hymecromone and estrone-sulfate

The uptake of estrone sulfate (E1S; 1 to 400 microM), harmol sulfate (HS; 5 to 900 microM), and 4-methylumbelliferyl sulfate (4MUS; 5 to 1000 microM) was investigated in isolated rat hepatocytes in the presence or absence of inhibitors. Uptake of all of the sulfate conjugates was rapid and exhibited saturation kinetics, best characterized by saturable and nonsaturable (linear transmembrane clearance) transport systems. The KM's were: 16 +/- 6, 123 +/- 28, and 64 +/- 6 microM for E1S, HS, and 4MUS, respectively, with corresponding Vmax's of 0.85 +/- 0.56, 0.48 +/- 14, and 0.42 +/- 0.07 nmol/min/10(6) cells. The nonsaturable uptake clearances, which displayed concentration-independent uptake, were 3 +/- 2, 1 +/- 0.1, 0.5 +/- 0.1 microliter/min/10(6) cells, respectively. Uptake of E1S was inhibited by ouabain (1 mM) and replacement of sodium by choline, whereas HS was insensitive to the addition or substitution. Uptake of both E1S and HS was significantly reduced by metabolic inhibitors (antimycin A, 2.7 microM, rotenone, 30 microM, and KCN, 2 mM) and temperature reduction (from 37 to 27 degrees C). 4,4'-Diisothiocyanostilbene-2-2-'disulfonic acid (2 mM), an inhibitor of anion transport, reduced E1S and HS uptake; E1S uptake was also reduced by HS. HS uptake by both saturable and nonsaturable transport components was depressed by 4MUS (300 microM); the apparent KM was increased by 83% while the Vmax remained unaltered, and the nonsaturable component was decreased by 48%. The data strongly suggest that multiple pathways exist for the uptake of E1S, HS, and 4MUS. E1S uptake is sodium-dependent, requires energy, and is inhibited by anions such as 4,4'diisothiocyanostilbene-2-2'-disulfonic acid and other sulfate conjugates. HS uptake, while being energy dependent, is not sodium dependent, and is inhibited by 4MUS in a competitive fashion. At least one of these pathways is shared.

Topics: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Animals; Biological Transport; Carrier Proteins; Choline; Estrogens, Conjugated (USP); Estrone; Harmine; Hymecromone; In Vitro Techniques; Liver; Male; Ouabain; Rats; Rats, Sprague-Dawley

Recessive X-linked ichthyosis (RXLI) has its biochemical basis in a defect of the enzyme steroid sulfatase. Since several studies have reported a simultaneous deficiency of arylsulfatase C and steroid sulfatase it has been hypothesized that both enzymes are identical. In human hair follicles, however, hydrolytic activity for 4-methylumbelliferone sulfate, the substrate for arylsulfatase C, is found, while dehydroepiandrosterone sulfate is not hydrolyzed at all. These findings suggested the possible existence of two different enzymes. In the present paper structure-activity studies and molecular energy calculations are used for the demonstration that the remaining sulfatase activity in hair follicles of RXLI patients can be explained on the basis of the assumption that the enzyme has not lost its total function but has become less efficient.

Topics: Adolescent; Adult; Dehydroepiandrosterone; Dehydroepiandrosterone Sulfate; Equilenin; Estrone; Female; Genetic Linkage; Hair; Humans; Hymecromone; Ichthyosis; Male; Middle Aged; Substrate Specificity; Sulfatases; X Chromosome

SWR/J mice possess two- to threefold higher 4-methylumbelliferyl sulfate (4MUS), dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate (E1S) sulfatase activities in liver and kidney extracts than do A/J mice. These interstrain activity differences are maintained throughout the 6- to 45-day postnatal period. Characteristics of the hepatic activities of SWR/J mice suggest that all three activities reside in the same enzyme. Biochemical properties of the SWR/J and A/J enzyme were not significantly different. Expression of hepatic enzyme activity is subject to regulation by an autosomal locus possessing two alleles with additive effects. Postnuclear E1S- and DHEAS-sulfatase activities are primarily microsomal. Although postnuclear hepatic 4MUS-sulfatase activity is predominantly microsomal, renal activity is primarily nonmicrosomal. Only that portion of 4MUS-sulfatase occurring in cell membranes appears capable of hydrolyzing E1S and DHEAS. The hepatic- and renal-specific subcellular distributions of 4MUS-sulfatase activity may reflect tissue differences in enzyme processing. Renal 4MUS-sulfatase activity is also controlled by an autosomal gene with two alleles having additive effects. Positive correlation between hepatic and renal 4MUS-sulfatase activities indicates that both activities are most likely influenced by the same gene.

Topics: Alleles; Animals; Arylsulfatases; Dehydroepiandrosterone; Dehydroepiandrosterone Sulfate; Estrone; Hymecromone; Kidney; Mice; Mice, Inbred Strains; Microsomes, Liver; Steryl-Sulfatase; Substrate Specificity; Sulfatases