TY - JOUR
T1 - Schistosoma mansoni
T2 - Cell-specific expression and secretion of a serine protease during development of cercariae
AU - Fishelson, Zvi
AU - Amiri, Payman
AU - Friend, Daniel S.
AU - Marikovsky, Moshe
AU - Petitt, Matthew
AU - Newport, George
AU - Mckerrow, James H.
N1 - Funding Information:
This work was supported by the NIAID (AI20452 to J.H.M.), the Edna McConnell Clark Foundation (G.N.), the John D. and Catherine T. MacArthur Foundation (Z.F.), and the Rockefeller Foundation (Z.F.).
PY - 1992/8
Y1 - 1992/8
N2 - Eukaryotic serine proteases are an important family of enzymes whose functions include fertilization, tissue degradation by neutrophils, and host invasion by parasites. To avoid damaging the cells or organisms that produced them, serine proteases must be tightly regulated and sequestered. This study elucidates how the parasitic blood fluke Schistosoma mansoni synthesizes, stores, and releases a serine protease during differentiation of its invasive larvae. In situ hybridization with a cDNA probe localized the protease mRNA to acetabular cells, the first morphologically distinguishable parasite cells that differentiate from the embryonic cell masses present in the intermediate host snail. The acetabular cells contained vimentin but not cytokeratins, consistent with a mesenchymal, not epithelial, origin. Antiprotease antibodies, localized by immunoperoxidase, showed that the protease progressively accumulated in these cells and was packaged in vesicles of three morphologic types. Extension of cytoplasmic processes containing protease vesicles formed "ducts" which reached the anterior end of fully differentiated larvae. During invasion of human skin, groups of intact vesicles were released through the acetabular cytoplasmic processes and ruptured within the host tissue. Ruptured protease vesicles were noted adjacent to degraded epidermal cells and dermal-epidermal basement membrane, as well as along the surface of the penetrating larvae themselves. These observations are consistent with the proposed dual role for the enzyme in facilitating invasion of host skin by larvae and helping to release the larval surface glycocalyx during metamorphosis to the next stage of the parasite.
AB - Eukaryotic serine proteases are an important family of enzymes whose functions include fertilization, tissue degradation by neutrophils, and host invasion by parasites. To avoid damaging the cells or organisms that produced them, serine proteases must be tightly regulated and sequestered. This study elucidates how the parasitic blood fluke Schistosoma mansoni synthesizes, stores, and releases a serine protease during differentiation of its invasive larvae. In situ hybridization with a cDNA probe localized the protease mRNA to acetabular cells, the first morphologically distinguishable parasite cells that differentiate from the embryonic cell masses present in the intermediate host snail. The acetabular cells contained vimentin but not cytokeratins, consistent with a mesenchymal, not epithelial, origin. Antiprotease antibodies, localized by immunoperoxidase, showed that the protease progressively accumulated in these cells and was packaged in vesicles of three morphologic types. Extension of cytoplasmic processes containing protease vesicles formed "ducts" which reached the anterior end of fully differentiated larvae. During invasion of human skin, groups of intact vesicles were released through the acetabular cytoplasmic processes and ruptured within the host tissue. Ruptured protease vesicles were noted adjacent to degraded epidermal cells and dermal-epidermal basement membrane, as well as along the surface of the penetrating larvae themselves. These observations are consistent with the proposed dual role for the enzyme in facilitating invasion of host skin by larvae and helping to release the larval surface glycocalyx during metamorphosis to the next stage of the parasite.
KW - Acetabular gland cells
KW - Cercaria
KW - Differentiation
KW - Protease
KW - Schistosoma mansoni
KW - Trematode
UR - http://www.scopus.com/inward/record.url?scp=0026902372&partnerID=8YFLogxK
U2 - 10.1016/0014-4894(92)90124-S
DO - 10.1016/0014-4894(92)90124-S
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AN - SCOPUS:0026902372
SN - 0014-4894
VL - 75
SP - 87
EP - 98
JO - Experimental Parasitology
JF - Experimental Parasitology
IS - 1
ER -