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， 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经历一个周期性的 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细胞内[无鞭毛体]形式 系统的宿主巨噬细胞和2）在其吸血的白蛉载体 宿主，它们分化成，并作为细胞外的， [前鞭毛体]在昆虫的消化道内形成。各种 这种生物的种类导致超过1200万例人类疾病 国际吧 在受感染的人体内，这些寄生虫破坏巨噬细胞 皮肤或内脏（脾、肝和骨髓）内 引起毁容的溃疡性皮肤损伤（例如，造成 由L.墨西哥）或变性和致命的内脏疾病（例如，造成 由L. Donovani）。 我们实验室以前的研究已经确定利什曼原虫 寄生虫是顶端极化的分泌细胞， 组成性分泌超过40种不同的可溶性蛋白质、糖蛋白 和碳水化合物成分添加到它们的体外生长培养基中。等 可溶性的细胞外分泌产物可以容易地从细胞中扩散出去， 这些寄生虫并渗透到它们的环境中。在自然界中，这些 生物体在各种水微环境中生存和繁殖 在他们的几个主机。 由于这些生物体主动分泌一种 各种不同的酶，可以改变这样的主机微- 环境，了解这些寄生虫酶的性质 似乎是必要的。为此，几种寄生虫分泌酶是 为了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 编码这些蛋白质正在被鉴定和表征， 定义了它们在寄生虫生长过程中的表达和调节， 发展和分化。实验涉及原位 这些基因的缺失和过度表达应该证明， 它们编码的蛋白质实际上是这种寄生虫 生存

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.