Sec8 regulates cytokeratin8 phosphorylation and cell migration by controlling the ERK and p38 MAPK signalling pathways

Lymphoma in Border Collies: Genome-Wide Association and Pedigree Analysis

There has been considerable interest in studying cancer in dogs and its potential as a model system for humans. One area of research has been the search for genetic risk variants in canine lymphoma, which is amongst the most common canine cancers. Previous studies have focused on a limited number of breeds, but none have included Border Collies. The aims of this study were to identify relationships between Border Collie lymphoma cases through an extensive pedigree investigation and to utilise relationship information to conduct genome-wide association study (GWAS) analyses to identify risk regions associated with lymphoma. The expanded pedigree analysis included 83,000 Border Collies, with 71 identified lymphoma cases. The analysis identified affected close relatives, and a common ancestor was identified for 54 cases. For the genomic study, a GWAS was designed to incorporate lymphoma cases, putative "carriers", and controls. A case-control GWAS was also conducted as a comparison. Both analyses showed significant SNPs in regions on chromosomes 18 and 27. Putative top candidate genes from these regions included DLA-79, WNT10B, LMBR1L, KMT2D, and CCNT1.

EXOC4 Promotes Diffuse-Type Gastric Cancer Metastasis via Activating FAK Signal

In comparison with intestinal-type gastric cancer, diffuse-type gastric cancer (DGC) is more likely to recur, metastasize, and exhibit worse clinical outcomes; however, the underlying mechanism of DGC recurrence remains elusive. By employing an LC/MS-MS proteomic approach, we identified that exocyst complex component 4 (EXOC4) was significantly upregulated in DGC with recurrence, compared to those with nonrecurrence. High expression of EXOC4 was correlated with tumor metastasis and poor prognosis in patients with DGC. Moreover, EXOC4 promoted cell migration and invasion as well as the tumor metastasis of DGC cells. Mechanistically, EXOC4 regulated the phosphorylation of focal adhesion kinase (FAK) at Y397 sites by stimulating the secretion of integrin α5/β1/EGF and enhancing the interaction of FAK and integrin or EGFR. The FAK inhibitor VS-4718 reversed the metastasis mediated by EXOC4 overexpression and suppressed the tumor growth of patient-derived xenografts derived from DGC with high EXOC4 expression. The EXOC4-FAK axis could be a potential therapeutic target for patients with DGC with high expression of EXOC4.

IMPLICATIONS

The EXOC4-FAK axis promoted DGC metastasis and could be a potential therapeutic target for patients with DGC.

Generation of a tissue-specific transgenic model for K8 phosphomutants: A tool to investigate the role of K8 phosphorylation during skin carcinogenesis in vivo

Keratin 8/18, the predominant keratin pair of simple epithelia, is known to be aberrantly expressed in several squamous cell carcinomas (SCCs), where its expression is often correlated with increased invasion, neoplastic progression, and poor prognosis. The majority of keratin 8/18 structural and regulatory functions are governed by posttranslational modifications, particularly phosphorylation. Apart from filament reorganization, cellular processes including cell cycle, cell growth, cellular stress, and apoptosis are known to be orchestrated by K8 phosphorylation at specific residues in the head and tail domains. Even though deregulation of K8 phosphorylation at two significant sites (Serine⁷³ /Serine⁴³¹ ) has been implicated in neoplastic progression of SCCs by various in vitro studies, including ours, it is reported to be highly context-dependent. Therefore, to delineate the precise role of Kereatin 8 phosphorylation in cancer initiation and progression, we have developed the tissue-specific transgenic mouse model expressing Keratin 8 wild type and phosphodead mutants under Keratin 14 promoter. Subjecting these mice to 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate-mediated skin carcinogenesis revealed that Keratin 8 phosphorylation may lead to an early onset of tumors compared to Keratin 8 wild-type expressing mice. Conclusively, the transgenic mouse model developed in the present study ascertained a positive impact of Keratin 8 phosphorylation on the neoplastic transformation of skin-squamous cells.

Qing-Yi Decoction in the Treatment of Acute Pancreatitis: An Integrated Approach Based on Chemical Profile, Network Pharmacology, Molecular Docking and Experimental Evaluation

Background: Qing-Yi Decoction (QYD) is a classic precompounded prescription with satisfactory clinical efficacy on acute pancreatitis (AP). However, the chemical profile and overall molecular mechanism of QYD in treating AP have not been clarified.

Methods: In the present study, a rapid, simple, sensitive and reliable ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS)-based chemical profile was first established. An integration strategy of network pharmacology analysis and molecular docking based identified ingredients was further performed to screen out the potential targets and pathways involved in the treatment of QYD on AP. Finally, SD rats with acute pancreatitis were constructed to verify the predicted results through a western blot experiment.

Results: A total of 110 compounds, including flavonoids, phenolic acids, alkaloids, monoterpenes, iridoids, triterpenes, phenylethanoid glycosides, anthraquinones and other miscellaneous compounds were identified, respectively. Eleven important components, 47 key targets and 15 related pathways based on network pharmacology analysis were obtained. Molecular docking simulation indicated that ERK1/2, c-Fos and p65 might play an essential role in QYD against AP. Finally, the western blot experiments showed that QYD could up-regulate the expression level of ERK1/2 and c-Fos, while down-regulate the expression level of p65.

Conclusion: This study predicted and validated that QYD may treat AP by inhibiting inflammation and promoting apoptosis, which provides directions for further experimental studies.

Genome-Wide Interaction and Pathway Association Studies for Body Mass Index

Objective: We investigated gene interactions (epistasis) for body mass index (BMI) in a European-American adult female cohort via genome-wide interaction analyses (GWIA) and pathway association analyses. Methods: Genome-wide pairwise interaction analyses were carried out for BMI in 493 extremely obese cases (BMI > 35 kg/m2) and 537 never-overweight controls (BMI < 25 kg/m2). To further validate the results, specific SNPs were selected based on the GWIA results for haplotype-based association studies. Pathway-based association analyses were performed using a modified Gene Set Enrichment Algorithm (GSEA) (GenGen program) to further explore BMI-related pathways using our genome wide association study (GWAS) data set, GIANT, ENGAGE, and DIAGRAM Consortia. Results: The EXOC4-1q23.1 interaction was associated with BMI, with the most significant epistasis between rs7800006 and rs10797020 (P = 2.63 × 10-11). In the pathway-based association analysis, Tob1 pathway showed the most significant association with BMI (empirical P < 0.001, FDR = 0.044, FWER = 0.040). These findings were further validated in different populations. Conclusion: Genome-wide pairwise SNP-SNP interaction and pathway analyses suggest that EXOC4 and TOB1-related pathways may contribute to the development of obesity.

Regulation of Cell Polarity by Exocyst-Mediated Trafficking

One requirement for establishing polarity within a cell is the asymmetric trafficking of intracellular vesicles to the plasma membrane. This tightly regulated process creates spatial and temporal differences in both plasma membrane composition and the membrane-associated proteome. Asymmetric membrane trafficking is also a critical mechanism to regulate cell differentiation, signaling, and physiology. Many eukaryotic cell types use the eight-protein exocyst complex to orchestrate polarized vesicle trafficking to certain membrane locales. Members of the exocyst were originally discovered in yeast while screening for proteins required for the delivery of secretory vesicles to the budding daughter cell. The same eight exocyst genes are conserved in mammals, in which the specifics of exocyst-mediated trafficking are highly cell-type-dependent. Some exocyst members bind to certain Rab GTPases on intracellular vesicles, whereas others localize to the plasma membrane at the site of exocytosis. Assembly of the exocyst holocomplex is responsible for tethering these vesicles to the plasma membrane before their soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated exocytosis. In this review, we will focus on the role and regulation of the exocyst complex in targeted vesicular trafficking as related to the establishment and maintenance of cellular polarity. We will contrast exocyst function in apicobasal epithelial polarity versus front-back mesenchymal polarity, and the dynamic regulation of exocyst-mediated trafficking during cell phenotype transitions.

Role of the c-Jun N-terminal kinase signaling pathway in the activation of trypsinogen in rat pancreatic acinar cells

Bile acid causes trypsinogen activation in pancreatic acinar cells through a complex process. Additional research is required to further elucidate which signaling pathways affect trypsinogen activation when activated. the changes in the whole‑genome expression profile of AR42J cells under the effect of taurolithocholic acid 3‑sulfate (TLC‑S) were investigated. Furthermore, gene groups that may play a regulatory role were analyzed using the modular approach of biological networks. The aim of the present study was to improve our understanding of the changes in TLC‑S‑stimulated AR42J cells through a genetic functional modular analysis. whole‑genome expression profile chip arrays were applied to detect genes that were differentially expressed in pancreatic acinar AR42J cells treated with TLC‑S for 20 min. Based on the human protein reference database, a protein‑protein interaction network was obtained, which was then processed by CFinder software to derive 14 modules. Among these 14 modules, the gene ontology biological processes enrichment analysis identified two as modules of interest. Kyoto encyclopedia of genes and genomes map analysis revealed that MAP2K4, MAPK8 and FLNA are part of the c-Jun N-terminal kinase (JNK) pathway. The JNK signaling pathway is involved in regulating trypsinogen activation in rat pancreatic AR42J cells. Next, a regulatory network of seven kinase inhibitors was constructed. SP600125 is an ATP‑competitive, efficient, selective and reversible inhibitor of JNK. the results were verified by four sets of experiments and demonstrated that trypsinogen activation is mediated by the JNK signaling pathway in the pathogenesis of acute pancreatitis (AP). The present study provided a useful reference for better understanding the pathogenesis of AP and identifying new targets to regulate trypsinogen activation, in addition to providing valuable information for the treatment of AP.

Quantitative phosphoproteomic analysis reveals system-wide signaling pathways regulated by site-specific phosphorylation of Keratin-8 in skin squamous cell carcinoma derived cell line

Keratin 8/18, a simple epithelia specific keratin pair, is often aberrantly expressed in squamous cell carcinomas (SCC) where its expression is correlated with increased invasion and poor prognosis. Majority of Keratin 8 (K8) functions are governed by its phosphorylation at Serine⁷³ (head-domain) and Serine⁴³¹ (tail-domain) residues. Although, deregulation of K8 phosphorylation is associated with progression of different carcinomas, its role in skin-SCC and the underlying mechanism is obscure. In this direction, we performed tandem mass tag-based quantitative phosphoproteomics by expressing K8 wild type, phosphodead, and phosphomimetic mutants in K8-deficient A431 cells. Further analysis of our phosphoproteomics data showed a significant proportion of total phosphoproteome associated with migratory, proliferative, and invasive potential of these cells to be differentially phosphorylated. Differential phosphorylation of CDK1^T14,Y15 , EIF4EBP1^T46,T50 , EIF4B^S422 , AKT1S1^T246,S247 , CTTN1^{T401,S405,Y421} , and CAP1^S307/309 in K8-S73A/D mutant and CTTN1^{T401,S405,Y421} , BUB1B^S1043 , and CARHSP1^S30,S32 in K8-S431A/D mutants as well as some anonymous phosphosites including MYC^S176 , ZYX^S344 , and PNN^S692 could be potential candidates associated with K8 phosphorylation mediated tumorigenicity. Biochemical validation followed by phenotypic analysis further confirmed our quantitative phosphoproteomics data. In conclusion, our study provides the first global picture of K8 site-specific phosphorylation function in neoplastic progression of A431 cells and suggests various potential starting points for further mechanistic studies.

SIAH ubiquitin ligases regulate breast cancer cell migration and invasion independent of the oxygen status

Seven-in-absentia homolog (SIAH) proteins are evolutionary conserved RING type E3 ubiquitin ligases responsible for the degradation of key molecules regulating DNA damage response, hypoxic adaptation, apoptosis, angiogenesis, and cell proliferation. Many studies suggest a tumorigenic role for SIAH2. In breast cancer patients SIAH2 expression levels correlate with cancer aggressiveness and overall patient survival. In addition, SIAH inhibition reduced metastasis in melanoma. The role of SIAH1 in breast cancer is still ambiguous; both tumorigenic and tumor suppressive functions have been reported. Other studies categorized SIAH ligases as either pro- or antimigratory, while the significance for metastasis is largely unknown. Here, we re-evaluated the effects of SIAH1 and SIAH2 depletion in breast cancer cell lines, focusing on migration and invasion. We successfully knocked down SIAH1 and SIAH2 in several breast cancer cell lines. In luminal type MCF7 cells, this led to stabilization of the SIAH substrate Prolyl Hydroxylase Domain protein 3 (PHD3) and reduced Hypoxia-Inducible Factor 1α (HIF1α) protein levels. Both the knockdown of SIAH1 or SIAH2 led to increased apoptosis and reduced proliferation, with comparable effects. These results point to a tumor promoting role for SIAH1 in breast cancer similar to SIAH2. In addition, depletion of SIAH1 or SIAH2 also led to decreased cell migration and invasion in breast cancer cells. SIAH knockdown also controlled microtubule dynamics by markedly decreasing the protein levels of stathmin, most likely via p27(Kip1). Collectively, these results suggest that both SIAH ligases promote a migratory cancer cell phenotype and could contribute to metastasis in breast cancer.

JNK Signaling: Regulation and Functions Based on Complex Protein-Protein Partnerships

The c-Jun N-terminal kinases (JNKs), as members of the mitogen-activated protein kinase (MAPK) family, mediate eukaryotic cell responses to a wide range of abiotic and biotic stress insults. JNKs also regulate important physiological processes, including neuronal functions, immunological actions, and embryonic development, via their impact on gene expression, cytoskeletal protein dynamics, and cell death/survival pathways. Although the JNK pathway has been under study for >20 years, its complexity is still perplexing, with multiple protein partners of JNKs underlying the diversity of actions. Here we review the current knowledge of JNK structure and isoforms as well as the partnerships of JNKs with a range of intracellular proteins. Many of these proteins are direct substrates of the JNKs. We analyzed almost 100 of these target proteins in detail within a framework of their classification based on their regulation by JNKs. Examples of these JNK substrates include a diverse assortment of nuclear transcription factors (Jun, ATF2, Myc, Elk1), cytoplasmic proteins involved in cytoskeleton regulation (DCX, Tau, WDR62) or vesicular transport (JIP1, JIP3), cell membrane receptors (BMPR2), and mitochondrial proteins (Mcl1, Bim). In addition, because upstream signaling components impact JNK activity, we critically assessed the involvement of signaling scaffolds and the roles of feedback mechanisms in the JNK pathway. Despite a clarification of many regulatory events in JNK-dependent signaling during the past decade, many other structural and mechanistic insights are just beginning to be revealed. These advances open new opportunities to understand the role of JNK signaling in diverse physiological and pathophysiological states.

Nuclear Translocation of p65 is Controlled by Sec6 via the Degradation of IκBα

Nuclear factor-κB (NF-κB) is an inducible transcription factor that mediates immune and inflammatory responses. NF-κB pathways are also involved in cell adhesion, differentiation, proliferation, autophagy, senescence, and protection against apoptosis. The deregulation of NF-κB activity is found in a number of disease states, including cancer, arthritis, chronic inflammation, asthma, neurodegenerative diseases, and heart disease. The 90 kDa ribosomal S6 kinase (p90RSK) family, which is serine/threonine kinases, is phosphorylated by extracellular signal-regulated kinase1/2 (ERK1/2) and is related to NF-κB pathways. Our previous studies revealed that Sec6, a component of the exocyst complex, plays specific roles in cell-cell adhesion and cell cycle arrest. However, the mechanism by which Sec6 regulates the NF-κB signaling pathway is unknown. We demonstrated that Sec6 knockdown inhibited the degradation of IκBα and delayed the nucleus-cytoplasm translocation of p65 in HeLa cells transfected with Sec6 siRNAs after treatment with tumor necrosis factor alpha (TNF-α). Furthermore, the binding of p65 and cAMP response element binding protein (CREB) binding protein (CBP) or p300 decreased and NF-κB related genes which were inhibitors of NF-κB alpha (IκBα), A20, B cell lymphoma protein 2 (Bcl-2), and monocyte chemoattractant protein-1 (MCP-1) were low in cells transfected with Sec6 siRNAs in response to TNF-α stimulation. Sec6 knockdown decreased the expression of p90RSKs and the phosphorylation of ERK or p90RSK1 at Ser380 or IκBα at Ser32. The present study suggests that Sec6 regulates NF-κB transcriptional activity via the control of the phosphorylation of IκBα, p90RSK1, and ERK.