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A novel putative helicase produced in early murine lymphocytes
C D Jarvis1, T Geiman, M P Vila-Storm
1LMI, Biological Response Modifiers Program, NCI, Frederick, MD 21702-1201, USA.
Insights
Researchers identified a novel DNA helicase, lymphoid-specific helicase (lsh), crucial for lymphocyte development. This gene is specifically expressed in early thymocytes and mature T and B cells, indicating its role in lymphopoiesis.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- DNA helicases (Hel) are essential enzymes involved in DNA strand separation during critical cellular processes.
- Receptor gene rearrangement in immature lymphocytes, vital for immune function, may involve DNA helicases.
Purpose of the Study:
- To clone and characterize a novel DNA helicase potentially involved in lymphocyte development.
- To investigate the expression pattern of this novel helicase in various murine tissues and cell types.
Main Methods:
- Cloning of a novel putative DNA helicase from murine fetal thymus.
- Northern blot analysis to determine gene expression in different tissues and cell lines.
- Examination of mouse embryonic tissues to assess early lymphopoiesis stages.
Main Results:
- A novel putative DNA helicase, named lymphoid-specific helicase (lsh), belonging to the DEGH subclass, was cloned.
- lsh expression was detected in early thymocytes, activated spleen cells, and both immature and mature T and B cell lines.
- lsh was absent in yolk sac but present in fetal liver and thymus during gestation, with high levels in the thymus by day 15.
Conclusions:
- The lymphoid-specific helicase (lsh) is a novel DNA helicase expressed during lymphocyte development.
- lsh plays a significant role in early lymphopoiesis, particularly in the thymus.
- Its specific expression pattern suggests a critical function in the development and/or function of T and B lymphocytes.
Abstract:
DNA helicases (Hel) play a role in a number of processes involving DNA strand separation, including replication, repair, recombination and transcription. Rearrangement of receptor genes, which occurs in immature lymphocytes, could also be mediated by Hel. We report here the cloning from murine fetal thymus tissue of a novel putative Hel containing seven conserved Hel domains and belonging to the DEGH subclass of DNA Hel. We term the encoding gene lsh (lymphoid-specific Hel), since the gene is expressed in early thymocytes, but not in heart, liver, lung, muscle, brain or kidney, as judged by Northern analysis. Spleen cells expressed lsh following activation. T- and B-cell lines, at both the immature and mature stage, expressed lsh. To examine the earliest stages of lymphopoiesis, mouse embryonic tissues were examined; lsh was not detected in the yolk sac of day 12 of gestation, but was expressed in fetal liver and at high levels in fetal thymus at day 15 of gestation.