Protein phosphatase 2A family members (PP2A and PP6) associate with U1 snRNP and the spliceosome during pre-mRNA splicing

Kamoun, Malek; Filali, Mohammed; Murray, Michael V.; Awasthi, Sita; Wadzinski, Brian E.

doi:10.1016/j.bbrc.2013.09.068

Cited by 15 publications

(16 citation statements)

References 28 publications

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“…In addition to DNA replication and repair, and inflammatory cytokine signaling, our results also support another functional role for PP6 that has been previously described, pre-mRNA splicing [20]. Although PP6 has an established role in TOR signaling in yeast [10], data confirming an analogous role in mammals has been scant.…”

Section: Discussionsupporting

confidence: 82%

“…This aspect of PP6 function likely reflects its ability to modulate signaling by DNA-dependent protein kinase [16] as well as its interactions with Aurora A kinase [17, 18]. More recent studies suggest a broader role for PP6 in endoplasmic reticulum-to-Golgi trafficking [19], pre-mRNA splicing [20], formation of adherens junctions through interaction with E-cadherin [21], control of apoptosis in immune cells [22], response to mitochondrial DNA damage [8], and modulation of signaling through the Hippo pathway [23]. With regard to its role in liver cells, PP6 has been identified as a tumor suppressor based on its ability to induce G1/S cell cycle arrest in two human hepatocellular carcinoma (HCC) cell lines [7].…”

Section: Introductionmentioning

confidence: 99%

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Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

Boylan

Salomon

Tantravahi

et al. 2015

Experimental Cell Research

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Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders.

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Section: Discussionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

Boylan

Salomon

Tantravahi

et al. 2015

Experimental Cell Research

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“…PP6 regulates the activities of many host proteins (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), and it is therefore possible that PP6 silencing perturbs the virus life cycle by affecting other cellular processes. However, the fact that PP6 interacts directly with the viral RdRP suggests that it plays a direct role in the viral life cycle by regulating the posttranslational modifications of viral proteins.…”

Section: Discussionmentioning

confidence: 99%

“…PP6 is a member of the PP2A subfamily of protein phosphatases, cellular enzymes that catalyze the liberation of inorganic phosphate from proteins and peptides at serine or threonine residues (22). PP6 is a significant regulator of a number of cellular processes, including chromosome stability and the DNA damage response (23)(24)(25)(26)(27), mitosis and the regulation of cell cycle progression (22,(28)(29)(30)(31), signaling (32,33), pre-mRNA splicing (34), and vesicular trafficking (35). The catalytic subunit PPP6C and the regulatory subunits PPP6R1 and PPP6R3 were found to copurify with the viral RdRP.…”

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confidence: 99%

Interactome Analysis of the Influenza A Virus Transcription/Replication Machinery Identifies Protein Phosphatase 6 as a Cellular Factor Required for Efficient Virus Replication

York

Hutchinson

Fodor

2014

J Virol

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The negative-sense RNA genome of influenza A virus is transcribed and replicated by the viral RNA-dependent RNA polymerase (RdRP). The viral RdRP is an important host range determinant, indicating that its function is affected by interactions with cellular factors. However, the identities and the roles of most of these factors remain unknown. Here, we employed affinity purification followed by mass spectrometry to identify cellular proteins that interact with the influenza A virus RdRP in infected human cells. We purified RdRPs using a recombinant influenza virus in which the PB2 subunit of the RdRP is fused to a Strep-tag. When this tagged subunit was purified from infected cells, copurifying proteins included the other RdRP subunits (PB1 and PA) and the viral nucleoprotein and neuraminidase, as well as 171 cellular proteins. Label-free quantitative mass spectrometry revealed that the most abundant of these host proteins were chaperones, cytoskeletal proteins, importins, proteins involved in ubiquitination, kinases and phosphatases, and mitochondrial and ribosomal proteins. Among the phosphatases, we identified three subunits of the cellular serine/threonine protein phosphatase 6 (PP6), including the catalytic subunit PPP6C and regulatory subunits PPP6R1 and PPP6R3. PP6 was found to interact directly with the PB1 and PB2 subunits of the viral RdRP, and small interfering RNA ( Viruses are obligate intracellular parasites that have been compelled by evolutionary processes to encode a minimal number of proteins for the completion of an infectious life cycle, in order to infect naive hosts and to persist in nature. This is exemplified by RNA viruses, the genomes of which are generally smaller than the genomes of DNA viruses, and therefore they greatly rely on the exploitation and subversion of host cellular proteins, structures, and pathways to facilitate virus replication (1). Transcription and replication of the influenza A virus genome are performed by the virally encoded RNA-dependent RNA polymerase (RdRP), a major determinant of species tropism and pathogenicity and a key player in the adaptation of avian influenza A viruses to mammalian hosts. These characteristics of the viral RdRP are thought to be governed by numerous interactions with cellular factors (reviewed in references 2 and 3). It is therefore of great importance to understand the relationship between the viral transcription/replication machinery and host cellular factors in order to understand how the host cell can influence the function of the viral transcription/replication machinery and vice versa. Insight into the molecular biology of these relationships could lead to novel antiviral strategies and has the potential to identify host-specific interactions that would act as a barrier to pandemic emergence.The genome of influenza A virus, like that of other members of the Orthomyxoviridae, is segmented and consists of eight individual viral ribonucleoprotein (vRNP) complexes. Each vRNP contains single-stranded viral RNA (vRNA) that is en...

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“…Sit4, the homolog in yeast, is required for G1/S progression and equal chromosome segregation in yeast (Sutton et al, 1991). The human PP6 has been shown to play a role in DNA damage response, cell cycle, apoptosis and pre-mRNA splicing by acting on DNA-dependent protein kinase (DNA-PK), histone γ-H2AX, Aurora A, NF-κB and the U1 small nuclear ribonucleic protein (snRNP) (Douglas et al, 2014(Douglas et al, , 2010Hammond et al, 2013;Hosing et al, 2012;Kajihara et al, 2014;Kamoun et al, 2013;Brautigan, 2006, 2007;Zeng et al, 2010;Zhong et al, 2011). However, the role of PP6 in reproductive cells remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Loss of protein phosphatase 6 in oocytes causes failure of meiosis II exit and impaired female fertility

Wang

Teng³

et al. 2015

Journal of Cell Science

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Dynamic protein phosphorylation and dephosphorylation, mediated by a conserved cohort of protein kinases and phosphatases, regulate cell cycle progression. Among the well-known PP2A-like protein phosphatases, protein phosphatase 6 (PP6) has been analyzed in mammalian mitosis, and Aurora A has recently been identified as its key substrate. However, the functions of PP6 in meiosis are still entirely unknown. To identify the physiological role of PP6 in female gametogenesis, Ppp6c F/F mice were first generated and crossed with Zp3-Cre mice to selectively disrupt Ppp6c expression in oocytes. Here, we report for the first time that PP6c is dispensable for oocyte meiotic maturation but essential for exit from meiosis II (MII) after fertilization. Depletion of PP6c caused an abnormal MII spindle and disrupted MII cytokinesis, resulting in zygotes with high risk of aneuploidy and defective early embryonic development, and thus severe subfertility. We also reveal that PP6 inactivation interferes with MII spindle formation and MII exit owing to increased Aurora A activity, and that Aurora A inhibition with MLN8237 can rescue the PP6c depletion phenotype. In conclusion, our findings uncover a hitherto unknown role for PP6 as an indispensable regulator of oocyte meiosis and female fertility.

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Protein phosphatase 2A family members (PP2A and PP6) associate with U1 snRNP and the spliceosome during pre-mRNA splicing

Cited by 15 publications

References 28 publications

Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

Interactome Analysis of the Influenza A Virus Transcription/Replication Machinery Identifies Protein Phosphatase 6 as a Cellular Factor Required for Efficient Virus Replication

Loss of protein phosphatase 6 in oocytes causes failure of meiosis II exit and impaired female fertility

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