Identification of upstream signals regulating interleukin-6 gene expression during in vitro treatment of human B cells with pokeweed mitogen.
The present studies have characterized the regulation of interleukin-6 (IL-6) gene expression during pokeweed mitogen (PWM)-driven human B-cell differentiation. PWM induced an early and transient increase in the expression of immediate-early response genes of the jun/fos leucine zipper family (c-jun, jun B, c-fos, and fos-B). The induction of c-jun mRNA by PWM was concentration dependent. Nuclear run-on assays showed that PWM treatment is associated with an increased rate of c-jun gene transcription. The induction of c-jun mRNA precedes the induction of IL-6 gene expression and IL-6 secretion by the B cells. c-Jun antisense, but not sense, oligodeoxynucleotide (ODN) significantly decreases PWM-related B-cell (1) proliferation; (2) IL-6 mRNA induction; (3) IL-6 secretion; and (4) nuclear extract binding to AP-1 in electrophoretic mobility shift assay. In contrast, c-Fos anti-sense ODN did not effect either IL-6 mRNA induction or IL-6 secretion triggered in B cells by PWM. The results further show activation of c-Raf-1 kinase in PWM-treated B cells. Raf-1 acts upstream to mitogen-activated protein (MAP) kinase; therefore, studies were performed to assay for MAP kinase activation in these cells. The results show an increase in phosphorylation of myelin basic protein (MBP) and c-Jun "Y" peptide in PWM-treated B cells. Taken together, these findings suggest that PWM is able to initiate an intracytoplasmic signaling cascade in normal human splenic B cells, which, at least in part, involves serine/threonine protein kinases. These results show transient induction of immediate-early response genes in B cells and support a potential role for the c-jun gene product in regulation of IL-6 transcription and secretion.
Chauhan
D
D
Division of Hematologic Malignancies, Dana-Farber Cancer Institute, Boston, MA 02115.
Kharbanda
S
S
Uchiyama
H
H
Urashima
M
M
Fragoso
R
R
Sen
J
J
Kufe
D W
DW
Anderson
K C
KC
D001402:B-Lymphocytes / Q000187:drug effects*; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects; D017781:Genes, Immediate-Early; D016762:Genes, fos; D016758:Genes, jun; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000235:genetics*; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D011043:Pokeweed Mitogens / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D017931:DNA Primers; D015850:Interleukin-6; D011043:Pokeweed Mitogens; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf