Two-step stimulation of B lymphocytes to enter DNA synthesis: synergy between anti-immunoglobulin antibody and cytochalasin on expression of c-myc and a G1-specific gene.
Previously we demonstrated that stimulation of resting murine splenic B lymphocytes with goat anti-mouse immunoglobulin antibody (GaMIg) plus cytochalasin D (CD) led to DNA synthesis; GaMIg and CD added simultaneously, or GaMIg added before CD, induced this response (T. L. Rothstein, J. Immunol. 136:813-816, 1986). Cells similarly treated with GaMIg or CD alone did not enter S phase. Here we have measured the effects of this two-signal stimulation on the c-myc, 2F1, and gamma-actin genes. The expression of these growth-related genes is known to change either during the G0-to-G1 transition or in the G1 phase of the cell cycle. For the 2F1 and c-myc genes, neither the GaMIg nor CD stimulus alone led to a prolonged increase in mRNA levels, whereas GaMIg plus CD allowed for continuous elevated expression of these genes. Furthermore, GaMIg pretreatment rendered expression of the c-myc and 2F1 genes susceptible to subsequent action by CD. In contrast, CD alone was sufficient to produce changes in gamma-actin gene expression. Thus there are synergistic effects of competence- and progressionlike factors on the expression of the c-myc and 2F1 genes, and these effects correlate with the progression of B lymphocytes to DNA synthesis.
Buckler
A J
AJ
Department of Microbiology, Boston University School of Medicine, Massachusetts 02118.
Rothstein
T L
TL
Sonenshein
G E
GE
D000199:Actins / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D015638:Cytochalasin D; D003572:Cytochalasins / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D005786:Gene Expression Regulation; D005796:Genes; D007399:Interphase; D009693:Nucleic Acid Hybridization; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000096:biosynthesis
D000199:Actins; D000888:Antibodies, Anti-Idiotypic; D003572:Cytochalasins; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D015638:Cytochalasin D; D004247:DNA