Keiichi I Nakayama

Kyushu University, Hukuoka, Fukuoka, Japan

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Publications (232)1853.27 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Gata3 acts as a master regulator for T helper 2 (Th2) cell differentiation by inducing chromatin remodeling of the Th2 cytokine loci, accelerating Th2 cell proliferation and repressing Th1 cell differentiation. Gata3 also directly transactivates the Interleukin-5 (Il5) gene via additional mechanisms that have not been fully elucidated. We herein identified a mechanism whereby the methylation of Gata3 at Arg261 regulates the transcriptional activation of the Il5 gene in Th2 cells. Although the methylation-mimicking Gata3 mutant retained the ability to induce IL-4 and repress IFNγ production, the IL-5 production was selectively impaired. We also demonstrated that Heat shock protein (Hsp) 60 strongly associates with the methylation-mimicking Gata3 mutant and negatively regulates elongation of the Il5 transcript by RNA polymerase II. Thus, arginine methylation appears to play a pivotal role in the organization of Gata3 complexes and the target gene specificity of Gata3. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 04/2015; DOI:10.1074/jbc.M114.621524 · 4.60 Impact Factor
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    ABSTRACT: The mechanism by which adult neural stem cells (NSCs) are established during development is unclear. In this study, analysis of cell cycle progression by examining retention of a histone 2B (H2B)-GFP fusion protein revealed that, in a subset of mouse embryonic neural progenitor cells (NPCs), the cell cycle slows between embryonic day (E) 13.5 and E15.5 while other embryonic NPCs continue to divide rapidly. By allowing H2B-GFP expressed at E9.5 to become diluted in dividing cells until the young adult stage, we determined that a majority of NSCs in the young adult subependymal zone (SEZ) originated from these slowly dividing embryonic NPCs. The cyclin-dependent kinase inhibitor p57 is highly expressed in this embryonic subpopulation, and the deletion of p57 impairs the emergence of adult NSCs. Our results suggest that a substantial fraction of adult SEZ NSCs is derived from a slowly dividing subpopulation of embryonic NPCs and identify p57 as a key factor in generating this embryonic origin of adult SEZ NSCs.
    Nature Neuroscience 03/2015; 18(5). DOI:10.1038/nn.3989 · 14.98 Impact Factor
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    ABSTRACT: A GATA family transcription factor GATA binding protein 2 (GATA2) participates in cell growth and differentiation of various cells such as hematopoietic stem cells. Although its expression level is controlled by transcriptional induction and proteolytic degradation, the responsible E3 ligase has not been identified. Here, we demonstrate that F-box/WD repeat-containing protein 7 (Fbw7/Fbxw7), a component of Skp1, Cullin 1, F-box containing complex (SCF)-type E3 ligase, is an E3 ligase for GATA2. GATA2 contains a cell division control protein (CDC) 4-phosphodegron (CPD), a consensus motif for ubiquitylation by Fbw7, which includes Thr-176. Ectopic expression of Fbw7 destabilized GATA2 and promoted its proteasomal degradation. Substitution of threonine 176 to alanine in GATA2 inhibited binding with Fbw7 and the ubiquitylation and degradation of GATA2 by Fbw7 was suppressed. The CPD kinase, which mediates the phosphorylation of Thr-176, was cyclin B-cyclin dependent kinase (CDK) 1. Moreover, depletion of endogenous Fbw7 stabilized endogenous GATA2 in K562 cells. Conditional Fbw7-depletion in mice increased GATA2 levels in hematopoietic stem cells and myeloid progenitors at the early stage. Increased GATA2 levels in Fbw7-conditional knockout mice were correlated with a decrease in a c-Kit high expressing population of myeloid progenitor cells. Our results suggest that Fbw7 is a bona fide E3 ubiquitin ligase for GATA2 in vivo. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 02/2015; 290(16). DOI:10.1074/jbc.M114.613018 · 4.60 Impact Factor
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    ABSTRACT: The gene encoding F-box protein FBXW7 is frequently mutated in many human cancers. Although most previous studies have focused on the tumor-suppressive capacity of FBXW7 in tumor cells themselves, we determined that FBXW7 in the host microenvironment also suppresses cancer metastasis. Deletion of Fbxw7 in murine BM-derived stromal cells induced accumulation of NOTCH and consequent transcriptional activation of Ccl2. FBXW7-deficient mice exhibited increased serum levels of the chemokine CCL2, which resulted in the recruitment of both monocytic myeloid-derived suppressor cells and macrophages, thereby promoting metastatic tumor growth. Administration of a CCL2 receptor antagonist blocked the enhancement of metastasis in FBXW7-deficient mice. Furthermore, in human breast cancer patients, FBXW7 expression in peripheral blood was associated with serum CCL2 concentration and disease prognosis. Together, these results suggest that FBXW7 antagonizes cancer development in not only a cell-autonomous manner, but also a non-cell-autonomous manner, and that modulation of the FBXW7/NOTCH/CCL2 axis may provide a potential approach to suppression of cancer metastasis.
    Journal of Clinical Investigation 01/2015; 125(2). DOI:10.1172/JCI78782 · 13.77 Impact Factor
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    ABSTRACT: Aberrant elevation of JARID1B and histone H3 lysine 4 trimethylation (H3K4me3) is frequently observed in many diseases including prostate cancer (PCa), yet the mechanisms on the regulation of JARID1B and H3K4me3 through epigenetic alterations still remain poorly understood. Here we report that Skp2 modulates JARID1B and H3K4me3 levels in vitro in cultured cells and in vivo in mouse models. We demonstrated that Skp2 inactivation decreased H3K4me3 levels, along with a reduction of cell growth, cell migration and malignant transformation of Pten/Trp53 double null MEFs, and further restrained prostate tumorigenesis of Pten/Trp53 mutant mice. Mechanistically, Skp2 decreased the K63-linked ubiquitination of JARID1B by E3 ubiquitin ligase TRAF6, thus decreasing JARID1B demethylase activity and in turn increasing H3K4me3. In agreement, Skp2 deficiency resulted in an increase of JARID1B ubiquitination and in turn a reduction of H3K4me3, and induced senescence through JARID1B accumulation in nucleoli of PCa cells and prostate tumors of mice. Furthermore, we showed that the elevations of Skp2 and H3K4me3 contributed to castration-resistant prostate cancer (CRPC) in mice, and were positively correlated in human PCa specimens. Taken together, our findings reveal a novel network of SKP2-JARID1B, and targeting SKP2 and JARID1B may be a potential strategy for PCa control.
    Oncotarget 12/2014; · 6.63 Impact Factor
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    ABSTRACT: Cellular homeostasis is regulated by signals through multiple molecular networks that include protein phosphorylation and metabolites. However, where and when the signal flows through a network and regulates homeostasis has not been explored. We have developed a reconstruction method for the signal flow based on time-course phosphoproteome and metabolome data, using multiple databases, and have applied it to acute action of insulin, an important hormone for metabolic homeostasis. An insulin signal flows through a network, through signaling pathways that involve 13 protein kinases, 26 phosphorylated metabolic enzymes, and 35 allosteric effectors, resulting in quantitative changes in 44 metabolites. Analysis of the network reveals that insulin induces phosphorylation and activation of liver-type phosphofructokinase 1, thereby controlling a key reaction in glycolysis. We thus provide a versatile method of reconstruction of signal flow through the network using phosphoproteome and metabolome data.
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    ABSTRACT: Low-density lipoprotein receptor (LDLR) mRNA is unstable, but is stabilized upon extracellular signal-regulated kinase (ERK) activation, possibly through the binding of certain proteins to the LDLR mRNA 3'-untranslated region (UTR), although the detailed mechanism underlying this stability control is unclear. Here, using a proteomic approach, we show that proteins ZFP36L1 and ZFP36L2 specifically bind to the 3'-UTR of LDLR mRNA and recruit the CCR4-NOT-deadenylase complex, resulting in mRNA destabilization. We also show that the C-terminal regions of ZFP36L1 and ZFP36L2 are directly phosphorylated by p90 ribosomal S6 kinase, a kinase downstream of ERK, resulting in dissociation of the CCR4-NOT-deadenylase complex and stabilization of LDLR mRNA. We further demonstrate that targeted disruption of the interaction between LDLR mRNA and ZFP36L1 and ZFP36L2 using antisense oligonucleotides results in upregulation of LDLR mRNA and protein. These results indicate that ZFP36L1 and ZFP36L2 regulate LDLR protein levels downstream of ERK. Our results also show the usefulness of our method for identifying critical regulators of specific RNAs and the potency of antisense oligonucleotide-based therapeutics.
    Nucleic Acids Research 08/2014; 42(15). DOI:10.1093/nar/gku652 · 8.81 Impact Factor
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    ABSTRACT: Sonic hedgehog (Shh) is a secreted morphogen that controls the patterning and growth of various tissues in the developing vertebrate embryo, including the central nervous system. Ablation of the FK506-binding protein 38 (FKBP38) gene results in activation of the Shh signaling pathway in mouse embryos, but the molecular mechanism by which FKBP38 suppresses Shh signaling has remained unclear. With the use of a proteomics approach, we have now identified ANKMY2, a protein with three ankyrin repeats and a MYND (myeloid, Nervy, and DEAF-1)-type Zn(2+)-finger domain, as a molecule that interacts with FKBP38. Co-immunoprecipitation analysis confirmed that endogenous FKBP38 and ANKMY2 interact in mouse brain. Depletion or overexpression of ANKMY2 resulted in down- and up-regulation of Shh signaling, respectively, in mouse embryonic fibroblasts. Furthermore, combined depletion of both FKBP38 and ANKMY2 attenuated Shh signaling in these cells, suggesting that ANKMY2 acts downstream of FKBP38 to activate the Shh signaling pathway. Targeting of the zebrafish ortholog of mouse Ankmy2 (ankmy2a) in fish embryos with an antisense morpholino oligonucleotide conferred a phenotype reflecting loss of function of the Shh pathway, suggesting that the regulation of Shh signaling by ANKMY2 is conserved between mammals and fish. Our findings thus indicate that the FKBP38-ANKMY2 axis plays a key role in regulation of Shh signaling in vivo.
    Journal of Biological Chemistry 07/2014; 289(37). DOI:10.1074/jbc.M114.558635 · 4.60 Impact Factor
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    ABSTRACT: MDM2 mediates the ubiquitylation and thereby triggers the proteasomal degradation of the tumor suppressor protein p53. However, genetic evidence suggests that MDM2 contributes to multiple regulatory networks independent of p53 degradation. We have now identified the DEAD-box RNA helicase DDX24 as a nucleolar protein that interacts with MDM2. DDX24 was found to bind to the central region of MDM2, resulting in the polyubiquitylation of DDX24 both in vitro and in vivo. Unexpectedly, however, the polyubiquitylation of DDX24 did not elicit its proteasomal degradation but rather promoted its association with pre-ribosomal ribonucleoprotein (pre-rRNP) processing complexes that are required for the early steps of pre-rRNA processing. Consistent with these findings, depletion of DDX24 in cells impaired pre-rRNA processing and resulted both in abrogation of MDM2 function and in consequent p53 stabilization. Our results thus suggest an unexpected role of MDM2 in nonproteolytic ubiquitylation of DDX24, which may contribute to the regulation of pre-rRNA processing.
    Molecular and Cellular Biology 06/2014; 34(17). DOI:10.1128/MCB.00320-14 · 5.04 Impact Factor
  • Michiko Shirane-Kitsuji, Keiichi I. Nakayama
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    ABSTRACT: FK506-binding protein 38 (FKBP38) is a membrane chaperone that is localized predominantly to mitochondria and contains a COOH-terminal tail anchor. FKBP38 also harbors an FKBP domain that confers peptidyl-prolyl cis–trans isomerase activity, but it differs from other FKBP family members in that this activity is dependent on the binding of Ca2+-calmodulin. FKBP38 inhibits apoptosis by recruiting the anti-apoptotic proteins Bcl-2 and Bcl-xL to mitochondria. Mice deficient in FKBP38 die soon after birth manifesting a defect in neural tube closure that results in part from unrestrained apoptosis. We recently found that FKBP38 and Bcl-2 translocate from mitochondria to the endoplasmic reticulum during mitophagy, a form of autophagy responsible for the elimination of damaged mitochondria. FKBP38 and Bcl-2 thus escape the degradative fate of most mitochondrial proteins during mitophagy. This escape of FKBP38 is dependent on the low basicity of its COOH-terminal sequence and is essential for the suppression of apoptosis during mitophagy. FKBP38 thus plays a key role in the regulation of apoptosis under normal and pathological conditions.
    The international journal of biochemistry & cell biology 06/2014; 51. DOI:10.1016/j.biocel.2014.03.007 · 4.24 Impact Factor
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    ABSTRACT: Spermatogonial stem cells (SSCs) undergo self-renewal divisions to support spermatogenesis throughout life. Although several positive regulators of SSC self-renewal have been discovered, little is known about the negative regulators. Here, we report that F-box and WD-40 domain protein 7 (FBXW7), a component of the Skp1-Cullin-F-box-type ubiquitin ligase, is a negative regulator of SSC self-renewal. FBXW7 is expressed in undifferentiated spermatogonia in a cell cycle-dependent manner. Although peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1), essential for spermatogenesis, is thought to destroy FBXW7, Pin1 depletion decreased FBXW7 expression. Spermatogonial transplantation showed that Fbxw7 overexpression compromised SSC activity whereas Fbxw7 deficiency enhanced SSC colonization and caused accumulation of undifferentiated spermatogonia, suggesting that the level of FBXW7 is critical for self-renewal and differentiation. Screening of putative FBXW7 targets revealed that Fbxw7 deficiency up-regulated myelocytomatosis oncogene (MYC) and cyclin E1 (CCNE1). Although depletion of Myc/Mycn or Ccne1/Ccne2 compromised SSC activity, overexpression of Myc, but not Ccne1, increased colonization of SSCs. These results suggest that FBXW7 regulates SSC self-renewal in a negative manner by degradation of MYC.
    Proceedings of the National Academy of Sciences 05/2014; 111(24). DOI:10.1073/pnas.1401837111 · 9.81 Impact Factor
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    ABSTRACT: Proper development of T cells depends on lineage-specific regulators controlled transcriptionally and post-translationally to ensure precise levels at appropriate times. Conditional inactivation of F-box protein Fbw7 in mice T-cell development resulted in reduced thymic CD4 single positive (SP), and splenic CD4(+) and CD8(+) subcell proportions. Fbw7 deficiency skewed CD8 SP lineage differentiation, which exhibited a higher incidence of apoptosis. Similar perturbations during development of CD8 positive cells were reported with transgenic mice, which enforced GATA3 (T-cell differentiation regulator) expression throughout T-cell development. We observed augmented GATA3 in CD4/CD8 double negative (DN) stage 4, CD4 SP, and CD8 SP lineages in Fbw7-deficient thymocytes. We demonstrated that Fbw7 bound to, ubiquitylated, and destabilized GATA3 using overexpressed proteins in cultured cells. Two Cdc4 phosphodegron (CPD) candidate sequences, consensus Fbw7 recognition domains, were identified in GATA3 and phosphorylation of Thr-156 in CPD was required for Fbw7-mediated ubiquitylation and degradation. Phosphorylation of Thr-156 GATA3 was detected in mouse thymocytes and CDK2 was identified as a respondent for phosphorylation at Thr-156. These observations suggest Fbw7-mediated GATA3 regulation with CDK2-mediated phosphorylation of CPD contributes to the precise differentiation of T-cell lineages.
    Molecular and Cellular Biology 05/2014; 34(14). DOI:10.1128/MCB.01549-13 · 5.04 Impact Factor
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    ABSTRACT: FBXL5 (F-box and leucine-rich repeat protein 5) is the F-box protein subunit of, and therefore responsible for substrate recognition by, the SCF(FBXL5) ubiquitin ligase complex, which targets iron regulatory protein 2 (IRP2) for proteasomal degradation. IRP2 plays a central role in the maintenance of cellular iron homeostasis in mammals through posttranscriptional regulation of proteins that contribute to control of the intracellular iron concentration. The FBXL5-IRP2 axis is integral to control of iron metabolism in vivo, given that mice lacking FBXL5 die during early embryogenesis as a result of unrestrained IRP2 activity and oxidative stress attributable to excessive iron accumulation. Despite its pivotal role in the control of iron homeostasis, however, little is known of the upstream regulation of FBXL5 activity. We now show that FBXL5 undergoes constitutive ubiquitin-dependent degradation at the steady state. With the use of a proteomics approach to the discovery of proteins that regulate the stability of FBXL5, we identified the large HECT-type ubiquitin ligase HERC2 (HECT and RLD domain containing E3 ubiquitin protein ligase 2) as an FBXL5-associated protein. Inhibition of the HERC2-FBXL5 interaction or depletion of endogenous HERC2 by RNA interference resulted in the stabilization of FBXL5 and a consequent increase in its abundance. Such accumulation of FBXL5 in turn led to a decrease in the intracellular content of ferrous iron. Our results thus suggest that HERC2 regulates the basal turnover of FBXL5, and that this ubiquitin-dependent degradation pathway contributes to the control of mammalian iron metabolism.
    Journal of Biological Chemistry 04/2014; 289(23). DOI:10.1074/jbc.M113.541490 · 4.60 Impact Factor
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    ABSTRACT: IL-12, which is produced in response to intracellular bacteria, such as Listeria monocytogenes, promotes the development of pathogen-specific Th1 cells that play an important role in host defense. However, it has also been known that CD44(high) memory-phenotype CD4 T cells with Th1 functions naturally occur in naive mice, and that lymphopenia-induced proliferation of naive CD4 T cells generates memory-phenotype CD4 T cells with Th1 functions, although their differentiation mechanism and contribution to host defense are unclear. In this study, we analyzed the development and the functions of the different subsets of Th1 cells by using mice lacking tyrosine kinase 2 (Tyk2), a member of the Janus kinase family critically involved in IL-12 signaling. In contrast with the case of conventional Ag-specific Th1 cells, the development of naturally occurring Th1 cells was not impaired in Tyk2-deficient mice. In addition, Th1 cells were normally generated from Tyk2-deficient naive CD4 T cells via lymphopenia-induced proliferation. Nevertheless, all these Th1 subsets, including conventional Ag-induced Th1 cells, produced IFN-γ in response to IL-12 in a Tyk2-dependent manner. Importantly, such Tyk2-dependent bystander IFN-γ production of any Th1 subsets conferred early protection against L. monocytogenes infection. Thus, Tyk2-mediated IL-12 signaling is differentially required for the development of different Th1 cell subsets but similarly induces their bystander IFN-γ production, which contributes to innate host defense against infection with intracellular bacteria.
    The Journal of Immunology 04/2014; 192(10). DOI:10.4049/jimmunol.1303067 · 5.36 Impact Factor
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    ABSTRACT: Protrudin is a membrane protein that regulates polarized vesicular trafficking in neurons. The protrudin gene (ZFYVE27) is mutated in a subset of individuals with hereditary spastic paraplegia (HSP), and protrudin is therefore also referred to as spastic paraplegia (SPG) 33. We have now generated mice that express a transgene for dual epitope-tagged protrudin under the control of a neuron-specific promoter, and we have subjected highly purified protrudin-containing complexes isolated from the brain of these mice to proteomics analysis in order to identify proteins that associate with protrudin. Protrudin was found to interact with other HSP-related proteins including myelin proteolipid protein 1 (SPG2), atlastin-1 (SPG3A), REEP1 (SPG31), REEP5 (similar to REEP1), KIF5A (SPG10), KIF5B, KIF5C, and reticulon 1, 3, and 4 (similar to reticulon 2, SPG12). Membrane topology analysis indicated that one of three hydrophobic segments of protrudin forms a hydrophobic hairpin domain similar to those of other SPG proteins. Protrudin was found to localize predominantly to the tubular endoplasmic reticulum (ER), and forced expression of protrudin promoted the formation and stabilization of the tubular ER network. The protrudin(G191V) mutant, which has been identified in a subset of HSP patients, manifested an increased intracellular stability, and cells expressing this mutant showed an increased susceptibility to ER stress. Our results thus suggest that protrudin contributes to the regulation of ER morphology and function, and that its deregulation by mutation is a causative defect in HSP.
    Journal of Biological Chemistry 03/2014; 289(19). DOI:10.1074/jbc.M113.528687 · 4.60 Impact Factor
  • Akinobu Matsumoto, Shoichiro Takeishi, Keiichi I Nakayama
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    ABSTRACT: T cells are key components of the immune system, playing a central role in cell-mediated immunity. The sequential differentiation of T cells is associated with strict regulation of the cell cycle at each developmental stage. Proliferation and differentiation decisions made by these cells are regulated by a balance between p53 activity and pre-T cell receptor (TCR) signaling. The relation between maintenance of this balance and the function of cell cycle regulators has remained largely unknown, however. We now show that mice with T cell-specific deficiency of the cyclin-dependent kinase inhibitor p57 manifest a differentiation block at the early stage of T cell maturation. Further genetic analysis revealed that this defect is attributable to an imbalance between p53 activity and pre-TCR signaling caused by hyperactivation of the E2F-p53 pathway. Moreover, ablation of both p57 and p53 in T cells led to the development of aggressive thymic lymphomas with a reduced latency compared with that apparent for p53-deficient mice, whereas ablation of p57 alone did not confer susceptibility to this hematologic malignancy. Our results thus reveal that the p57-E2F-p53 axis plays a pivotal role in the proper development of T cells as well as in the prevention of lymphomagenesis.
    Blood 03/2014; 123(22). DOI:10.1182/blood-2013-10-532390 · 9.78 Impact Factor
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    ABSTRACT: Cyclin-dependent kinase 2 (Cdk2) is dispensable for mitotic cell cycle progression and Cdk2 knockout mice are viable due to the compensatory functions of other Cdks. In order to assess the role of Cdk2 under limiting conditions, we used Skp2 knockout mice that exhibit increased levels of Cdk inhibitor, p27(Kip1), which is able to inhibit Cdk2 and Cdk1. Knockdown of Cdk2 abrogated proliferation of Skp2(-/-) mouse embryonic fibroblasts, encouraging us to generate Cdk2(-/-)Skp2(-/-) double knockout mice. Cdk2(-/-)Skp2(-/-) double knockout mice are viable and display similar phenotypes as Cdk2(-/-) and Skp2(-/-) mice. Unexpectedly, fibroblasts generated from Cdk2(-/-)Skp2(-/-) double knockout mice proliferated at normal rates. The increased stability of p27 observed in Skp2(-/-) MEFs was not observed in Cdk2(-/-)Skp2(-/-) double knockout fibroblasts indicating that in the absence of Cdk2, p27 is regulated by Skp2-independent mechanisms. Ablation of other ubiquitin ligases for p27 such as KPC1, DDB1, and Pirh2 did not restore stability of p27 in Cdk2(-/-)Skp2(-/-) MEFs. Our findings point towards novel and alternate pathways for p27 regulation.
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 01/2014; 1843:436-445. DOI:10.1016/j.bbamcr.2013.11.005 · 5.30 Impact Factor
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    ABSTRACT: Mammalian cardiomyocytes actively proliferate during embryonic stages, following which cardiomyocytes exit their cell cycle after birth. The irreversible cell cycle exit inhibits cardiac regeneration by the proliferation of pre-existing cardiomyocytes. Exactly how the cell cycle exit occurs remains largely unknown. Previously, we showed that cyclin E- and cyclin A-CDK activities are inhibited before the CDKs levels decrease in postnatal stages. This result suggests that factors such as CDK inhibitors (CKIs) inhibit CDK activities, and contribute to the cell cycle exit. In the present study, we focused on a Cip/Kip family, which can inhibit cyclin E- and cyclin A-CDK activities. Expression of p21(Cip1) and p27(Kip1) but not p57(Kip2) showed a peak around postnatal day 5, when cyclin E- and cyclin A-CDK activities start to decrease. p21(Cip1) and p27(Kip1) bound to cyclin E, cyclin A and CDK2 at postnatal stages. Cell cycle distribution patterns of postnatal cardiomyocytes in p21(Cip1) and p27(Kip1) knockout mice showed failure in the cell cycle exit at G1-phase, and endoreplication. These results indicate that p21(Cip1) and p27(Kip) play important roles in the cell cycle exit of postnatal cardiomyocytes.
    Biochemical and Biophysical Research Communications 12/2013; 443(3). DOI:10.1016/j.bbrc.2013.12.109 · 2.28 Impact Factor
  • Journal of Neurology 11/2013; 261(1). DOI:10.1007/s00415-013-7134-5 · 3.84 Impact Factor
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    ABSTRACT: Protrudin is a membrane protein that regulates polarized vesicular transport. Now, we have identified a novel isoform of protrudin (protrudin-L) that contains an additional seven amino acids between the FFAT motif and the coiled-coil domain compared with the conventional isoform (protrudin-S) as a result of alternative splicing of a microexon (exon L). Protrudin-L mRNA was found to be mostly restricted to the central nervous system in mice, whereas protrudin-S mRNA was detected in all tissues examined. With the use of a splicing reporter minigene that produces two distinct fluorescent proteins in a manner dependent on the splicing pattern of protrudin transcripts, we found that most neurons express protrudin-L, whereas astrocytes express both protrudin isoforms and oligodendrocytes express only protrudin-S. Protrudin-L associated to a greater extent with vesicle-associated membrane protein-associated protein (VAP) than protrudin-S. Expression of protrudin-L in hippocampal neurons of protrudin-deficient mice also promoted neurite outgrowth more efficiently than protrudin-S. Our results suggest that protrudin-L is a neuron-specific protrudin isoform that promotes axonal elongation and contributes to the establishment of neuronal polarity.
    Genes to Cells 11/2013; 19(2). DOI:10.1111/gtc.12109 · 2.86 Impact Factor

Publication Stats

11k Citations
1,853.27 Total Impact Points


  • 2003–2015
    • Kyushu University
      • Department of Molecular and Cellular Biology
      Hukuoka, Fukuoka, Japan
    • Hokkaido University Hospital
      • Division of Ophthalmology
      Sapporo-shi, Hokkaido, Japan
  • 2008–2014
    • Japan Science and Technology Agency (JST)
      Edo, Tōkyō, Japan
    • Emory University
      • Center for Neurodegenerative Disease
      Atlanta, Georgia, United States
    • University of Arkansas at Little Rock
      Little Rock, Arkansas, United States
  • 2011
    • Albert Einstein College of Medicine
      • Department of Cell Biology
      New York, New York, United States
  • 2007–2011
    • Tohoku University
      • Graduate School of Medicine
    • Fukuoka University
      Hukuoka, Fukuoka, Japan
    • Juntendo University
      Edo, Tōkyō, Japan
  • 2009
    • Nagasaki University
      • Graduate School of Biomedical Sciences
      Nagasaki-shi, Nagasaki-ken, Japan
  • 2006–2007
    • Tokoha University
      • Division of Biochemistry
      Hamamatu, Shizuoka, Japan
    • Niigata University
      • Division of Neuropathology
      Niahi-niigata, Niigata, Japan
  • 2004–2007
    • Daiichi University
      Hukuoka, Fukuoka, Japan
    • National Institute of Advanced Industrial Science and Technology
      • Biomedicinal Information Research Center
      Tokyo, Tokyo-to, Japan
    • Keio University
      • Department of Molecular Biology
      Edo, Tōkyō, Japan
  • 2005
    • Kumamoto University
      Kumamoto, Kumamoto, Japan
    • Hokkaido University
      • Department of Oral Biochemistry and Molecular Biology
      Sapporo-shi, Hokkaido, Japan
  • 2002–2003
    • Centre for Cellular and Molecular Biology
      Bhaganagar, Andhra Pradesh, India