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The JAK/STAT pathway in Drosophila hematopoiesis: function and regulatory mechanisms

Shen, Ying
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1194628059

Abstract Details

2007, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).
The evolutionarily conserved JAK/STAT pathway plays a critical role in Drosophila hematopoiesis. A gain-of-function mutation of the Janus kinase (JAK), hopscotchTumorous-lethal (hopTum-l), leads to hemocyte overproliferation and abnormal lamellocyte differentiation. In this study, I demonstrated that effects of hopTum-l were manifested in different types of hemocytes and its activity was regulated in various ways. Firstly, hopTum-l affects proliferation and differentiation of hemocytes in a temperature-dependent manner. Male larvae raised at a lower temperature exhibited the most pronounced effect in hemocyte proliferation and were used for further study. Activation of the JAK/STAT pathway in specific compartments of the lymph gland resulted in different proportions of terminally differentiated hemocytes. Furthermore, to understand the regulatory roles of the Drosophila SUMO conjugase Lesswright (Lwr) and the putative Drosophila SUMO ligase protein inhibitor of activated STAT (dPIAS) in the JAK/STAT pathway, lwr and dpias were expressed in the hopTum-l background. Expression of lwr and dpias both suppressed hopTum-l-induced hemocyte overproduction and the effects were additive, which raises the possibility that lwr and dpias egatively regulate the JAK/STAT pathway through SUMOylation. Finally, the JAK/STAT pathway interacts with the Toll (Tl) pathway, another important pathway involved in larval hematopoiesis. Removal of the Tl pathway transcription factors, Dl and Dif, did not diminish hopTum-l-induced hemocyte overproduction. Moreover, activation of the Tl pathway led to nuclear accumulation of activated Stat mainly in lamellocytes, which suggests that the Tl pathway may be functionally upstream of the JAK/STAT pathway in lamellocyte differentiation. On the other hand, activation of the Tl pathway suppressed hopTum-l-induced hemocyte overproduction, possibly through downstream component Dl. This suppression was observed primarily in plasmatocytes, the professional phagocytes of Drosophila. This study revealed specific requirements of the JAK/STAT pathway and its interactions with the Tl pathway in a hemocyte type-specific manner. It has also demonstrated a functional relationship between the JAK/STAT and the Tl pathways in Drosophilalarval hematopoiesis.
Soichi Tanda (Advisor)
182 p.
Drosophila hematopoiesis; JAK/STAT pathway; SUMOylation; Toll pathway

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Citations

  • Shen, Y. (2007). The JAK/STAT pathway in Drosophila hematopoiesis: function and regulatory mechanisms [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1194628059

    APA Style (7th edition)

  • Shen, Ying. The JAK/STAT pathway in Drosophila hematopoiesis: function and regulatory mechanisms. 2007. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1194628059.

    MLA Style (8th edition)

  • Shen, Ying. "The JAK/STAT pathway in Drosophila hematopoiesis: function and regulatory mechanisms." Doctoral dissertation, Ohio University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1194628059

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Ohio University and OhioLINK.