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Shigeo Ohno

Publications and source records attributed to Shigeo Ohno.

At least 19 recordsLinked to original sources
PubMed2025

High p62 and ALDH1A3 Reduce the Effectiveness of Endocrine Therapy in Luminal B Breast Cancer.

BACKGROUND/AIM: High expression of p62 and ALDH1A3 indicates a poor clinical outcome in luminal B breast cancer, and p62 is involved in the progression of ALDH1-positive luminal B breast cancer stem cells. However, the association between endocrine therapy and high p62 and ALDH1A3 expression, in luminal B breast cancer remains unclear. MATERIALS AND METHODS: Two datasets with gene expression and clinical data for patients with primary breast cancer (METABRIC, n=2,509; The Cancer Genome Atlas, n=1,084) were downloaded and statistically analyzed. To evaluate the association between the p62 and ALDH1A3 expression levels and endocrine therapy, including tamoxifen and aromatase inhibitor, in patients with luminal B breast cancer, disease-specific survival was examined using Kaplan-Meier and multivariate Cox regression analyses. RESULTS: Patients with p62 high ALDH1A3 high luminal B breast cancer treated with endocrine therapy exhibited a poor prognosis. Moreover, patients with p62 high ALDH1A3 high luminal B breast cancer treated with tamoxifen showed a trend towards a poor prognosis, but those treated with aromatase inhibitors showed a significantly poor prognosis. These results suggest that endocrine therapy, especially aromatase inhibitors, exhibits a reduced effectiveness against p62 high ALDH1A3 high luminal B tumors. CONCLUSION: p62 and ALDH1A3 could be used together as a prognostic biomarker for predicting the efficacy of endocrine therapy for luminal B breast cancer.

ALDH1A3↗
PubMed2025

PKCζ, CTNNBIP1 and ALDH1A3 Expression in Luminal B Breast Cancer Indicates Decreased Hormone Therapy Effectiveness.

BACKGROUND/AIM: The role of catenin β interacting protein 1 (CTNNBIP1), a negative regulator of the canonical Wnt/β-catenin signaling pathway, in luminal A and B breast cancer stem cells treated with hormone therapy is unknown. This study investigated the relationship between CTNNBIP1 and aldehyde dehydrogenase 1 family member A3 (ALDH1A3) expression and its impact on disease-specific survival in luminal A and B breast cancer. Given that high protein kinase ζ (PKCζ) expression, together with elevated CTNNBIP1 or ALDH1A3, is linked to poor prognosis in luminal B tumors, we also examined their combined influence. MATERIALS AND METHODS: Gene expression and clinical data from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=2,509) were analyzed using Kaplan-Meier and Cox proportional hazards models. Findings were validated with The Cancer Genome Atlas Pan-Cancer Atlas (TCGA; n=1,084). RESULTS: CTNNBIP1 high ALDH1A3 high indicated a poor prognosis in patients with luminal B breast cancer treated with hormone therapy in the METABRIC dataset and aromatase inhibitors as hormone therapy in the TCGA data set, suggesting that high CTNNBIP1 and ALDH1A3 expression contributed to decreased effectiveness of hormone therapy in patients with luminal B breast cancer. PKC ζ high CTNNBIP1 high ALDH1A3 high was associated with a poor prognosis in patients with luminal B breast cancer treated with hormone therapy and aromatase inhibitors, suggesting that high PKC ζ , CTNNBIP1 and ALDH1A3 expression contributed to decreased effectiveness of hormone therapy in patients with luminal B breast cancer. CONCLUSION: PKC ζ and CTNNBIP1 may be involved in the progression of ALDH1A3-positive luminal B breast cancer. In luminal B breast cancer, PKC ζ , CTNNBIP1 and ALDH1A3 could serve as molecular drug targets and prognostic biomarkers to predict the effectiveness of hormone therapy.

ALDH1A3↗
PubMed2007

Distant N- and C-terminal domains are required for intrinsic kinase activity of SMG-1, a critical component of nonsense-mediated mRNA decay.

Phosphatidylinositol 3-kinase-related kinases (PIKKs) consisting of SMG-1, ATM, ATR, DNA-PKcs, and mTOR are a family of proteins involved in the surveillance of gene expression in eukaryotic cells. They are involved in mechanisms responsible for genome stability, mRNA quality, and translation. They share a large N-terminal domain and a C-terminal FATC domain in addition to the unique serine/threonine protein kinase (PIKK) domain that is different from classical protein kinases. However, structure-function relationships of PIKKs remain unclear. Here we have focused on one of the PIKK members, SMG-1, which is involved in RNA surveillance, termed nonsense-mediated mRNA decay (NMD), to analyze the roles of conserved and SMG-1-specific sequences on the intrinsic kinase activity. Analyses of sets of point and deletion mutants of SMG-1 in a purified system and intact cells revealed that the long N-terminal region and the conserved leucine in the FATC domain were essential for SMG-1 kinase activity. However, the conserved tryptophan in the TOR SMG-1 (TS) homology domain and the FATC domain was not. In addition, the long insertion region between PIKK and FATC domains was not essential for SMG-1 kinase activity. These results indicated an unexpected feature of SMG-1, i.e. that distantly located N- and C-terminal sequences were essential for the intrinsic kinase activity.

Cell Line↗
PubMed2006

The c-Jun N-terminal kinase activator dual leucine zipper kinase regulates axon growth and neuronal migration in the developing cerebral cortex.

Mammalian corticogenesis substantially depends on migration and axon projection of newborn neurons that are coordinated by a yet unidentified molecular mechanism. Dual leucine zipper kinase (DLK) induces activation of c-Jun N-terminal kinase (JNK), a molecule that regulates morphogenesis in various organisms. We show here, using gene targeting in mice, that DLK is indispensable for establishing axon tracts, especially those originating from neocortical pyramidal neurons of the cerebrum. Direct and quantitative analysis of radial migration of pyramidal neurons using slice culture and a time-lapse imaging system revealed that acceleration around the subplate was affected by DLK gene disruption and by administration of a JNK inhibitor. Phosphorylation of JNK substrates, including c-Jun and doublecortin, and of JNK itself at the activation loop were partially affected in brains of DLK-deficient mouse embryos. These data suggest that DLK plays a significant role in the coordinated regulation of radial migration and axon projection by modulating JNK activity.

Animals↗
PubMed2006

Neonatal pancreatic cells redifferentiate into both neural and pancreatic lineages.

Studies of islet neogenesis have suggested that the regeneration of islet cells can be achieved through redifferentiation of pre-existing islet cells. However, this hypothesis is largely unproven and fails to account for the diversity of observed islet neogenesis. Here we show that cultured neonatal pancreatic cells dedifferentiate into betaIII tubulin-expressing precursors, which then expand and redifferentiate into both neural and pancreatic lineage progenies. Redifferentiation happens not only in the islet cells, but also in the ductal cells that may represent what are called ductal origin "pancreatic stem cells". The in vitro redifferentiation of neonatal pancreatic cells recapitulates the embryonic development by sequential endocrine differentiation accompanied by the coexpression of neuronal marker betaIII tubulin with endocrine hormones until terminal differentiation. The neuronal differentiation of pancreatic cells, however, occurs prior to endocrine differentiation and gradually becomes dominant, thus implying a default neuronal lineage specification for cultured pancreatic cells.

Animals↗
PubMed2006

A distinct PAR complex associates physically with VE-cadherin in vertebrate endothelial cells.

A cell polarity complex consisting of partitioning defective 3 (PAR-3), atypical protein kinase C (aPKC) and PAR-6 has a central role in the development of cell polarity in epithelial cells. In vertebrate epithelial cells, this complex localizes to tight junctions. Here, we provide evidence for the existence of a distinct PAR protein complex in endothelial cells. Both PAR-3 and PAR-6 associate directly with the adherens junction protein vascular endothelial cadherin (VE-cadherin). This association is direct and mediated through non-overlapping domains in VE-cadherin. PAR-3 and PAR-6 are recruited independently to cell-cell contacts. Surprisingly, the VE-cadherin-associated PAR protein complex lacks aPKC. Ectopic expression of VE-cadherin in epithelial cells affects tight junction formation. Our findings suggest that in endothelial cells, another PAR protein complex exists that localizes to adherens junctions and does not promote cellular polarization through aPKC activity. They also point to a direct role of a cadherin in the regulation of cell polarity in vertebrates.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Specific inhibition of nonsense-mediated mRNA decay components, SMG-1 or Upf1, rescues the phenotype of Ullrich disease fibroblasts.

Nonsense-mediated mRNA decay (NMD) is an mRNA quality-control mechanism that degrades aberrant mRNAs containing premature translation termination codons (PTCs). The essential proteins for NMD include SMG-1, a protein kinase, and Upf1, a substrate of SMG-1 with RNA helicase activity. In this study, we evaluated the effects of NMD inhibition by siRNA-mediated knockdown of SMG-1 or Upf1 on the phenotype of Ullrich disease, an autosomal recessive congenital muscular dystrophy. The patient studied showed a homozygous frameshift mutation with a PTC in the collagen VI alpha2 gene, which encodes a truncated but partially functional protein. The patient's fibroblasts showed a nearly complete loss of the triple-helical collagen VI protein and functional defects in the extracellular matrix (ECM) due to the crucial deficiency of the collagen VI alpha2 protein. We have shown that siRNA-mediated knockdown of SMG-1 or Upf1 causes the up-regulation of the mutant triple-helical collagen VI, resulting in the formation of partially functional ECM. We suggest that the inhibition of NMD may be useful as a therapeutic approach to treat some human genetic diseases exacerbated by NMD.

Adult↗
PubMed2006

Lgl mediates apical domain disassembly by suppressing the PAR-3-aPKC-PAR-6 complex to orient apical membrane polarity.

The basolateral tumor suppressor protein Lgl is important for the regulation of epithelial cell polarity and tissue morphology. Recent studies have shown a physical and functional interaction of Lgl with another polarity-regulating protein machinery, the apical PAR-3-aPKC-PAR-6 complex, in epithelial cells. However, the mechanism of Lgl-mediated regulation of epithelial cell polarity remains obscure. By an siRNA method, we here show that endogenous Lgl is required for the disassembly of apical membrane domains in depolarizing MDCK cells induced by Ca2+ depletion. Importantly, this Lgl function is mediated by the suppression of the apical PAR-3-aPKC-PAR-6 complex activity. Analysis using 2D- or 3D-cultured cells in collagen gel suggests the importance of this suppressive regulation of Lgl on the collagen-mediated re-establishment of apical membrane domains and lumen formation. These results indicate that basolateral Lgl plays a crucial role in the disassembly of apical membrane domains to induce the orientation of apical membrane polarity, which is mediated by the suppression of apical PAR-3-aPKC-PAR-6 complex activity.

Animals↗
PubMed2006

Inactivation of aPKClambda results in the loss of adherens junctions in neuroepithelial cells without affecting neurogenesis in mouse neocortex.

In developing mammalian telencephalon, the loss of adherens junctions and cell cycle exit represent crucial steps in the differentiation of neuroepithelial cells into neurons, but the relationship between these cellular events remains obscure. Atypical protein kinase C (aPKC) is known to contribute to junction formation in epithelial cells and to cell fate determination for Drosophila neuroblasts. To elucidate the functions of aPKClambda, one out of two aPKC members, in mouse neocortical neurogenesis, a Nestin-Cre mediated conditional gene targeting system was employed. In conditional aPKClambda knockout mice, neuroepithelial cells of the neocortical region lost aPKClambda protein at embryonic day 15 and demonstrated a loss of adherens junctions, retraction of apical processes and impaired interkinetic nuclear migration that resulted in disordered neuroepithelial tissue architecture. These results are evidence that aPKClambda is indispensable for the maintenance of adherens junctions and may function in the regulation of adherens junction integrity upon differentiation of neuroepithelial cells into neurons. In spite of the loss of adherens junctions in the neuroepithelium of conditional aPKClambda knockout mice, neurons were produced at a normal rate. Therefore, we concluded that, at least in the later stages of neurogenesis, regulation of cell cycle exit is independent of adherens junctions.

Adherens Junctions↗
PubMed2006

The PAR-aPKC system: lessons in polarity.

Ten years ago, par-1 and par-3 were cloned as two of the six par genes essential for the asymmetric division of the Caenorhabditis elegans zygote. PAR-1 is a protein kinase, whereas PAR-3 is a PDZ-domain-containing scaffold protein. Work over the past decade has shown that they are part of an evolutionarily conserved PAR-aPKC system involved in cell polarity in various biological contexts. Recent progress has illustrated the common principle that the PAR-aPKC system is the molecular machinery that converts initial polarity cues in the establishment of complementary membrane domains along the polarity axis. In most cases, this is achieved by mutually antagonistic interactions between the aPKC-PAR-3-PAR-6 complex and PAR-1 or PAR2 located opposite. However, accumulating evidence has also revealed that mechanisms by which the asymmetrically localized components of the PAR-aPKC system are linked with other cellular machinery for developing polarity are divergent depending on the cell type.

14-3-3 Proteins↗
PubMed2006

The gamma-parvin-integrin-linked kinase complex is critically involved in leukocyte-substrate interaction.

Leukocyte extravasation is an important step of inflammation, in which integrins have been demonstrated to play an essential role by mediating the interaction of leukocytes with the vascular endothelium and the subendothelial extracellular matrix. Previously, we identified an integrin-linked kinase (ILK)-binding protein affixin (beta-parvin), which links initial integrin signals to rapid actin reorganization, and thus plays critical roles in fibroblast migration. In this study, we demonstrate that gamma-parvin, one of three mammalian parvin family members, is specifically expressed in several lymphoid and monocytic cell lines in a complementary manner to affixin. Like affixin, gamma-parvin directly associates with ILK through its CH2 domain and colocalizes with ILK at focal adhesions as well as the leading edge of PMA-stimulated U937 cells plated on fibronectin. The overexpression of the C-terminal fragment containing CH2 domain or the depletion of gamma-parvin by RNA interference inhibits the substrate adhesion of MCP-1-stimulated U937 cells and the spreading of PMA-stimulated U937 cells on fibronectin. Interestingly, the overexpression of the CH2 fragment or the gamma-parvin RNA interference also disrupts the asymmetric distribution of PTEN and F-actin observed at the very early stage of cell spreading, suggesting that the ILK-gamma-parvin complex is essential for the establishment of cell polarity required for leukocyte migration. Taken together with the results that gamma-parvin could form a complex with some important cytoskeletal proteins, such as alphaPIX, alpha-actinin, and paxillin as demonstrated for affixin and actopaxin (alpha-parvin), the results in this study suggest that the ILK-gamma-parvin complex is critically involved in the initial integrin signaling for leukocyte migration.

Actinin↗
PubMed2006

Developmental changes in the expression pattern of the JNK activator kinase MUK/DLK/ZPK and active JNK in the mouse cerebellum.

JNK is one of the key molecules regulating cell differentiation and migration in a variety of cell types, including cerebral cortical neurons. MUK/DLK/ZPK belongs to the MAP kinase-kinase-kinase class of protein kinases for the JNK pathway and is expressed predominantly in neural tissue. We have determined the expression pattern of MUK/DLK/ZPK and active JNK in the cerebellum at different stages of postnatal development. Quantitative analysis by Western blotting has showed that high expression levels of MUK/DLK/ZPK and active JNK are maintained during the postnatal development of the cerebellum, and that these levels decrease in the adult cerebellum. Immunohistochemical staining has revealed, however, that their distribution in the developing cerebellum is considerably different. Although active JNK is highly concentrated in the premigratory zone of the external germinal layer (EGL), high expression of MUK/DLK/ZPK has been observed in the molecular layer and in the premigratory zone. Neither the active JNK nor MUK protein has been detected in the proliferative zone of the EGL. These observations suggest that during the postnatal development of the cerebellum, the MUK-JNK signaling pathway contributes to the regulation of granule cell differentiation and migration; further, the activity of MUK/DLK/ZPK is tightly regulated by posttranslational mechanisms and by its expression level.

Animals↗
PubMed2006

PAR3 is essential for cyst-mediated epicardial development by establishing apical cortical domains.

Epithelial cysts are one of the fundamental architectures for mammalian organogenesis. Although in vitro studies using cultured epithelial cells have revealed proteins required for cyst formation, the mechanisms that orchestrate the functions of these proteins in vivo remain to be clarified. We show that the targeted disruption of the mouse Par3 gene results in midgestational embryonic lethality with defective epicardial development. The epicardium is mainly derived from epicardial cysts and essential for cardiomyocyte proliferation during cardiac morphogenesis. PAR3-deficient epicardial progenitor (EPP) cells do not form cell cysts and show defects in the establishment of apical cortical domains, but not in basolateral domains. In PAR3-deficient EPP cells, the localizations of aPKC, PAR6beta and ezrin to the apical cortical domains are disturbed. By contrast, ZO1 and alpha4/beta1 integrins normally localize to cell-cell junctions and basal domains, respectively. Our observations indicate that EPP cell cyst formation requires PAR3 to interpret the polarity cues from cell-cell and cell-extracellular matrix interactions so that each EPP cell establishes apical cortical domains. These results also provide a clear example of the proper organization of epithelial tissues through the regulation of individual cell polarity.

Animals↗
PubMed2006

Nucleotide exchange factor ECT2 regulates epithelial cell polarity.

Cell polarity regulates diverse biological events such as localization of embryonic determinants and establishment of tissue and organ architecture. Epithelial cell polarity is regulated by the polarity complex Par6/Par3/atypical protein kinase C (aPKC). We previously found that the nucleotide exchange factor ECT2 associates with this polarity complex and regulates aPKC activity, but the role of ECT2 in cell polarity is still unclear. Here we show that expression of a dominant negative (ECT2-N2) or constitutively active (ECT2-DeltaN5) form of ECT2 inhibits normal cyst formation of MDCK cells in 3-dimensional collagen gels. Central lumens were not observed in cysts formed by cells expressing either ECT2-DeltaN5 or ECT2-N2. Apical localization of ZO-1 and basolateral localization of beta-catenin were no longer observed in these cells. Interestingly, cells expressing ECT2-N2 did form normal cysts when cultured in the basement membrane matrix Matrigel instead of collagen gels. Addition of a major Matrigel component, laminin, partially rescued the normal cyst formation inhibited by ECT2-N2 in 3-dimensional collagen gels. Thus, signaling through laminin might override the defects of signaling through collagen and ECT2. Whereas ECT2-N2 inhibited the lumen formation of MDCK cysts, caspase-3, which is reportedly involved in lumen formation through apoptosis, was activated at various locations of cells in the cysts. It is likely that perturbation of ECT2 signaling inhibits the establishment of epithelial cell polarity leading to the inhibition of selected elimination of cells at the center of cysts. Thus, ECT2 appears to play a critical role in epithelial cell polarity.

Animals↗
PubMed2006

Binding of a novel SMG-1-Upf1-eRF1-eRF3 complex (SURF) to the exon junction complex triggers Upf1 phosphorylation and nonsense-mediated mRNA decay.

Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that degrades mRNA containing premature termination codons (PTCs). In mammalian cells, recognition of PTCs requires translation and depends on the presence on the mRNA with the splicing-dependent exon junction complex (EJC). While it is known that a key event in the triggering of NMD is phosphorylation of the trans-acting factor, Upf1, by SMG-1, the relationship between Upf1 phosphorylation and PTC recognition remains undetermined. Here we show that SMG-1 binds to the mRNA-associated components of the EJC, Upf2, Upf3b, eIF4A3, Magoh, and Y14. Further, we describe a novel complex that contains the NMD factors SMG-1 and Upf1, and the translation termination release factors eRF1 and eRF3 (SURF). Importantly, an association between SURF and the EJC is required for SMG-1-mediated Upf1 phosphorylation and NMD. Thus, the SMG-1-mediated phosphorylation of Upf1 occurs on the association of SURF with EJC, which provides the link between the EJC and recognition of PTCs and triggers NMD.

Codon, Nonsense↗