Activation of pp90rsk and early growth response-1 gene expression by pokeweed mitogen in human B cells.
The present studies have examined the effects of pokeweed mitogen (PWM) on the induction of early growth response-1 gene (EGR-1) in normal human B cells. PWM regulates EGR-1 gene expression by both transcriptional and post-transcriptional mechanisms. Transient transfection assays with EGR-1 promoter fragments linked to the chloramphenicol acetyltransferase (CAT) gene demonstrated that PWM induced EGR-1 transcription is conferred by the CArG motif (C C[AT]6GG) in the EGR-1 promoter. The results further demonstrated the activation of S6 kinase (pp90rsk), evidenced by phosphorylation of S6 and serum response factor (SRF) peptides, in PWM treated B cells. Taken together, these findings suggest that PWM is able to initiate an intracytoplasmic signalling cascade and EGR-1 induction in normal human B cells.
Chauhan
D
D
Dana Farber Cancer Institute, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
Kharbanda
S M
SM
Uchiyama
H
H
Urashima
M
M
Anderson
K C
KC
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000235:genetics*; D051766:Early Growth Response Protein 1; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D017874:Immediate-Early Proteins; D008969:Molecular Sequence Data; D011043:Pokeweed Mitogens / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D019893:Ribosomal Protein S6 Kinases; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D011043:Pokeweed Mitogens; D012333:RNA, Messenger; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D019893:Ribosomal Protein S6 Kinases