Ubiquitin‐dependent proteolysis of trihydrophobin 1 (TH1) by the human papilloma virus E6‐associated protein (E6‐AP)

Yang, Yanzhong; Liu, Weicheng; Wu, Zhongze; Wang, Hanzhou; Zong, Hong; Jiang, Jianhai; Wang, Yanlin; Gu, Jianxin

doi:10.1002/jcb.21164

Cited by 12 publications

(14 citation statements)

References 46 publications

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“…Overexpresion of UBE3A in cells can mediate degradation of its target proteins. For example, Yang et al [37] found that overexpression of UBE3A in HeLa cells leads to degradation of its target protein trihydrophobin 1 (TH1). Shimoji et al [38] demonstrated that overexpression of UBE3A decreased the level of annexin A1 protein in HEK 293T cells.…”

Section: Discussionmentioning

confidence: 99%

Angelman Syndrome Protein UBE3A Interacts with Primary Microcephaly Protein ASPM, Localizes to Centrosomes and Regulates Chromosome Segregation

Singhmar

Kumar

2011

PLoS ONE

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Many proteins associated with the phenotype microcephaly have been localized to the centrosome or linked to it functionally. All the seven autosomal recessive primary microcephaly (MCPH) proteins localize at the centrosome. Microcephalic osteodysplastic primordial dwarfism type II protein PCNT and Seckel syndrome (also characterized by severe microcephaly) protein ATR are also centrosomal proteins. All of the above findings show the importance of centrosomal proteins as the key players in neurogenesis and brain development. However, the exact mechanism as to how the loss-of-function of these proteins leads to microcephaly remains to be elucidated. To gain insight into the function of the most commonly mutated MCPH gene ASPM, we used the yeast two-hybrid technique to screen a human fetal brain cDNA library with an ASPM bait. The analysis identified Angelman syndrome gene product UBE3A as an ASPM interactor. Like ASPM, UBE3A also localizes to the centrosome. The identification of UBE3A as an ASPM interactor is not surprising as more than 80% of Angelman syndrome patients have microcephaly. However, unlike in MCPH, microcephaly is postnatal in Angelman syndrome patients. Our results show that UBE3A is a cell cycle regulated protein and its level peaks in mitosis. The shRNA knockdown of UBE3A in HEK293 cells led to many mitotic abnormalities including chromosome missegregation, abnormal cytokinesis and apoptosis. Thus our study links Angelman syndrome protein UBE3A to ASPM, centrosome and mitosis for the first time. We suggest that a defective chromosome segregation mechanism is responsible for the development of microcephaly in Angelman syndrome.

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Section: Discussionmentioning

confidence: 99%

Angelman Syndrome Protein UBE3A Interacts with Primary Microcephaly Protein ASPM, Localizes to Centrosomes and Regulates Chromosome Segregation

Singhmar

Kumar

2011

PLoS ONE

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“…Myc-tagged full-length cIAP2, cIAP2⌬BIR1, cIAP2⌬BIR1-2, cIAP2⌬BIR1-3, and cIAP2N were constructed using conventional molecular cloning methods by amplifying the corresponding sequences with PCR and inserting them into the pCMV-Myc vector. pcDNA3-HA-ubiquitin expresses amino-terminally hemagglutinin (HA) tagged ubiquitin (44). pcDNA3.1-3ϫFLAG-polymerase and pCMV-Myc-polymerase, expressing aminoterminally FLAG tagged or Myc tagged HBV polymerase, were constructed by inserting the HBV polymerase coding sequence into the corresponding vectors.…”

Section: Methodsmentioning

confidence: 99%

Inhibition of Hepatitis B Virus Replication by cIAP2 Involves Accelerating the Ubiquitin-Proteasome-Mediated Destruction of Polymerase

Wang

et al. 2011

J Virol

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Cellular inhibitor of apoptosis protein 2 (cIAP2) is a potent suppressor of apoptotic cell death. We have shown previously that cIAP2 is involved in the tumor necrosis factor alpha (TNF-␣)-induced anti-hepatitis B virus (HBV) response; however, the mechanism for this antiviral effect remains unclear. In the present study, we demonstrate that cIAP2 can significantly reduce the levels of HBV DNA replication intermediates but not the total viral RNA or core protein levels. Domain-mapping analysis revealed that the carboxy-terminal domains of cIAP2 were indispensable for this anti-HBV ability and that an E3 ligase-deficient mutant of cIAP2 (termed cIAP2*) completely lost its antiviral activity. We further identified HBV polymerase as the target of cIAP2. Overexpression of cIAP2 but not cIAP2* reduced polymerase protein levels, while cIAP2 knockdown increased polymerase expression. In addition, we observed that cIAP2 promoted the degradation of the viral polymerase through a proteasome-dependent pathway. Further experiments demonstrated that cIAP2 can bind to polymerase and promote its polyubiquitylation. Finally, we found that cIAP2 downregulated the encapsidation of HBV pregenomic RNA. Taken together, these data reveal a novel mechanism for the inhibition of HBV replication by cIAP2 via acceleration of the ubiquitin-proteasome-mediated decay of polymerase and reduction of the encapsidation of HBV pregenomic RNA, making this mechanism a novel strategy for HBV therapy.Infection with hepatitis B virus (HBV) is a public health problem worldwide. It is estimated that at least 10% of the population of tropical Africa and Far East Asia are chronic carriers of the virus (40). Epidemiological studies have estimated that 350 million people are chronic carriers of HBV, with the potential to develop chronic active hepatitis, liver cirrhosis, or hepatocellular carcinoma (HCC) (9). HBV is a small double-stranded DNA virus belonging to the family Hepadnaviridae and replicates primarily in hepatocytes. In the nuclei of hepatocytes, the covalently closed circular DNA (cccDNA) of HBV serves as the transcription template for the viral pregenomic RNA (pgRNA) and subgenomic RNAs. The pgRNA is a multifunctional transcript. This transcript encodes the viral polymerase and core protein while also functioning as the template for HBV reverse transcription. HBV genome replication is initiated upon the recognition and binding of pgRNA by the viral polymerase protein. The complex formed by pgRNA and polymerase is then packaged into nucleocapsids, and in the nucleocapsids, polymerase catalyzes the conversion of pgRNA into single-stranded DNA (ssDNA) and relaxed circular DNA (rcDNA). The mature nucleocapsids are then enveloped and secreted (37).

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“…Recently, data from our laboratory indicate that TH1, as a new negative regulator of A-RAF kinase in MAPK signal transduction pathways, can specifically bind to A-RAF and inhibit its kinase activity (31). TH1 also interacts with human papilloma virus E6-associated protein (E6AP) and induces ubiquitin-dependent proteolysis (32). In addition, it is also found to be identical to NELF-C/D, an integral subunit of the human negative transcription elongation factor (NELF) complex (33).…”

mentioning

confidence: 99%

Trihydrophobin 1 Interacts with PAK1 and Regulates ERK/MAPK Activation and Cell Migration

Cheng

Kong

Wang

et al. 2009

Journal of Biological Chemistry

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The Rac1/Cdc42 effector, p21-activated kinase (PAK), is activated by various signaling cascades, including receptor-tyrosine kinases and integrins, and regulates a number of processes such as cell proliferation and motility. PAK activity has been shown to be required for maximal activation of the canonical RAF-MEK-MAPK signaling cascade, possibly because of PAK co-activation of RAF and MEK. Here we have shown that trihydrophobin 1 (TH1), originally identified as a negative regulator of A-RAF kinase, also interacted with PAK1 in cultured cells. Confocal microscopy assay indicated that TH1 colocalized with PAK1 in both the cytoplasm and nucleus, which is consistent with our previous results. GST pulldown and coimmunoprecipitation experiments demonstrated that TH1 interacted directly with PAK1 and bound selectively to the carboxyl-terminal kinase domain of PAK1, and the ability of the binding was enhanced along with activation of PAK1. The binding pattern of PAK1 implies that this interaction was mediated in part by PAK1 kinase activity. As indicated by in vitro kinase activity assays and Western blot detections, TH1 inhibited PAK1 kinase activity and negatively regulated MAPK signal transduction. Interestingly, TH1 bound with MEK1/ERK in cells and in vitro without directly suppressing their kinase activity. Furthermore, we observed that TH1 localized to focal adhesions and filopodia in the leading edge of cells, where TH1 reduced cell migration through affecting actin and adhesion dynamics. Based on these observations, we propose a model in which TH1 interacts with PAK1 and specifically restricts the activation of MAPK modules through the upstream region of the MAPK pathway, thereby influencing cell migration.

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Ubiquitin‐dependent proteolysis of trihydrophobin 1 (TH1) by the human papilloma virus E6‐associated protein (E6‐AP)

Cited by 12 publications

References 46 publications

Angelman Syndrome Protein UBE3A Interacts with Primary Microcephaly Protein ASPM, Localizes to Centrosomes and Regulates Chromosome Segregation

Angelman Syndrome Protein UBE3A Interacts with Primary Microcephaly Protein ASPM, Localizes to Centrosomes and Regulates Chromosome Segregation

Inhibition of Hepatitis B Virus Replication by cIAP2 Involves Accelerating the Ubiquitin-Proteasome-Mediated Destruction of Polymerase

Trihydrophobin 1 Interacts with PAK1 and Regulates ERK/MAPK Activation and Cell Migration

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