scholarly journals Radiosensitization and downregulation of heterogeneous nuclear ribonucleoprotein K (hnRNP K) upon inhibition of mitogen/extracellular signal-regulated kinase (MEK) in malignant melanoma cells

Oncotarget ◽  
2015 ◽  
Vol 6 (19) ◽  
pp. 17178-17191 ◽  
Author(s):  
Stefan Eder ◽  
Andreas Lamkowski ◽  
Markus Priller ◽  
Matthias Port ◽  
Konrad Steinestel
Keyword(s):  
Malignant Melanoma ◽  
Melanoma Cells ◽  
Hnrnp K ◽  
Extracellular Signal Regulated Kinase ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Extracellular Signal ◽  
Nuclear Ribonucleoprotein

scholarly journals Heterogeneous nuclear ribonucleoprotein K is a transcription factor.

1996 ◽  
Vol 16 (5) ◽  
pp. 2350-2360 ◽  
Author(s):  
E F Michelotti ◽  
G A Michelotti ◽  
A I Aronsohn ◽  
D Levens
Keyword(s):  
Transcription Factor ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Hnrnp K ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Transcription In Vitro ◽  
Nuclear Ribonucleoprotein ◽  
Rna Polymerase Ii Transcription

The CT element is a positively acting homopyrimidine tract upstream of the c-myc gene to which the well-characterized transcription factor Spl and heterogeneous nuclear ribonucleoprotein (hnRNP) K, a less well-characterized protein associated with hnRNP complexes, have previously been shown to bind. The present work demonstrates that both of these molecules contribute to CT element-activated transcription in vitro. The pyrimidine-rich strand of the CT element both bound to hnRNP K and competitively inhibited transcription in vitro, suggesting a role for hnRNP K in activating transcription through this single-stranded sequence. Direct addition of recombinant hnRNP K to reaction mixtures programmed with templates bearing single-stranded CT elements increased specific RNA synthesis. If hnRNP K is a transcription factor, then interactions with the RNA polymerase II transcription apparatus are predicted. Affinity columns charged with recombinant hnRNP K specifically bind a component(s) necessary for transcription activation. The depleted factors were biochemically complemented by a crude TFIID phosphocellulose fraction, indicating that hnRNP K might interact with the TATA-binding protein (TBP)-TBP-associated factor complex. Coimmunoprecipitation of a complex formed in vivo between hnRNP K and epitope-tagged TBP as well as binding in vitro between recombinant proteins demonstrated a protein-protein interaction between TBP and hnRNP K. Furthermore, when the two proteins were overexpressed in vivo, transcription from a CT element-dependent reporter was synergistically activated. These data indicate that hnRNP K binds to a specific cis element, interacts with the RNA polymerase II transcription machinery, and stimulates transcription and thus has all of the properties of a transcription factor.

scholarly journals SPRY2 Is an Inhibitor of the Ras/Extracellular Signal-Regulated Kinase Pathway in Melanocytes and Melanoma Cells with Wild-Type BRAF but Not with the V599E Mutant

2004 ◽  
Vol 64 (16) ◽  
pp. 5556-5559 ◽  
Author(s):  
Dimitra Tsavachidou ◽  
Mathew L. Coleman ◽  
Galene Athanasiadis ◽  
Shuixing Li ◽  
Jonathan D. Licht ◽  
...  
Keyword(s):  
Melanoma Cells ◽  
Wild Type ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Kinase Pathway

scholarly journals Heterogeneous nuclear ribonucleoprotein K represses transcription from a cytosine/thymidine-rich element in the osteocalcin promoter

2005 ◽  
Vol 385 (2) ◽  
pp. 613-623 ◽  
Author(s):  
Joseph P. STAINS ◽  
Fernando LECANDA ◽  
Dwight A. TOWLER ◽  
Roberto CIVITELLI
Keyword(s):  
Gene Transcription ◽  
Nuclear Extract ◽  
Binding Activity ◽  
Proximal Promoter ◽  
Luciferase Reporter ◽  
Mobility Shift ◽  
Hnrnp K ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Osteocalcin Gene ◽  
Nuclear Ribonucleoprotein

HnRNP K (heterogeneous nuclear ribonucleoprotein K) was biochemically purified from a screen of proteins co-purifying with binding activity to the osteocalcin promoter. We identify hnRNP K as a novel repressor of osteocalcin gene transcription. Overexpression of hnRNP K lowers the expression of osteocalcin mRNA by 5-fold. Furthermore, luciferase reporter assays demonstrate that overexpression of hnRNP K represses osteocalcin transcription from a CT (cytosine/thymidine)-rich element in the proximal promoter. Electrophoretic mobility-shift analysis reveals that recombinant hnRNP K binds to the CT-rich element, but binds ss (single-stranded), rather than ds (double-stranded) oligonucleotide probes. Accordingly, hnRNP K antibody can supershift a binding activity present in nuclear extracts using ss sense, but not antisense or ds oligonucleotides corresponding to the CT-rich −95 to −47 osteocalcin promoter. Importantly, addition of recombinant hnRNP K to ROS 17/2.8 nuclear extract disrupts formation of a DNA–protein complex on ds CT element oligonucleotides. This action is mutually exclusive with hnRNP K's ability to bind ss DNA. These results demonstrate that hnRNPK, although co-purified with a dsDNA-binding activity, does not itself bind dsDNA. Rather, hnRNP K represses osteocalcin gene transcription by inhibiting the formation of a transcriptional complex on the CT element of the osteocalcin promoter.

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