Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of colchicine on lysosomal fusion and lysosomal enzyme induction in the cultivated mouse peritoneal macrophage have been examined. Colchicine (10- minus 6 M), but not lumicolchicine, inhibited lysosomal enzyme induction by both phagocytic and pinocytic stimuli. In addition, the drug significantly retarded pinocytic uptake of [3-H] sucrose and transport of the amino acids [3-H] alpha aminoisobutyric acid and L-[3-H] leucine. In contrast, lumicolchicine had no effect on pinocytosis or amino acid transport. Thus, a role for intact microtubules in lysosomal enzyme induction, pinocytosis, and amino acid uptake in these cells is suggested. That colchicine inhibited lysosomal enzyme induction by phagocytic stimuli under conditions in which pinocytosis contributed little to the enzyme rise indicated that inhibition of pinocytosis was unlikely to account for colchicine effects on lysosomal enzyme induction. Effects of colchicine on degradation of phagocytized and pinocytized substrates were examined to determine if intact microtubules are required for fusion among lysosomes, pinosomes, and phagosomes. Colchicine did not alter the rate of intracellular digestion of radiolabeled bacteria by the cultivated macrophage. Similarly, it had no effect on enzymatic hydrolysis of intracellular [3-H] sucrose resulting from uptake of exogenous invertase. The finding that colchicine had no effect on the functional consequences of fusion of lysosomes with endosomes suggests that intact microtubules are not required for fusion among these constituents of the vacuolar apparatus.
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PMID:Colchicine effects on lysosomal enzyme induction and intracellular degradation in the cultivated macrophage. 80 4

The uptake of macromolecular markers by fluid pinocytosis in the rat yolk sac was inhibited by glucagon, with half-maximal effect at a hormone concentration of approximately 3 X 10(-8) M. Glucagon had no effect on the cellular distribution of the marker subsequent to its uptake. Rates of uptake promptly returned to normal when the yolk sacs were transferred from a glucagon-containing to a glucagon-free medium. Epinephrine also inhibited, but only at much higher concentrations. The effect of the latter was augmented by theophylline. Insulin (10(-6) M) had no effect when added alone or with an inhibitory level of glucagon (10(-7) M). The presumption that the hormone effect was mediated by cyclic AMP was supported by the findings that the cellular levels of cyclic AMP were elevated in the presence of glucagon and that dibutyryl cyclic AMP could replace glucagon as an effective inhibitor. The conclusion that the hormone effect was on uptake rather than on subsequent regurgitation was based on the linearity of accumulation in both the presence and absence of glucagon and the inability of glucagon to stimulate loss of invertase from preloaded cells. Colchicine and vinblastine also inhibited uptake. This finding and those of others which are discussed suggest the possibility that effects of cyclic nucleotides on certain cell functions may involve their regulation of microtubular status.
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PMID:Effect of glucagon on pinocytosis by the yolk sac of the rat. 90 54