scholarly journals The E1^E4 Protein of Human Papillomavirus Interacts with the Serine-Arginine-Specific Protein Kinase SRPK1

2007 ◽  
Vol 81 (11) ◽  
pp. 5437-5448 ◽  
Author(s):  
Ian Bell ◽  
Ashley Martin ◽  
Sally Roberts

ABSTRACT Human papillomavirus (HPV) infections of the squamous epithelium are associated with high-level expression of the E1^E4 protein during the productive phase of infection. However, the precise mechanisms of how E1^E4 contributes to the replication cycle of the virus are poorly understood. Here, we show that the serine-arginine (SR)-specific protein kinase SRPK1 is a novel binding partner of HPV type 1 (HPV1) E1^E4. We map critical residues within an arginine-rich domain of HPV1 E1^E4, and in a region known to facilitate E1^E4 oligomerization, that are requisite for SRPK1 binding. In vitro kinase assays show that SRPK1 binding is associated with phosphorylation of an HPV1 E1^E4 polypeptide and modulates autophosphorylation of the kinase. We show that SRPK1 is sequestered into E4 inclusion bodies in terminally differentiated cells within HPV1 warts and that colocalization between E1^E4 and SRPK1 is not dependent on additional HPV1 factors. Moreover, we also identify SRPK1 binding of E1^E4 proteins of HPV16 and HPV18. Our findings indicate that SRPK1 binding is a conserved function of E1^E4 proteins of diverse virus types. SRPK1 influences important biochemical processes within the cell, including nuclear organization and RNA metabolism. While phosphorylation of HPV1 E4 by SRPK1 may directly influence HPV1 E4 function during the infectious cycle, the modulation and sequestration of SRPK1 by E1^E4 may affect the ability of SRPK1 to phosphorylate its cellular targets, thereby facilitating the productive phase of the HPV replication cycle.

1985 ◽  
Vol 5 (10) ◽  
pp. 2543-2551 ◽  
Author(s):  
I MacDonald ◽  
J Levy ◽  
T Pawson

The avian c-fps and mammalian c-fes proto-oncogenes are cognate cellular sequences. Antiserum raised against the P140gag-fps transforming protein of Fujinami avian sarcoma virus specifically recognized a 92,000-Mr protein in human and mouse hematopoietic cells which was closely related in structure to Snyder-Theilen feline sarcoma virus P87gag-fes. This polypeptide was apparently the product of the human c-fes gene and was therefore designated p92c-fes. Human p92c-fes was associated with a tyrosine-specific protein kinase activity in vitro and was capable of both autophosphorylation and phosphorylation of enolase as an exogenous protein substrate. The synthesis of human and mouse p92c-fes was largely, though not entirely, confined to myeloid cells. p92c-fes was expressed to relatively high levels in a multipotential murine myeloid cell line, in more mature human and mouse granulocyte-macrophage progenitors, and in differentiated macrophage like cells as well as in the mononuclear fraction of normal and leukemic human peripheral blood. p92c-fes was not found in erythroid cells, with the exception of a human erythroleukemia line which retains the capacity to differentiate into macrophage like cells. These results suggest a normal role for the p92c-fes tyrosine kinase in hematopoiesis, particularly in granulocyte-macrophage differentiation. In addition, a distinct 94,000-Mr polypeptide, antigenically related to p92c-fes, was identified in a number of hematopoietic and nonhematopoietic human and mouse cells and was also found to be associated with a tyrosine-specific protein kinase activity.


1988 ◽  
Vol 8 (7) ◽  
pp. 2976-2979
Author(s):  
J A Hadwiger ◽  
S I Reed

The phosphorylation level of the Saccharomyces cerevisiae Cdc28 protein remained invariant under conditions that resulted in cell cycle arrest in the G1 phase and loss of Cdc28-specific protein kinase activity when the activity was assayed in vitro. These results are in contrast to the proposed regulation of the homologous Cdc2 protein kinase of Schizosaccharomyces pombe.


1984 ◽  
Vol 4 (10) ◽  
pp. 1999-2009 ◽  
Author(s):  
M F Roussel ◽  
C W Rettenmier ◽  
A T Look ◽  
C J Sherr

The viral oncogene v-fms encodes a transforming glycoprotein with in vitro tyrosine-specific protein kinase activity. Although most v-fms-coded molecules remain internally sequestered in transformed cells, a minor population of molecules is transported to the cell surface. An engineered deletion mutant lacking 348 base pairs of the 3.0-kilobase-pair v-fms gene encoded a polypeptide that was 15 kilodaltons smaller than the wild-type v-fms gene product. The in-frame deletion of 116 amino acids was adjacent to the transmembrane anchor peptide located near the middle of the predicted protein sequence and 432 amino acids from the carboxyl terminus. The mutant polypeptide acquired N-linked oligosaccharide chains, was proteolytically processed in a manner similar to the wild-type glycoprotein, and exhibited an associated tyrosine-specific protein kinase activity in vitro. However, the N-linked oligosaccharides of the mutant glycoprotein were not processed to complex carbohydrate chains, and the glycoprotein was not detected at the cell surface. Cells expressing high levels of the mutant glycoprotein did not undergo morphological transformation and did not form colonies in semisolid medium. The transforming activity of the v-fms gene product therefore appears to be mediated through target molecules on the plasma membrane.


1997 ◽  
Vol 8 (10) ◽  
pp. 1889-1899 ◽  
Author(s):  
Meirav Matto-Yelin ◽  
Alastair Aitken ◽  
Shoshana Ravid

Myosin II heavy chain (MHC) specific protein kinase C (MHC-PKC), isolated from Dictyostelium discoideum, regulates myosin II assembly and localization in response to the chemoattractant cyclic AMP. Immunoprecipitation of MHC-PKC revealed that it resides as a complex with several proteins. We show herein that one of these proteins is a homologue of the 14–3-3 protein (Dd14–3-3). This protein has recently been implicated in the regulation of intracellular signaling pathways via its interaction with several signaling proteins, such as PKC and Raf-1 kinase. We demonstrate that the mammalian 14–3-3 ζ isoform inhibits the MHC-PKC activity in vitro and that this inhibition is carried out by a direct interaction between the two proteins. Furthermore, we found that the cytosolic MHC-PKC, which is inactive, formed a complex with Dd14–3-3 in the cytosol in a cyclic AMP-dependent manner, whereas the membrane-bound active MHC-PKC was not found in a complex with Dd14–3-3. This suggests that Dd14–3-3 inhibits the MHC-PKC in vivo. We further show that MHC-PKC binds Dd14–3-3 as well as 14–3-3ζ through its C1 domain, and the interaction between these two proteins does not involve a peptide containing phosphoserine as was found for Raf-1 kinase. Our experiments thus show an in vivo function for a member of the 14–3-3 family and demonstrate that MHC-PKC interacts directly with Dd14–3-3 and 14–3-3ζ through its C1 domain both in vitro and in vivo, resulting in the inhibition of the kinase.


1988 ◽  
Vol 8 (7) ◽  
pp. 2976-2979 ◽  
Author(s):  
J A Hadwiger ◽  
S I Reed

The phosphorylation level of the Saccharomyces cerevisiae Cdc28 protein remained invariant under conditions that resulted in cell cycle arrest in the G1 phase and loss of Cdc28-specific protein kinase activity when the activity was assayed in vitro. These results are in contrast to the proposed regulation of the homologous Cdc2 protein kinase of Schizosaccharomyces pombe.


1984 ◽  
Vol 4 (10) ◽  
pp. 1999-2009
Author(s):  
M F Roussel ◽  
C W Rettenmier ◽  
A T Look ◽  
C J Sherr

The viral oncogene v-fms encodes a transforming glycoprotein with in vitro tyrosine-specific protein kinase activity. Although most v-fms-coded molecules remain internally sequestered in transformed cells, a minor population of molecules is transported to the cell surface. An engineered deletion mutant lacking 348 base pairs of the 3.0-kilobase-pair v-fms gene encoded a polypeptide that was 15 kilodaltons smaller than the wild-type v-fms gene product. The in-frame deletion of 116 amino acids was adjacent to the transmembrane anchor peptide located near the middle of the predicted protein sequence and 432 amino acids from the carboxyl terminus. The mutant polypeptide acquired N-linked oligosaccharide chains, was proteolytically processed in a manner similar to the wild-type glycoprotein, and exhibited an associated tyrosine-specific protein kinase activity in vitro. However, the N-linked oligosaccharides of the mutant glycoprotein were not processed to complex carbohydrate chains, and the glycoprotein was not detected at the cell surface. Cells expressing high levels of the mutant glycoprotein did not undergo morphological transformation and did not form colonies in semisolid medium. The transforming activity of the v-fms gene product therefore appears to be mediated through target molecules on the plasma membrane.


1985 ◽  
Vol 5 (10) ◽  
pp. 2543-2551
Author(s):  
I MacDonald ◽  
J Levy ◽  
T Pawson

The avian c-fps and mammalian c-fes proto-oncogenes are cognate cellular sequences. Antiserum raised against the P140gag-fps transforming protein of Fujinami avian sarcoma virus specifically recognized a 92,000-Mr protein in human and mouse hematopoietic cells which was closely related in structure to Snyder-Theilen feline sarcoma virus P87gag-fes. This polypeptide was apparently the product of the human c-fes gene and was therefore designated p92c-fes. Human p92c-fes was associated with a tyrosine-specific protein kinase activity in vitro and was capable of both autophosphorylation and phosphorylation of enolase as an exogenous protein substrate. The synthesis of human and mouse p92c-fes was largely, though not entirely, confined to myeloid cells. p92c-fes was expressed to relatively high levels in a multipotential murine myeloid cell line, in more mature human and mouse granulocyte-macrophage progenitors, and in differentiated macrophage like cells as well as in the mononuclear fraction of normal and leukemic human peripheral blood. p92c-fes was not found in erythroid cells, with the exception of a human erythroleukemia line which retains the capacity to differentiate into macrophage like cells. These results suggest a normal role for the p92c-fes tyrosine kinase in hematopoiesis, particularly in granulocyte-macrophage differentiation. In addition, a distinct 94,000-Mr polypeptide, antigenically related to p92c-fes, was identified in a number of hematopoietic and nonhematopoietic human and mouse cells and was also found to be associated with a tyrosine-specific protein kinase activity.


1987 ◽  
Vol 253 (2) ◽  
pp. C286-C295 ◽  
Author(s):  
D. Hillsgrove ◽  
C. G. Shores ◽  
J. C. Parker ◽  
P. F. Maness

We have identified in the plasma membrane of the chicken erythrocyte a 60-kDa tyrosine-specific protein kinase immunologically related to the transforming protein pp60v-src of Rous sarcoma virus. The erythrocyte protein kinase phosphorylated heavy chains of tumor-bearing rabbit (TBR) antibodies reactive with pp60c-src at tyrosine in immune complex protein kinase assays. The kinase was identified as a 60-kDa protein by [35S]methionine labeling of erythrocytes and by autophosphorylation in immune complexes. The kinase migrated on two-dimensional gel electrophoresis with an apparent pI and molecular mass similar to pp60c-src. A plasma membrane-enriched fraction isolated from chicken red cells contained the majority of the kinase activity. The kinase was solubilized from the plasma membrane by the detergents 0.5% (wt/vol) Na-deoxycholate and 1% (vol/vol) Nonidet P-40. One molar NaCl was much less effective, indicating a strong association of the kinase with the plasma membrane. Incubation of the plasma membrane fraction with [32P]ATP resulted in tyrosine phosphorylation of the anion transport protein band 3. Band 3 phosphorylation was blocked by TBR antibodies, indicating that the kinase recognized by pp60c-src antibodies was responsible for band 3 phosphorylation. These results demonstrate that the avian erythrocyte plasma membrane contains a tightly bound tyrosine-specific protein kinase identical or closely related to pp60c-src and that this kinase is responsible for band 3 phosphorylation in vitro.


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