RNA-binding protein HuR modulates the stability and translational efficiency of messenger RNAs (mRNAs) encoding essential components of the cellular proliferation, growth and survival pathways. Consistent with these functions, HuR levels are often elevated in cancer cells and reduced in senescent and quiescent cells. However, the molecular mechanisms that control HuR expression are poorly understood. Here we show that HuR protein autoregulates its abundance through a negative feedback loop that involves interaction of the nuclear HuR protein with a GU-rich element (GRE) overlapping with the HuR major polyadenylation signal (PAS2). An increase in the cellular HuR protein levels stimulates the expression of long HuR mRNA species containing an AU-rich element (ARE) that destabilizes the mRNAs and thus reduces the protein production output. The PAS2 read-through occurs due to a reduced recruitment of the CstF-64 subunit of the pre-mRNA cleavage stimulation factor in the presence of the GRE-bound HuR. We propose that this mechanism maintains HuR homeostasis in proliferating cells. Since only the nuclear HuR is expected to contribute to the auto-regulation, our model may explain the longstanding observation that the increase in the total HuR expression in cancer cells often correlates with the accumulation of its substantial fraction in the cytoplasm.

Establishment of symbiosis between certain host plants and nitrogen-fixing bacteria ("rhizobia") depends on type 3 effector proteins secreted via the bacterial type 3 secretion system (T3SS). Here, we report that the open reading frame y4zC of strain NGR234 encodes a novel rhizobial type 3 effector, termed NopT (for nodulation outer protein T). Analysis of secreted proteins from NGR234 and T3SS mutants revealed that NopT is secreted via the T3SS. NopT possessed autoproteolytic activity when expressed in Escherichia coli or human HEK 293T cells. The processed NopT exposed a glycine (G50) to the N terminus, which is predicted to be myristoylated in eukaryotic cells. NopT with a point mutation at position C93, H205, or D220 (catalytic triad) showed strongly reduced autoproteolytic activity, indicating that NopT is a functional protease of the YopT-AvrPphB effector family. When transiently expressed in tobacco plants, proteolytically active NopT elicited a rapid hypersensitive reaction. Arabidopsis plants transformed with nopT showed chlorotic and necrotic symptoms, indicating a cytotoxic effect. Inoculation experiments with mutant derivatives of NGR234 indicated that NopT affected nodulation either positively (Phaseolus vulgaris cv. Yudou No. 1; Tephrosia vogelii) or negatively (Crotalaria juncea). We suggest that NopT-related polymorphism may be involved in evolutionary adaptation of NGR234 to particular host legumes.In root nodules of legumes, symbiotic bacteria ("rhizobia" belonging to the Rhizobiaceae family) reduce N 2 gas into ammonia by the process termed nitrogen fixation. Nodule formation requires specific bacterial signals and determinants (12). Rhizobial nodulation factors (Nod factors) trigger various host responses, including root hair deformation, expression of symbiosis-related host genes, and cortical cell divisions resulting in nodule formation (31, 32). Host-specific nodulation depends also on surface carbohydrates, such as oligosaccharides released from exopolysaccharides, lipopolysaccharides, cyclic ␤-glucans, and K antigens (also named capsular polysaccharides). In Rhizobium sp. strain NGR234, for example, mutants that do not produce exo-oligosaccharides or flavonoid-inducible lipopolysaccharide are unable to establish symbiosis with various host plants (36,48). In addition to these symbiotic determinants, host-specific nodulation depends on proteins secreted via a pilus-like secretory apparatus, the type 3 secretion system (T3SS) of NGR234. Recent data from various laboratories provide evidence that T3SSs of certain rhizobial strains modulate establishment of symbiosis and the efficiency of nitrogen fixation (14,23,25,56).T3SSs from pathogenic bacteria deliver effector proteins (type 3 effectors) into eukaryotic cells to manipulate the host metabolism, e.g., to suppress defense responses. Many reports indicate that type 3 effectors are virulence factors that play a key role in the pathogenesis of humans, animals, and plants (9,20). On the other hand, eukaryotic host cells developed strategies ...

Colorectal cancer (CRC) is the third most common malignancy in developed countries, and its incidence rate has been continuously increasing in developing countries over the past few decades. Taurine-upregulated gene 1 (TUG1) plays an important role in signal transduction, regulation of cell morphology, migration, proliferation and apoptosis. The aim of the present study was to evaluate the role of TUG1 in CRC, and whether knockdown of TUG1 expression could affect cell proliferation, migration and invasion of CRC cell lines. Here, we reported that TUG1 was upregulated in CRC. Further experiments revealed that TUG1 knockdown significantly inhibited cell proliferation, migration and invasion of CRC in vitro. Above all, knockdown of TUG1 may represent a rational therapeutic strategy for CRC patients in future.

Long noncoding RNAs (lncRNAs) are implicated in various cancers, including colon cancer. Liver metastasis is the main cause of colon cancer-related death. However, the roles of lncRNAs in colon cancer liver metastasis are still largely unclear. In this study, we identified a novel lncRNA B3GALT5-AS1, which is reduced in colon cancer tissues and further reduced in colon cancer liver metastasis tissues. Reduced expression of B3GALT5-AS1 is associated with liver metastasis and poor outcome of colon cancer patients. Gain-of-function and loss-of-function assays revealed that B3GALT5-AS1 inhibited proliferation but promoted migration and invasion of colon cancer cells. Further investigation revealed that B3GALT5-AS1 directly bound to the promoter of miRNA-203, repressed miR-203 expression, upregulated miR-203 targets ZEB2 and SNAI2, and induced epithelial-to-mesenchymal transition (EMT). In vivo study revealed that B3GALT5-AS1 suppressed colon cancer liver metastasis via its binding on miR-203 promoter and the repression of miR-203. miR-203 is increased and epithelial phenotype is preferred in colon cancer liver metastasis tissues. Collectively, our data revealed the suppressive roles of B3GALT5-AS1/miR-203/EMT regulation axis in colon cancer liver metastasis. Our data suggested that the activating B3GALT5-AS1/miR-203/EMT axis may be potential therapeutic strategy for colon cancer liver metastasis.

Benign multicystic peritoneal mesothelioma (BMPM) is a rare cystic mesothelial lesion that occurs predominantly in reproductive aged women. A 56-year-old Caucasian male was admitted to our surgical department with a chief complaint of a painful mass in his right lower abdomen for almost 2 years. The physical examination revealed a palpable painful mass. Computed tomography demonstrated an irregular, cystic tumor in his right lower abdomen. There was no obvious capsule or internal septations. No enhancement after intravenous administration of contrast was noted. An exploratory laparotomy was performed, and a multicystic tumor and adherent to the caecum was noted. The walls of the cysts were thin and smooth, filled with clear fluid, and very friable. An en bloc resection of the tumor, including appendix and caecum, was performed. Histological examination revealed multiple cysts lined with flattened simple epithelial cells, and the capsule walls of the cysts were composed of fibrous tissue. Immunohistochemical analysis documented positive expression of mesothelial cells and calretinin. The final diagnosis was BMPM. The patient was well at 6-mo follow-up. BMPM is exceedingly rare lesion. A complete resection of the tumor is required. The diagnosis of BMPM is based on pathological analysis.