Effects of lysosomal proteinase inhibition on the development of the rat embryo in vitro

Abstract

Altered lysosomal function in the visceral yolk sac can result in abnormal development. As proteolysis is an important function of the rodent visceral yolk sac during early and mid-gestation, we characterized the lysosomal proteolytic enzyme activity of this extraembryonic membrane and determined the effects of inhibitors of protein degradation on embryonic development. Constituent activities of cysteine and aspartic acid proteinases were measured in rat visceral yolk sac on gestation day 12, and the effects of the cysteine proteinase inhibitors leupeptin, E-64 [trans-epoxysuccinyl-l-leucylamido(4-guanido)butane] and N-ethylmaleimide and the aspartic acid proteinase inhibitor pepstatin were determined in Sprague-Dawley rat embryos cultured in vitro from gestation days 10-12. It was determined that only cysteine proteinases, primarily cathepsins B and L, are active in the mid-gestation visceral yolk sac. The cysteine proteinase inhibitors leupeptin and E-64 both produced a concentration-related decrease in embryonic growth, as measured by crown-rump length, somite number, and embryonic protein content, and a concentration-related increase in incidence of abnormalities. A characteristic pattern of abnormalities was produced which involved a decrease in neural tube volume and the formation of a subectodermal blister opposite the point of attachment of the vitelline vessels. At high concentrations, anophthalmia was also observed. The decreased neural tube volume was associated with increased osmolality of the exocoelomic fluid, the major extraembryonic fluid compartment. It is possible that the osmotic change decreased neural tube volume by causing water to move to the compartment with a higher solute concentration, out of the embryo.(ABSTRACT TRUNCATED AT 250 WORDS)

Cathepsin L Is Essential for Embryogenesis and Development ofCaenorhabditis elegans

“…D, the protein is also localized on the surface (arrowheads) of the late-stage embryos (emb) (bar, 500 nm). inhibitors E-64 or leupeptin, resulted in decreased protein processing and embryo growth retardation in rat (37), confirming the postulated role of cathepsin L for normal breakdown of proteins during embryogenesis in this system (38). In C. elegans this potential function is supported by preliminary studies that have shown defects in yolk processing in Ce-cpl-1 RNAi mutant embryos.…”

The Developing Chicken Yolk Sac Acquires Nutrient Transport Competence by an Orchestrated Differentiation Process of Its Endodermal Epithelial Cells

“…In regard to lysosomal degradation of yolk precursors, the activities of lysosomal proteases cathepsin B and D have been shown to be high in the endodermal cells of the quail yolk sac (45). Furthermore, inhibition of the rat visceral YS lysosomal proteinases cathepsin B and L result in a decrease in embryonic growth and an increase in fetal abnormalities, including neural tube defects (46).…”

Expression of cathepsins B, H, K, L, and S during human fetal lung development

“…Additionally, various proteolytically processed hormones and growth factors are involved in growth and differentiation. It has been shown consistently that inhibition of cysteine proteases produces a concentrationdependent decrease in embryonic growth and an increase in abnormalities (Daston et al, 1991).…”