RBM10 C761Y mutation induced oncogenic ASPM isoforms and regulated β-catenin signaling in cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma (CCA) comprises a heterogeneous group of biliary tract cancer. Our previous CCA mutation pattern study focused on genes in the post-transcription modification process, among which the alternative splicing factor RBM10 captured our attention. However, the roles of RBM10 wild type and mutations in CCA remain unclear.

METHODS

RBM10 mutation spectrum in CCA was clarified using our initial data and other CCA genomic datasets from domestic and international sources. Real-time PCR and tissue microarray were used to detect RBM10 clinical association. Function assays were conducted to investigate the effects of RBM10 wild type and mutations on CCA. RNA sequencing was to investigate the changes in alternative splicing events in the mutation group compared to the wild-type group. Minigene splicing reporter and interaction assays were performed to elucidate the mechanism of mutation influence on alternative splicing events.

RESULTS

RBM10 mutations were more common in Chinese CCA populations and exhibited more protein truncation variants. RBM10 exerted a tumor suppressive effect in CCA and correlated with favorable prognosis of CCA patients. The overexpression of wild-type RBM10 enhanced the ASPM exon18 exon skipping event interacting with SRSF2. The C761Y mutation in the C2H2-type zinc finger domain impaired its interaction with SRSF2, resulting in a loss-of-function mutation. Elevated ASPM203 stabilized DVL2 and enhanced β-catenin signaling, which promoted CCA progression.

CONCLUSIONS

Our results showed that RBM10C761Y-modulated ASPM203 promoted CCA progression in a Wnt/β-catenin signaling-dependent manner. This study may enhance the understanding of the regulatory mechanisms that link mutation-altering splicing variants to CCA.

Irbesartan overcomes gemcitabine resistance in pancreatic cancer by suppressing stemness and iron metabolism via inhibition of the Hippo/YAP1/c-Jun axis

BACKGROUND

Chemoresistance is the main reason for the poor prognosis of pancreatic ductal adenocarcinoma (PDAC). Thus, there is an urgent need to screen out new targets and compounds to reverse chemotherapeutic resistance.

METHODS

We established a bio-bank of human PDAC organoid models, covering a representative range of PDAC tumor subtypes. We screened a library of 1304 FDA-approved compounds to identify candidates efficiently overcoming chemotherapy resistance. The effects of the compounds were evaluated with a CellTiter-Glo-3D assay, organoid apoptosis assay and in vivo patient-derived xenograft (PDX), patient-derived organoid (PDO) and LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) genetically engineered mouse models. RNA-sequencing, genome editing, sphere formation assays, iron assays and luciferase assays were conducted to elucidate the mechanism.

RESULTS

High-throughput drug screening of chemotherapy-resistant PDOs identified irbesartan, an angiotensin ‖ type 1 (AT1) receptor antagonist, which could synergistically enhance the ability of chemotherapy to kill PDAC cells. In vitro and in vivo validation using PDO, PDX and KPC mouse models showed that irbesartan efficiently sensitized PDAC tumors to chemotherapy. Mechanistically, we found that irbesartan decreased c-Jun expression by inhibiting the Hippo/YAP1 pathway and further overcame chemotherapy resistance in PDAC. We also explored c-Jun, a potential target of irbesartan, which can transcriptionally upregulate the expression of key genes involved in stemness maintenance (SOX9/SOX2/OCT4) and iron metabolism (FTH1/FTL/TFRC). More importantly, we observed that PDAC patients with high levels of c-Jun expression demonstrated poor responses to the current standard chemotherapy regimen (gemcitabine plus nab-paclitaxel). Moreover, patients with PDAC had significant survival benefits from treatment with irbesartan plus a standard chemotherapy regimen in two-center retrospective clinical cohorts and patients with high c-Jun expression exhibited a better response to combination chemotherapy.

CONCLUSIONS

Irbesartan could be used in combination with chemotherapy to improve the therapeutic efficacy in PDAC patients with high levels of c-Jun expression. Irbesartan effectively inhibited chemotherapy resistance by suppressing the Hippo/YAP1/c-Jun/stemness/iron metabolism axis. Based on our findings, we are designing an investigator-initiated phase II clinical trial on the efficacy and safety of irbesartan plus a standard gemcitabine/nab-paclitaxel regimen in the treatment of patients with advanced III/IV staged PDAC and are hopeful that we will observe patient benefits.

Aberrant Bcl-x splicing in cancer: from molecular mechanism to therapeutic modulation

Bcl-x pre-mRNA splicing serves as a typical example to study the impact of alternative splicing in the modulation of cell death. Dysregulation of Bcl-x apoptotic isoforms caused by precarious equilibrium splicing is implicated in genesis and development of multiple human diseases, especially cancers. Exploring the mechanism of Bcl-x splicing and regulation has provided insight into the development of drugs that could contribute to sensitivity of cancer cells to death. On this basis, we review the multiple splicing patterns and structural characteristics of Bcl-x. Additionally, we outline the cis-regulatory elements, trans-acting factors as well as epigenetic modifications involved in the splicing regulation of Bcl-x. Furthermore, this review highlights aberrant splicing of Bcl-x involved in apoptosis evade, autophagy, metastasis, and therapy resistance of various cancer cells. Last, emphasis is given to the clinical role of targeting Bcl-x splicing correction in human cancer based on the splice-switching oligonucleotides, small molecular modulators and BH3 mimetics. Thus, it is highlighting significance of aberrant splicing isoforms of Bcl-x as targets for cancer therapy.

High-dose rapamycin exerts a temporary impact on T. reesei RUT-C30 through gene trFKBP12

BACKGROUND

Knowledge with respect to regulatory systems for cellulase production is prerequisite for exploitation of such regulatory networks to increase cellulase production, improve fermentation efficiency and reduce the relevant production cost. The target of rapamycin (TOR) signaling pathway is considered as a central signaling hub coordinating eukaryotic cell growth and metabolism with environmental inputs. However, how and to what extent the TOR signaling pathway and rapamycin are involved in cellulase production remain elusive.

RESULT

At the early fermentation stage, high-dose rapamycin (100 μM) caused a temporary inhibition effect on cellulase production, cell growth and sporulation of Trichoderma reesei RUT-C30 independently of the carbon sources, and specifically caused a tentative morphology defect in RUT-C30 grown on cellulose. On the contrary, the lipid content of T. reesei RUT-C30 was not affected by rapamycin. Accordingly, the transcriptional levels of genes involved in the cellulase production were downregulated notably with the addition of rapamycin. Although the mRNA levels of the putative rapamycin receptor trFKBP12 was upregulated significantly by rapamycin, gene trTOR (the downstream effector of the rapamycin-FKBP12 complex) and genes associated with the TOR signaling pathways were not changed markedly. With the deletion of gene trFKBP12, there is no impact of rapamycin on cellulase production, indicating that trFKBP12 mediates the observed temporary inhibition effect of rapamycin.

CONCLUSION

Our study shows for the first time that only high-concentration rapamycin induced a transient impact on T. reesei RUT-C30 at its early cultivation stage, demonstrating T. reesei RUT-C30 is highly resistant to rapamycin, probably due to that trTOR and its related signaling pathways were not that sensitive to rapamycin. This temporary influence of rapamycin was facilitated by gene trFKBP12. These findings add to our knowledge on the roles of rapamycin and the TOR signaling pathways play in T. reesei.

The Fungal Effector Avr-Pita Suppresses Innate Immunity by Increasing COX Activity in Rice Mitochondria

BACKGROUND

Avr-Pita was the first effector identified in the blast fungus (Magnaporthe oryzae)-rice (Oryza sativa) pathosystem. However, the molecular mechanism underlying its effects on the host plant has remained a long-standing mystery.

RESULTS

Here, we report that ectopically expressing Avr-Pita in rice enhances susceptibility to M. oryzae and suppresses pathogen-associated molecular pattern (PAMP)-triggered defense responses. Avr-Pita targets the host mitochondria and interacts with the cytochrome c oxidase (COX) assembly protein OsCOX11, a key regulator of mitochondrial reactive oxygen species (ROS) metabolism in rice. Overexpressing Avr-Pita or OsCOX11 increased COX activity and decreased ROS accumulation triggered by the fungal PAMP chitin. OsCOX11-overexpressing plants showed increased susceptibility to M. oryzae, whereas OsCOX11-knockdown plants showed resistance to M. oryzae.

CONCLUSIONS

Taken together, these findings suggest that the fungal pathogen M. oryzae delivers the effector Avr-Pita to the host plant, where it enhances COX activity thus decreasing ROS accumulation. Therefore, this effector suppresses host innate immunity by perturbing ROS metabolism in the mitochondria.

Berberine attenuates mitochondrial dysfunction by inducing autophagic flux in myocardial hypoxia/reoxygenation injury

Berberine (BBR) is routinely prescribed in many Asian countries to treat diarrhea. Evidence from both animal and clinical investigations suggests that BBR exerts diverse pharmacological activities, including antidiabetic, antineoplastic, antihypertensive, and antiatherosclerotic effects. This study aimed to explore the cardioprotective mechanisms of BBR and to elucidate the modulations between autophagy and mitochondrial function during hypoxia/reoxygenation (H/R) in H9c2 cells. The degree of autophagic flux was assessed by pretreating H9c2 cells with BBR prior to H/R exposure and measuring the expression levels of Beclin-1 and green fluorescent protein (GFP)-labeled LC3B fusion proteins as well as the LC3II/LC3I ratio. The mitochondrial membrane potential (△Ψm) in H9c2 cells was evaluated by detecting rhodamine-123 fluorescence using flow cytometry. The results revealed that pretreatment with BBR upregulated autophagic flux and protected against the loss of the △Ψm in H9c2 cells subjected to H/R. We conclude that BBR attenuates mitochondrial dysfunction by inducing autophagic flux.

The R2R3 MYB transcription factor MdMYB30 modulates plant resistance against pathogens by regulating cuticular wax biosynthesis

BACKGROUND

The MYB transcription factor family is one of the largest transcriptional factor families in plants and plays a multifaceted role in plant growth and development. However, MYB transcription factors involved in pathogen resistance in apple remain poorly understood.

RESULTS

We identified a new MYB family member from apple, and named it MdMYB30. MdMYB30 was localized to the nucleus, and was highly expressed in young apple leaves. Transcription of MdMYB30 was induced by abiotic stressors, such as polyethylene glycol and abscisic acid. Scanning electron microscopy and gas chromatograph-mass spectrometry analyses demonstrated that ectopically expressing MdMYB30 in Arabidopsis changed the wax content, the number of wax crystals, and the transcription of wax-related genes. MdMYB30 bound to the MdKCS1 promoter to activate its expression and regulate wax biosynthesis. MdMYB30 also contributed to plant surface properties and increased resistance to the bacterial strain Pst DC3000. Furthermore, a virus-based transformation in apple fruits and transgenic apple calli demonstrated that MdMYB30 increased resistance to Botryosphaeria dothidea. Our findings suggest that MdMYB30 plays a vital role in the accumulation of cuticular wax and enhances disease resistance in apple.

CONCLUSIONS

MdMYB30 bound to the MdKCS1 gene promoter to activate its transcription and regulate cuticular wax content and composition, which influenced the surface properties and expression of pathogenesis-related genes to resistance against pathogens. MdMYB30 appears to be a crucial element in the formation of the plant cuticle and confers apple with a tolerance to pathogens.

Properties of a Tightly Focused Circularly Polarized Anomalous Vortex Beam and Its Optical Forces on Trapped Nanoparticles

The characteristics of a circularly polarized anomalous vortex beam (CPAVB), focused by an objective lens with a high numerical aperture (NA), are studied analytically and theoretically. It shows that the topological charge can affect the beam profile significantly and a flat-topped (FT) beam can be obtained by modulating the NA and topological charge. It is interesting to find that spin-to-orbital angular momentum conversion can occur in the longitudinal component after tight focusing. Furthermore, optical forces of the tightly focused CPAVB on nanoparticles are analyzed in detail. It can be expected to trap two kinds of nanoparticles using such beam near the focus.

Isolation and functional characterization of the SpCBF1 gene from Solanum pinnatisectum

Low temperature causes a negative impact on plant growth and development, but plants evolve a series of mechanisms to respond to chilling stress, and one of them is CBF [C-repeat (CRT)/dehydration-responsive element (DRE) binding factor] gene family which has been well studied in different crops. In this paper, a new CBF1 gene, named as SpCBF1, was isolated from frost-tolerant Solanum pinnatisectum by PCR and analyzed for its function in cold-tolerance by over-expression technique. The ORF of SpCBF1 was 666 bp long and encoded a protein of 221 amino acids with a predicted molecular mass 24.5821 kDa and theoretically isoelectric point 5.0. SpCBF1 protein contained a highly conserved specific AP2/ERF domain. SpCBF1 was expressed in all tested tissues with the highest level in tuber and the lowest in root, and induced by chilling stress (0 °C). Under natural low temperature condition (1-10 °C), plants over-expressing SpCBF1 (OE) exhibited slighter necrotic lesion and lower necrotic injury, compared with untransformed Solanum tuberosum cv. Désirée (WT) and antisense-StCBF1 control lines. Over-expression of CBF1 increased the level of COR (cold-regulated) gene transcripts in OE lines, and the physiological indexes related to cold tolerance like the contents of SOD, soluble protein, MDA, proline and soluble sugar were higher in OE lines than in WT except RWC which was lower. All these results indicated that SpCBF1 gene plays a promoting role in potato responding to cold stress.

Fabrication and Photocatalytic Property of Novel SrTiO3/Bi5O7I Nanocomposites

The novel SrTiO3/Bi5O7I nanocomposites were successfully fabricated by a thermal decomposition approach. The as-prepared samples were characterized by XRD, XPS, SEM, EDS, FTIR, DRS and PL spectra. The results show that the SrTiO3/Bi5O7I nanocomposites are composed of perovskite SrTiO3 nanoparticles and tetragonal Bi5O7I nanorods. The SrTiO3/Bi5O7I nanocomposites exhibit an excellent photocatalytic performance for the degradation of RhB solution under simulated solar light irradiation, which is superior to that of pristine Bi5O7I and SrTiO3. In particular, the 30 wt% SrTiO3/Bi5O7I nanocomposite is found as the optimal composites, over which the dye degradation reaches 89.6% for 150 min of photocatalysis. The photocatalytic degradation rate of the 30 wt% SrTiO3/Bi5O7I nanocomposite is found to be 3.97 times and 12.5 times higher than that of bare Bi5O7I and SrTiO3, respectively. The reactive species trapping experiments suggest that [Formula: see text] and holes are the main active species responsible for the RhB degradation. In addition, the PL spectra elucidate the effective separation of photoinduced electron-hole pairs. Further, the possible photocatalytic mechanism of the SrTiO3/Bi5O7I nanocomposites is also elucidated based on the experimental evidences.

Role of abscisic acid in strigolactone-induced salt stress tolerance in arbuscular mycorrhizal Sesbania cannabina seedlings

BACKGROUND

Strigolactones (SLs) are considered to be a novel class of phytohormone involved in plant defense responses. Currently, their relationships with other plant hormones, such as abscisic acid (ABA), during responses to salinity stress are largely unknown.

RESULTS

In this study, the relationship between SL and ABA during the induction of H₂O₂ - mediated tolerance to salt stress were studied in arbuscular mycorrhizal (AM) Sesbania cannabina seedlings. The SL levels increased after ABA treatments and decreased when ABA biosynthesis was inhibited in AM plants. Additionally, the expression levels of SL-biosynthesis genes in AM plants increased following treatments with exogenous ABA and H₂O₂. Furthermore, ABA-induced SL production was blocked by a pre-treatment with dimethylthiourea, which scavenges H₂O₂. In contrast, ABA production was unaffected by dimethylthiourea. Abscisic acid induced only partial and transient increases in the salt tolerance of TIS108 (a SL synthesis inhibitor) treated AM plants, whereas SL induced considerable and prolonged increases in salt tolerance after a pre-treatment with tungstate.

CONCLUSIONS

These results strongly suggest that ABA is regulating the induction of salt tolerance by SL in AM S. cannabina seedlings.

Grid-based prediction of torsion angle probabilities of protein backbone and its application to discrimination of protein intrinsic disorder regions and selection of model structures

BACKGROUND

Protein structure can be described by backbone torsion angles: rotational angles about the N-Cα bond (φ) and the Cα-C bond (ψ) or the angle between Cαi-1-Cαi-Cαi + 1 (θ) and the rotational angle about the Cαi-Cαi + 1 bond (τ). Thus, their accurate prediction is useful for structure prediction and model refinement. Early methods predicted torsion angles in a few discrete bins whereas most recent methods have focused on prediction of angles in real, continuous values. Real value prediction, however, is unable to provide the information on probabilities of predicted angles.

RESULTS

Here, we propose to predict angles in fine grids of 5° by using deep learning neural networks. We found that this grid-based technique can yield 2-6% higher accuracy in predicting angles in the same 5° bin than existing prediction techniques compared. We further demonstrate the usefulness of predicted probabilities at given angle bins in discrimination of intrinsically disorder regions and in selection of protein models.

CONCLUSIONS

The proposed method may be useful for characterizing protein structure and disorder. The method is available at http://sparks-lab.org/server/SPIDER2/ as a part of SPIDER2 package.

Efficient isolation of Magnolia protoplasts and the application to subcellular localization of MdeHSF1

BACKGROUND

Magnolia is a woody ornamental plant, which is widely used in urban landscaping. However, its lengthy juvenile period and recalcitrance to regeneration impedes functional characterization of its genes.

RESULTS

We developed an efficient protoplast isolation and transient expression system for Magnolia denudata × Magnolia acuminata 'Yellow River'. The highest yield of protoplasts was obtained from young leaves digested in 3% Cellulase R10, 0.8% Macerozyme R10, 0.04% pectinase and 0.4 M mannitol enzymolysis solution for 6 h. For transfection of protoplasts, 20% PEG4000 for 5 min was optimal. To verify the protoplast system and begin to understand heat tolerance in Magnolia, a heat shock transcription factor MdeHSF1 was cloned from 'Yellow River', which belongs to the HSF subfamily A and has significant homology with AtHSFA1A. Subcellular localization analysis indicated that MdeHSF1 was expressed in the cell nucleus. Furthermore, qPCR analysis of the MdeHSF1 transcript level in response to high temperature stress suggested that MdeHSF1 might be involved in regulating heat stress tolerance in 'Yellow River'.

CONCLUSION

The described protocol provides a simple and straightforward method for isolating protoplast and exploring gene subcellular localization of MdeHSF1 in Magnolia. This expands the new research of protoplast isolation and transfection in Magnolia.

Streptavidin Modified ZnO Film Bulk Acoustic Resonator for Detection of Tumor Marker Mucin 1

A ZnO-based film bulk acoustic resonator has been fabricated using a magnetron sputtering technology, which was employed as a biosensor for detection of mucin 1. The resonant frequency of the thin-film bulk acoustic resonator was located near at 1503.3 MHz. The average electromechanical coupling factor [Formula: see text] and quality factor Q were 2.39 % and 224, respectively. Using the specific binding system of avidin-biotin, the streptavidin was self-assembled on the top gold electrode as the sensitive layer to indirectly test the MUC1 molecules. The resonant frequency of the biosensor decreases in response to the mass loading in range of 20-500 nM. The sensor modified with the streptavidin exhibits a high sensitivity of 4642.6 Hz/nM and a good selectivity.