SR proteins ASF/SF2 and SRp55 participate in tissue factor biosynthesis in human monocytic cells

Tardos, Jonathan G.; Eisenreich, Andreas; Deikus, Gintaras; Bechhofer, David H.; Chandradas, Sajiv; Zafar, U.; Rauch, Ursula; Bogdanov, Vladimir Y.

doi:10.1111/j.1538-7836.2008.02946.x

Cited by 29 publications

(50 citation statements)

References 40 publications

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“…In association with these results, we found overexpression of SF2/ASF and SRp75 alone or in combination influenced the mRNA expression pattern of the TF isoforms in TNF-α-induced HUVECs in differing modalities. It has been shown by other groups that the phosphorylation state of SR proteins determines their activity in alternative splicing processes, 17,20,36 and the activity of distinct SR proteins determines the expression of different isoforms, as shown for TF and other proteins. 10,17,18,36,37 Blaustein et al showed Akt to be an SR protein kinase that is involved in regulation of the phosphorylation and the activity of SR proteins such as SF2/ASF and 9G8.…”

Section: Discussionmentioning

confidence: 99%

“…23,24 Finally, Tardos et al reported that exon 5 of the human TF gene contains ESE motifs for SR proteins, such as SF2/ASF and SRp55. 36 The binding of SR proteins to these motifs was shown to be essential for the differential TF isoform expression in human monocytic cells. 14 Altogether, the results of the present study point to the PI3K/Akt pathway being, at least in part, involved in the differential TF isoform expression at the mRNA level by regulation of alternative splicing processes, possibly mediated through the phosphorylation state and activity of the SR proteins SRp75, SRp55 and SF2/ASF in TNF-α-induced human ECs.…”

Section: Discussionmentioning

confidence: 99%

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Role of the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Regulating Alternative Splicing of Tissue Factor mRNA in Human Endothelial Cells

Eisenreich

Malz

Pepke

et al. 2009

Circ J

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Background: Tissue factor (TF) is the primary initiator of blood coagulation. In response to tumor necrosis factor (TNF)-α human umbilical vein endothelial cells (HUVECs) express 2 TF isoforms: a soluble alternatively spliced isoform (asHTF) and membrane-bound "full length" (fl)TF. How the differential TF isoform expression is regulated is still unknown. This study compared the impact of PI3K/Akt pathway inhibition on alternative splicing of TF in HUVECs, to the influence of transcriptional regulation by inhibiting nuclear factor κ B (NFκB). Methods and Results:The mRNA expression of TF isoforms was assessed by real-time PCR, the thrombogenic activity was measured by a chromogenic TF activity assay and the phosphorylation state of serine/arginine-rich (SR) proteins was analyzed by western blotting. Transfection of HUVECs was done 72 h before the inhibition experiments were performed. PI3K/Akt pathway inhibition reduced the mRNA expression of asHTF but not flTF. Inhibition of NFκB reduced the expression of both isoforms. Moreover, the PI3K/Akt pathway inhibition, but not that of NFκB, modified the phosphorylation of the SR proteins SRp75, SRp55 and SF2/ASF. Additionally, overexpression of SF2/ASF and SRp75 influenced the differential TF-isoform expression in HUVECs. Conclusions: The PI3K/Akt pathway modulates alternative splicing of TF in HUVECs, distinct from transcriptional regulation. (Circ J 2009; 73: 1746 -1752

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Role of the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Regulating Alternative Splicing of Tissue Factor mRNA in Human Endothelial Cells

Eisenreich

Malz

Pepke

et al. 2009

Circ J

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“…Differences in secreted asTF levels and presence of a functional flTF-PAR2 axis in MDA-MB-231-mfp cells may explain why asTF differently affects vascular density in these two xenograft models. Alternative splicing has been deemed critical to the proliferation of BrCa cells: overexpression of ASF/SF2, a major SR protein and regulator of the flTF/asTF mRNA ratio in monocytes (18), leads to enhanced proliferation, transformation, and BrCa growth in vivo (1). Furthermore, the expression of SRp40-the spliceosomal protein that promotes asTF synthesis (17), the levels of which are up-regulated in MDA-MB-231-mfp cells-is increased in human BrCa and associates with lymph node metastasis (32).…”

Section: Discussionmentioning

confidence: 99%

“…Regulated splicing of TF pre-mRNA in human monocytes is controlled by several serine-rich (SR) proteins, including ASF/SF2 and SRp55 (17,18). Expression of SR proteins is frequently perturbed in BrCa tumors (2), and it is thus plausible that the relative abundance of flTF and asTF is also altered in BrCa.…”

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confidence: 99%

Alternatively spliced tissue factor promotes breast cancer growth in a β1 integrin-dependent manner

Kocatürk¹,

Berg²,

Tieken³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

126

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Full-length tissue factor (flTF), the coagulation initiator, is overexpressed in breast cancer (BrCa), but associations between flTF expression and clinical outcome remain controversial. It is currently not known whether the soluble alternatively spliced TF form (asTF) is expressed in BrCa or impacts BrCa progression. We are unique in reporting that asTF, but not flTF, strongly associates with both tumor size and grade, and induces BrCa cell proliferation by binding to β1 integrins. asTF promotes oncogenic gene expression, anchorage-independent growth, and strongly up-regulates tumor expansion in a luminal BrCa model. In basal BrCa cells that constitutively express both TF isoforms, asTF blockade reduces tumor growth and proliferation in vivo. We propose that asTF plays a major role in BrCa progression acting as an autocrine factor that promotes tumor progression. Targeting asTF may comprise a previously unexplored therapeutic strategy in BrCa that stems tumor growth, yet does not impair normal hemostasis.regulated pre-mRNA processing | outside-in signaling I n breast cancer (BrCa), proteins that modulate splicing events such as ASF/SF2 and SR(Serine/Arginine-rich)p55, are frequently up-regulated and contribute to cell transformation (1, 2). BrCa cells exhibit specific alternative splicing signatures that were proposed as potential prognostic factors in BrCa (3). Alternative splicing of proteins, such as spleen tyrosine kinase (Syk), p53, phosphatase and tensin homolog (PTEN), chemokine (C-X-C motif) receptor 3 (CXCR3), and ras-related C3 botulinum toxin substrate 1 (Rac1) impacts BrCa cell behavior and therefore, disease progression (4-8).Full-length tissue factor (flTF) is the initiator of blood coagulation (9). Following vascular damage, flTF binds its ligand FVII(a), which triggers clot formation. Aside from subendothelial tissues, flTF is also abundant on cancer cells (9) and fuels tumor progression by modulating integrin α3β1 function, cell migration (10), and FVIIa-dependent protease activated receptor (PAR)2 activation, but flTF-β1 integrin complexation enhances PAR2 activation (11). flTF-dependent PAR2 activation results in the production of VEGF, CXCL1, and IL-8, thus promoting the angiogenic switch and consequently, tumor growth in vivo (10, 11).Alternative splicing of TF pre-mRNA results in the deletion of exon 5 and thus a frameshift in exon 6, yielding a transmembrane domain-lacking isoform that can be secreted (12). Human and murine alternatively spliced TF (asTF) contain novel C termini with poor homology to one another or any other protein, and the murine asTF C terminus is longer than that of human asTF (12,13). High expression of asTF in tumor cell lines suggests a role in tumor progression (10,14). Subcutaneous growth of pancreatic cancer cells overexpressing asTF results in larger and more vascularized tumors (15). We recently discovered that asTF induces angiogenesis, independent of PAR2 activation, by acting as an integrin ligand (16). Thus, flTF and asTF facilitate cellular signaling via ...

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“…asTF can be secreted, exhibits minimal coagulant potential compared with the membrane-bound full-length TF (flTF) and is detectable, alongside flTF, in spontaneously formed arterial thrombi. Discernible procoagulant activity of native asTF was demonstrated to be low and phospholipid dependent (14); biosynthesis of asTF in monocytes and endothelial cells is controlled by several splicing regulator (SR) proteins, most notably ASF/ SF2 and SRp55, and a group of kinases comprising Cdc2-like kinase, deoxyribonucleic acid (DNA) topoisomerase I and phosphatidylinositol 3-kinase (15)(16)(17). After the discovery of human asTF (hasTF), its murine homolog (masTF) was identified and characterized (18).…”

Section: Introductionmentioning

confidence: 99%

Nonproteolytic Properties of Murine Alternatively Spliced Tissue Factor: Implications for Integrin-Mediated Signaling in Murine Models

Godby

Berg

Srinivasan

et al. 2012

Mol Med

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This study was performed to determine whether murine alternatively spliced tissue factor (masTF) acts analogously to human alternatively spliced tissue factor (hasTF) in promoting neovascularization via integrin ligation. Immunohistochemical evaluation of a spontaneous murine pancreatic ductal adenocarcinoma model revealed increased levels of masTF and murine full-length tissue factor (mflTF) in tumor lesions compared with benign pancreas; furthermore, masTF colocalized with mflTF in spontaneous aortic plaques of Ldlr -/-mice, indicating that masTF is likely involved in atherogenesis and tumorigenesis. Recombinant masTF was used to perform in vitro and ex vivo studies examining its integrin-mediated biologic activity. Murine endothelial cells (ECs) rapidly adhered to masTF in a β3-dependent fashion. Using adult and embryonic murine ECs, masTF potentiated cell migration in transwell assays. Scratch assays were performed using murine and primary human ECs; the effects of masTF and hasTF were comparable in murine ECs, but in human ECs, the effects of hasTF were more pronounced. In aortic sprouting assays, the potency of masTF-triggered vessel growth was undistinguishable from that observed with hasTF. The proangiogenic effects of masTF were found to be Ccl2-mediated, yet independent of vascular endothelial growth factor. In murine ECs, masTF and hasTF upregulated genes involved in inflammatory responses; murine and human ECs stimulated with masTF and hasTF exhibited increased interaction with murine monocytic cells under orbital shear. We propose that masTF is a functional homolog of hasTF, exerting some of its key effects via β3 integrins. Our findings have implications for the development of murine models to examine the interplay between blood coagulation, atherosclerosis and cancer.

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SR proteins ASF/SF2 and SRp55 participate in tissue factor biosynthesis in human monocytic cells

Cited by 29 publications

References 40 publications

Role of the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Regulating Alternative Splicing of Tissue Factor mRNA in Human Endothelial Cells

Role of the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Regulating Alternative Splicing of Tissue Factor mRNA in Human Endothelial Cells

Alternatively spliced tissue factor promotes breast cancer growth in a β1 integrin-dependent manner

Nonproteolytic Properties of Murine Alternatively Spliced Tissue Factor: Implications for Integrin-Mediated Signaling in Murine Models

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