Pang-Hung Hsu

Academia Sinica, T’ai-pei, Taipei, Taiwan

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Publications (27)179.65 Total impact

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    ABSTRACT: In yeast, the initiation of telomere replication at the late S phase involves in combined actions of kinases on Cdc13, the telomere binding protein. Cdc13 recruits telomerase to telomeres through its interaction with Est1, a component of telomerase. However, how cells terminate the function of telomerase at G2/M is still elusive. Here we show that the protein phosphatase 2A (PP2A) subunit Pph22 and the yeast Aurora kinase homologue Ipl1 coordinately inhibit telomerase at G2/M by dephosphorylating and phosphorylating the telomerase recruitment domain of Cdc13, respectively. While Pph22 removes Tel1/Mec1-mediated Cdc13 phosphorylation to reduce Cdc13-Est1 interaction, Ipl1-dependent Cdc13 phosphorylation elicits dissociation of Est1-TLC1, the template RNA component of telomerase. Failure of these regulations prevents telomerase from departing telomeres, causing perturbed telomere lengthening and prolonged M phase. Together our results demonstrate that differential and additive actions of PP2A and Aurora on Cdc13 limit telomerase action by removing active telomerase from telomeres at G2/M phase.
    Nature Communications 11/2014; 5:5312. · 10.74 Impact Factor
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    ABSTRACT: The type VI secretion system (T6SS) is a widespread protein secretion system found in many Gram-negative bacteria. T6SSs are highly regulated by various regulatory systems at multiple levels, including post-translational regulation via threonine (Thr) phosphorylation. The Ser/Thr protein kinase PpkA is responsible for this Thr phosphorylation regulation, and the forkhead-associated (FHA) domain-containing Fha-family protein is the sole T6SS phosphorylation substrate identified to date. Here we discovered that TssL, the T6SS inner-membrane core component, is phosphorylated and the phosphorylated TssL (p-TssL) activates type VI subassembly and secretion in a plant pathogenic bacterium, Agrobacterium tumefaciens. Combining genetic and biochemical approaches, we demonstrate that TssL is phosphorylated at Thr 14 in a PpkA-dependent manner. Further analysis revealed that the PpkA kinase activity is responsible for the Thr 14 phosphorylation, which is critical for the secretion of the T6SS hallmark protein Hcp and the putative toxin effector Atu4347. TssL phosphorylation is not required for the formation of the TssM-TssL inner-membrane complex but is critical for TssM conformational change and binding to Hcp and Atu4347. Importantly, Fha specifically interacts with phosphothreonine of TssL via its pThr-binding motif in vivo and in vitro and this interaction is crucial for TssL interaction with Hcp and Atu4347 and activation of type VI secretion. In contrast, pThr-binding ability of Fha is dispensable for TssM structural transition. In conclusion, we discover a novel Thr phosphorylation event, in which PpkA phosphorylates TssL to activate type VI secretion via its direct binding to Fha in A. tumefaciens. A model depicting an ordered TssL phosphorylation-induced T6SS assembly pathway is proposed.
    PLoS Pathogens 03/2014; 10(3):e1003991. · 8.06 Impact Factor
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    ABSTRACT: Erythropoiesis is a highly regulated process during which BFU-E are differentiated into RBCs through CFU-E, Pro-E, PolyCh-E, OrthoCh-E, and reticulocyte stages. Uniquely, most erythroid-specific genes are activated during the Pro-E to Baso-E transition. We show that a wave of nuclear import of the erythroid-specific transcription factor EKLF occurs during the Pro-E to Baso-E transition. We further demonstrate that this wave results from a series of finely tuned events, including timed activation of PKCθ, phosphorylation of EKLF at S68 by P-PKCθ(S676), and sumoylation of EKLF at K74. The latter EKLF modifications modulate its interactions with a cytoplasmic ankyrin-repeat-protein FOE and importinβ1, respectively. The role of FOE in the control of EKLF nuclear import is further supported by analysis of the subcellular distribution patterns of EKLF in FOE-knockout mice. This study reveals the regulatory mechanisms of the nuclear import of EKLF, which may also be utilized in the nuclear import of other factors.
    Developmental Cell 02/2014; 28(4):409-22. · 10.37 Impact Factor
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    ABSTRACT: O-linked N-acetylglucosamine (GlcNAc) transferase (OGT) is the only known enzyme that catalyzes the O-GlcNAcylation of proteins at the Ser or Thr side chain hydroxyl group. OGT participates in transcriptional and epigenetic regulation, and dysregulation of OGT has been implicated in diseases such as cancer. However, the underlying mechanism is largely unknown. Here we show that OGT is required for the trimethylation of histone 3 at K27 to form the product H3K27me3, a process catalyzed by the histone methyltransferase enhancer of zeste homolog 2 (EZH2) in the polycomb repressive complex 2 (PRC2). H3K27me3 is one of the most important histone modifications to mark the transcriptionally silenced chromatin. We found that the level of H3K27me3, but not other H3 methylation products, was greatly reduced upon OGT depletion. OGT knockdown specifically down-regulated the protein stability of EZH2, without altering the levels of H3K27 demethylases UTX and JMJD3, and disrupted the integrity of the PRC2 complex. Furthermore, the interaction of OGT and EZH2/PRC2 was detected by coimmunoprecipitation and cosedimentation experiments. Importantly, we identified that serine 75 is the site for EZH2 O-GlcNAcylation, and the EZH2 mutant S75A exhibited reduction in stability. Finally, microarray and ChIP analysis have characterized a specific subset of potential tumor suppressor genes subject to repression via the OGT-EZH2 axis. Together these results indicate that OGT-mediated O-GlcNAcylation at S75 stabilizes EZH2 and hence facilitates the formation of H3K27me3. The study not only uncovers a functional posttranslational modification of EZH2 but also reveals a unique epigenetic role of OGT in regulating histone methylation.
    Proceedings of the National Academy of Sciences 01/2014; 111(4):1355-60. · 9.81 Impact Factor
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    ABSTRACT: Salt-inducible kinase 2 (SIK2) is an important regulator of cAMP response element-binding protein (CREB)-mediated gene expression in various cell types and is the only AMP-activated protein kinase (AMPK) family member known to interact with the p97/VCP ATPase. Previously, we have demonstrated that SIK2 could regulate autophagy when proteasomal function is compromised. Here we report that physical and functional interactions between SIK2 and p97/VCP underlie the regulation of ERAD. SIK2 co-localizes with p97/VCP in the ER membrane and stimulates its ATPase activity through direct phosphorylation. While the expression of wild-type recombinant SIK2 accelerated the degradation and removal of ERAD substrates, the kinase-deficient variant conversely had no effect. Furthermore, down-regulation of endogenous SIK2 or mutation of the SIK2 target site on p97/VCP led to impaired degradation of ERAD substrates and disruption of ER homeostasis. Collectively, these findings highlight a mechanism by which the interplay between SIK2 and p97/VCP contributes to the regulation of ERAD in mammalian cells.
    Journal of Biological Chemistry 10/2013; · 4.60 Impact Factor
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    ABSTRACT: Ethylene is an important plant hormone that regulates developmental processes in plants. The ethylene biosynthesis pathway is a highly regulated process at both the transcriptional and post-translational level. The transcriptional regulation of these ethylene biosynthesis genes is well known. However, post-translational modifications of the key ethylene biosynthesis enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) are little understood. In vitro kinase assays were conducted on the type III ACS, AtACS7, fusion protein and peptides to determine whether the AtACS7 protein can be phosphorylated by calcium-dependent protein kinase (CDPK). AtACS7 was phosphorylated at Ser216, Thr296, and Ser299 by AtCDPK16 in vitro. To investigate further the function of the ACS7 gene in Arabidopsis, an acs7-1 loss-of-function mutant was isolated. The acs7-1 mutant exhibited less sensitivity to the inhibition of root gravitropism by treatment with the calcium chelator ethylene glycol tetraacetic acid (EGTA). Seedlings were treated with gradient concentrations of ACC. The results showed that a certain concentration of ethylene enhanced the gravity response. Moreover, the acs7-1 mutant was less sensitive to inhibition of the gravity response by treatment with the auxin polar transport inhibitor 1-naphthylphthalamic acid, but exogenous ACC application recovered root gravitropism. Altogether, the results indicate that AtACS7 is involved in root gravitropism in a calcium-dependent manner in Arabidopsis.
    Journal of Experimental Botany 08/2013; · 5.79 Impact Factor
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    ABSTRACT: BACKGROUND: Turnover of mRNA is a critical step in the regulation of gene expression, and an important step in mRNA decay is removal of the 5' cap. We previously demonstrated that the expression of some immediate early gene mRNAs is controlled by RNA stability during early differentiation of 3T3-L1 preadipocytes. METHODOLOGYPRINCIPAL FINDINGS: Here we show that the mouse decapping protein Dcp1a is phosphorylated via the ERK signaling pathway during early differentiation of preadipocytes. Mass spectrometry analysis and site-directed mutagenesis combined with a kinase assay identified ERK pathway-mediated dual phosphorylation at Ser 315 and Ser 319 of Dcp1a. To understand the functional effects of Dcp1a phosphorylation, we examined protein-protein interactions between Dcp1a and other decapping components with co-immunoprecipitation. Dcp1a interacted with Ddx6 and Edc3 through its proline-rich C-terminal extension, whereas the conserved EVH1 (enabled vasodilator-stimulated protein homology 1) domain in the N terminus of Dcp1a showed a stronger interaction with Dcp2. Once ERK signaling was activated, the interaction between Dcp1a and Ddx6, Edc3, or Edc4 was not affected by Dcp1a phosphorylation. Phosphorylated Dcp1a did, however, enhanced interaction with Dcp2. Protein complexes immunoprecipitated with the recombinant phosphomimetic Dcp1a(S315D/S319D) mutant contained more Dcp2 than did those immunoprecipitated with the nonphosphorylated Dcp1a(S315A/S319A) mutant. In addition, Dcp1a associated with AU-rich element (ARE)-containing mRNAs such as MAPK phosphatase-1 (MKP-1), whose mRNA stability was analyzed under the overexpression of Dcp1a constructs in the Dcp1a knockdown 3T3-L1 cells. CONCLUSIONSSIGNIFICANCE: Our findings suggest that ERK-phosphorylated Dcp1a enhances its interaction with the decapping enzyme Dcp2 during early differentiation of 3T3-L1 cells.
    PLoS ONE 04/2013; 8(4):e61697. · 3.53 Impact Factor
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    ABSTRACT: While numerous small ubiquitin-like modifier (SUMO) conjugated substrates have been identified, very little is known about the cellular signalling mechanisms that differentially regulate substrate sumoylation. Here, we show that acetylation of SUMO E2 conjugase Ubc9 selectively downregulates the sumoylation of substrates with negatively charged amino acid-dependent sumoylation motif (NDSM) consisting of clustered acidic residues located downstream from the core ψ-K-X-E/D consensus motif, such as CBP and Elk-1, but not substrates with core ψ-K-X-E/D motif alone or SUMO-interacting motif. Ubc9 is acetylated at residue K65 and K65 acetylation attenuates Ubc9 binding to NDSM substrates, causing a reduction in NDSM substrate sumoylation. Furthermore, Ubc9 K65 acetylation can be downregulated by hypoxia via SIRT1, and is correlated with hypoxia-elicited modulation of sumoylation and target gene expression of CBP and Elk-1 and cell survival. Our data suggest that Ubc9 acetylation/deacetylation serves as a dynamic switch for NDSM substrate sumoylation and we report a previously undescribed SIRT1/Ubc9 regulatory axis in the modulation of protein sumoylation and the hypoxia response.
    The EMBO Journal 02/2013; · 10.75 Impact Factor
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    ABSTRACT: Salt-inducible kinase 2 (SIK2) is a serine/threonine protein kinase belonging to the AMP-activated protein kinase (AMPK) family. SIK2 has been shown to function in the insulin-signaling pathway during adipocyte differentiation and to modulate CREB-mediated gene expression in response to hormones and nutrients. However, molecular mechanism underlying the regulation of SIK2 kinase activity remains largely elusive. Here we report a dynamic, post-translational regulation of its kinase activity that is coordinated by an acetylation-deaceytlation switch - p300/CBP-mediated Lys53-acetylation inhibits SIK2 kinase activity, while HDAC6-mediated deacetylation restores the activity. Interestingly, overexpression of acetylation-mimetic mutant of SIK2 (SIK2-K53Q), but not the non-acetylatable K53R variant, resulted in accumulation of autophagosomes. Further consistent with a role in autophagy, knockdown of SIK2 abrogated autophagosome and lysosome fusion. Consequently, SIK2 and its kinase activity are indispensable for the removal of TDP-43Δ inclusion bodies. Our findings uncover SIK2 as a critical determinant in autophagy progression and further suggest a mechanism in which the interplay among kinase and deacetylase activities contributes to cellular protein pool homeostasis.
    Journal of Biological Chemistry 01/2013; · 4.60 Impact Factor
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    ABSTRACT: NPGPx is a member of the glutathione peroxidase (GPx) family; however, it lacks GPx enzymatic activity due to the absence of a critical selenocysteine residue, rendering its function an enigma. Here, we show that NPGPx is a newly identified stress sensor that transmits oxidative stress signals by forming the disulfide bond between its Cys57 and Cys86 residues. This oxidized form of NPGPx binds to glucose-regulated protein (GRP)78 and forms covalent bonding intermediates between Cys86 of NPGPx and Cys41/Cys420 of GRP78. Subsequently, the formation of the disulfide bond between Cys41 and Cys420 of GRP78 enhances its chaperone activity. NPGPx-deficient cells display increased reactive oxygen species, accumulated misfolded proteins, and impaired GRP78 chaperone activity. Complete loss of NPGPx in animals causes systemic oxidative stress, increases carcinogenesis, and shortens life span. These results suggest that NPGPx is essential for releasing excessive ER stress by enhancing GRP78 chaperone activity to maintain physiological homeostasis.
    Molecular cell 10/2012; · 14.46 Impact Factor
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    ABSTRACT: The forkhead-associated (FHA) domain recognizes phosphothreonine (pT) with high specificity and functional diversity. TIFA (TRAF-interacting protein with an FHA domain) is the smallest FHA-containing human protein. Its overexpression was previously suggested to provoke NF-κB activation, yet its exact roles in this signaling pathway and the underlying molecular mechanism remain unclear. Here we identify a novel threonine phosphorylation site on TIFA and show that this phosphorylated threonine (pT) binds with the FHA domain of TIFA, leading to TIFA oligomerization and TIFA-mediated NF-κB activation. Detailed analysis indicated that unphosphorylated TIFA exists as an intrinsic dimer and that the FHA-pT9 binding occurs between different dimers of TIFA. In addition, silencing of endogenous TIFA resulted in attenuation of tumor necrosis factor alpha (TNF-α)-mediated downstream signaling. We therefore propose that the TIFA FHA-pT9 binding provides a previously unidentified link between TNF-α stimulation and NF-κB activation. The intermolecular FHA-pT9 binding between dimers also represents a new mechanism for the FHA domain.
    Molecular and Cellular Biology 05/2012; 32(14):2664-73. · 5.04 Impact Factor
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    ABSTRACT: Transcriptional repressor B lymphocyte-induced maturation protein-1 (Blimp-1) is a master regulator of plasma cell differentiation. Here we show that Blimp-1 is covalently modified by SUMO1 at lysine 816, a modification mediated by SUMO E3 ligase PIAS1. Mutation of Blimp-1 lysine 816 reduces transcriptional repression--correlating with a reduced interaction with a histone deacetylase, HDAC2--and impairs differentiation of antibody-secreting cells. Thus, the SUMO pathway critically regulates Blimp-1 function during plasma cell differentiation.
    EMBO Reports 05/2012; 13(7):631-7. · 7.86 Impact Factor
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    ABSTRACT: Plants respond to salt stress by initiating phosphorylation cascades in their cells. Many key phosphorylation events take place at membranes. Microsomal fractions from 400 mM salt-treated Arabidopsis suspension plants were isolated, followed by trypsin shaving, enrichment using Zirconium ion-charged or TiO(2) magnetic beads, and tandem mass spectrometry analyses for site mapping. A total of 27 phosphorylation sites from 20 Arabidopsis proteins including photosystem II reaction center protein H PsbH were identified. In addition to Arabidopsis, microsomal fractions from shoots of 200 mM salt-treated rice was carried out, followed by trypsin digestion using shaving or tube-gel, and enrichment using Zirconium ion-charged or TiO(2) magnetic beads. This yielded identification of 13 phosphorylation sites from 8 proteins including photosystem II reaction center protein H PsbH. Label-free quantitative analysis suggests that the phosphorylation sites of PsbH were regulated by salt stress in Arabidopsis and rice. Sequence alignment of PsbH phosphorylation sites indicates that Thr-2 and Thr-4 are evolutionarily conserved in plants. Four conserved phosphorylation motifs were predicted, and these suggest that a specific unknown kinase or phosphatase is involved in high-salt stress responses in plants.
    Plant Science 04/2012; 185-186:131-42. · 4.11 Impact Factor
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    ABSTRACT: Glucagon is important for regulating lipid metabolism in part through its inhibition of fatty acid synthesis in adipocytes. Acetyl-CoA carboxylase 1 (ACC1) is the rate-limiting enzyme for fatty acid synthesis. Glucagon has been proposed to activate cAMP-dependent protein kinase A (PKA), which phosphorylates ACC1 to attenuate the lipogenic activity of ACC1. Because AMP-activated protein kinase (AMPK) also inhibits fatty acid synthesis by phosphorylation of ACC1, we examined the involvement of AMPK and its upstream kinase in the glucagon-elicited signaling in adipocytes in vitro and in vivo. LC-MS-MS analysis suggested that ACC1 was phosphorylated only at Ser(79), an AMPK-specific site, in glucagon-treated adipocytes. Pharmacological inhibitors and siRNA knockdown of AMPK or PKA in adipocytes demonstrate that glucagon regulates ACC1 and ACC2 activity through AMPK but not PKA. By using Ca(2+)/calmodulin-dependent protein kinase kinase-β knockout (CaMKKβ(-/-)) mice and cultured adipocytes, we further show that glucagon activates the CaMKKβ/AMPK/ACC cascade. Additionally, fasting increases the phosphorylation of AMPK and ACC in CaMKKβ(+/+) but not CaMKKβ(-/-) mice. These results indicate that CaMKKβ/AMPK signaling is an important molecular component in regulating lipid metabolism in adipocytes responding to glucagon and could be a therapeutic target for the dysregulation of energy storage.
    AJP Endocrinology and Metabolism 03/2012; 302(12):E1560-8. · 4.51 Impact Factor
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    ABSTRACT: Cell division in eukaryotes depends on a fine control of the dynamic changes of microtubules. Nucleolar and spindle-associated protein (NuSAP) is a microtubule-binding and -bundling protein essential for the integrity of the anaphase spindle and cell division. NuSAP contains two consensus cdk phosphorylation sites in its microtubule-binding domain. Here we show NuSAP is phosphorylated by cdk1 in early mitosis. This phosphorylation inhibits the binding of NuSAP to microtubules. During metaphase-to anaphase transition, NuSAP is dephosphorylated to promote spindle midzone formation and cell cycle progression. Expression of cdk1 phosphorylation-null mutant causes extensive bundling of microtubules in the prometaphase spindle. Our results suggest that phosphorylation and dephosphorylation of NuSAP during progression of mitosis regulate spindle organization through modulation of the dynamics of microtubules.
    Cell cycle (Georgetown, Tex.) 12/2011; 10(23):4083-9. · 5.24 Impact Factor
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    ABSTRACT: The nucleoprotein (NP) of the influenza virus exists as trimers, and its tail-loop binding pocket has been suggested as a potential target for antiinfluenza therapeutics. The possibility of NP as a drug target was validated by the recent reports that nucleozin and its analogs can inhibit viral replication by inducing aggregation of NP trimers. However, these inhibitors were identified by random screening, and the binding site and inhibition mechanism are unclear. We report a rational approach to target influenza virus with a new mechanism--disruption of NP-NP interaction. Consistent with recent work, E339A, R416A, and deletion mutant Δ402-428 were unable to support viral replication in the absence of WT NP. However, only E339A and R416A could form hetero complex with WT NP, but the complex was unable to bind the RNA polymerase, leading to inhibition of viral replication. These results demonstrate the importance of the E339…R416 salt bridge in viral survival and establish the salt bridge as a sensitive antiinfluenza target. To provide further support, we showed that peptides encompassing R416 can disrupt NP-NP interaction and inhibit viral replication. Finally we performed virtual screening to target E339…R416, and some small molecules identified were shown to disrupt the formation of NP trimers and inhibit replication of WT and nucleozin-resistant strains. This work provides a new approach to design antiinfluenza drugs.
    Proceedings of the National Academy of Sciences 09/2011; 108(40):16515-20. · 9.81 Impact Factor
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    ABSTRACT: Global histone H1 phosphorylation correlates with cell cycle progression. However, the function of site-specific H1 variant phosphorylation remains unclear. Our mass spectrometry analysis revealed a novel N-terminal phosphorylation of the major H1 variant H1.4 at serine 35 (H1.4S35ph), which accumulates at mitosis immediately after H3 phosphorylation at serine 10. Protein kinase A (PKA) was found to be a kinase for H1.4S35. Importantly, Ser-35-phosphorylated H1.4 dissociates from mitotic chromatin. Moreover, H1.4S35A substitution mutant cannot efficiently rescue the mitotic defect following H1.4 depletion, and inhibition of PKA activity increases the mitotic chromatin compaction depending on H1.4. Our results not only indicate that PKA-mediated H1.4S35 phosphorylation dissociates H1.4 from mitotic chromatin but also suggest that this phosphorylation is necessary for specific mitotic functions.
    Journal of Biological Chemistry 08/2011; 286(41):35843-51. · 4.60 Impact Factor
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    ABSTRACT: BK virus (BKV) infection may cause polyomavirus-associated nephropathy in patients with renal transplantation. Recently, the phosphorylated amino acids on the structural proteins VP1, VP2 and VP3 of BKV have been identified by liquid chromatography-tandem mass spectrometry in our laboratory. In this study, we further analysed the biological effects of these phosphorylation events. Phosphorylation of the BKV structural proteins was demonstrated by [(32)P]orthophosphate labelling in vivo. Site-directed mutagenesis was performed to replace all of the phosphorylated amino acids. The mutated BKV genomes were transfected into Vero cells for propagation analysis. The results showed that expression of the early protein LT and of the late protein VP1 by the mutants VP1-S80A, VP1-S80-133A, VP1-S80-327A, VP1-S80-133-327A and VP2-S254A was abolished. However, propagation of other mutants was similar to that of wild-type BKV. The results suggest that phosphorylation of Ser-80 of VP1 and Ser-254 of VP2 is crucial for BKV propagation.
    Journal of General Virology 07/2011; 92(Pt 11):2637-45. · 3.53 Impact Factor
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    ABSTRACT: Proper assembly of mitotic spindles requires Hice1, a spindle-associated protein. Hice1 possesses direct microtubule binding activity at its N-terminal region and contributes to intraspindle microtubule nucleation as a subunit of the Augmin complex. However, whether microtubule binding activity of Hice1 is modulated by mitotic regulators remains unexplored. Here, we found that Aurora-A kinase, a major mitotic kinase, specifically binds to and phosphorylates Hice1. We identified four serine/threonine clusters on Hice1 that can be phosphorylated by Aurora-A in vitro. Of the four clusters, the Ser/Thr-17-21 cluster was the most critical for bipolar spindle assembly, whereas other phospho-deficient point mutants had a minimal effect on spindle assembly. Immunostaining with a phospho-Ser-19/20 phospho-specific antibody revealed that phosphorylated Hice1 primarily localizes to spindle poles during prophase to metaphase but gradually diminishes after anaphase. Consistently, the phospho-mimic 17-21E mutant reduced microtubule binding activity in vitro and diminished localization to spindles in vivo. Furthermore, expression of the 17-21E mutant led to decreased association of Fam29a, an Augmin component, with spindles. On the other hand, expression of the phospho-deficient 17-21A mutant permitted intraspindle nucleation but delayed the separation of early mitotic spindle poles and the timely mitotic progression. Taken together, these results suggest that Aurora-A modulates the microtubule binding activity of Hice1 in a spatiotemporal manner for proper bipolar spindle assembly.
    Journal of Biological Chemistry 06/2011; 286(34):30097-106. · 4.60 Impact Factor
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    ABSTRACT: The dynamics of histone methylation have emerged as an important issue since the identification of histone demethylases. We studied the regulatory function of Rph1/KDM4 (lysine demethylase), a histone H3K36 demethylase, on transcription in Saccharomyces cerevisiae. Overexpression of Rph1 reduced the expression of PHR1 and increased UV sensitivity. The catalytically deficient mutant (H235A) of Rph1 diminished the repressive transcriptional effect on PHR1 expression, which indicates that histone demethylase activity contributes to transcriptional repression. Chromatin immunoprecipitation analysis demonstrated that Rph1 was associated at the upstream repression sequence of PHR1 through zinc-finger domains and was dissociated after UV irradiation. Notably, overexpression of Rph1 and H3K36A mutant reduced histone acetylation at the URS, which implies a crosstalk between histone demethylation and acetylation at the PHR1 promoter. In addition, the crucial checkpoint protein Rad53 acted as an upstream regulator of Rph1 and dominated the phosphorylation of Rph1 that was required for efficient PHR1 expression and the dissociation of Rph1. The release of Rph1 from chromatin also required the phosphorylation at S652. Our study demonstrates that the histone demethylase Rph1 is associated with a specific chromatin locus and modulates histone modifications to repress a DNA damage responsive gene under control of damage checkpoint signaling.
    Nucleic Acids Research 02/2011; 39(10):4151-65. · 8.81 Impact Factor

Publication Stats

255 Citations
179.65 Total Impact Points

Institutions

  • 2010–2014
    • Academia Sinica
      • Genomics Research Center
      T’ai-pei, Taipei, Taiwan
    • University of Illinois at Chicago
      • Center for Outcomes Research
      Chicago, IL, United States
  • 2012–2013
    • National Taiwan Ocean University
      • Institute of Bioscience and Biotechnology
      Keelung, Taiwan, Taiwan
  • 2007–2009
    • The Ohio State University
      • • Department of Molecular Virology, Immunology and Medical Genetics
      • • Department of Chemistry and Biochemistry
      Columbus, OH, United States