The human cytomegalovirus protein TRS1 inhibits autophagy via its interaction with Beclin 1

Human cytomegalovirus modulates macroautophagy in two opposite directions. First, HCMV stimulates autophagy during the early stages of infection, as evident by an increase in the number of autophagosomes and a rise in the autophagic flux. This stimulation occurs independently of de novo viral protein synthesis since UV-inactivated HCMV recapitulates the stimulatory effect on macroautophagy. At later time points of infection, HCMV blocks autophagy (M. Chaumorcel, S. Souquere, G. Pierron, P. Codogno, and A. Esclatine, Autophagy 4:1-8, 2008) by a mechanism that requires de novo viral protein expression. Exploration of the mechanisms used by HCMV to block autophagy unveiled a robust increase of the cellular form of Bcl-2 expression. Although this protein has an anti-autophagy effect via its interaction with Beclin 1, it is not responsible for the inhibition induced by HCMV, probably because of its phosphorylation by c-Jun N-terminal kinase. Here we showed that the HCMV TRS1 protein blocks autophagosome biogenesis and that a TRS1 deletion mutant is defective in autophagy inhibition. TRS1 has previously been shown to neutralize the PKR antiviral effector molecule. Although phosphorylation of eIF2α by PKR has been described as a stimulatory signal to induce autophagy, the PKR-binding domain of TRS1 is dispensable to its inhibitory effect. Our results show that TRS1 interacts with Beclin 1 to inhibit autophagy. We mapped the interaction with Beclin 1 to the N-terminal region of TRS1, and we demonstrated that the Beclin 1-binding domain of TRS1 is essential to inhibit autophagy.     

Phosphorylation of p27Kip1 at Thr-157 interferes with its association with importin alpha during G1 and prevents nuclear re-entry

We have studied mechanisms of Akt-mediated phosphorylation and regulation of cellular localization of p27. Akt phosphorylates Thr-157 in p27 and retains it in the cytosol. In cells arrested in G(1) and then synchronized to enter into S phase, Akt-mediated phosphorylation of Thr-157 p27 occurred in the cytosol during G(1) phase of the cell cycle. Both T157A and S10A p27 mutants localized in the nucleus in all phases of the cell cycle regardless of the expression of active Akt. Thr-157 phosphorylation was undetectable in S10A-p27, suggesting that Ser-10 phosphorylation is required for p27 localization in the cytosol and subsequent phosphorylation at Thr-157. Phosphorylation at Thr-157 interrupted the association of p27 with importin alpha. A T157A-p27 mutant protein exhibited higher association with importin alpha than wild-type-p27. Treatment of transfected and endogenous p27 with alkaline phosphatase rescued its association with importin alpha. Leptomycin B inhibited cytosolic Thr-157 P-p27 staining, implying that CRM1-dependent nuclear export is required for Akt-mediated Thr-157 phosphorylation. Heterokaryon shuttling assays with NIH3T3 (mouse) cells transfected with FLAG-p27 and HeLa (human) cells revealed that both wild type and T157A-p27 shuttled from NIH3T3 to HeLa cell nuclei with similar frequencies. However, S10A-p27 was found only in the NIH3T3 nuclei of NIH3T3-HeLa cell fusions. These results suggest that 1) Ser-10 phosphorylation is required for nuclear export of p27, 2) subsequent Akt-mediated phosphorylation at Thr-157 during G(1) phase corrals p27 in the cytosol, and 3) Thr-157 phosphorylation inhibits the association of p27 with importin alpha thus preventing its re-entry into the nucleus.     

A tumor-associated beta 1 integrin mutation that abrogates epithelial differentiation control

SCC4 human keratinocytes are derived from a squamous cell carcinoma of the tongue and undergo very little spontaneous differentiation. Introduction of a wild-type beta 1 integrin subunit into SCC4 cells stimulates differentiation, suggesting either that the cells have a defect in the integrin signaling pathways that control differentiation or that the beta1 subunit itself is defective. Here we describe a heterozygous mutation in the SCC4 beta 1 subunit. The mutation, T188I, maps to the I-like domain. It results in constitutive activation of ligand binding, irrespective of the partner alpha subunit, in solid phase assays with recombinant protein and in living cells. The mutation promotes cell spreading, but not proliferation, motility, or invasiveness. It results in sustained activation of Erk MAPK independent of cell spreading. When introduced into SCC4 keratinocytes, the wild-type beta1 integrin stimulates differentiation, whereas the mutant is inactive. Activation of beta 1 integrins in normal keratinocytes also suppresses differentiation. These results establish, for the first time, mutation as a mechanism by which integrins can contribute to neoplasia, because the degree of differentiation in epithelial cancers is inversely correlated with prognosis. They also provide new insights into how integrins regulate keratinocyte differentiation.     

SRC directly phosphorylates Bif-1 and prevents its interaction with Bax and the initiation of anoikis

Bif-1 interacts with Bax and enhances its conformational rearrangement, resulting in apoptosis. However, the molecular mechanism governing the interaction between Bif-1 and Bax is poorly defined. Here we provide evidence that Bif-1 is phosphorylated, an event that can be repressed by apoptotic stimuli. The protein kinase c-Src binds to and directly phosphorylates Bif-1 on tyrosine 80. Moreover, Src phosphorylation of Bif-1 suppresses the interaction between Bif-1 and Bax, resulting in the inhibition of Bax activation during anoikis. Together, these results suggest that phosphorylation of Bif-1 impairs its binding to Bax and represses apoptosis, providing another mechanism by which Src oncogenic signaling can prevent cell death.     

Phosphorylation of caldesmon prevents its interaction with smooth muscle myosin

Caldesmon is known to bind to smooth muscle myosin. Ca2+/calmodulin-dependent phosphorylation of caldesmon completely blocks its interaction with myosin. Cleavage of caldesmon at its 2 cysteine residues by 2-nitro-5-thiocyanobenzoic acid (NTCB) occurs initially at one site to yield 108-kDa and 21.2-kDa peptides and subsequently at the second site within the 108-kDa peptide to yield 85-kDa and 23.5-kDa fragments. The 23.5-kDa peptide retains the ability to bind to myosin. The N-terminal (95 kDa) and C-terminal (42 kDa) chymotryptic peptides of caldesmon were isolated and digested with NTCB: the C-terminal actin- and calmodulin-binding peptide was not cleaved, indicating that it does not contain either of the cysteine residues, whereas the 95-kDa N-terminal peptide was cleaved at two sites to yield 56-kDa, 23.5-kDa, and 21.2-kDa fragments. The arrangement of NTCB fragments in caldesmon is, therefore: 21.2 kDa/23.5 kDa/85 kDa from N to C terminus. Digestion of phosphorylated caldesmon with NTCB suggested a single phosphorylation site in the 21.2-kDa peptide and three sites in the 23.5-kDa peptide. These results lead to the development of a model whereby caldesmon may cross-link actin to myosin and such cross-linking is blocked by phosphorylation of caldesmon. This mechanism may explain the formation of reversible "latch bridges" which permit force maintenance at low levels of myosin phosphorylation in intact smooth muscles.     

Homocysteine modifies structural and functional properties of fibronectin and interferes with the fibronectin-fibrillin-1 interaction

Homocystinuria is a genetic disorder resulting in elevated levels of homocysteine in plasma and tissues. Some of the skeletal and ocular symptoms such as long bone overgrowth, scoliosis, and ectopia lentis overlap with symptoms seen in Marfan syndrome. Marfan syndrome is caused by mutations in the extracellular matrix protein fibrillin-1. We previously showed that fibrillin-1 is a target for homocysteine and that the deposition of homocysteinylated fibrillin-1 in the extracellular matrix is compromised. Since the assembly of fibrillin-1 is critically dependent on fibronectin, we analyzed the consequences of fibronectin homocysteinylation and its interaction with fibrillin-1. Cellular fibronectin and proteolytic fragments were homocysteinylated and tested in various interaction assays with recombinant fibrillin-1 and heparin. Fibronectin homocysteinylation consistently compromised the fibronectin-fibrillin-1 interaction, while the interaction with heparin was not affected. Fibronectin homocysteinylation, but not cysteinylation, reduced the fibronectin dimers to monomers as shown by Western blotting. ELISA analyses of homocysteinylated fibronectin with three monoclonal antibodies demonstrated structural changes in the disulfide-containing FNI domains FNI(2), FNI(4), and FNI(9). Using fluorescently labeled fibronectin, we studied the consequence of fibronectin homocysteinylation on assembly in cell culture. Modified fibronectin showed deficiencies in denovo matrix incorporation and initial assembly. In conclusion, we define here characteristic structural changes of fibronectin upon homocysteinylation that translate into functional deficiencies in the fibronectin-fibrillin-1 interaction and in fibronectin assembly. Since fibronectin is a major organizer of various extracellular protein networks, these structural and functional alterations may contribute to the pathogenesis of homocystinuria and Marfan syndrome.     

Common and divergent functions of Beclin 1 and Beclin 2

In a recent paper published in Cell, He and colleagues reported the identification and functional characterization of Beclin 2, a mammal-specific homolog of the evolutionarily conserved autophagy-regulatory and oncosuppressive factor Beclin 1. In spite of a non-negligible degree of sequence identity, Beclin 1 and Beclin 2 differ from each other in multiple aspects, including their functional profile as well as the genomic organization of the respective loci.Originally identified as a BCL-2-interacting partner capable of protecting mice from viral encephalitis¹, Beclin 1 — the mammalian ortholog of yeast Atg6 — is nowadays well known as a core component of the class III phosphoinosite-3-kinase (PI3K) enzymatic complex that initiates the formation of autophagosomes in the course of macroautophagy (hereafter referred to as autophagy)². Presumably owing to the critical function of autophagy in embryonic development, mice lacking both copies of the Beclin 1-coding gene (Becn1) die early during embryogenesis. Moreover, Becn1^+/− mice suffer from a high incidence of spontaneous tumors, indicating that Beclin 1 acts as a haploinsufficient tumor suppressor³. At least in part, this reflects the central role that autophagy plays in the maintenance of intracellular homeostasis. Indeed, baseline levels of autophagy mediate the removal of various cytoplasmic entities that might favor oncogenesis, including damaged mitochondria and protein aggregates⁴. Conversely, established neoplasms often harness the cytoprotective functions of autophagy to their own benefit². The pathophysiological relevance of autophagy is not limited to cancer, but extends to a large panel of human diseases, including neurodegenerative, cardiovascular and infectious conditions⁵. Thus, during the last decade autophagy-regulatory signaling pathways have been intensively investigated.Until now, Beclin 1 was considered as the only Beclin encoded by the mammalian genome, sharing some degree of structural homology with so-called “BH3-only” proteins, pro-apoptotic members of the BCL-2 family that are involved in the activation of cell death in response to stress⁶. In a recent paper published in Cell, the research group led by Beth Levine⁷ identified a human and a mouse protein sharing 57% and 44% sequence identity with human and mouse Beclin 1, respectively, de facto unveiling the existence of an additional, mammal-specific ortholog of Atg6, Beclin 2. The mouse Beclin 2 mRNA was detected in multiple organs including the brain, skeletal muscle, placenta, thymus and uterus, as was the human protein in both fetal and adult brain tissues. These data demonstrate that the current classification of mouse and human Beclin 2-encoding genes (i.e., {"type":"entrez-nucleotide","attrs":{"text":"NG_022940","term_id":"298676453","term_text":"NG_022940"}}NG_022940 and {"type":"entrez-nucleotide","attrs":{"text":"NG_028451","term_id":"331028236","term_text":"NG_028451"}}NG_028451) as pseudogenes is incorrect.The knockdown of Beclin 2 reduced several manifestations of basal or starvation-induced autophagy in cultured mammalian cells, including the degradation of the autophagic substrate p62, the aggregation of a fluorescent form of LC3 into cytoplasmic dots and the lipidation of endogenous LC3. All such effects, which were not due to an increased autophagosomal turnover (as verified in the presence of the lysosomal inhibitor bafilomycin A1), could be rescued upon the transgene-driven expression of a non-interferable Beclin 2 variant. Thus, similar to Beclin 1, Beclin 2 regulates autophagy⁷. In fact, Beclin 2 turned out to physically interact with several (but not all) components of the class III PI3K complex organized around Beclin 1, including the catalytic subunit VPS34 as well as the regulatory factors ATG14, AMBRA1 and UVRAG, but not RUBICON (Figure 1A). Beclin 2 also appeared to share with Beclin 1 the ability to bind BCL-2, although only the latter gets dissociated from such an interaction in the course of stress-induced autophagy^7,8. As the greatest divergence between mammalian Beclins involves their N terminus, He and colleagues employed the N-terminal domain of Beclin 2 as a bait in a yeast two-hybrid screen, and identified G protein-coupled receptor (GPCR)-associated sorting protein 1 (GASP1) as a Beclin 2-specific interactor. Thus, similar to GASP1 (but not to Beclin 1), Beclin 2 was required for the agonist-induced lysosomal degradation of a subset of GPCRs including opioid receptor δ1 (DOR) and cannabinoid receptor 1 (CB1R). Importantly, such an activity, but not the capacity of Beclin 2 to regulate autophagic responses, appears to rely on the physical interaction between Beclin 2 and GASP1.Open in a separate windowFigure 1Common and divergent functions of mammalian Beclins. Specificity of the main interactors (A) and functions (B) ascribed to mammalian Beclin 1 and Beclin 2 to date. GPCR, G protein-coupled receptor; RTK, receptor tyrosine kinase.To obtain insights into the physiological functions of Beclin 2, He and colleagues attempted to generate Becn2^−/− mice, finding that these animals survived embryonic and early post-natal development at sub-Mendelian rates (approximately 4%). Not only Becn2^+/− and Becn2^−/− mouse embryonic fibroblasts, but also the brain of Becn2^+/− animals exhibited significant autophagic defects, corroborating the role of Beclin 2 in the regulation of autophagy in vivo. Moreover, these genotypes were associated with increased basal levels of multiple GPCRs, including CB1R and dopamine receptor D2 (DRD2)⁷. In line with the notion that increased CB1R signaling accrues food intake and hence favors obesity and insulin resistance, while pharmacological or genetic CB1R inhibition has opposite effects⁹, Becn2^+/− mice accumulated more weight than their wild-type littermates in response to a standard (as well as to a high-fat) diet. At odds with their Becn1^+/− counterparts, Becn2^+/− mice also exhibited impaired glucose tolerance and decreased insulin sensitivity, two effects that could be reverted by a chemical CB1R antagonist⁷. Taken together, these data demonstrate that besides regulating autophagy, Beclin 2 plays a unique role in glucose metabolism.Beclin 1 is known to regulate various processes other than autophagy, including vacuolar protein sorting and the degradation of specific growth factor receptors¹⁰. Thus, in spite of 44% - 57% sequence identity, the two mammalian Beclins described to date are relatively different from each other, exhibiting functional profiles that overlap to a limited degree (Figure 1B). Interestingly, He and colleagues have previously shown that defects in stimulus-induced autophagy (including those introduced by the Becn1^+/− genotype) are coupled to decreased endurance and altered glucose metabolism during acute exercise, as well as with an impaired capacity of training to protect mice against diet-induced glucose intolerance⁸. Part of these phenomena were shown to reflect defects in the AMP-activated protein kinase (AMPK)-dependent exposure of glucose transporters on the plasma membrane of skeletal muscle cells. It is therefore tempting to speculate that the metabolic phenotype of Becn2^+/− may in part originate from peripheral defects in glucose handling linked to autophagy. Thus, although the force driving the divergence of mammalian Beclins remains to be elucidated, it may reflect the need for an integrated regulation of central and peripheral mechanisms of metabolic homeostasis. Further studies are required to address this hypothesis.     

A phosphatidylinositol 3-kinase class III sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 regulates cytokinesis and degradative endocytic traffic

The mammalian class III phosphatidylinositol 3-kinase (PI3K-III) complex regulates fundamental cellular functions, including growth factor receptor degradation, cytokinesis and autophagy. Recent studies suggest the existence of distinct PI3K-III sub-complexes that can potentially confer functional specificity. While a substantial body of work has focused on the roles of individual PI3K-III subunits in autophagy, functional studies on their contribution to endocytic receptor downregulation and cytokinesis are limited. We therefore sought to elucidate the specific nature of the PI3K-III complexes involved in these two processes. High-content microscopy-based assays combined with siRNA-mediated depletion of individual subunits indicated that a specific sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 regulates both receptor degradation and cytokinesis, whereas ATG14L, a PI3K-III subunit involved in autophagy, is not required. The unanticipated role of UVRAG and BIF-1 in cytokinesis was supported by a strong localisation of these proteins to the midbody. Importantly, while the tumour suppressive functions of Beclin 1, UVRAG and BIF-1 have previously been ascribed to their roles in autophagy, these results open the possibility that they may also contribute to tumour suppression via downregulation of mitogenic signalling by growth factor receptors or preclusion of aneuploidy by ensuring faithful completion of cell division.     

Akt phosphorylation of zyxin mediates its interaction with acinus-S and prevents acinus-triggered chromatin condensation

Zyxin, a focal adhesion molecule, contains LIM domains and shuttles between the cytoplasm and the nucleus. Nuclear zyxin promotes cardiomyocyte survival, which is mediated by nuclear-activated Akt. However, the molecular mechanism of how zyxin antagonizes apoptosis remains elusive. Here, we report that zyxin binds to acinus-S, a nuclear speckle protein inducing apoptotic chromatin condensation after cleavage by caspases, and prevents its apoptotic action, which is regulated by Akt. Akt binds and phosphorylates zyxin on serine 142, leading to its association with acinus. Interestingly, 14-3-3gamma, but not zeta isoform selectively, triggers zyxin nuclear translocation, which is Akt phosphorylation dependent. Zyxin is also a substrate of caspases, but Akt phosphorylation is unable to prevent its apoptotic cleavage. Expression of zyxin S142D, a phosphorylation mimetic mutant, diminishes acinus proteolytic cleavage and chromatin condensation; by contrast, wild-type zyxin or unphosphorylated S142A mutant fails. Thus, Akt regulates zyxin/acinus complex formation in the nucleus, contributing to suppression of apoptosis.     

A beta-tubulin mutation selectively uncouples nuclear division and cytokinesis in Tetrahymena thermophila

The ciliated protozoan Tetrahymena thermophila contains two distinct nuclei within a single cell-the mitotic micronucleus and the amitotic macronucleus. Although microtubules are required for proper division of both nuclei, macronuclear chromosomes lack centromeres and the role of microtubules in macronuclear division has not been established. Here we describe nuclear division defects in cells expressing a mutant beta-tubulin allele that confers hypersensitivity to the microtubule-stabilizing drug paclitaxel. Macronuclear division is profoundly affected by the btu1-1 (K350M) mutation, producing cells with widely variable DNA contents, including cells that lack macronuclei entirely. Protein expressed by the btu1-1 allele is dominant over wild-type protein expressed by the BTU2 locus. Normal macronuclear division is restored when the btu1-1 allele is inactivated by targeted disruption or expressed as a truncated protein. Immunofluorescence studies reveal elongated microtubular structures that surround macronuclei that fail to migrate to the cleavage furrows. In contrast, other cytoplasmic microtubule-dependent processes, such as cytokinesis, cortical patterning, and oral apparatus assembly, appear to be unaffected in the mutant. Micronuclear division is also perturbed in the K350M mutant, producing nuclei with elongated early-anaphase spindle configurations that persist well after the initiation of cytokinesis. The K350M mutation affects tubulin dynamics, as the macronuclear division defect is exacerbated by three treatments that promote microtubule polymerization: (i) elevated temperatures, (ii) sublethal concentrations of paclitaxel, and (iii) high concentrations of dimethyl sulfoxide. Inhibition of phosphatidylinositol 3-kinase (PI 3-kinase) with 3-methyladenine or wortmannin also induces amacronucleate cell formation in a btu1-1-dependent manner. Conversely, the myosin light chain kinase inhibitor ML-7 has no effect on nuclear division in the btu1-1 mutant strain. These findings provide new insights into microtubule dynamics and link the evolutionarily conserved PI 3-kinase signaling pathway to nuclear migration and/or division in Tetrahymena.     

Vesicular stomatitis virus oncolytic treatment interferes with tumor-associated dendritic cell functions and abrogates tumor antigen presentation

Oncolytic virotherapy is a promising biological approach to cancer treatment that contributes to tumor eradication via immune- and non-immune-mediated mechanisms. One of the remaining challenges for these experimental therapies is the necessity to develop a durable adaptive immune response against the tumor. Vesicular stomatitis virus (VSV) is a prototypical oncolytic virus (OV) that exemplifies the multiple mechanisms of oncolysis, including direct cell lysis, cellular hypoxia resulting from the shutdown of tumor vasculature, and inflammatory cytokine release. Despite these properties, the generation of sustained antitumor immunity is observed only when VSV is engineered to express a tumor antigen directly. In the present study, we sought to increase the number of tumor-associated dendritic cells (DC) in vivo and tumor antigen presentation by combining VSV treatment with recombinant Fms-like tyrosine kinase 3 ligand (rFlt3L), a growth factor promoting the differentiation and proliferation of DC. The combination of VSV oncolysis and rFLt3L improved animal survival in two different tumor models, i.e., VSV-resistant B16 melanoma and VSV-sensitive E.G7 T lymphoma; however, increased survival was independent of the adaptive CD8 T cell response. Tumor-associated DC were actively infected by VSV in vivo, which reduced their viability and prevented their migration to the draining lymph nodes to prime a tumor-specific CD8 T cell response. These results demonstrate that VSV interferes with tumor DC functions and blocks tumor antigen presentation.     

Photomorphogenic development of the Arabidopsisshy2–1D mutation and its interaction with phytochromes in darkness

We previously reported a photomorphogenic mutation of Arabidopsis thaliana, shy2–1D, as a dominant suppressor of a hy2 mutation. Here, we report that shy2–1D confers various photo-responsive phenotypes in darkness and the dark phenotypes of the mutant are affected by phytochrome deficiency. Dark-grown seedlings of the mutant developed several photomorphogenic characteristics such as short hypocotyls, cotyledon expansion and opening, and partial differentiation of plastids. When grown further in darkness, the mutant plant underwent most of the developmental stages of a light-grown wild-type plant, including development of foliar leaves, an inflorescence stem with cauline leaves, and floral organs. In addition, two light-inducible genes, the nuclear-encoded CAB and the plastid-encoded PSBA genes, were highly expressed in the dark-grown mutant seedlings. Furthermore, reduced gravitropism, a phytochrome-modulated response, was observed in the mutant hypocotyl in darkness. Thus, shy2–1D is one of the most pleiotropic photomorphogenic mutations identified so far. The results indicate that SHY2 may be a key component regulating photomorphogenesis in Arabidopsis. Surprisingly, double mutants of the shy2–1D mutant with the phytochrome-deficient mutants hy2, hy3 (phyB-1) and fre1–1 (phyA-201) showed reduced photomorphogenic response in darkness with a longer hypocotyl, a longer inflorescence stem, and a lower level expression of the CAB gene than the shy2–1D single mutant. These results showed that phytochromes function in darkness in the shy2–1D mutant background. The implications of these results are discussed.     

A single-nucleotide polymorphism in lnc-LAMC2-1:1 interferes with its interaction with miR-128 to alter the expression of deleted in colorectal cancer and its effect on the survival rate of subjects with ovarian cancer

This study aimed to identify the association between lnc-LAMC2-1:1 polymorphism rs2147578 and the recurrence of ovary cancer, as well as to study the underlying mechanism of rs2147578 in ovary cancer. Real-time polymerase chain reaction, Western blot analysis, immunohistochemistry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, Logrank test, and Kaplan-Meier analysis were carried out to explore the role of rs2147578 in ovary cancer. No obvious difference was observed concerning all clinical characteristics among 90 patients genotyped as CC (N = 28), CG (N = 38), and GG (N = 24) in their rs2147578 polymorphism. In addition, the subjects carrying the CC genotype had longer recurrence-free survival time and showed a lower level of malignancy compared with those carrying CG and GG genotypes. Lnc-LAMC2-1:1 and miR-128 were lowly expressed in the CC group, while deleted in colorectal cancer (DCC) was highly expressed in the CC group. Furthermore, DCC was identified as a target gene of miR-128, and miR-128 mimics decreased the luciferase activity of cells cotransfected with wild-type DCC 3′-untranslated region. Lnc-LAMC2:1-1 directly targeted and affected miR-128 expression, and the G allele in lnc-LAMC2-1:1 rs2147578 upregulated miR-128 expression. Transfection with a miR-128 precursor evidently downregulated the expression of lnc-LAMC2-1:1, miR-128, and DCC expression, but did not affect the expression of ABCC5 and body mass index. Finally, miR-128 precursor promoted cell proliferation and inhibited cell apoptosis. Compared with lnc-LAMC2-1:1 rs2147578C allele, the G allele increases the risk of ovarian cancer by reducing the binding between lnc-LAMC2-1:1 and miR-128-3p, which in turn further decreases the expression of DCC and inhibits cell apoptosis.     

Dma1 prevents mitotic exit and cytokinesis by inhibiting the septation initiation network (SIN)

In the fission yeast Schizosaccharomyces pombe, the septation initiation network (SIN) triggers cytokinesis after mitosis. We investigated the relationship between Dma1p, a spindle checkpoint protein and cytokinesis inhibitor, and the SIN. Deletion of dma1 inactivates the spindle checkpoint and allows precocious SIN activation, while overexpressing Dma1p reduces SIN signaling. Dma1p seems to function by inhibiting the SIN activator, Plo1p kinase, since dma1 overexpression and deletion phenotypes suggest that Dma1p antagonizes Plo1p localization. Furthermore, failure to maintain high cyclin-dependent kinase (CDK) activity during spindle checkpoint activation in dma1 deletion cells requires Plo1p. Dma1p itself localizes to spindle pole bodies through interaction with Sid4p. Our observations suggest that Dma1p functions to prevent mitotic exit and cytokinesis during spindle checkpoint arrest by inhibiting SIN signaling.