Arginine-vasopressin effect on the content of cyclic nucleotides, cellular protein phosphorylation, and adhesion to plastic of peritoneal mouse macrophages

1998 ◽  
Vol 126 (1) ◽  
pp. 712-714
Author(s):  
N. A. Igonina ◽  
S. G. Dzgoev ◽  
V. A. Evseev
Keyword(s):  
Protein Phosphorylation ◽  
Arginine Vasopressin ◽  
Cyclic Nucleotides ◽  
Cellular Protein ◽  
Mouse Macrophages

Towards a molecular description of cell transformation by avian sarcoma virus

1980 ◽  
Vol 210 (1180) ◽  
pp. 387-396 ◽  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphorylation ◽  
Molecular Mass ◽  
Cellular Protein ◽  
Transformed Cells ◽  
Relative Molecular Mass ◽  
Protein Kinase Activity ◽  
Avian Sarcoma Virus ◽  
Sarcoma Virus ◽  
Avian Sarcoma

The avian sarcoma virus transforming gene product has been identified and partially purified from extracts of transformed cells. It is a phosphoprotein with a relative molecular mass of 60 000 (pp60 src ) with two major sites of phosphorylation. pp60 src appears to be a cyclic-AMP-independent protein kinase as judged by protein phosphorylation with partly purified fractions. The specificity of the phosphorylation observed was judged by inhibition with anti-pp60 src IgG but not by normal IgG and by the fact that the protein kinase activity isolated from ts transformation-mutant infected cells was more thermolabile than that from wild-type transformed cells, thus showing more directly the origin of the enzymic activity. A cellular protein substrate of pp60 src has been identified as a 34000 molecular mass protein. These data together suggest that protein phosphorylation by pp60 src may be a function of the molecule that plays a major role in transformation.

scholarly journals ACTH, cyclic nucleotides, and brain protein phosphorylation in vitro

1976 ◽  
Vol 1 (6) ◽  
pp. 669-677 ◽  
Author(s):  
H. Zwiers ◽  
H. D. Veldhuis ◽  
P. Schotman ◽  
W. H. Gispen
Keyword(s):  
Protein Phosphorylation ◽  
Cyclic Nucleotides ◽  
Brain Protein

scholarly journals Identification of SRPK1 and SRPK2 as the Major Cellular Protein Kinases Phosphorylating Hepatitis B Virus Core Protein

2002 ◽  
Vol 76 (16) ◽  
pp. 8124-8137 ◽  
Author(s):  
Henrik Daub ◽  
Stephanie Blencke ◽  
Peter Habenberger ◽  
Alexander Kurtenbach ◽  
Julia Dennenmoser ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Protein Kinase ◽  
Hepatitis B ◽  
Protein Phosphorylation ◽  
Protein Kinases ◽  
Kinase Activity ◽  
Core Protein ◽  
Cellular Protein ◽  
Total Cell ◽  
B Virus

ABSTRACT Phosphorylation of hepatitis B virus (HBV) core protein has recently been shown to be a prerequisite for pregenomic RNA encapsidation into viral capsids, but the host cell kinases mediating this essential step of the HBV replication cycle have not been identified. We detected two kinases of 95 and 115 kDa in HuH-7 total cell lysates which interacted specifically with the HBV core protein and phosphorylated its arginine-rich C-terminal domain. The 95-kDa kinase was purified and characterized as SR protein-specific kinase 1 (SRPK1) by mass spectrometry. Based on this finding, the 115-kDa kinase could be identified as the related kinase SRPK2 by immunoblot analysis. In vitro, both SRPKs phosphorylated HBV core protein on the same serine residues which are found to be phosphorylated in vivo. Moreover, the major cellular HBV core kinase activity detected in the total cell lysate showed biochemical properties identical to those of SRPK1 and SRPK2, as examined by measuring binding to a panel of chromatography media. We also clearly demonstrate that neither the cyclin-dependent kinases Cdc2 and Cdk2 nor protein kinase C, previously implicated in HBV core protein phosphorylation, can account for the HBV core protein kinase activity. We conclude that both SRPK1 and SRPK2 are most likely the cellular protein kinases mediating HBV core protein phosphorylation during viral infection and therefore represent important host cell targets for therapeutic intervention in HBV infection.

scholarly journals Mutations in the Splicosome Lead to Alternative Splicing of CSF3R in Promoting Myelodysplastic Syndromes

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3897-3897
Author(s):  
Frances Austin ◽  
Hrishikesh M Mehta ◽  
Seth J. Corey ◽  
Chonghui Cheng
Keyword(s):  
Protein Phosphorylation ◽  
Myelodysplastic Syndromes ◽  
Conflicts Of Interest ◽  
Intron Retention ◽  
Cellular Protein ◽  
Class I ◽  
Cell Phenotype ◽  
Splicing Factors ◽  
Wild Type ◽  
Class Iv

Abstract Despite advances into the genetic basis of myelodysplastic syndromes (MDS), the mechanisms of their pathophysiology remain poorly understood, and frequently terminates in acute myeloid leukemia. Mutually exclusive mutations have been identified in splicing factors U2AF1, SF3B1, SRSF2, SF3A1, ZRSR2 and LUcL7 in 85% of MDS cases. We and others have identified aberrant forms of Granulocyte Colony Stimulating Factor Receptor (CSF3R) in patients with myeloid malignancies and partially characterized their phenotypic and signal transduction effects. Two of the seven isoforms of CSF3R have clinical relevance: Class I (full-length form) and Class IV (alternatively spliced form). Compared to Class I, Class IV isoform is differentiation defective and displays enhanced proliferation. Increased expression of the Class IV isoform has been found in MDS/AML and results in enhanced cell proliferation and impaired differentiation of granulocytes (Mehta et al, Leukemia 2014). The Class IV CSF3R transcript is derived by intron excision, whereas Class I results from retention of that intron. We hypothesize aberrant splicing of the CSF3R transcript promoted by mutations in splicing factors drives abnormal granulopoiesis in MDS due to increased expression of the differentiation defective Class IV CSF3R. We identified U2AF1, SRSF2, and SAM68 sites within the nucleotide sequence of the spliced intron. To study the effect of splicing factor mutations on CSF3R splicing, we constructed a minigene consisting of 5' exon of the CAT gene with an ATG site and a partial intron fused to intron region of G-CSFR upstream of Exon 17. The retained intron is present in the exon 17 of CSF3R. The minigene consists of 2 introns and 3 exons. We transduced 293FT cells with the minigene ± wild-type U2AF1 or U2AF1 S34F mutant, as well as the minigene ± wild-type SF3B1 or SF3B1 K300E. The cells were then treated with either 1µM sodium orthovanadate (Na3VO4) or 10 nM phorbol myristic acetate (PMA). The former inhibits tyrosine phosphatases, promoting tyrosine protein phosphorylation, whereas the latter promotes activation of the protein kinase C pathway, which eventually activates ERK1/2 an upstream activator of SAM68. Protein phosphorylation of spliceosome proteins is fundamental to regulation of splicing. The effect of PMA and Na3VO4 were compared with each other and those treated with control diluent. Qualitative and semi-quantitative evaluations were performed. We identified expression with SF3B1 K700E enhances CSF3R splicing resulting in increased Class IV, however the U2AF1 S34F inhibits splicing resulting in reduced Class IV. The increase and decrease were in relation to the wild type. Further exploration of how cellular protein phosphorylation influences splicing using Na3VO4 (identified that cells transduced with SF3B1, U2AF1 wt or mutant shown decreased splicing resulting in Class IV transcript. PMA however had no effect on either class expression. These data suggest that CSF3R transcript processing is sensitive to diverse tyrosine kinase signaling, resulting in increased intron retention, suggesting that phosphorylation events inhibit Class IV transcript formation. Additionally the mutations in splicing factors which are recurrently found in MDS are associated with altered CSF3R transcripts and may affect CSF3R signaling and cell phenotype. (This work is supported by DOD and NIH R01R01HL128173.) Disclosures No relevant conflicts of interest to declare.

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