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Mechanism by Which PF-3758309, a Pan Isoform Inhibitor of p21-Activated Kinases, Blocks Reactivation of HIV-1 Latency. Biomolecules 2023; 13:biom13010100. [PMID: 36671485 PMCID: PMC9855626 DOI: 10.3390/biom13010100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/28/2022] [Accepted: 01/01/2023] [Indexed: 01/06/2023] Open
Abstract
The "block and lock" strategy is one approach that might elicit a sterilizing cure for HIV-1 infection. The "block" refers to a compound's ability to inhibit latent HIV-1 proviral transcription, while the "lock" refers to its capacity to induce permanent proviral silencing. We previously identified PF-3758309, a pan-isoform inhibitor of p21-activated kinases (PAKs), as a potent inhibitor of HIV-1 latency reversal. The goal of this study was to define the mechanism(s) involved. We found that both 24ST1NLESG cells (a cell line model of HIV-1 latency) and purified CD4+ naïve and central memory T cells express high levels of PAK2 and lower levels of PAK1 and PAK4. Knockdown of PAK1 or PAK2, but not PAK4, in 24ST1NLESG cells resulted in a modest, but statistically significant, decrease in the magnitude of HIV-1 latency reversal. Overexpression of PAK1 significantly increased the magnitude of latency reversal. A phospho-protein array analysis revealed that PF-3758309 down-regulates the NF-κB signaling pathway, which provides the most likely mechanism by which PF-3758309 inhibits latency reversal. Finally, we used cellular thermal shift assays combined with liquid chromatography and mass spectrometry to ascertain whether PF-3758309 off-target binding contributed to its activity. In 24ST1NLESG cells and in peripheral blood mononuclear cells, PF-3758309 bound to mitogen-activated protein kinase 1 and protein kinase A; however, knockdown of either of these kinases did not impact HIV-1 latency reversal. Collectively, our study suggests that PAK1 and PAK2 play a key role in the maintenance of HIV-1 latency.
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Usmani SM, Murooka TT, Deruaz M, Koh WH, Sharaf RR, Di Pilato M, Power KA, Lopez P, Hnatiuk R, Vrbanac VD, Tager AM, Allen TM, Luster AD, Mempel TR. HIV-1 Balances the Fitness Costs and Benefits of Disrupting the Host Cell Actin Cytoskeleton Early after Mucosal Transmission. Cell Host Microbe 2019; 25:73-86.e5. [PMID: 30629922 DOI: 10.1016/j.chom.2018.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 09/11/2018] [Accepted: 12/11/2018] [Indexed: 01/23/2023]
Abstract
HIV-1 primarily infects T lymphocytes and uses these motile cells as migratory vehicles for effective dissemination in the host. Paradoxically, the virus at the same time disrupts multiple cellular processes underlying lymphocyte motility, seemingly counterproductive to rapid systemic infection. Here we show by intravital microscopy in humanized mice that perturbation of the actin cytoskeleton via the lentiviral protein Nef, and not changes to chemokine receptor expression or function, is the dominant cause of dysregulated infected T cell motility in lymphoid tissue by preventing stable cellular polarization required for fast migration. Accordingly, disrupting the Nef hydrophobic patch that facilitates actin cytoskeletal perturbation initially accelerates systemic viral dissemination after female genital transmission. However, the same feature of Nef was subsequently critical for viral persistence in immune-competent hosts. Therefore, a highly conserved activity of lentiviral Nef proteins has dual effects and imposes both fitness costs and benefits on the virus at different stages of infection.
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Affiliation(s)
- Shariq M Usmani
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Thomas T Murooka
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA; University of Manitoba, Department of Immunology, Winnipeg, MB, Canada
| | - Maud Deruaz
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Wan Hon Koh
- University of Manitoba, Department of Immunology, Winnipeg, MB, Canada
| | - Radwa R Sharaf
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Mauro Di Pilato
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Karen A Power
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Paul Lopez
- University of Manitoba, Department of Immunology, Winnipeg, MB, Canada
| | - Ryan Hnatiuk
- University of Manitoba, Department of Immunology, Winnipeg, MB, Canada
| | - Vladimir D Vrbanac
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Andrew M Tager
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Todd M Allen
- Harvard Medical School, Boston, MA 02115, USA; Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Andrew D Luster
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Thorsten R Mempel
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA.
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3
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Chan CP, Kok KH, Jin DY. Human T-Cell Leukemia Virus Type 1 Infection and Adult T-Cell Leukemia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1018:147-166. [PMID: 29052136 DOI: 10.1007/978-981-10-5765-6_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the first retrovirus discovered to cause adult T-cell leukemia (ATL), a highly aggressive blood cancer. HTLV-1 research in the past 35 years has been most revealing in the mechanisms of viral oncogenesis. HTLV-1 establishes a lifelong persistent infection in CD4+ T lymphocytes. The infection outcome is governed by host immunity. ATL develops in 2-5% of infected individuals 30-50 years after initial exposure. HTLV-1 encodes two oncoproteins Tax and HBZ, which are required for initiation of cellular transformation and maintenance of cell proliferation, respectively. HTLV-1 oncogenesis is driven by a clonal selection and expansion process during which both host and viral factors cooperate to impair genome stability, immune surveillance, and other mechanisms of tumor suppression. A better understanding of HTLV-1 biology and leukemogenesis will reveal new strategies and modalities for ATL prevention and treatment.
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Affiliation(s)
- Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong
| | - Kin-Hang Kok
- Department of Microbiology, The University of Hong Kong, 145 Pokfulam Road, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong.
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Suppression of Type I Interferon Production by Human T-Cell Leukemia Virus Type 1 Oncoprotein Tax through Inhibition of IRF3 Phosphorylation. J Virol 2016; 90:3902-3912. [PMID: 26819312 DOI: 10.1128/jvi.00129-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 01/24/2016] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Infection with human T-cell leukemia virus type 1 (HTLV-1) is associated with adult T-cell leukemia (ATL) and tropical spastic paraparesis. Type I interferons (IFNs) are key effectors of the innate antiviral response, and IFN-α combined with the nucleoside reverse transcriptase inhibitor zidovudine is considered the standard first-line therapy for ATL. HTLV-1 oncoprotein Tax is known to suppress innate IFN production and response but the underlying mechanisms remain to be fully established. In this study, we report on the suppression of type I IFN production by HTLV-1 Tax through interaction with and inhibition of TBK1 kinase that phosphorylates IRF3. Induced transcription of IFN-β was severely impaired in HTLV-1-transformed ATL cells and freshly infected T lymphocytes. The ability to suppress IRF3 activation was ascribed to Tax. The expression of Tax alone sufficiently repressed the induction of IFN production by RIG-I plus PACT, cGAMP synthase plus STING, TBK1, IKKε, IRF3, and IRF7, but not by IRF3-5D, a dominant-active phosphomimetic mutant. This suggests that Tax perturbs IFN production at the step of IRF3 phosphorylation. Tax mutants deficient for CREB or NF-κB activation were fully competent in the suppression of IFN production. Coimmunoprecipitation experiments confirmed the association of Tax with TBK1, IKKε, STING, and IRF3.In vitrokinase assay indicated an inhibitory effect of Tax on TBK1-mediated phosphorylation of IRF3. Taken together, our findings suggested a new mechanism by which HTLV-1 oncoprotein Tax circumvents the production of type I IFNs in infected cells. Our findings have implications in therapeutic intervention of ATL. IMPORTANCE Human T-cell leukemia virus type 1 (HTLV-1) is the cause of adult T-cell leukemia (ATL), an aggressive and fatal blood cancer, as well as another chronic disabling disease of the spinal cord. Treatments are unsatisfactory, and options are limited. A combination of antiviral cellular protein alpha interferon and zidovudine, which is an inhibitor of a viral enzyme called reverse transcriptase, has been recommended as the standard first-line therapy for ATL. Exactly how HTLV-1 interacts with the cellular machinery for interferon production and action is not well understood. Our work sheds light on the mechanism of action for the inhibition of interferon production by an HTLV-1 oncogenic protein called Tax. Our findings might help to improve interferon-based anti-HTLV-1 and anti-ATL therapy.
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SIRT1 Suppresses Human T-Cell Leukemia Virus Type 1 Transcription. J Virol 2015; 89:8623-31. [PMID: 26063426 DOI: 10.1128/jvi.01229-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/02/2015] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Human T-cell leukemia virus type 1 (HTLV-1)-associated diseases are poorly treatable, and HTLV-1 vaccines are not available. High proviral load is one major risk factor for disease development. HTLV-1 encodes Tax oncoprotein, which activates transcription from viral long terminal repeats (LTR) and various types of cellular promoters. Counteracting Tax function might have prophylactic and therapeutic benefits. In this work, we report on the suppression of Tax activation of HTLV-1 LTR by SIRT1 deacetylase. The transcriptional activity of Tax on the LTR was largely ablated when SIRT1 was overexpressed, but Tax activation of NF-κB was unaffected. On the contrary, the activation of the LTR by Tax was boosted when SIRT1 was depleted. Treatment of cells with resveratrol shunted Tax activity in a SIRT1-dependent manner. The activation of SIRT1 in HTLV-1-transformed T cells by resveratrol potently inhibited HTLV-1 proviral transcription and Tax expression, whereas compromising SIRT1 by specific inhibitors augmented HTLV-1 mRNA expression. The administration of resveratrol also decreased the production of cell-free HTLV-1 virions from MT2 cells and the transmission of HTLV-1 from MT2 cells to uninfected Jurkat cells in coculture. SIRT1 associated with Tax in HTLV-1-transformed T cells. Treatment with resveratrol prevented the interaction of Tax with CREB and the recruitment of CREB, CRTC1, and p300 to Tax-responsive elements in the LTR. Our work demonstrates the negative regulatory function of SIRT1 in Tax activation of HTLV-1 transcription. Small-molecule activators of SIRT1 such as resveratrol might be considered new prophylactic and therapeutic agents in HTLV-1-associated diseases. IMPORTANCE Human T-cell leukemia virus type 1 (HTLV-1) causes a highly lethal blood cancer or a chronic debilitating disease of the spinal cord. Treatments are unsatisfactory, and vaccines are not available. Disease progression is associated with robust expression of HTLV-1 genes. Suppressing HTLV-1 gene expression might have preventive and therapeutic benefits. It is therefore critical that host factors controlling HTLV-1 gene expression be identified and characterized. This work reveals a new host factor that suppresses HTLV-1 gene expression and a natural compound that activates this suppression. Our findings not only provide new knowledge of the host control of HTLV-1 gene expression but also suggest a new strategy of using natural compounds for prevention and treatment of HTLV-1-associated diseases.
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Tang HMV, Gao WW, Chan CP, Cheng Y, Chaudhary V, Deng JJ, Yuen KS, Wong CM, Ng IOL, Kok KH, Zhou J, Jin DY. Requirement of CRTC1 coactivator for hepatitis B virus transcription. Nucleic Acids Res 2014; 42:12455-68. [PMID: 25300488 PMCID: PMC4227773 DOI: 10.1093/nar/gku925] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Transcription of hepatitis B virus (HBV) from the covalently closed circular DNA (cccDNA) template is essential for its replication. Suppressing the level and transcriptional activity of cccDNA might have anti-HBV effect. Although cellular transcription factors, such as CREB, which mediate HBV transcription, have been well described, transcriptional coactivators that facilitate this process are incompletely understood. In this study we showed that CREB-regulated transcriptional coactivator 1 (CRTC1) is required for HBV transcription and replication. The steady-state levels of CRTC1 protein were elevated in HBV-positive hepatoma cells and liver tissues. Ectopic expression of CRTC1 or its homolog CRTC2 or CRTC3 in hepatoma cells stimulated the activity of the preS2/S promoter of HBV, whereas overexpression of a dominant inactive form of CRTC1 inhibited HBV transcription. CRTC1 interacts with CREB and they are mutually required for the recruitment to the preS2/S promoter on cccDNA and for the activation of HBV transcription. Accumulation of pregenomic RNA (pgRNA) and cccDNA was observed when CRTC1 or its homologs were overexpressed, whereas the levels of pgRNA, cccDNA and secreted HBsAg were diminished when CRTC1 was compromised. In addition, HBV transactivator protein HBx stabilized CRTC1 and promoted its activity on HBV transcription. Our work reveals an essential role of CRTC1 coactivator in facilitating and supporting HBV transcription and replication.
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Affiliation(s)
- Hei-Man Vincent Tang
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wei-Wei Gao
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Yun Cheng
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Vidyanath Chaudhary
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jian-Jun Deng
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kit-San Yuen
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chun-Ming Wong
- State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Irene Oi-Lin Ng
- State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong Department of Pathology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kin-Hang Kok
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jie Zhou
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong
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7
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Siu KL, Yeung ML, Kok KH, Yuen KS, Kew C, Lui PY, Chan CP, Tse H, Woo PCY, Yuen KY, Jin DY. Middle east respiratory syndrome coronavirus 4a protein is a double-stranded RNA-binding protein that suppresses PACT-induced activation of RIG-I and MDA5 in the innate antiviral response. J Virol 2014; 88:4866-76. [PMID: 24522921 PMCID: PMC3993821 DOI: 10.1128/jvi.03649-13] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/07/2014] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging pathogen that causes severe disease in human. MERS-CoV is closely related to bat coronaviruses HKU4 and HKU5. Evasion of the innate antiviral response might contribute significantly to MERS-CoV pathogenesis, but the mechanism is poorly understood. In this study, we characterized MERS-CoV 4a protein as a novel immunosuppressive factor that antagonizes type I interferon production. MERS-CoV 4a protein contains a double-stranded RNA-binding domain capable of interacting with poly(I · C). Expression of MERS-CoV 4a protein suppressed the interferon production induced by poly(I · C) or Sendai virus. RNA binding of MERS-CoV 4a protein was required for IFN antagonism, a property shared by 4a protein of bat coronavirus HKU5 but not by the counterpart in bat coronavirus HKU4. MERS-CoV 4a protein interacted with PACT in an RNA-dependent manner but not with RIG-I or MDA5. It inhibited PACT-induced activation of RIG-I and MDA5 but did not affect the activity of downstream effectors such as RIG-I, MDA5, MAVS, TBK1, and IRF3. Taken together, our findings suggest a new mechanism through which MERS-CoV employs a viral double-stranded RNA-binding protein to circumvent the innate antiviral response by perturbing the function of cellular double-stranded RNA-binding protein PACT. PACT targeting might be a common strategy used by different viruses, including Ebola virus and herpes simplex virus 1, to counteract innate immunity. IMPORTANCE Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging and highly lethal human pathogen. Why MERS-CoV causes severe disease in human is unclear, and one possibility is that MERS-CoV is particularly efficient in counteracting host immunity, including the sensing of virus invasion. It will therefore be critical to clarify how MERS-CoV cripples the host proteins that sense viruses and to compare MERS-CoV with its ancestral viruses in bats in the counteraction of virus sensing. This work not only provides a new understanding of the abilities of MERS-CoV and closely related bat viruses to subvert virus sensing but also might prove useful in revealing new strategies for the development of vaccines and antivirals.
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Affiliation(s)
- Kam-Leung Siu
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Man Lung Yeung
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Kin-Hang Kok
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Kit-San Yuen
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Chun Kew
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Pak-Yin Lui
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Herman Tse
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Patrick C. Y. Woo
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Kwok-Yung Yuen
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
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8
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Van den Broeke C, Jacob T, Favoreel HW. Rho'ing in and out of cells: viral interactions with Rho GTPase signaling. Small GTPases 2014; 5:e28318. [PMID: 24691164 DOI: 10.4161/sgtp.28318] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rho GTPases are key regulators of actin and microtubule dynamics and organization. Increasing evidence shows that many viruses have evolved diverse interactions with Rho GTPase signaling and manipulate them for their own benefit. In this review, we discuss how Rho GTPase signaling interferes with many steps in the viral replication cycle, especially entry, replication, and spread. Seen the diversity between viruses, it is not surprising that there is considerable variability in viral interactions with Rho GTPase signaling. However, several largely common effects on Rho GTPases and actin architecture and microtubule dynamics have been reported. For some of these processes, the molecular signaling and biological consequences are well documented while for others we just begin to understand them. A better knowledge and identification of common threads in the different viral interactions with Rho GTPase signaling and their ultimate consequences for virus and host may pave the way toward the development of new antiviral drugs that may target different viruses.
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Affiliation(s)
- Céline Van den Broeke
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
| | - Thary Jacob
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
| | - Herman W Favoreel
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
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9
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Magini P, Pippucci T, Tsai IC, Coppola S, Stellacci E, Bartoletti-Stella A, Turchetti D, Graziano C, Cenacchi G, Neri I, Cordelli DM, Marchiani V, Bergamaschi R, Gasparre G, Neri G, Mazzanti L, Patrizi A, Franzoni E, Romeo G, Bordo D, Tartaglia M, Katsanis N, Seri M. A mutation in PAK3 with a dual molecular effect deregulates the RAS/MAPK pathway and drives an X-linked syndromic phenotype. Hum Mol Genet 2014; 23:3607-17. [PMID: 24556213 DOI: 10.1093/hmg/ddu070] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Loss-of-function mutations in PAK3 contribute to non-syndromic X-linked intellectual disability (NS-XLID) by affecting dendritic spine density and morphology. Linkage analysis in a three-generation family with affected males showing ID, agenesis of corpus callosum, cerebellar hypoplasia, microcephaly and ichthyosis, revealed a candidate disease locus in Xq21.33q24 encompassing over 280 genes. Subsequent to sequencing all coding exons of the X chromosome, we identified a single novel variant within the linkage region, affecting a conserved codon of PAK3. Biochemical studies showed that, similar to previous NS-XLID-associated lesions, the predicted amino acid substitution (Lys389Asn) abolished the kinase activity of PAK3. In addition, the introduced residue conferred a dominant-negative function to the protein that drives the syndromic phenotype. Using a combination of in vitro and in vivo studies in zebrafish embryos, we show that PAK3(N389) escapes its physiologic degradation and is able to perturb MAPK signaling via an uncontrolled kinase-independent function, which in turn leads to alterations of cerebral and craniofacial structures in vivo. Our data expand the spectrum of phenotypes associated with PAK3 mutations, characterize a novel mechanism resulting in a dual molecular effect of the same mutation with a complex PAK3 functional deregulation and provide evidence for a direct functional impact of aberrant PAK3 function on MAPK signaling.
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Affiliation(s)
- Pamela Magini
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - Tommaso Pippucci
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - I-Chun Tsai
- Center for Human Disease Modeling, Duke University Medical Center, Durham 27710, USA
| | - Simona Coppola
- Centro Nazionale per le Malattie Rare, Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy
| | - Emilia Stellacci
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy
| | - Anna Bartoletti-Stella
- Laboratorio di Neuropatologia, Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM)
| | - Daniela Turchetti
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - Claudio Graziano
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - Giovanna Cenacchi
- U.O. Anatomia e Istologia Patologica, Dipartimento di Scienze Biomediche e Neuromotorie (DIBINEM)
| | - Iria Neri
- U.O. Dermatologia, Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES)
| | - Duccio Maria Cordelli
- U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and
| | - Valentina Marchiani
- U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and
| | - Rosalba Bergamaschi
- Pediatria d'Urgenza, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), Università di Bologna, Bologna 40138, Italy
| | - Giuseppe Gasparre
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - Giovanni Neri
- Istituto di Genetica Medica, Università Cattolica del Sacro Cuore, Roma 00168, Italy
| | - Laura Mazzanti
- S.S. Malattie Rare e Sindromologia, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), Università di Bologna, Policlinico S.Orsola-Malpighi, Bologna 40138, Italy
| | - Annalisa Patrizi
- U.O. Dermatologia, Dipartimento di Medicina Specialistica, Diagnostica e Sperimentale (DIMES)
| | - Emilio Franzoni
- U.O. Neuropsichiatria Infantile, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC) and
| | - Giovanni Romeo
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC)
| | - Domenico Bordo
- IRCCS AOU S. Martino - IST, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy
| | - Marco Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Roma 00161, Italy
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Duke University Medical Center, Durham 27710, USA
| | - Marco Seri
- U.O. Genetica Medica, Dipartimento di Scienze Mediche e Chirurgiche (DIMEC),
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10
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Romanelli MG, Diani E, Bergamo E, Casoli C, Ciminale V, Bex F, Bertazzoni U. Highlights on distinctive structural and functional properties of HTLV Tax proteins. Front Microbiol 2013; 4:271. [PMID: 24058363 PMCID: PMC3766827 DOI: 10.3389/fmicb.2013.00271] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/20/2013] [Indexed: 12/15/2022] Open
Abstract
Human T cell leukemia viruses (HTLVs) are complex human retroviruses of the Deltaretrovirus genus. Four types have been identified thus far, with HTLV-1 and HTLV-2 much more prevalent than HTLV-3 or HTLV-4. HTLV-1 and HTLV-2 possess strictly related genomic structures, but differ significantly in pathogenicity, as HTLV-1 is the causative agent of adult T cell leukemia and of HTLV-associated myelopathy/tropical spastic paraparesis, whereas HTLV-2 is not associated with neoplasia. HTLVs code for a protein named Tax that is responsible for enhancing viral expression and drives cell transformation. Much effort has been invested to dissect the impact of Tax on signal transduction pathways and to identify functional differences between the HTLV Tax proteins that may explain the distinct oncogenic potential of HTLV-1 and HTLV-2. This review summarizes our current knowledge of Tax-1 and Tax-2 with emphasis on their structure, role in activation of the NF-κB (nuclear factor kappa-B) pathway, and interactions with host factors.
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Chan CP, Kok KH, Tang HMV, Wong CM, Jin DY. Internal ribosome entry site-mediated translational regulation of ATF4 splice variant in mammalian unfolded protein response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2165-75. [PMID: 23665047 DOI: 10.1016/j.bbamcr.2013.05.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 04/30/2013] [Accepted: 05/02/2013] [Indexed: 02/04/2023]
Abstract
Activating transcription factor 4 (ATF4) is a master regulator of genes involved in unfolded protein response (UPR) and its translation is regulated through reinitiation at upstream open reading frames. Here, we demonstrate internal ribosome entry site (IRES)-mediated translation of an alternatively spliced variant of human ATF4. This variant that contains four upstream open reading frames in the 5' leader region was expressed in leukocytes and other tissues. mRNA and protein expression of this variant was activated in the UPR. Its translation was neither inhibited by steric hindrance nor affected by eIF4G1 inactivation, indicating a cap-independent and IRES-dependent mechanism not mediated by ribosome scanning-reinitiation. The IRES activity mapped to a highly structured region that partially overlaps with the third and fourth open reading frames was unlikely attributed to cryptic promoter or splicing, but was activated by PERK-induced eIF2α phosphorylation. Taken together, our findings reveal a new mechanism for translational regulation of ATF4 in mammalian UPR.
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Affiliation(s)
- Ching-Ping Chan
- Department of Biochemistry, The University of Hong Kong, Pokfulam, Hong Kong
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