The amino acid sensor MetRS is required for methionine-induced milk protein synthesis in a domestic pigeon model.

This study was conducted to investigate whether methionyl-tRNA synthetase (MetRS) is a mediator of Met-induced crop milk protein synthesis via the janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) signalling pathway in breeding pigeons. In Experiment 1, a total of 216 pairs of breeding pigeons were divided into 3 groups (control, Met-deficient, and Met-rescue groups). In Experiments 2 and 3, forty pairs of breeding pigeons from each experiment were allocated into 4 groups. The 2nd experiment included a control group and 3 MetRS inhibitor (REP8839) groups. The 3rd experiment included a Met-deficient group, Met-sufficient group, REP8839 + Met-deficient group, and REP8839 + Met-sufficient group. Experiment 1 showed that Met supplementation increased crop development, crop milk protein synthesis, the protein expression of MetRS and JAK2/STAT5 signalling pathway, and improved squab growth. Experiment 2 showed that crop development, crop milk protein synthesis, and the protein expression of MetRS and the JAK2/STAT5 signalling pathway were decreased, and squab growth was inhibited by the injection of 1.0 mg/kg BW REP8839, which was the selected dose for the 3rd experiment. These results showed that Met supplementation increased crop development, crop milk protein synthesis, and the expression of MetRS and JAK2/STAT5 signalling pathway and rescued squab growth after the injection of REP8839. Moreover, the Co-IP results showed that there was an interaction between MetRS and JAK2. Taken together, these findings indicate that MetRS mediates Met-induced crop milk protein synthesis via the JAK2/STAT5 signalling pathway, resulting in improved squab growth in breeding pigeons.

Ovariectomy with simulated vaginal delivery to establish a rat model for pelvic organ prolapse.

The widespread prevalence of Pelvic Organ Prolapse (POP) and the paucity of ongoing treatments prompted us to develop a unique rat model combining ovariectomy and simulated vaginal delivery. We hypothesized that the tissue changes caused by low hormone levels and mechanical stretch could complement each other. Thus, the combined model can potentially mimic the collagen metabolism of vaginal wall tissue as well as mechanical stretch properties to complement disease progression in POP. Ovariectomy with sequential simulated vaginal delivery was performed on rats in the modeling group. Sham surgeries were performed as control. At 2, 4, and 12 weeks after modeling, the vaginal tissues of rats were evaluated by Masson's trichrome staining, Picro-Sirius red staining, immunohistochemistry, western blotting, and uniaxial tensile tests. Compared to the control group, the vaginal tissues of the model rats showed an atrophic epithelial layer and loose collagen fibers. The smooth muscle fibers were ruptured, smaller in diameter, and disorganized. The ratio of collagen type I/III significantly increased, but the contents of both Collagen I and III decreased. The expression of metalloproteinases 2 and 9 in the tissues increased, and the expression of tissue inhibitors of metalloproteinases 1 and 2 decreased. The tangent modulus of the tissues was significantly increased in the model rats. We verified a novel method to establish a pelvic organ prolapse model in rats. This approach combined the advantages of low hormone levels and mechanical stretch effects.

L-glutamate requires ß-catenin signalling through Frizzled7 to stimulate porcine intestinal stem cell expansion.

Intestinal stem cells (ISCs) decode and coordinate various types of nutritional information from the diet to support the crypt-villus axis architecture, but how specific dietary molecules affect intestinal epithelial homeostasis remains unclear. In the current study, L-glutamate (Glu) supplementation in either a nitrogen-free diet (NFD) or a corn-soybean meal diet (CSMD) stimulated gut growth and ISC expansion in weaned piglets. Quantitative proteomics screening identified the canonical Wnt signalling pathway as a central regulator of intestinal epithelial development and ISC activity in vivo. Importantly, the Wnt transmembrane receptor Frizzled7 (FZD7) was upregulated in response to dietary Glu patterns, and its perturbations in intestinal organoids (IOs) treated with a specific inhibitor and in FZD7-KO IPEC-J2 cells disrupted the link between Glu inputs and ß-catenin signalling and a subsequent reduction in cell viability. Furthermore, co-localization, coimmunoprecipitation (Co-IP), isothermal titration calorimetry (ITC), and microscale thermophoresis (MST) revealed that Glu served as a signalling molecule directly bound to FZD7. We propose that FZD7-mediated integration of the extracellular Glu signal controls ISC proliferation and differentiation, which provides new insights into the crosstalk of nutrients and ISCs.

Dietary supplementation with probiotics increases growth performance, improves the intestinal mucosal barrier and activates the Wnt/ß-catenin pathway activity in chicks.

BACKGROUND: Probiotics comprise effective feed additives that can replace antibiotics in animal livestock production. However, mono-strain probiotics appear less effective because of their instability. Therefore, the present study aimed to investigate dietary supplementation with compound probiotics (CPP) on growth performance, diarrhea rate and intestinal mucosal barrier, as well as the possible molecular mechanism, in chicks. In total, 360 1-day-old chicks of the Hy-Line Brown Chicks were randomly divided into the control group (CON, basal diet), chlortetracycline group (500 mg kg-1 CTC) and compound probiotics group (1000 mg kg-1 CPP, consisting of Bacillus subtilis, Bacillus licheniformis, Enterococcus faecium and yeast). The experiment period was 56 days. RESULTS: The results showed that, in comparison with the CON group, CPP significantly increased the average daily feed intake and average daily gain of chicks and reduced diarrhea (P < 0.05). The probiotic group exhibited increased immune organ (i.e. spleen and thymus) mass and increased levels of serum immunoglobulin (Ig)A, IgM and IgG (P < 0.05) compared to the CTC group. In addition, the jejunal mass and morphology were improved in the probiotic group (P < 0.05). Moreover, CPP reinforced jejunal barrier function, as indicated by increased transepithelial electrical resistance, protein expression of occludin and claudin-1, and diamine oxidase levels in the jejunum (P < 0.05). Likewise, enhanced fluorescence signals of proliferating cell nuclear antigen-labeled mitotic cells and villin-labeled absorptive cells in the jejunum (P < 0.05) suggested that CPP promoted intestinal stem cells activity. Mechanistically, the Wnt/ß-catenin signaling pathway, including ß-catenin, TCF4, c-Myc, cyclin D1 and Lgr5, was amplified in the jejunum by CPP addition (P < 0.05). CONCLUSION: The present study demonstrated that dietary supplementation with CPP reinforced the jejunal epithelial integrity by activating Wnt/ß-catenin signaling and enhanced immune function in chicks. © 2023 Society of Chemical Industry.

Heat-stable enterotoxin inhibits intestinal stem cell expansion to disrupt the intestinal integrity by downregulating the Wnt/ß-catenin pathway.

Enterotoxigenic Escherichia coli causes severe infectious diarrhea with high morbidity and mortality in newborn and weanling pigs mainly through the production of heat-stable enterotoxins (STs). However, the precise regulatory mechanisms involved in ST-induced intestinal epithelium injury remain unclear. Consequently, we conducted the experiments in vivo (mice), ex vivo (mouse and porcine enteroids), and in vitro (MODE-K and IPEC-J2 cells) to explore the effect of STp (one type of STa) on the integrity of the intestinal epithelium. The results showed that acute STp exposure led to small intestinal edema, disrupted intestinal integrity, induced crypt cell expansion into spheroids, and downregulated Wnt/ß-catenin activity in the mice. Following a similar trend, the enteroid-budding efficiency and the expression of Active ß-catenin, ß-catenin, Lgr5, PCNA, and KRT20 were significantly decreased after STp treatment, as determined ex vivo. In addition, STp inhibited cell proliferation, induced cell apoptosis, destroyed cell barriers, and reduced Wnt/ß-catenin activity by downregulating its membrane receptor Frizzled7 (FZD7). In contrast, Wnt/ß-catenin reactivation protected the IPEC-J2 cells from STp-induced injury. Taking these findings together, we conclude that STp inhibits intestinal stem cell expansion to disrupt the integrity of the intestinal mucosa through the downregulation of the Wnt/ß-catenin signaling pathway.

Impaired intestinal stem cell activity in ETEC infection: enterotoxins, cyclic nucleotides, and Wnt signaling.

Enterotoxigenic Escherichia coli (ETEC) in humans and animals colonizes the intestine and thereafter secrets heat-stable enterotoxin (ST) with or without heat-labile enterotoxin (LT), which triggers massive fluid and electrolyte secretion into the gut lumen. The crosstalk between the cyclic nucleotide-dependent protein kinase/cystic fibrosis transmembrane conductance regulator (cAMP or cGMP/CFTR) pathway involved in ETEC-induced diarrhea channels, and the canonical Wnt/ß-catenin signaling pathway leads to changes in intestinal stem cell (ISC) fates, which are strongly associated with developmental disorders caused by diarrhea. We review how alterations in enterotoxin-activated ion channel pathways and the canonical Wnt/ß-catenin signaling pathway can explain inhibited intestinal epithelial activity, characterize alterations in the crosstalk of cyclic nucleotides, and predict harmful effects on ISCs in targeted therapy. Besides, we discuss current deficits in the understanding of enterotoxin-intestinal epithelial cell activity relationships that should be considered when interpreting sequelae of diarrhea.

Current situation of complications related to reconstructive surgery for pelvic organ prolapse: a multicenter study.

INTRODUCTION AND HYPOTHESIS: This study aimed to investigate the evaluation and management of complications after pelvic floor reconstructive surgery for pelvic organ prolapse in China. METHODS: Complications of pelvic floor reconstructive surgery for pelvic organ prolapses from 27 institutions were reported from November 2017 to October 2019. All complications were coded according to the category-time-site system proposed by the International Urogynecological Association (IUGA) and the International Continence Society (ICS). The severity of the complications was graded by the Clavien-Dindo grading system. Four scales were used to evaluate patient satisfaction and quality of life after management of the complications: the Patient Global Impression of Improvement (PGI-I), the Pelvic Floor Impact Questionnaire Short Form (PFIQ-7), the Pelvic Organ Prolapse Symptom Score (POP-SS), and a 5-point Likert-type scale that evaluated the patient's choice of surgery. RESULTS: Totally, 256 cases were reported. The occurrence of complications related to transvaginal mesh (TVM) and laparoscopic sacrocolpopexy (LSC) had a significantly longer post-surgery delay than those of native tissue repair surgery (p < 0.001 and p = 0.010, respectively). Both PFIQ-7 and POP-SS score were lower after management of complications (p < 0.001). Most respondents (81.67%) selected very much better, much better, or a little better on the PGI-I scale. Only 13.3% respondents selected unlikely or highly unlikely on the 5-point Likert-type scale. CONCLUSIONS: The occurrence of complications related to TVM surgery and LSC had a longer post-surgery delay than native tissue repair surgery. Long-term regular follow-up was vital in complication management. Patient satisfaction with the management of TVM complications was acceptable.

Wnt/ß-catenin-mediated heat exposure inhibits intestinal epithelial cell proliferation and stem cell expansion through endoplasmic reticulum stress.

Heat stress induced by continuous high ambient temperatures or strenuous exercise in humans and animals leads to intestinal epithelial damage through the induction of intracellular stress response. However, the precise mechanisms involved in the regulation of intestinal epithelial cell injury, especially intestinal stem cells (ISCs), remain unclear. Thereby, in vitro a confluent monolayer of IPEC-J2 cells was exposed to the high temperatures (39, 40, and 41°C), the IPEC-J2 cell proliferation, apoptosis, differentiation, and barrier were determined, as well as the expression of GRP78, which is a marker protein of endoplasmic reticulum stress (ERS). The Wnt/ß-catenin pathway-mediated regenerative response was validated using R-spondin 1 (Rspo1). And ex-vivo, three-dimensional cultured enteroids were developed from piglet jejunal crypt and employed to assess the ISC activity under heat exposure. The results showed that exposure to 41°C for 72 hr, rather than 39°C and 40°C, decreased IPEC-J2 cell viability, inhibited cell proliferation and differentiation, induced ERS and cell apoptosis, damaged barrier function and restricted the Wnt/ß-catenin pathway. Nevertheless, Wnt/ß-catenin reactivation via Rspo1 protects the intestinal epithelium from heat exposure-induced injury. Furthermore, exposure to 41°C for 24 hr reduced ISC activity, stimulated crypt-cell apoptosis, upregulated the expression of GRP78 and caspase-3, and downregulated the expression of ß-catenin, Lgr5, Bmi1, Ki67, KRT20, ZO-1, occludin, and claudin-1. Taken together, we conclude that heat exposure induces ERS and downregulates the Wnt/ß-catenin signaling pathway to disrupt epithelial integrity by inhibiting the intestinal epithelial cell proliferation and stem cell expansion.

Regulation of mTORC1 by Small GTPases in Response to Nutrients.

Mechanistic target of rapamycin complex 1 (mTORC1) is a highly evolutionarily conserved serine/threonine kinase that regulates cell growth and metabolism in response to multiple environmental cues, such as nutrients, hormones, energy, and stress. Deregulation of mTORC1 can lead to diseases such as diabetes, obesity, and cancer. A series of small GTPases, including Rag, Ras homolog enriched in brain (Rheb), adenosine diphosphate ribosylation factor 1 (Arf1), Ras-related protein Ral-A, Ras homolog (Rho), and Rab, are involved in regulating mTORC1 in response to nutrients, and mTORC1 is differentially regulated via these small GTPases according to specific conditions. Leucine and arginine sensing are considered to be well-confirmed amino acid-sensing signals, activating mTORC1 via a Rag GTPase-dependent mechanism as well as the Ragulator complex and vacuolar H+-adenosine triphosphatase (v-ATPase). Glutamine promotes mTORC1 activation via Arf1 independently of the Rag GTPase. In this review, we summarize current knowledge regarding the regulation of mTORC1 activity by small GTPases in response to nutrients, focusing on the function of small GTPases in mTORC1 activation and how small GTPases are regulated by nutrients.

Prostatic Artery Embolization for Benign Prostatic Hyperplasia: Bleomycin-Eluting versus Bland Microspheres in a Canine Model.

PURPOSE: To prospectively assess safety and efficacy of prostatic artery embolization (PAE) with bleomycin-eluting microspheres for benign prostatic hyperplasia (BPH) in a canine model. MATERIALS AND METHODS: Twelve adult male beagles (mean age, 1.6 y ± 0.2; range, 1.2-2.0 y) were randomly assigned to group A (n = 6; PAE with bleomycin-eluting 30-60-µm HepaSphere microspheres) and group B (n = 6; PAE with bland 30-60-µm HepaSphere microspheres) between April 2017 and November 2018. Plasma bleomycin concentration in group A was measured within 7 days. Prostate volume (PV) and ischemic volume after PAE were measured by magnetic resonance imaging. Prostates and adjacent organs were harvested after the last magnetic resonance study and histopathologically examined. RESULTS: Plasma bleomycin concentration peaked at 10 minutes at 2,055.0 ng/mL ± 606.1 and lasted for 1,440 min at low levels after PAE. PV reduction percentage was greater in group A than in group B at 1 month (74.1% ± 4.3 vs 63.7% ± 3.5; P = .006) and 3 months (61.5% ± 6.7 vs 46.1% ± 3.8; P = .001) after PAE. Proportion of prostate ischemic volume was greater in group A than in group B (75.3% ± 3.0 vs 62.0% ± 7.1; P = .006) at 1 month after PAE. Proportion of prostate ischemic volume at 1 month positively correlated with PV percentage reduction at 3 months in group A (r = 0.840, P = .036) and group B (r = 0.844, P = .035). There were no complications or nontarget embolization to surrounding organs after the procedures. CONCLUSIONS: In a canine model, PAE with bleomycin-eluting microspheres was feasible and well tolerated and caused ischemic necrosis and reduction in PV.

Dietary supplementation with pioglitazone hydrochloride improves intramuscular fat, fatty acid profile, and antioxidant ability of thigh muscle in yellow-feathered chickens.

BACKGROUND: Muscle fat content and fatty acid composition play an important role in poultry flavor and taste. To investigate the effects of pioglitazone hydrochloride (PGZ) on growth performance and thigh muscle quality in yellow-feathered chickens, 360 female chickens were randomly divided into three groups and treated with three doses of PGZ (0, 7.5, and 15 mg kg-1 ) for 28 days. Each group had six replicates of 20 chickens. RESULTS: The results showed that dietary supplementation with 15 mg kg-1 PGZ increased average daily feed intake (ADFI) and the average daily gain (ADG) from 0 to 14 days. Furthermore, the triglyceride (TG) level was decreased by 15 mg kg-1 PGZ, whereas the eviscerated yield was increased. The relative weight of the heart and kidneys showed a linear increase with dietary PGZ supplementation, and the drip loss of the thigh muscle was significantly decreased by 15 mg kg-1 PGZ supplementation. Moreover, a* value, intramuscular fat (IMF), and polyunsaturated fatty acids (PUFAs) showed a linear increase, and pH24 h and drip loss showed a quadratic influence with the levels of PGZ supplementation. In particular, the PUFA proportion was increased by 7.63% and 9.14% in the 7.5 mg kg-1 PGZ and 15 mg kg-1 PGZ groups, respectively. Additionally, 15 mg kg-1 of PGZ increased the total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX ) activity. CONCLUSION: In summary, 15 mg kg-1 PGZ has substantial effects on growth performance and meat quality, particularly by decreasing drip loss and increasing IMF content, PUFA proportions, and antioxidant ability. © 2019 Society of Chemical Industry.

Dietary supplementation with pioglitazone hydrochloride and chromium methionine manipulates lipid metabolism with related genes to improve the intramuscular fat and fatty acid profile of yellow-feathered chickens.

BACKGROUND: Intramuscular fat (IMF) and polyunsaturated fatty acids (PUFAs) have been thought to play a crucial role in improving meat quality. Considering the ability of pioglitazone hydrochloride (PGZ) to deposit fat, and the anti-stress capability of chromium methionine (CrMet), we combined these compounds to produce higher quality meat in poultry. A total of 3000 female chickens were divided into four groups (five replicates, each with 150 chickens): control, control plus15 mg·kg-1 PGZ, control plus 200 µg·kg-1 CrMet, and control plus15 mg·kg-1 PGZ plus 200 µg·kg-1 CrMet. The experiment lasted for 28 days. RESULTS: Compared to the control group and the PGZ group, the average daily gain (ADG) was significantly increased in the PGZ plus CrMet group, whereas the feed-to-gain ratio (F/G) was decreased from 0 to 14 days. Meanwhile, the redness value of breast muscle and IMF of thigh muscle increased in the PGZ plus CrMet group compared with the control group and these detections in the PGZ plus CrMet group exhibited highest value among the four groups. The cooking loss decreased in the breast muscle and thigh muscle after PGZ combined with CrMet in diets. The percentages of C16:1, C18:2n-6 and PUFAs increased in the PGZ plus CrMet group. The mRNA abundance of peroxisome proliferator activated receptor (PPAR) γ, PPAR coactivator 1 α, and fatty acid binding protein 3 was significantly enhanced with PGZ plus CrMet supplementation. CONCLUSION: Collectively, dietary supplementation with PGZ plus CrMet improved growth performance and meat quality by decreasing the cooking loss and increasing the IMF and PUFA levels. © 2019 Society of Chemical Industry.

mTORC1 signaling activation increases intestinal stem cell activity and promotes epithelial cell proliferation.

The crypt-villus axis of the intestine undergoes a continuous renewal process that is driven by intestinal stem cells (ISCs). However, the homeostasis is disturbed under constant exposure to high ambient temperatures, and the precise mechanism is unclear. We found that both EdU+ and Ki67+ cell ratios were significantly reduced after exposure to 41°C, as well as the protein synthesis rate of IPEC-J2 cells, and the expression of ubiquitin and heat shock protein 60, 70, and 90 were significantly increased. Additionally, heat exposure decreased enteroid expansion and budding efficiency, as well as induced apoptosis after 48 hr; however, no significant difference was observed in the apoptosis ratio after 24 hr. In the process of heat exposure, the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway was significantly inhibited in both IPEC-J2 cells and enteroids. Correspondingly, treatment of IPEC-J2 and enteroids with the mTORC1 agonist MHY1485 at 41°C significantly attenuated the inhibition of proliferation and protein synthesis, increased the ISC activity, and promoted expansion and budding of enteroid. In summary, we conclude that the mTORC1 signaling pathway regulates intestinal epithelial cell and stem cell activity during heat exposure-induced injury.

LGR5 and BMI1 Increase Pig Intestinal Epithelial Cell Proliferation by Stimulating WNT/ß-Catenin Signaling.

Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) and B-cell-specific Moloney murine leukemia virus insertion site 1 (BMI1) are markers of fast-cycling and quiescent intestinal stem cells, respectively. To determine the functions of these proteins in large animals, we investigated their effects on the proliferation of intestinal epithelial cells from pigs. Our results indicated that LGR5 and BMI1 are highly conserved proteins and that the pig proteins have greater homology with the human proteins than do mouse proteins. Overexpression of either LGR5 or BMI1 promoted cell proliferation and WNT/ß-catenin signaling in pig intestinal epithelial cells (IPEC-J2). Moreover, the activation of WNT/ß-catenin signaling by recombinant human WNT3A protein increased cell proliferation and LGR5 and BMI1 protein levels. Conversely, inhibition of WNT/ß-catenin signaling using XAV939 reduced cell proliferation and LGR5 and BMI1 protein levels. This is the first report that LGR5 and BMI1 can increase proliferation of pig intestinal epithelial cells by activating WNT/ß-catenin signaling.

GSK1904529A, a Potent IGF-IR Inhibitor, Reverses MRP1-Mediated Multidrug Resistance.

Overexpression of multidrug-resistant efflux transporters is one of the major causes of chemotherapy failure. MRP1, a 190 kDa efflux transporter, confers resistance to a wide of range of chemotherapeutic drugs. Here we study the cellular effects of GSK1904529A in reversing MRP1-mediated drug resistance. Cytotoxicity of GSK1904529A was determined by MTT assay. Reversal effects of GSK1904529A in combination with MRP1 substrates were determined. The intracellular accumulation and efflux of MRP1 substrate was measured by scintillation counter and protein expression was determined by Western blotting analysis. Cell cycle effects of GSK1904529A in combination with MRP1 substrates were determined by flow cytometric analysis. GSK1904529A, at non-toxic concentrations, enhanced the cytotoxicity of MRP1 substrates in HEK293/MRP1 cells. Furthermore, GSK1904529A increased the intracellular accumulation of [3 H]-vinblastine by inhibiting the efflux function of MRP1. GSK1904529A did not alter the expression level of MRP1, induced a G0/G1 phase cell cycle arrest. Our results indicated that GSK1904529A significantly increased the sensitivity of MRP1 overexpressing cells to chemotherapeutic agents. Furthermore, GSK1904529A enhanced the efficacy of chemotherapeutic drugs that are substrates of MRP1. J. Cell. Biochem. 118: 3260-3267, 2017. © 2017 Wiley Periodicals, Inc.

CDX2 Stimulates the Proliferation of Porcine Intestinal Epithelial Cells by Activating the mTORC1 and Wnt/ß-Catenin Signaling Pathways.

Caudal type homeobox 2 (CDX2) is expressed in intestinal epithelial cells and plays a role in gut development and homeostasis by regulating cell proliferation. However, whether CDX2 cooperates with the mammalian target of rapamycin complex 1 (mTORC1) and Wnt/ß-catenin signaling pathways to stimulate cell proliferation remains unknown. The objective of this study was to investigate the effect of CDX2 on the proliferation of porcine jejunum epithelial cells (IPEC-J2) and the correlation between CDX2, the mTORC1 and Wnt/ß-catenin signaling pathways. CDX2 overexpression and knockdown cell culture models were established to explore the regulation of CDX2 on both pathways. Pathway-specific antagonists were used to verify the effects. The results showed that CDX2 overexpression increased IPEC-J2 cell proliferation and activated both the mTORC1 and Wnt/ß-catenin pathways, and that CDX2 knockdown decreased cell proliferation and inhibited both pathways. Furthermore, the mTORC1 and Wnt/ß-catenin pathway-specific antagonist rapamycin and XAV939 (3,5,7,8-tetrahydro-2-[4-(trifluoromethyl)]-4H -thiopyrano[4,3-d]pyrimidin-4-one) both suppressed the proliferation of IPEC-J2 cells overexpressing CDX2, and that the combination of rapamycin and XAV939 had an additive effect. Regardless of whether the cells were treated with rapamycin or XAV939 alone or in combination, both mTORC1 and Wnt/ß-catenin pathways were down-regulated, accompanied by a decrease in CDX2 expression. Taken together, our data indicate that CDX2 stimulates porcine intestinal epithelial cell proliferation by activating the mTORC1 and Wnt/ß-catenin signaling pathways.

Osimertinib (AZD9291), a Mutant-Selective EGFR Inhibitor, Reverses ABCB1-Mediated Drug Resistance in Cancer Cells.

In recent years, tyrosine kinase inhibitors (TKIs) have been shown capable of inhibiting the ATP-binding cassette (ABC) transporter-mediated multidrug resistance (MDR). In this study, we determine whether osimertinib, a novel selective, irreversible EGFR (epidermal growth factor receptor) TKI, could reverse ABC transporter-mediated MDR. The results showed that, at non-toxic concentrations, osimertinib significantly sensitized both ABCB1-transfected and drug-selected cell lines to substrate anticancer drugs colchicine, paclitaxel, and vincristine. Osimertinib significantly increased the accumulation of [³H]-paclitaxel in ABCB1 overexpressing cells by blocking the efflux function of ABCB1 transporter. In contrast, no significant alteration in the expression levels and localization pattern of ABCB1 was observed when ABCB1 overexpressing cells were exposed to 0.3 µM osimertinib for 72 h. In addition, ATPase assay showed osimertinib stimulated ABCB1 ATPase activity. Molecular docking and molecular dynamic simulations showed osimertinib has strong and stable interactions at the transmembrane domain of human homology ABCB1. Taken together, our findings suggest that osimertinib, a clinically-approved third-generation EGFR TKI, can reverse ABCB1-mediated MDR, which supports the combination therapy with osimertinib and ABCB1 substrates may potentially be a novel therapeutic stategy in ABCB1-positive drug resistant cancers.

Low dose of IGF-I increases cell size of skeletal muscle satellite cells via Akt/S6K signaling pathway.

The objective of this study was to investigate the effect of insulin growth factor-I (IGF-I) on the size of pig skeletal muscle satellite cells (SCs). Using microarray, real-time RT-PCR, radioimmunoassay analysis and western blot, we first showed that supplementation of low-dose of IGF-I in culture medium resulted in enlarged cell size of Lantang SCs, only Akt and S6K were up-regulated at both the mRNA and protein levels among almost all of the mTOR pathway key genes, but had no effect on cell number. To elucidate the signaling mechanisms responsible for regulating cell size under low-dose of IGF-I treatment, we blocked Akt and S6K activity with the specific inhibitors MK2206 and PF4708671, respectively. Both inhibitors caused a decrease in cell size. In addition, MK2206 lowered the protein level of p-Akt (Ser473), p-S6K (Thr389), and p-rpS6 (Ser235/236), whereas PF4708671 lowered the protein level of p-S6K (Thr389) and p-rpS6 (Ser235/236). However, low dose of IGF-I didn't affect the protein level of p-mTOR (Ser2448) and p-mTOR (Ser2481). When both inhibitors were applied simultaneously, the effect was the same as that of the Akt inhibition alone. Taken together, we report for the first time that low-dose of IGF-I treatment increases cell size via Akt/S6K signaling pathway.

Mulberry Leaf-Derived Morin Activates ß-Catenin by Binding to Frizzled7 to Promote Intestinal Stem Cell Expansion upon Heat-Stable Enterotoxin b Injury.

Intestinal stem cells (ISCs) sustain epithelial renewal by dynamically altering behaviors of proliferation and differentiation in response to various nutrition and stress inputs. However, how ISCs integrate bioactive substance morin cues to protect against heat-stable enterotoxin b (STb) produced by Escherichia coli remains an uncertain question with implications for treating bacterial diarrhea. Our recent work showed that oral mulberry leaf-derived morin improved the growth performance in STb-challenged mice. Furthermore, morin supplementation reinstated the impaired small-intestinal epithelial structure and barrier function by stimulating ISC proliferation and differentiation as well as supporting intestinal organoid expansion ex vivo. Importantly, the Wnt/ß-catenin pathway, an ISC fate commitment signal, was reactivated by morin to restore the jejunal crypt-villus architecture in response to STb stimulation. Mechanically, the extracellular morin-initiated ß-catenin axis is dependent or partially dependent on the Wnt membrane receptor Frizzled7 (FZD7). Our data reveal an unexpected role of leaf-derived morin, which represents molecular signaling targeting the FZD7 platform instrumental for controlling ISC regeneration upon STb injury.

Activation of PPAR-α attenuates myocardial ischemia/reperfusion injury by inhibiting ferroptosis and mitochondrial injury via upregulating 14-3-3η.

This study aimed to explore the effects of peroxisome proliferator-activated receptor α (PPAR-α), a known inhibitor of ferroptosis, in Myocardial ischemia/reperfusion injury (MIRI) and its related mechanisms. In vivo and in vitro MIRI models were established. Our results showed that activation of PPAR-α decreased the size of the myocardial infarct, maintained cardiac function, and decreased the serum contents of creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), and Fe2+ in ischemia/reperfusion (I/R)-treated mice. Additionally, the results of H&E staining, DHE staining, TUNEL staining, and transmission electron microscopy demonstrated that activation of PPAR-α inhibited MIRI-induced heart tissue and mitochondrial damage. It was also found that activation of PPAR-α attenuated MIRI-induced ferroptosis as shown by a reduction in malondialdehyde, total iron, and reactive oxygen species (ROS). In vitro experiments showed that intracellular contents of malondialdehyde, total iron, LDH, reactive oxygen species (ROS), lipid ROS, oxidized glutathione disulphide (GSSG), and Fe2+ were reduced by the activation of PPAR-α in H9c2 cells treated with anoxia/reoxygenation (A/R), while the cell viability and GSH were increased after PPAR-α activation. Additionally, changes in protein levels of the ferroptosis marker further confirmed the beneficial effects of PPAR-α activation on MIRI-induced ferroptosis. Moreover, the results of immunofluorescence and dual-luciferase reporter assay revealed that PPAR-α achieved its activity via binding to the 14-3-3η promoter, promoting its expression level. Moreover, the cardioprotective effects of PPAR-α could be canceled by pAd/14-3-3η-shRNA or Compound C11 (14-3-3η inhibitor). In conclusion, our results indicated that ferroptosis plays a key role in aggravating MIRI, and PPAR-α/14-3-3η pathway-mediated ferroptosis and mitochondrial injury might be an effective therapeutic target against MIRI.