A mitogen-activated protein kinase controls differentiation of bloodstream forms of Trypanosoma brucei
A mitogen-activated protein kinase controls differentiation of bloodstream forms of Trypanosoma brucei
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DOI：
10.1128/ec.00094-06
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发表时间：
2006-07-01
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影响因子：
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通讯作者：
Vassella, Erik
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作者：
Pfister, Debora Domenicali;Burkard, Gabriela;Vassella, Erik
非洲锥虫经过分化以适应哺乳动物宿主和采采蝇媒介。为了表征有丝分裂原激活蛋白（MAP）激酶同源物TbMAPK5在布鲁氏锥虫分化中的作用，我们从分化能力强（多形性）的种群中构建了原环（昆虫）形式的基因敲除。两个独立的基因敲除克隆在培养中正常增殖，在果蝇的其他生命周期阶段不是必需的。它们也能感染免疫抑制的小鼠，但峰值寄生率比野生型低16倍。从增生的长而细长的血流形态向非增生的短而粗壮的血流形态分化是由一种自分泌因子——粗壮诱导因子（SIF）触发的。敲除在小鼠和培养物中过早分化，提示对SIF的敏感性增加。相反，对SIF不耐受的细胞系的零突变体能够正常增殖。通过与野生型TbMAPK5的互补，分化表型得到了部分恢复，但引入不可激活的突变形式则加剧了分化表型。我们的研究结果表明，TbMAPK5在布鲁氏杆菌血流形态分化中的调节功能可能被开发为治疗人类昏睡病的化疗靶点。
African trypanosomes undergo differentiation in order to adapt to the mammalian host and the tsetse fly vector. To characterize the role of a mitogen-activated protein (MAP) kinase homologue, TbMAPK5, in the differentiation of Trypanosoma brucei, we constructed a knockout in procyclic (insect) forms from a differentiation-competent (pleomorphic) stock. Two independent knockout clones proliferated normally in culture and were not essential for other life cycle stages in the fly. They were also able to infect immunosuppressed mice, but the peak parasitemia was 16-fold lower than that of the wild type. Differentiation of the proliferating long slender to the nonproliferating short stumpy bloodstream form is triggered by an autocrine factor, stumpy induction factor (SIF). The knockout differentiated prematurely in mice and in culture, suggestive of increased sensitivity to SIF. In contrast, a null mutant of a cell line refractory to SIF was able to proliferate normally. The differentiation phenotype was partially rescued by complementation with wild-type TbMAPK5 but exacerbated by introduction of a nonactivatable mutant form. Our results indicate a regulatory function for TbMAPK5 in the differentiation of bloodstream forms of T. brucei that might be exploitable as a target for chemotherapy against human sleeping sickness.