unclear. Here, we reported that Erbin, a protein required for the polarity of epithelial cells, is conserved across species and highly expressed in the intestinal mucosa in mice and zebrafish. Pathologically, Erbin expression in the intestinal mucosa was significantly decreased in DSS induced acute colitis mice, IL-10 deficient mice and clinical biopsy specimens from patients with ulcerative colitis. Moreover, Erbin deficient mice are more susceptible to experimental colitis, exhibiting more severe intestinal barrier disruption, with increased histological scores and excessive production of proinflammatory cytokines. Mechanistically, Erbin deficiency or knockdown significantly exacerbated activation of autophagic program and autophagic cell death in vivo and in vitro. And, inhibition of autophagy by Chloroquine attenuates excessive inflammatory response in the DSS-induced colitis mouse model of Erbin deletion. Generally, our study uncovers a crucial role of Erbin in autophagic cell death and IBD, giving rise to a new strategy for IBD therapy by inhibiting excessive activation of autophagy and autophagic cell death.

Rice false smut caused by the fungal pathogen Ustilaginoidea virens is becoming a destructive disease throughout major rice-growing countries. Information about its genetic diversity and population structure is essential for rice breeding and efficient control of the disease. This study compared the genome sequences of two U. virens isolates. Three SNP-rich genomic regions were identified as molecular markers that could be used to analyze the genetic diversity and population structure of U. virens in China. A total of 56 multilocus sequence types (haplotypes) were identified out of 162 representative isolates from 15 provinces covering five major rice-growing areas in China. However, the phylogeny, based on sequences at individual SNP-rich regions, strongly conflicted with each other and there were significant genetic differences between different geographical populations. Gene flow between the different geographical populations and genetic differentiation within each geographical population were also detected. In addition, genetic recombination and genetic isolation resulting from geographic separation was also found.

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The mechanisms and key factors involved in tumor environments for lung metastasis of CRC are still unclear. Here, using clinical samples from lung metastases of CRC patients, we found that intestinal immune network for IgA production was significantly dysregulated in lung metastases of CRC. Single-cell RNA sequencing discovered a subtype of B cells positive for Erbin, one member of the leucine-rich repeat and PDZ domain (LAP) family, was involved in the lung metastases. Erbin deletion in B cells suppressed lung metastasis of CRC in vivo. And, deletion of Erbin in B cells enhanced the killing effects of CD8+ T cells on tumor cells. Mechanistically, Erbin knockout attenuated TGFβ-mediated suppression of migration of CXCR5+ IgA+ cells and STAT6-mediated PD1 expression. Our study uncovered a key role of Erbin in regulating PD1+ IgA+ B cells in lung metastasis of CRC. Targeting Erbin as well as combined use of neutralizing B cells and antibodies neutralizing PD1 suppresses lung metastasis of CRC in mice, suggesting the potential option for treatment of lung metastasis of CRC.