STAT5 regulation of BCL10 parallels constitutive NFkappaB activation in lymphoid tumor cells.
BACKGROUND
Signal Transducer and Activator of Transcription 5 A and B (STAT5) are key survival factors in cells of the lymphoid lineage. Identification of novel, tissue-specific STAT5 regulated genes would advance the ability to combat diseases due to aberrant STAT5 signaling. In the present work a library of human STAT5 bound genomic elements was created and validated.


RESULTS
Of several STAT5 responsive genomic regulatory elements identified, one was located within the first intron of the human BCL10 gene. Chromatin immuno-precipitation reactions confirmed constitutive in vivo STAT5 binding to this intronic fragment in various human lymphoid tumor cell lines. Interestingly, non-phosphorylated STAT5 was found in the nuclei of Kit225 and YT cells in the absence of cytokine stimulation that paralleled constitutive NFkappaB activation. Inhibition of the hyperactive JAK3/STAT5 pathway in MT-2 cells via the Mannich-base, NC1153, diminished the constitutive in vivo occupancy of BCL10-SBR by STAT5, reduced NFkappaB activity and BCL10 protein expression in a dose dependent manner. Moreover, depletion of STAT5 via selective antisense oligonucleotide treatment similarly resulted in decreased BCL10 mRNA and protein expression, cellular viability and impaired NFkappaB activity independent of IL-2.


CONCLUSIONS
These results suggest that the NFkappaB regulator BCL10 is an IL-2-independent STAT5 target gene. These findings proffer a model in which un-activated STAT5 can regulate pathways critical for lymphoid cell survival and inhibitors that disrupt STAT5 function independent of tyrosine phosphorylation may be therapeutically effective in treating certain leukemias/lymphomas.
Nagy
Zsuzsanna S
ZS
Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968, USA. znagy@utep.edu
LeBaron
Matthew J
MJ
Ross
Jeremy A
JA
Mitra
Abhisek
A
Rui
Hallgeir
H
Kirken
Robert A
RA
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000074018:B-Cell CLL-Lymphoma 10 Protein; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D015972:Gene Expression Regulation, Neoplastic; D015698:Genomic Library; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D008223:Lymphoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008352:Mannich Bases / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D048868:Adaptor Proteins, Signal Transducing; D000074018:B-Cell CLL-Lymphoma 10 Protein; C118591:BCL10 protein, human; D007376:Interleukin-2; D008352:Mannich Bases; C503557:NC 1153; D016328:NF-kappa B; D020319:Oligodeoxyribonucleotides, Antisense; D050799:STAT5 Transcription Factor; C507933:JAK3 protein, human; D053616:Janus Kinase 3