Clusterin/ApoJ enhances central leptin signaling through Lrp2‐mediated endocytosis

Hypothalamic leptin signaling plays a central role in maintaining body weight homeostasis. Here, we show that clusterin/ApoJ, recently identified as an anorexigenic neuropeptide, is an important regulator in the hypothalamic leptin signaling pathway. Coadministration of clusterin potentiates the anorexigenic effect of leptin and boosts leptin‐induced hypothalamic Stat3 activation. In cultured neurons, clusterin enhances receptor binding and subsequent endocytosis of leptin. These effects are mainly mediated through the LDL receptor‐related protein‐2 (Lrp2). Notably, inhibition of hypothalamic clusterin, Lrp2 or endocytosis abrogates anorexia and hypothalamic Stat3 activation caused by leptin. These findings propose a novel regulatory mechanism in central leptin signaling pathways.     

CUE domain‐containing protein 2 promotes the Warburg effect and tumorigenesis

Cancer progression depends on cellular metabolic reprogramming as both direct and indirect consequence of oncogenic lesions; however, the underlying mechanisms are still poorly understood. Here, we report that CUEDC2 (CUE domain‐containing protein 2) plays a vital role in facilitating aerobic glycolysis, or Warburg effect, in cancer cells. Mechanistically, we show that CUEDC2 upregulates the two key glycolytic proteins GLUT3 and LDHA via interacting with the glucocorticoid receptor (GR) or 14‐3‐3ζ, respectively. We further demonstrate that enhanced aerobic glycolysis is essential for the role of CUEDC2 to drive cancer progression. Moreover, using tissue microarray analysis, we show a correlation between the aberrant expression of CUEDC2, and GLUT3 and LDHA in clinical HCC samples, further demonstrating a link between CUEDC2 and the Warburg effect during cancer development. Taken together, our findings reveal a previously unappreciated function of CUEDC2 in cancer cell metabolism and tumorigenesis, illustrating how close oncogenic lesions are intertwined with metabolic alterations promoting cancer progression.     

Characterization of mice deficient in interleukin-1β converting enzyme

Interleukin-1β converting enzyme (ICE) processes the inactive proIL-1β to the proinflammatory mature IL-1β. ICE belongs to a family of cysteine proteases that have been implicated in apoptosis. To address the biological functions of ICE, we generated ICE-deficient mice through gene targeting technology. ICE-deficient mice developed normally, appeared healthy, and were fertile. Peritoneal macrophages from ICE-deficient mice underwent apoptosis normally upon ATP treatment. Thymocytes from young ICE-deficient mice also underwent apoptosis when triggered by dexamethasone, gamma irradiation, or aging. ICE-deficient mice had a major defect in the production of mature IL-1β and had impaired IL-1α production on LPS stimulation in vitro and in vivo. ICE-deficient mice were resistant to LPS-induced endotoxic shock. J. Cell. Biochem. 64:27–32. © 1997 Wiley-Liss, Inc.     

Tissue inhibitor of metalloproteinase‐2(TIMP‐2)‐deficient mice display motor deficits

The degradation of the extracellular matrix is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Matrix components of the basement membrane play critical roles in the development and maintenance of the neuromuscular junction (NMJ), yet almost nothing is known about the regulation of MMP and TIMP expression in either the pre‐ or postsynaptic compartments. Here, we demonstrate that TIMP‐2 is expressed by both spinal motor neurons and skeletal muscle. To determine whether motor function is altered in the absence of TIMP‐2, motor behavior was assessed using a battery of tests (e.g., RotaRod, balance beam, hindlimb extension, grip strength, loaded grid, and gait analysis). TIMP‐2^?/? mice fall off the RotaRod significantly faster than wild‐type littermates. In addition, hindlimb extension is reduced and gait is both splayed and lengthened in TIMP‐2^?/? mice. Motor dysfunction is more pronounced during early postnatal development. A preliminary analysis revealed NMJ alterations in TIMP‐2^?/? mice. Juvenile TIMP‐2^?/? mice have increased nerve branching and acetylcholine receptor expression. Adult TIMP‐2^?/? endplates are enlarged and more complex. This suggests a role for TIMP‐2 in NMJ sculpting during development. In contrast to the increased NMJ nerve branching, cerebellar Purkinje cells have decreased neurite outgrowth. Thus, the TIMP‐2^?/? motor phenotype is likely due to both peripheral and central defects. The tissue specificity of the nerve branching phenotype suggests the involvement of different MMPs and/or extracellular matrix molecules underlying the TIMP‐2^?/? motor phenotype. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006     

MiR‐129‐5p promotes docetaxel resistance in prostate cancer by down‐regulating CAMK2N1 expression

This study focuses on the effect of miR‐129‐5p on docetaxel‐resistant (DR) prostate cancer (PCa) cells invasion, migration and apoptosis. In our study, the expression of CAMK2N1 was assessed by qRT‐PCR in PCa patient tissues and cell lines including PC‐3 and PC‐3‐DR. Cells transfected with miR‐129‐5p mimics, inhibitor, CAMK2N1 or negative controls (NC) were used to interrogate their effects on DR cell invasions, migrations and apoptosis during docetaxel (DTX) treatments. The apoptosis rate of the PCa cells was validated by flow cytometry. Relationships between miR‐129‐5p and CAMK2N1 levels were identified by qRT‐PCR and dual‐luciferase reporter assay. CAMK2N1 was found to be down‐expressed in DR PCa tissue sample, and low levels of CAMK2N1 were correlated with high docetaxel resistance and clinical prediction of poor survival. CAMK2N1 levels were decreased in DR PCa cells treated with DXT. We further explored that up‐regulation of miR‐129‐5p could promote DR PCa cells viability, invasion and migration but demote apoptosis. Involved molecular mechanism studies revealed that miR‐129‐5p reduced downstream CAMK2N1 expression to further impact on chemoresistance to docetaxel of PCa cells, indicating its vital role in PCa docetaxel resistance. Our findings revealed that miR‐129‐5p contributed to the resistance of PC‐3‐DR cells to docetaxel through suppressing CAMK2N1 expression, and thus targeting miR‐129‐5p may provide a novel therapeutic approach in sensitizing PCa to future docetaxel treatment.     

PRMT5 promotes epithelial‐mesenchymal transition via EGFR‐β‐catenin axis in pancreatic cancer cells

Protein arginine methyltransferase 5 (PRMT5) has been implicated in the development and progression of human cancers. However, few studies reveal its role in epithelial‐mesenchymal transition (EMT) of pancreatic cancer cells. In this study, we find that PRMT5 is up‐regulated in pancreatic cancer, and promotes proliferation, migration and invasion in pancreatic cancer cells, and promotes tumorigenesis. Silencing PRMT5 induces epithelial marker E‐cadherin expression and down‐regulates expression of mesenchymal markers including Vimentin, collagen I and β‐catenin in PaTu8988 and SW1990 cells, whereas ectopic PRMT5 re‐expression partially reverses these changes, indicating that PRMT5 promotes EMT in pancreatic cancer. More importantly, we find that PRMT5 knockdown decreases the phosphorylation level of EGFR at Y1068 and Y1172 and its downstream p‐AKT and p‐GSK3β, and then results in down‐regulation of β‐catenin. Expectedly, ectopic PRMT5 re‐expression also reverses the above changes. It is suggested that PRMT5 promotes EMT probably via EGFR/AKT/β‐catenin pathway. Taken together, our study demonstrates that PRMT5 plays oncogenic roles in the growth of pancreatic cancer cell and provides a potential candidate for pancreatic cancer treatment.     

Deoxycholic acid activates epidermal growth factor receptor and promotes intestinal carcinogenesis by ADAM17‐dependent ligand release

High fat diet is implicated in the elevated deoxycholic acid (DCA) in the intestine and correlated with increased colon cancer risk. However, the potential mechanisms of intestinal carcinogenesis by DCA remain unclarified. Here, we investigated the carcinogenic effects and mechanisms of DCA using the intestinal tumour cells and Apc^min/+ mice model. We found that DCA could activate epidermal growth factor receptor (EGFR) and promote the release of EGFR ligand amphiregulin (AREG), but not HB‐EGF or TGF‐α in intestinal tumour cells. Moreover, ADAM‐17 was required in DCA‐induced promotion of shedding of AREG and activation of EGFR/Akt signalling pathway. DCA significantly increased the multiplicity of intestinal tumours and accelerated adenoma‐carcinoma sequence in Apc^min/+ mice. ADAM‐17/EGFR signalling axis was also activated in intestinal tumours of DCA‐treated Apc^min/+ mice, whereas no significant change occurred in tumour adjacent tissues after DCA exposure. Conclusively, DCA activated EGFR and promoted intestinal carcinogenesis by ADAM17‐dependent ligand release.     

Fe2+ binding on amyloid β‐peptide promotes aggregation

The metal ions Zn²⁺, Cu²⁺, and Fe²⁺ play a significant role in the aggregation mechanism of Aβ peptides. However, the nature of binding between metal and peptide has remained elusive; the detailed information on this from the experimental study is very difficult. Density functional theory (dft) (M06‐2X/6‐311++G (2df,2pd) +LANL2DZ) has employed to determine the force field resulting due to metal and histidine interaction. We performed 200 ns molecular dynamics (MD) simulation on Aβ_1‐42‐Zn²⁺, Aβ_1‐42‐Cu²⁺, and Aβ_1‐42‐Fe²⁺ systems in explicit water with different combination of coordinating residues including the three Histidine residues in the N‐terminal. The present investigation, the Aβ_1‐42‐Zn²⁺ system possess three turn conformations separated by coil structure. Zn²⁺ binding caused the loss of the helical structure of N‐terminal residues which transformed into the S‐shaped conformation. Zn²⁺ has reduced the coil and increases the turn content of the peptide compared with experimental study. On the other hand, the Cu²⁺ binds with peptide, β sheet formation is observed at the N‐terminal residues of the peptide. Fe²⁺ binding is to promote the formation of Glu22‐Lys28 salt‐bridge which stabilized the turn conformation in the Phe19‐Gly25 residues, subsequently β sheets were observed at His13‐Lys18 and Gly29‐Gly37 residues. The turn conformation facilitates the β sheets are arranged in parallel by enhancing the hydrophobic contact between Gly25 and Met35, Lys16 and Met35, Leu17 and Leu34, Val18 and Leu34 residues. The Fe²⁺ binding reduced the helix structure and increases the β sheet content in the peptide, which suggested, Fe²⁺ promotes the oligomerization by enhancing the peptide‐peptide interaction. Proteins 2016; 84:1257–1274. © 2016 Wiley Periodicals, Inc.