Tudor Domain Research Articles

Discovery of Small-Molecule Antagonists of the H3K9me3 Binding to UHRF1 Tandem Tudor Domain

Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is a multidomain protein that plays a critical role in maintaining DNA methylation patterns through concurrent recognition of hemimethylated DNA and histone marks by various domains, and recruitment of DNA methyltransferase 1 (DNMT1). UHRF1 is overexpressed in various cancers, including breast cancer. The tandem tudor domain (TTD) of UHRF1 specifically and tightly binds to histone H3 di- or trimethylated at lysine 9 (H3K9me2 or H3K9me3, respectively), and this binding is essential for UHRF1 function. We developed an H3K9me3 peptide displacement assay, which was used to screen a library of 44,000 compounds for small molecules that disrupt the UHRF1-H3K9me3 interaction. This screen resulted in the identification of NV01, which bound to UHRF1-TTD with a Kd value of 5 μM. The structure of UHRF1-TTD in complex with NV01 confirmed binding to the H3K9me3-binding pocket. Limited structure-based optimization of NV01 led to the discovery of NV03 (Kd of 2.4 μM). These well-characterized small-molecule antagonists of the UHRF1-H3K9me2/3 interaction could be valuable starting chemical matter for developing more potent and cell-active probes toward further characterizing UHRF1 function, with possible applications as anticancer therapeutics.

MiR-409 Inhibits Human Non-Small-Cell Lung Cancer Progression by Directly Targeting SPIN1

Lung cancers, the leading cause of cancer mortality worldwide, are characterized by a high metastatic potential. Growing evidence reveals that Spindlin 1 (SPIN1) is involved in tumor progression and carcinogenesis. However, the role of SPIN1 in non-small-cell lung cancer (NSCLC) and the molecular mechanisms underlying SPIN1 in human NSCLC remain undetermined. Here we examined the function of SPIN1 in human NSCLC and found that the expression of SPIN1 was closely correlated with the overall survival and poor prognosis of NSCLC patients. Aberrant regulation of microRNAs (miRNAs) has an important role in cancer progression. We revealed that miR-409 inhibits the expression of SPIN1 by binding directly to the 3′ UTR of SPIN1 using dual-luciferase reporter assays. Overexpression of miR-409 significantly suppressed cell migration, growth, and proliferation by inhibiting SPIN1 in vitro and in vivo. SPIN1 overexpression in miR-409-transfected NSCLC cells effectively rescued the suppression of cell migration, growth, and proliferation regulated by miR-409. miR-409 regulates the PI3K/AKT (protein kinase B) pathway in NSCLC. Moreover, clinical data showed that NSCLC patients with high levels of miR-409 experienced significantly better survival. miR-409 expression was also negatively associated with SPIN1 expression. Taken together, these findings highlight that the miR-409/SPIN1 axis is a useful pleiotropic regulatory network and could predict the metastatic potential in NSCLC patients early, indicating the possibility that miR-409 and SPIN1 might be attractive prognostic markers for treating NSCLC patients.

Establishment of a SVM classifier to predict recurrence of ovarian cancer.

Gene expression data using retrieved ovarian cancer (OC) samples were used to identify genes of interest and a support vector machine (SVM) classifier was subsequently established to predict the recurrence of OC. Three datasets (GSE17260, GSE44104 and GSE51088) investigating OC gene expression were downloaded from the Gene Expression Omnibus. Differentially expressed genes (DEGs) in samples from patients with non-recurrent and recurrent OC were revealed via a homogeneity test and quality control analysis. A protein-protein interaction (PPI) network was subsequently established for the DEGs using data from Biological General Repository for Interaction Datasets, Human Protein Reference Database and Database of Interacting Proteins. Degrees of interaction and betweenness centrality (BC) scores were calculated for each node in the PPI network. The top 100 genes ranked by BC scores were selected to identify feature genes via recursive feature elimination using the GSE17260 dataset. Following this, a SVM classifier was constructed and further validated using the GSE44104 and GSE51088 datasets and independent gene expression data obtained from the Cancer Genome Atlas (TCGA). A total of 639 DEGs were identified from the three gene expression datasets, and a PPI network including 249 nodes and 354 edges was constructed. A SVM classifier consisting of 39 feature genes (including cullin 3, mouse double minute 2 homolog, aurora kinase A, WW domain containing oxidoreducatase, large tumor suppressor kinase 2, sirtuin 6, staphylococcal nuclease and tudor domain containing 1, leucine rich repeats and immunoglobulin like domains 1 and aurora kinase 1 interacting protein 1) was subsequently constructed. The prediction accuracies of the SVM classifier for GSE17260, GSE44104 and GSE51088 datasets as well as data downloaded from TCGA were revealed to be 92.7, 93.3, 96.6 and 90.4%, respectively. Furthermore, the results of the present study revealed that patients with predicted non-recurrent OC survived significantly longer compared with the patients with predicted recurrent OC (P=6.598×10−6). A SVM classifier consisting of 39 feature genes was established for predicting the recurrence and prognosis of OC. Therefore, the results of the present study suggested that the 39 feature genes may serve important roles in the development of OC and may represent therapeutic biomarkers of OC.

A complex of C9ORF72 and p62 uses arginine methylation to eliminate stress granules by autophagy

Mutations in proteins like FUS which cause Amyotrophic Lateral Sclerosis (ALS) result in the aberrant formation of stress granules while ALS-linked mutations in other proteins impede elimination of stress granules. Repeat expansions in C9ORF72, the major cause of ALS, reduce C9ORF72 levels but how this impacts stress granules is uncertain. Here, we demonstrate that C9ORF72 associates with the autophagy receptor p62 and controls elimination of stress granules by autophagy. This requires p62 to associate via the Tudor protein SMN with proteins, including FUS, that are symmetrically methylated on arginines. Mice lacking p62 accumulate arginine-methylated proteins and alterations in FUS-dependent splicing. Patients with C9ORF72 repeat expansions accumulate symmetric arginine dimethylated proteins which co-localize with p62. This suggests that C9ORF72 initiates a cascade of ALS-linked proteins (C9ORF72, p62, SMN, FUS) to recognize stress granules for degradation by autophagy and hallmarks of a defect in this process are observable in ALS patients.

Molecular basis for the inhibition of the methyl-lysine binding function of 53BP1 by TIRR

53BP1 performs essential functions in DNA double-strand break (DSB) repair and it was recently reported that Tudor interacting repair regulator (TIRR) negatively regulates 53BP1 during DSB repair. Here, we present the crystal structure of the 53BP1 tandem Tudor domain (TTD) in complex with TIRR. Our results show that three loops from TIRR interact with 53BP1 TTD and mask the methylated lysine-binding pocket in TTD. Thus, TIRR competes with histone H4K20 methylation for 53BP1 binding. We map key interaction residues in 53BP1 TTD and TIRR, whose mutation abolishes complex formation. Moreover, TIRR suppresses the relocation of 53BP1 to DNA lesions and 53BP1-dependent DNA damage repair. Finally, despite the high-sequence homology between TIRR and NUDT16, NUDT16 does not directly interact with 53BP1 due to the absence of key residues required for binding. Taken together, our study provides insights into the molecular mechanism underlying TIRR-mediated suppression of 53BP1-dependent DNA damage repair.

Abstract 4445: Post-transcriptional inhibition of PTPN23 by SND1: Potential mechanism for hepatocellular carcinoma

Abstract Oncoprotein SND1 regulates gene expression at a post-transcriptional level in multiple cancers including hepatocellular carcinoma (HCC). Staphylococcal nuclease domains of SND1 function as an RNAse and tudor domain facilitates protein-oligonucleotide interaction. In the present study, we aimed to identify RNA interactome of SND1 to obtain better insights into gene regulation by SND1. RNA interactome was identified by immunoprecipitation of RNA using anti-SND1 antibody from human HCC cells followed by RNA-sequencing (RIP-Seq). With an adjusted p value of <0.01 and >2-fold enrichment over control, 282 mRNAs were identified to significantly associate with SND1 protein. We focused on the tumor suppressor PTPN23 because its regulation by SND1 and its role in HCC are not known. PTPN23 levels were downregulated in human HCC cells versus normal hepatocytes and in human HCC tissues versus normal adjacent liver as revealed by immunohistochemistry. In human HCC cells, knocking down SND1 increased and overexpression of SND1 decreased PTPN23 protein. RNA binding and degradation assays revealed that SND1 specifically binds to and degrades 3'-UTR of PTPN23 mRNA. Tetracycline-inducible PTPN23 overexpression in human HCC cells resulted in significant inhibition in proliferation, migration and invasion and in vivo tumorigenesis. PTPN23 induction caused inhibition in activation of c-Met, EGFR, Src and FAK, suggesting that as a phosphatase PTPN23 inhibits activation of these oncogenic kinases. The present study unravels a novel function of SND1 in targeting PTPN23 and identifies PTPN23 as a unique tumor suppressor for HCC. PTPN23 might function as a homeostatic regulator of multiple kinases restraining their activation. Citation Format: Nidhi H. Jariwala, Rachel G. Mendoza, Garcia Dawn, Lai Zhao, Mark A. Subler, Jolene J. Windle, Paul B. Fisher, Chen Yidong, Devanand Sarkar. Post-transcriptional inhibition of PTPN23 by SND1: Potential mechanism for hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4445.

Tdrd1 is a germline-specific and sexually dimorphically expressed gene in Paralichthys olivaceus

Tudor domain containing protein 1 (tdrd1) is a member of the Tudor family and has shown essential functions during embryogenesis and gametogenesis. In this study, we cloned the full length cDNA of Paralichthys olivaceus tdrd1 (Potdrd1). PoTDRD1 is a multidomain protein with an N-terminal MYND zinc finger domain, followed by four tandem extended Tudor domains. Sequence comparison, genomic structure, phylogenetic analyses and synteny analyses showed that Potdrd1 was homologous to those of other teleosts. In adult individuals, the expression of Potdrd1 was higher in testis than in ovary, demonstrating a sexually dimorphic gene expression pattern. In situ hybridization (ISH) showed that Potdrd1 mRNA was detected in oogonia and oocytes of ovary as well as in spermatogonia and spermatocytes of testis. In juveniles during gonad differentiation its expression level increased rapidly from 30 dph to 100 dph and showed obvious sexual dimorphism that was in accordance with the expression of anti-Mullerian hormone (amh). Potdrd1 mRNA was consistently detected during embryogenesis, and its level was higher from unfertilzed eggs to the blastula stage and subsequently decreased until hatching. When chimeric RNA containing green fluorescent protein (GFP) and 3′ untranslated regions (UTR) of Potdrd1 was microinjected into zebrafish fertilized eggs, the green fluorescence could be visualized only in putative PGCs. These results indicated that Potdrd1 is a germline specific and sexually dimorphic factor that potentially functionate in germline development and gametogenesis in Japanese flounder.

PHD finger protein 1 (PHF1) is a novel reader for histone H4R3 symmetric dimethylation and coordinates with PRMT5-WDR77/CRL4B complex to promote tumorigenesis.

Histone post–translational modifications regulate chromatin structure and function largely through interactions with effector proteins that often contain multiple histone-binding domains. PHF1 [plant homeodomain (PHD) finger protein 1], which contains two kinds of histone reader modules, a Tudor domain and two PHD fingers, is an essential factor for epigenetic regulation and genome maintenance. While significant progress has been made in characterizing the function of the Tudor domain, the roles of the two PHD fingers are poorly defined. Here, we demonstrated that the N-terminal PHD finger of PHF1 recognizes symmetric dimethylation of H4R3 (H4R3me2s) catalyzed by PRMT5–WDR77. However, the C-terminal PHD finger of PHF1, instead of binding to modified histones, directly interacts with DDB1, the main component of the CUL4B-Ring E3 ligase complex (CRL4B), which is responsible for H2AK119 mono-ubiquitination (H2AK119ub1). We showed that PHF1, PRMT5–WDR77, and CRL4B reciprocally interact with one another and collaborate as a functional unit. Genome-wide analysis of PHF1/PRMT5/CUL4B targets identified a cohort of genes including E-cadherin and FBXW7, which are critically involved in cell growth and migration. We demonstrated that PHF1 promotes cell proliferation, invasion, and tumorigenesis in vivo and in vitro and found that its expression is markedly upregulated in a variety of human cancers. Our data identified a new reader for H4R3me2s and provided a molecular basis for the functional interplay between histone arginine methylation and ubiquitination. The results also indicated that PHF1 is a key factor in cancer progression, supporting the pursuit of PHF1 as a target for cancer therapy.

Structural basis for recognition of 53BP1 tandem Tudor domain by TIRR

P53-binding protein 1 (53BP1) regulates the double-strand break (DSB) repair pathway choice. A recently identified 53BP1-binding protein Tudor-interacting repair regulator (TIRR) modulates the access of 53BP1 to DSBs by masking the H4K20me2 binding surface on 53BP1, but the underlying mechanism remains unclear. Here we report the 1.76-Å crystal structure of TIRR in complex with 53BP1 tandem Tudor domain. We demonstrate that the N-terminal region (residues 10–24) and the L8-loop of TIRR interact with 53BP1 Tudor through three loops (L1, L3, and L1′). TIRR recognition blocks H4K20me2 binding to 53BP1 Tudor and modulates 53BP1 functions in vivo. Structure comparisons identify a TIRR histidine (H106) that is absent from the TIRR homolog Nudt16, but essential for 53BP1 Tudor binding. Remarkably, mutations mimicking TIRR binding modules restore the disrupted binding of Nudt16-53BP1 Tudor. Our studies elucidate the mechanism by which TIRR recognizes 53BP1 Tudor and functions as a cellular inhibitor of the histone methyl-lysine readers.

Structural plasticity of the TDRD3 Tudor domain probed by a fragment screening hit.

Structural data are available in the PDB under the accession number 5YJ8.

Targeting lysine specific demethylase 4A (KDM4A) tandem TUDOR domain – A fragment based approach

The tandem TUDOR domains present in the non-catalytic C-terminal half of the KDM4A, 4B and 4C enzymes play important roles in regulating their chromatin localizations and substrate specificities. They achieve this regulatory role by binding to different tri-methylated lysine residues on histone H3 (H3-K4me3, H3-K23me3) and histone H4 (H4-K20me3) depending upon the specific chromatin environment. In this work, we have used a 2D-NMR based fragment screening approach to identify a novel fragment (1a), which binds to the KDM4A-TUDOR domain and shows modest competition with H3-K4me3 binding in biochemical as well as in vitro cell based assays. A co-crystal structure of KDM4A TUDOR domain in complex with 1a shows that the fragment binds stereo-specifically to the methyl lysine binding pocket forming a network of strong hydrogen bonds and hydrophobic interactions. We anticipate that the fragment 1a can be further developed into a novel allosteric inhibitor of the KDM4 family of enzymes through targeting their C-terminal tandem TUDOR domain.

TRPM2 promotes the proliferation and invasion of pancreatic ductal adenocarcinoma.

The aim of the present study was to investigate transient receptor potential cation channel subfamily M member 2 (TRPM2), a promising therapeutic target and biomarker for pancreatic ductal adenocarcinoma (PDAC) prognosis, in addition to determining its effects regarding tumor progression and invasion. PDAC is a fatal disease with a poor prognosis, and its associated pathogenic molecular mechanisms remain to be determined. In the present study, combined analysis using genomic and transcriptomic data from two PDAC studies was performed to discover a survival-associated biomarker of PDAC. Survival analysis for genes mutated in ≥10 patients was performed using a Kaplan-Meier curve and tested for significance using a log-rank test. Furthermore, gene-expression correlation analysis was performed to determine the genes with the strongest correlations to TRPM2. In addition, a Cell Counting Kit-8 assay, a scratch wound-healing assay and a Transwell assay were performed in the present study to investigate the proliferative, invasive and metastatic ability of PANC-1 cells in TRPM2-overexpressing and downregulated groups. The mutated TRPM2 gene had a strong negative correlation with patient survival probability compared with the normal control group (P=1.06×10-4). Expression of TRPM2 was strongly correlated with expression of probable phospholipid-transporting ATPase IM, γ-parvin, tudor domain containing 9, Toll-like receptor 7 and Scm-like with four MBT domains protein 2 according to the criterion of a correlation coefficient >0.5. Furthermore, the results of the present study demonstrated that the TRPM2 overexpression in a PDAC cell line (PANC-1) promoted cell proliferation, invasion and metastatic ability. TRPM2 represents a potential therapeutic target and prognostic marker for patients with PDAC. TRPM2 regulates cell proliferation, invasion and migration; however, the underlying mechanism requires further investigation in future studies.

Protein arginine methyltransferase 5 mediates enolase-1 cell surface trafficking in human lung adenocarcinoma cells

ObjectivesEnolase-1-dependent cell surface proteolysis plays an important role in cell invasion. Although enolase-1 (Eno-1), a glycolytic enzyme, has been found on the surface of various cells, the mechanism responsible for its exteriorization remains elusive. Here, we investigated the involvement of post-translational modifications (PTMs) of Eno-1 in its lipopolysaccharide (LPS)-triggered trafficking to the cell surface. ResultsWe found that stimulation of human lung adenocarcinoma cells with LPS triggered the monomethylation of arginine 50 (R50me) within Eno-1. The Eno-1R50me was confirmed by its interaction with the tudor domain (TD) from TD-containing 3 (TDRD3) protein recognizing methylarginines. Substitution of R50 with lysine (R50K) reduced Eno-1 association with epithelial caveolar domains, thereby diminishing its exteriorization. Similar effects were observed when pharmacological inhibitors of arginine methyltransferases were applied. Protein arginine methyltransferase 5 (PRMT5) was identified to be responsible for Eno-1 methylation. Overexpression of PRMT5 and caveolin-1 enhanced levels of membrane-bound extracellular Eno-1 and, conversely, pharmacological inhibition of PRMT5 attenuated Eno-1 cell-surface localization. Importantly, Eno-1R50me was essential for cancer cell motility since the replacement of Eno-1 R50 by lysine or the suppression of PRMT 5 activity diminished Eno-1-triggered cell invasion. ConclusionsLPS-triggered Eno-1R50me enhances Eno-1 cell surface levels and thus potentiates the invasive properties of cancer cells. Strategies to target Eno-1R50me may offer novel therapeutic approaches to attenuate tumor metastasis in cancer patients.

Hierarchical roles of mitochondrial Papi and Zucchini in Bombyx germline piRNA biogenesis.

PIWI-interacting RNAs (piRNAs) are small regulatory RNAs that bind to PIWI proteins to control transposons and maintain genome integrity in animal germ lines. piRNA 3' end formation in the silkworm Bombyx mori has been shown to be mediated by the 3'-to-5' exonuclease Trimmer (Trim; known as PNLDC1 in mammals), and piRNA intermediates are bound with PIWI anchored onto mitochondrial Tudor domain protein Papi. However, it remains unclear whether the Zucchini (Zuc) endonuclease and Nibbler (Nbr) 3'-to-5' exonuclease, both of which have pivotal roles in piRNA biogenesis in Drosophila, are required for piRNA processing in other species. Here we show that the loss of Zuc in Bombyx had no effect on the levels of Trim and Nbr, but resulted in the aberrant accumulation of piRNA intermediates within the Papi complex, and that these were processed to form mature piRNAs by recombinant Zuc. Papi exerted its RNA-binding activity only when bound with PIWI and phosphorylated, suggesting that complex assembly involves a hierarchical process. Both the 5' and 3' ends of piRNA intermediates within the Papi complex showed hallmarks of PIWI 'slicer' activity, yet no phasing pattern was observed in mature piRNAs. The loss of Zuc did not affect the 5'- and 3'-end formation of the intermediates, strongly supporting the idea that the 5' end of Bombyx piRNA is formed by PIWI slicer activity, but independently of Zuc, whereas the 3' end is formed by the Zuc endonuclease. The Bombyx piRNA biogenesis machinery is simpler than that of Drosophila, because Bombyx has no transcriptional silencing machinery that relies on phased piRNAs.

Tudor staphylococcal nuclease is a structure-specific ribonuclease that degrades RNA at unstructured regions during microRNA decay.

Tudor staphylococcal nuclease (TSN) is an evolutionarily conserved ribonuclease in eukaryotes that is composed of five staphylococcal nuclease-like domains (SN1–SN5) and a Tudor domain. TSN degrades hyper-edited double-stranded RNA, including primary miRNA precursors containing multiple I•U and U•I pairs, and mature miRNA during miRNA decay. However, how TSN binds and degrades its RNA substrates remains unclear. Here, we show that the C. elegans TSN (cTSN) is a monomeric Ca2+-dependent ribonuclease, cleaving RNA chains at the 5′-side of the phosphodiester linkage to produce degraded fragments with 5′-hydroxyl and 3′-phosphate ends. cTSN degrades single-stranded RNA and double-stranded RNA containing mismatched base pairs, but is not restricted to those containing multiple I•U and U•I pairs. cTSN has at least two catalytic active sites located in the SN1 and SN3 domains, since mutations of the putative Ca2+-binding residues in these two domains strongly impaired its ribonuclease activity. We further show by small-angle X-ray scattering that rice osTSN has a flexible two-lobed structure with open to closed conformations, indicating that TSN may change its conformation upon RNA binding. We conclude that TSN is a structure-specific ribonuclease targeting not only single-stranded RNA, but also unstructured regions of double-stranded RNA. This study provides the molecular basis for how TSN cooperates with RNA editing to eliminate duplex RNA in cell defense, and how TSN selects and degrades RNA during microRNA decay.

A new mechanism of interferon's antiviral action: Induction of autophagy, essential for paramyxovirus replication, is inhibited by the interferon stimulated gene, TDRD7.

The interferon (IFN) system represents the first line of defense against a wide range of viruses. Virus infection rapidly triggers the transcriptional induction of IFN-β and IFN Stimulated Genes (ISGs), whose protein products act as viral restriction factors by interfering with specific stages of virus life cycle, such as entry, transcription, translation, genome replication, assembly and egress. Here, we report a new mode of action of an ISG, IFN-induced TDRD7 (tudor domain containing 7) inhibited paramyxovirus replication by inhibiting autophagy. TDRD7 was identified as an antiviral gene by a high throughput screen of an ISG shRNA library for blocking IFN’s protective effect against Sendai virus (SeV) replication. The antiviral activity of TDRD7 against SeV, human parainfluenza virus 3 and respiratory syncytial virus was confirmed by its genetic ablation or ectopic expression in several types of mouse and human cells. TDRD7’s antiviral action was mediated by its ability to inhibit autophagy, a cellular catabolic process which was robustly induced by SeV infection and required for its replication. Mechanistic investigation revealed that TDRD7 interfered with the activation of AMP-dependent kinase (AMPK), an enzyme required for initiating autophagy. AMPK activity was required for efficient replication of several paramyxoviruses, as demonstrated by its genetic ablation or inhibition of its activity by TDRD7 or chemical inhibitors. Therefore, our study has identified a new antiviral ISG with a new mode of action.

An Intramolecular Interaction of UHRF1 Reveals Dual Control for Its Histone Association

UHRF1 (ubiquitin-like, containing PHD and RING finger domains, 1) is one of the essential components of mammalian DNA methylation machinery. Chromatin association of UHRF1 is controlled via an interplay between its intramolecular interaction and dual recognition of histone H3 trimethylated at lysine 9 (H3K9me3) and hemimethylated DNA. Here, we report the crystal structure of the N-terminal tandem Tudor domain (TTD) of UHRF1 in complex with the C-terminal polybasic region (PBR). Structural analysis reveals that PBR binding leads to displacement of the TTD-plant homeodomain (PHD) linker, as wellas blockage of the H3K9me3-engaging cage, bothof which contribute to a chromatin-occluded UHRF1 conformation. Disruption of the TTD-PBR interaction, which is facilitated by the binding of UHRF1 to hemimethylated DNA or regulatory protein USP7, shifts the UHRF1 conformation toward an open state, allowing for efficient H3K9me3 binding. Together, this study provides structural basis for the allosteric regulation of UHRF1.

Investigation of piwi-interacting RNA pathway genes role in idiopathic non-obstructive azoospermia

Genes involved in piwi-interacting RNAs (piRNAs) pathway have an essential role in spermatogenesis. HIWI and TDRD proteins are critical for piRNA biogenesis and function. Therefore, Mutations and polymorphisms in HIWI and TDRD genes may play role in male infertility. The aim of the present study was to investigate the role of HIWI2 rs508485 (T>C) and HIWI3 rs11703684 (C>T) polymorphisms and mutational analysis of TDRD5 gene in idiopathic non-obstructive azoospermia in a case-control study including 226 non-obstructive azoospermia patients and 200 fertile males. Genotyping for both polymorphisms was performed using Tetra-Primer ARMS PCR. Mutation analysis of TDRD5 gene was done using multi-temperature single strand conformation polymorphism technique (MSSCP). The frequency of rs508485TC genotype was significantly different in the studied groups (P = 0.0032; OR = 2.12; 95% CI, 1.29–3.48). In addition, the genotype frequencies showed a significant difference under dominant model (P = 0.005; OR = 2.79; 95% CI, 1.22–3.13). No mutation was detected in the Tudor domain of the TDRD5 in the studied patients. In conclusion, we provide evidence for association between genetic variation in the HIWI2 gene and idiopathic non-obstructive azoospermia in Iranian patients. Therefore, piRNA pathway genes variants can be considered as risk factors for male infertility.

The multifaceted oncogene SND1 in cancer: focus on hepatocellular carcinoma.

Staphylococcal nuclease and tudor domain containing 1 (SND1) is a protein that regulates a complex array of functions. It controls gene expression through transcriptional activation, mRNA degradation, mRNA stabilization, ubiquitination and alternative splicing. More than two decades of research has accumulated evidence of the role of SND1 as an oncogene in various cancers. It is a promoter of cancer hallmarks like proliferation, invasion, migration, angiogenesis and metastasis. In addition to these functions, it has a role in lipid metabolism, inflammation and stress response. The participation of SND1 in such varied functions makes it distinct from most oncogenes that are relatively more focused in their role. This becomes important in the case of hepatocellular carcinoma (HCC) since in addition to typical cancer drivers, factors like lipid metabolism deregulation and chronic inflammation can predispose hepatocytes to HCC. The objective of this review is to provide a summary of the current knowledge available on SND1, specifically in relation to HCC and to shed light on its prospect as a therapeutic target.

Conformational Selection of Dimethylarginine Recognition by the Survival Motor Neuron Tudor Domain.

Tudor domains bind to dimethylarginine (DMA) residues, which are post-translational modifications that play a central role in gene regulation in eukaryotic cells. NMR spectroscopy and quantum calculations are combined to demonstrate that DMA recognition by Tudor domains involves conformational selection. The binding mechanism is confirmed by a mutation in the aromatic cage that perturbs the native recognition mode of the ligand. General mechanistic principles are delineated from the combined results, indicating that Tudor domains utilize cation-π interactions to achieve ligand recognition.