BIOCHEMICAL AND MOLECULAR CHARACTERIZATION OF ENZYMES SECRETED BY LEISHMANIA

该项目正在进行的研究涉及基础细胞生物学， 原生动物利什曼原虫的生物化学和分子生物学 人类的病原体。所有利什曼原虫都会经历一次循环 发育周期：1)在哺乳动物中，它们转化为 吞噬溶酶体内的专性胞内[无鞭毛体] 宿主巨噬细胞系统和2)它们的嗜血沙蝇载体 宿主，它们分化为细胞外，并以细胞外的形式繁殖 [前鞭毛体]在昆虫的消化道内形成。五花八门 这种生物的物种导致了1200多万例人类疾病 全世界。在受感染的人类中，这些寄生虫破坏巨噬细胞 在皮肤或内脏(脾、肝和骨髓)内 导致毁容的溃疡性皮肤损害(例如，引起 由墨西哥乳杆菌引起)或退行性和致命性内脏疾病(例如 作者L.Donovani)。 我们实验室以前的研究已经证实利什曼原虫 寄生虫是顶端极化的分泌细胞，它们 组成分泌40多种不同的可溶性蛋白质、糖蛋白 和碳水化合物成分放入它们的体外生长介质中。是这样的 可溶性的、细胞外分泌的产品很容易从 这些寄生虫渗透到它们的环境中。在自然界中，这些 生物在不同的水微环境中居住和繁殖 在它们的几个宿主中。因为这些生物会主动分泌一种 各种不同的酶可以改变这种宿主微生物- 环境，了解这些寄生虫酶的性质 似乎是必不可少的。为此，几种寄生虫分泌酶 研究确定它们在生存中的功能作用， 这些生物的维持、生长和传播。此外，基因 对这些蛋白质的编码正在被识别和表征为 确定它们在寄生虫生长过程中的表达和调控， 发展与差异化。实验涉及到两个现场 这些基因的缺失和过度表达应该证明 事实上，它们的编码蛋白对这种寄生虫的 生死存亡。

Ongoing studies in this project concern the basic cell biology, biochemistry and molecular biology of Leishmania, a group of protozoan pathogens of humans. All Leishmania parasites undergo a cyclic developmental cycle: 1) in mammals, they transform into and multiply as obligate intracellular [amastigote] forms within the phago-lysosomal system of host macrophages and 2) in their hematophagous sandfly-vector hosts, they differentiate into, and multiply as, extracellular [promastigote] forms within the insect's alimentary tract. Various species of this organism cause over 12 million cases of human disease worldwide. In infected humans, these parasites destroy macrophages within the skin or internal organs (spleen, liver and bone marrow) causing either disfiguring ulcerative cutaneous lesions (e.g., caused by L. mexicana) or degenerative and fatal visceral disease (e.g., caused by L. donovani). Previous studies from our laboratory have established that Leishmania parasites are apically polarized secretory cells and that they constitutively secrete over 40 different soluble protein, glycoprotein and carbohydrate constituents into their growth media in vitro. Such soluble, extracellularly secreted products can readily diffuse away from these parasites and permeate their environments. In nature, these organisms reside and multiply within various aqueous micro environments in their several hosts. Since these organisms actively secrete a variety of different enzymes that could alter such host micro- environments, an understanding of the nature of these parasite enzymes seems essential. To that end, several parasite secretory enzymes are investigated toward defining their functional roles in the survival, maintenance, growth and transmission of these organisms. Further, genes encoding these proteins are being identified and characterized toward defining their expression and regulation during parasite growth, development and differentiation. Experiments involving both the in situ deletion and over-expression of such genes should demonstrate whether their encoded proteins are, in fact, essential to this parasite's survival.