Expression of diverse and functional TCR gamma and Ig heavy chain transcripts in fetal liver cells cultured with interleukin-7.
We have previously shown that specific T cell receptor (TCR) gamma V regions genes (V gamma 4 and V gamma 6) are rearranged and expressed by murine fetal liver (FL) cells cultured with IL-7. The present studies determined that the sequences of the TCR V region gene transcripts expressed in response to IL-7 included diverse and functional sequences expressed by thymocyte and peripheral V gamma 4+ and V gamma 6+ T cells, indicating that the IL-7-induced expression of these genes is functionally relevant and mimics normal in vivo developmental events of gamma delta T cells. We found that more than 50% of these TCR transcripts had N region diversity. The presence of N region diversity indicates that these TCR rearrangements took place in vitro, presumably in response to IL-7, because fresh (uncultured) FL cells do not produce detectable terminal deoxynucleotidyl transferase (TdT) mRNA or protein. We also found that 100% of immunoglobulin (Ig) VH7183-JH4 transcripts from FL cells cultured with IL-7 had N region diversity at the V-DJ region, while only 40% of Ig VH7183-JH4 transcripts from FL cells cultured in the absence of IL-7 had N region diversity at this region. FL cell cultures supplemented for 7 days with IL-7 had increased TdT mRNA and protein levels. However, since 1-day culture of FL cells with or without IL-7 resulted in induction of expression of TdT, IL-7 probably does not directly stimulate TdT expression, but increases the development and expansion of TdT+ lymphoid cells. These findings implicate IL-7 as a regulator of the molecular signals involved in controlling TCR gamma rearrangement and diversity, and provide an in vitro system for studying the regulation of TdT and N region diversity in B and T lymphoid progenitors by environmental signals.
Appasamy
P M
PM
Pittsburgh Cancer Institute, University of Pittsburgh, PA 15213, USA.
Weng
Y
Y
Kenniston
T W
TW
Deleo
A B
AB
Tang
L
L
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D005260:Female; D005786:Gene Expression Regulation; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics; D015851:Interleukin-7 / Q000494:pharmacology*; D008099:Liver / Q000196:embryology / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D011247:Pregnancy; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic
D007143:Immunoglobulin Heavy Chains; D015851:Interleukin-7; D016692:Receptors, Antigen, T-Cell, gamma-delta