The structure, expression and function prediction of DAZAP2, a down-regulated gene in multiple myeloma

MicroRNA-150-3p enhances the antitumour effects of CGP57380 and is associated with a favourable prognosis in non-small cell lung cancer

MicroRNA (miRNA) dysregulation has been identified in several carcinomas, including non-small cell lung cancer (NSCLC), and is known to play a role in the development and progression of this disease. We initially conducted a miRNA microarray analysis, which revealed that the MNK inhibitor CGP57380 increased the expression of miR-150-3p. A similar analysis was performed using data from The Cancer Genome Atlas (TCGA). Cell proliferation, colony formation and migration assays were validated in A549 and H157 cells treated with miR-150-3p mimics. Quantitative polymerase chain reaction (qPCR) was then used to detect potential target genes. We observed significant downregulation of miR-150-3p in NSCLC samples compared with normal samples (P = 0.035). High miR-150-3p expression was associated with longer overall survival (P = 0.005), as determined via a tissue microarray (TMA). These results were validated in the TCGA and revealed that miR-150-3p was expressed at low levels in NSCLC tissues (P < 0.0001) and that patients with high miR-150-3p expression had a better prognosis (P = 0.042). Moreover, the combination of miR-150-3p and CGP57380 exerted a synergistic inhibitory effect on colony formation, growth, and migration and induced apoptosis in NSCLC cell lines. We investigated the potential targets of miR-150-3p and successfully validated six potential target genes through qPCR analysis. High miR-150-3p expression may enhance the response to immunotherapy, cisplatin and gemcitabine. In summary, this study underscores the promising therapeutic implications of combining miR-150-3p and CGP57380 for NSCLC treatment. Additionally, this study provides valuable insights into the molecular mechanisms underlying the effects of this treatment.

Epigenome-wide association study of depression symptomatology in elderly monozygotic twins

Depression is a severe and debilitating mental disorder diagnosed by evaluation of affective, cognitive and physical depression symptoms. Severity of these symptoms strongly impacts individual's quality of life and is influenced by a combination of genetic and environmental factors. One of the molecular mechanisms allowing for an interplay between these factors is DNA methylation, an epigenetic modification playing a pivotal role in regulation of brain functioning across lifespan. The aim of this study was to investigate if there are DNA methylation signatures associated with depression symptomatology in order to identify molecular mechanisms contributing to pathophysiology of depression. We performed an epigenome-wide association study (EWAS) of continuous depression symptomatology score measured in a cohort of 724 monozygotic Danish twins (346 males, 378 females). Through EWAS analyses adjusted for sex, age, flow-cytometry based blood cell composition, and twin relatedness structure in the data we identified depression symptomatology score to be associated with blood DNA methylation levels in promoter regions of neuropsin (KLK8, p-value = 4.7 × 10^-7) and DAZ associated protein 2 (DAZAP2, p-value = 3.13 × 10^-8) genes. Other top associated probes were located in gene bodies of MAD1L1 (p-value = 5.16 × 10^-6), SLC29A2 (p-value = 6.15 × 10^-6) and AKT1 (p-value = 4.47 × 10^-6), all genes associated before with development of depression. Additionally, the following three measures (a) DNAmAge (calculated with Horvath and Hannum epigenetic clock estimators) adjusted for chronological age, (b) difference between DNAmAge and chronological age, and (c) DNAmAge acceleration were not associated with depression symptomatology score in our cohort. In conclusion, our data suggests that depression symptomatology score is associated with DNA methylation levels of genes implicated in response to stress, depressive-like behaviors, and recurrent depression in patients, but not with global DNA methylation changes across the genome.

Deleted in azoospermia-associated protein 2 regulates innate immunity by stimulating Hippo signaling in crab

The Hippo-signaling pathway plays a critical role in both normal animal physiology and pathogenesis. Because pharmacological interventions targeting this pathway have diverse clinical implications, a better understanding of its regulation in various conditions and organisms is crucial. Here, we identified deleted in azoospermia-associated protein 2 (DAZAP2) in the Chinese mitten crab (Eriocheir sinensis), designated EsDAZAP2, as a Hippo-regulatory protein highly similar to proteins in various species of insects, fish, and mammals. We found that a bacterial infection significantly induces EsDAZAP2 expression, and an EsDAZAP2 knockdown both suppresses antimicrobial peptide (AMP) expression in vitro and results in increased viable bacterial counts and mortality in vivo, suggesting that EsDAZAP2 plays a critical role in innate immunity. Using yeast two-hybrid screening and co-immunoprecipitation assays, we found that EsDAZAP2 regulates the Toll pathway rather than the immune deficiency and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways. Our findings also demonstrate that EsDAZAP2 binds to the Hippo protein, Salvador (Sav). Moreover, by examining the regulation of Dorsal, a transcription factor that regulates AMP expression in E. sinensis, we provide experimental evidence indicating that EsDAZAP2 promotes Hippo pathway activation in innate immunity, with EsDAZAP2 and Hippo binding to different Sav domains. To the best of our knowledge, this is the first report of a DAZAP2-regulated Hippo-signaling pathway operating in animal innate immunity.

Promoter methylation induced epigenetic silencing of DAZAP2, a downstream effector of p38/MAPK pathway, in multiple myeloma cells

Multiple myeloma (MM) is hematological malignancy characterized by clonal proliferation of malignant plasma cells in the bone marrow environment. Previously, we identified DAZAP2 as a candidate cancer suppressor gene, the downregulation of which is regulated by its own promoter methylation status. In the current study, we analyzed the DAZAP2 promoter in MM cell lines KM3, MM.1S, OPM-2, and ARH77 by bisulfite genomic sequencing assay. We identified the binding site for transcription factor cyclic adenosine monophosphate response element binding (CREB) in the DAZAP2 promoter CpG2, and we found that hypermethylation of the CREB binding motif in the DAZAP2 promoter is responsible for the reduced DAZAP2 expression in MM cells. Later we checked the p38/MAPK signaling cascade, which is reported to regulate expression and function of CREB. Our results showed that the p38/MAPK signaling pathway drives the expression of DAZAP2 by phosphorylation of CREB, and hypermethylation of CREB binding motif in DAZAP2 promoter can inhibit binding of CREB to the latter, thus downregulating DAZAP2 expression. Moreover, treating the MM cells with 5-aza-2' deoxycytidine to demethylate DAZAP2 promoter restored the binding of CREB to its binding motif, and thus upregulated DAZAP2 expression. Our results not only identified DAZAP2 as a new downstream target of p38/MAPK/CREB signaling cascade, but we also clarified that the downregulation of DAZAP2 in MM cells is caused by hypermethylation of CREB binding motif in its own promoter region, which implies that demethylation of DAZAP2 promoter can be a novel therapeutic strategy for MM treatment.

TRAF4-SMURF2-mediated DAZAP2 degradation is critical for IL-25 signaling and allergic airway inflammation

IL-25 promotes type 2 immunity by inducing the expression of Th2-associated cytokines. Although it is known that the IL-25R (IL-17RB) recruits the adaptor protein ACT1, the IL-25R signaling mechanism remains poorly understood. While screening for IL-25R components, we found that IL-25 responses were impaired in Traf4 (-/-) cells. Administering IL-25 to Traf4 (-/-) mice resulted in blunted airway eosinophilia and Th2 cytokine production. Notably, IL-25R recruitment of TRAF4 was required for the ACT1/IL-25R interaction. Mechanistically, TRAF4 recruited the E3-ligase SMURF2, to degrade the IL-25R-inhibitory molecule DAZAP2. Silencing Dazap2 increased ACT1/IL-25R interaction and IL-25 responsiveness. Moreover, a tyrosine within the IL-25R elicited DAZAP2 interference. This study indicates that TRAF4-SMURF2-mediated DAZAP2 degradation is a crucial initiating event for the IL-25 response.

Clustering nuclear receptors in liver regeneration identifies candidate modulators of hepatocyte proliferation and hepatocarcinoma

Background & Aims

Liver regeneration (LR) is a valuable model for studying mechanisms modulating hepatocyte proliferation. Nuclear receptors (NRs) are key players in the control of cellular functions, being ideal modulators of hepatic proliferation and carcinogenesis.

Methods & Results

We used a previously validated RT-qPCR platform to profile modifications in the expression of all 49 members of the NR superfamily in mouse liver during LR. Twenty-nine NR transcripts were significantly modified in their expression during LR, including fatty acid (peroxisome proliferator-activated receptors, PPARs) and oxysterol (liver X receptors, Lxrs) sensors, circadian masters RevErbα and RevErbβ, glucocorticoid receptor (Gr) and constitutive androxane receptor (Car). In order to detect the NRs that better characterize proliferative status vs. proliferating liver, we used the novel Random Forest (RF) analysis to selected a trio of down-regulated NRs (thyroid receptor alpha, Trα; farsenoid X receptor beta, Fxrβ; Pparδ) as best discriminators of the proliferating status. To validate our approach, we further studied PPARδ role in modulating hepatic proliferation. We first confirmed the suppression of PPARδ both in LR and human hepatocellular carcinoma at protein level, and then demonstrated that PPARδ agonist GW501516 reduces the proliferative potential of hepatoma cells.

Conclusions

Our data suggest that NR transcriptome is modulated in proliferating liver and is a source of biomarkers and bona fide pharmacological targets for the management of liver disease affecting hepatocyte proliferation.

The effects of promoter methylation on downregulation of DAZAP2 in multiple myeloma cell lines

Our previous studies had shown that DAZAP2 was profoundly downregulated in bone marrow mononuclear cells from multiple myeloma patients. In this report, we analyzed epigenetic changes in multiple myeloma cell lines to understand the molecular mechanisms underlying the downregulation of DAZAP2. Four multiple myeloma cell lines, KM3, MM.1S, OPM-2 and ARH-77, were studied. The results of methylation specific PCR (MSP) showed that the promoter of DAZAP2 was methylated for KM3, MM.1S, OPM-2 and unmethylated for ARH-77. The DAZAP2 promoter region was amplified to obtain a series of different length sequences. All of the amplified sequences were inserted to luciferase reporter vector. The constructs were transfected into COS-7 cells and the luciferase activities were measured to search for the core region of DAZAP2 promoter. Two CpG islands were found in DAZAP2 promoter region. The results of luciferase assay showed that CpG island 1 displayed weak transcriptional activity, whereas CpG island 2 exhibited strong transcriptional activity (273 folds) compared to the control. The sequence that covered both CpG islands 1 and 2 showed higher activity (1,734 folds) compared to the control, suggesting that the two islands had synergistic effect on regulating DAZAP2 expression. We also found that M. Sss I methylase could inhibit the luciferase activity, whereas demethylation using 5-aza-2′-deoxycytidine treatment rescued the expression of DAZAP2 for multiple myeloma cell lines. These data revealed that methylation of DAZAP2 promoter was involved in downregulation of DAZAP2 in multiple myeloma cells.

Dazap2 modulates transcription driven by the Wnt effector TCF-4

A major outcome of the canonical Wnt/beta-catenin-signalling pathway is the transcriptional activation of a specific set of target genes. A typical feature of the transcriptional response induced by Wnt signalling is the involvement of Tcf/Lef factors that function in the nucleus as the principal mediators of signalling. Vertebrate Tcf/Lef proteins perform two well-characterized functions: in association with beta-catenin they activate gene expression, and in the absence of Wnt ligands they bind TLE/Groucho proteins to act as transcriptional repressors. Although the general characteristics of Tcf/Lef factors are well understood, the mechanisms that control their specific roles in various cellular backgrounds are much less defined. In this report we reveal that the evolutionary conserved Dazap2 protein functions as a TCF-4 interacting partner. We demonstrate that a short region proximal to the TCF-4 HMG box mediates the interaction and that all Tcf/Lef family members associate with Dazap2. Interestingly, knockdown of Dazap2 not only reduced the activity of Wnt signalling as measured by Tcf/beta-catenin reporters but additionally altered the expression of Wnt-signalling target genes. Finally, chromatin immunoprecipitation studies indicate that Dazap2 modulates the affinity of TCF-4 for its DNA-recognition motif.

Proline-rich transcript in brain protein induces stress granule formation

The repression of translation in environmentally stressed eukaryotic cells causes the sequestration of translation initiation factors and the 40S ribosomal subunit into discrete cytoplasmic foci called stress granules (SGs). Most components of the preinitiation complex, such as eIF3, eIF4A, eIF4E, eIF4G, and poly(A)-binding protein, congregate into SGs under stress conditions. However, the molecular basis of translation factor sequestration into SGs has not been clearly elucidated. Here, we report that proline-rich transcript in brain (PRTB) protein interacts with eIF4G and participates in SG formation. PRTB was recruited to SG under sodium arsenite and heat stress conditions. When overexpressed, PRTB inhibited global translation and formed SGs containing TIA-1, eIF4G, and eIF3. Knockdown of PRTB reduced the SG formation induced by sodium arsenite. These results suggest that PRTB not only is a component of SG formed by cellular stresses but also plays an important role in SG formation via an interaction with the scaffold protein eIF4G, which is associated with many translation factors and mRNAs.

A two-hybrid screen identifies cathepsins B and L as uncoating factors for adeno-associated virus 2 and 8

Vectors based on different serotypes of adeno-associated virus hold great promise for human gene therapy, based on their unique tissue tropisms and distinct immunological profiles. A particularly interesting candidate is AAV8, which can efficiently and rapidly transduce a wide range of tissues in vivo. To further unravel the mechanisms behind AAV8 transduction, we used yeast two-hybrid analyses to screen a mouse liver complementary DNA library for cellular proteins capable of interacting with the viral capsid proteins. In total, we recovered approximately 700 clones, comprising over 300 independent genes. Sequence analyses revealed multiple hits for over 100 genes, including two encoding the endosomal cysteine proteases cathepsins B and L. Notably, these two proteases also physically interacted with the corresponding portion of the AAV2 capsid in yeast, but not with AAV5. We demonstrate that cathepsins B and L are essential for efficient AAV2- and AAV8-mediated transduction of mammalian cells, and document the ability of purified cathepsin B and L proteins to bind and cleave intact AAV2 and AAV8 particles in vitro. These data suggest that cathepsin-mediated cleavage could prime AAV capsids for subsequent nuclear uncoating, and indicate that analysis of additional genes recovered in our screen may help to further elucidate the mechanisms behind transduction by AAV8 and related serotypes.