Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because protein degradation in liver and skeletal muscle is increased by thyroid hormones and decreased by thyroidectomy; we investigated the influence of thyroid hormones on the level of lysosomal enzymes. Hypophysectomized rats received daily injections of L-thyroxine or L-triiodothyronine. After 3 days of this regimen, homogenates of liver and skeletal muscle showed a 2- to 3-fold increase in the activities of cathepsin D, cathepsin B, and other lysosomal enzymes including leucine aminopeptidase, acid phosphatase, beta-galactosidase, N-acetylglucosaminidase, and alpha-mannosidase. In liver, this effect reflected increased enzyme activity in the two subcellular fractions that normally contain lysosomes. Titration of cathepsin D with pepstatin indicated that the increase in this activity resulted from an increase in the number of enzyme molecules. These effects occurred with both pharmacologic (thyrotoxic) and physiologic (growth-promoting) doses of thyroid hormones. Liver and skeletal muscle from thyroidectomized rats had approximately 50% of the normal levels of lysosomal enzyme activities. Under these various conditions, heart and kidney, tissues in which protein degradation does not appear to be influenced by thyroid hormones, showed no significant changes in lysosomal hydrolases. Thus, thyroid hormones regulate proteolytic and other lysosomal enzyme activities in those tissues in which these hormones influence protein degradation. Many characteristic features of hyperthyroidism and hypothyroidism may result from changes in levels of lysosomal enzymes.
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PMID:Thyroid hormones control lysosomal enzyme activities in liver and skeletal muscle. 27 25

The changes in the activities of certain lysosomal hydrolases, viz., beta-glucuronidase, beta-N-acetylglucosaminidase, beta-galactosidase, beta-glucosidase, alpha-glucosidase, alpha-galactosidase, alpha-mannosidase, cathepsin B, cathepsin D, and collagenolytic cathepsin, in serum and heart of rats subject to myocardial infarction with isoproterenol, were studied during the periods of peak infarction and recovery. The activities of all the enzymes assayed exhibited a significant increase both in serum and in heart at peak infarction stage and these levels returned to normal during the stage of recovery and repair. The infiltration of inflammatory cells at the infarct regions and the altered lysosomal fragility are probably responsible for the increased activity of the enzymes studied. This may also bring about the catabolism of connective tissue constituents as reported in literature.
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PMID:Influence of isoproterenol-induced myocardial infarction on certain glycohydrolases and cathepsins in rats. 201 10

The synthesis and secretion of pro-cathepsin D is increased by estrogens in MCF7 cells. We quantified the effect of estradiol on other lysosomal enzymes in order to investigate the mechanism of this hypersecretion. Precursors of beta-hexosaminidase, cathepsin B and beta-galactosidase, which are routed to lysosomes via the mannose-6-phosphate (Man-6-P) receptor, were secreted in much lower amounts than pro-cathepsin D, but their secretion was also increased by estradiol. The activity of acid phosphatase, which is routed to lysosomes via a different transmembrane mechanism, was not altered by estradiol. While estradiol stimulated gene expression of pro-cathepsin D, it had no effect on that of pro-cathepsin B. We conclude that estradiol stimulates the secretion of several lysosomal pro-enzymes in MCF7 cells, suggesting that a general mechanism is responsible for this derouting rather than a specific alteration of cathepsin D structure.
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PMID:Estradiol increases the secretion by MCF7 cells of several lysosomal pro-enzymes. 222 57

The involvement of lysosomes in the normal secretory process of the exocrine pancreas and in the onset of acute, hormone-induced pancreatitis was studied. The enzymatic activities of cathepsin B and beta-galactosidase were determined in the pancreas of rats that had been stimulated by either maximal (0.25 microgram X kg-1 h-1) or supramaximal (5 micrograms X kg-1 h-1) concentrations of cerulein. Maximal stimulation led to a moderate increase in cathepsin B activity and the ultrastructural appearance of multivesicular bodies. Supramaximal stimulation resulted in formation of large cytoplasmic vacuoles and progressive destruction of acinar cells which was paralleled by a marked increase of lysosomal enzyme activity.
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PMID:Cerulein-induced pancreatitis in rats: increased lysosomal enzyme activity and autophagocytosis. 241 Mar 15

Quantitative comparisons of the time course of biochemical and morphological changes induced by peroxisome proliferators resulting in low and high incidences of hepatic cancer have not been conducted previously under bioassay conditions. [4-Chloro-6-(2,3-xylidino)-2-pyrimidyl-thio]acetic acid (Wy-14,643) at 0.1% in the diet produced a much higher incidence of hepatic cancer in male rats than 1.2% di(2-ethylhexyl)phthalate (DEHP) in the diet. Both diets, however, caused similar degrees of peroxisome proliferation. To investigate this difference in carcinogenicity, H2O2-detoxification mechanisms and indices of oxidative damage were evaluated in male F-344 rats fed 1.2% DEHP or 0.1% Wy-14,643 for up to one year. DEHP or Wy-14,643 treatment increased hepatic catalase activity approximately 25% from 8 to 365 days. DEHP or Wy-14,643 treatment decreased hepatic glutathione peroxidase activity by 50% from 8 to 365 days. Glutathione concentrations were not affected by 151 days of DEHP or Wy-14,643 feeding. The similar effects of DEHP and Wy on H2O2 detoxification enzymes and glutathione concentrations suggests that these factors are not responsible for the widely different carcinogenicities of Wy-14,643 and DEHP. Hepatic vitamin E concentrations were 50% lower in rats receiving Wy-14,643 for 151 days as compared to rats fed DEHP or control diets. Lipofuscin, which was contained within lysosomes, was increased 3-fold after 39 days of DEHP and remained at this level up to 365 days of treatment. In comparison, lipofuscin was increased 4-fold after 18 days of Wy-14,643 and continued to accumulate in a linear manner reaching values 30-fold over controls after 365 days of treatment. DEHP treatment for 39-365 days increased the activities of the lysosomal enzymes alpha-fucosidase, beta-galactosidase and N-acetylglucosaminidase 50-100%. The same enzyme activities were increased approximately 4-fold after 39-365 days of Wy-14,643. Lysosomal cathepsin B activity was unchanged by DEHP but doubled by 151 and 365 days of Wy-14,643. Acid phosphatase activity was unchanged by DEHP but increased by 50% after 151 and 365 days of Wy-14,643. In addition, conjugated dienes were increased (approximately 45%) only in rats receiving Wy-14,643 for 151 and 365 days. These data show for the first time that the magnitude and time course of lipofuscin deposition, induction of lysosomal enzymes and conjugated diene accumulation, is correlated closely with the degree of carcinogenicity. Wy-14,643-induced decreases in hepatic vitamin E concentrations could contribute to the observed accumulation of conjugated dienes at later time points.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Relationship of oxidative damage to the hepatocarcinogenicity of the peroxisome proliferators di(2-ethylhexyl)phthalate and Wy-14,643. 292 96

Cultures of dissociated brain cells from 15-day-old fetal mice were grown in the presence and absence of 20 or 50 nM triiodothyronine (T3), 30 or 300 nM cortisol, and 30 nM cortisol plus 50 nM T3 added to chemically defined media or in media supplemented with 15% serum from control and hypothyroid calves. The specific activities of five lysosomal enzymes--N-acetyl galactosaminidase, beta-glucuronidase, beta-galactosidase, cathepsin B, and dipeptidyl aminopeptidase I (DAP-I)--were higher in cells grown in calf serum than in cells grown in defined media. Of these enzymes, only DAP-I was elevated in activity when the cells were grown in hypothyroid calf serum instead of control calf serum. Elevation of DAP-I activity was reversed by addition of 20 nM T3 to hypothyroid calf serum. The enzymatic properties of DAP-I were similar whether the cells were grown in control or hypothyroid calf serum and were similar to those reported for human fibroblasts and the purified enzyme. When the cells were grown in defined media, cortisol decreased the activities of all lysosomal enzymes, with 300 nM cortisol being more effective than 30 nM cortisol. Addition of 50 nM T3 to 30 nM cortisol decreased DAP-I activity more than 30 nM cortisol alone, but 50 nM T3 alone in defined media did not alter DAP-I levels. The reduction of DAP-I activity in these cells by T3 required cortisol, unidentified components in serum, or both.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of dipeptidyl aminopeptidase I and angiotensin converting enzyme activities in cultured murine brain cells by cortisol and thyroid hormone. 302 71

The activities of Z-Phe-Arg-NMec(ZPA) hydrolase, cathepsin B and cathepsin H and the concentration of endogenous thiol protease inhibitor in fibroblasts from patients with galactosialidosis were found not to be significantly different from those in control fibroblasts. Culture for 5 days with thiol protease inhibitors such as leupeptin, E-64 or Z-Phe-Phe-CHN2 partially restored the beta-galactosidase activity of fibroblasts from patients, but did not affect the beta-galactosidase activity of fibroblasts from control subjects. However, culture with leupeptin, but not other protease inhibitors, increased the ZPA hydrolase and cathepsin B activities of fibroblasts from both patients and controls 2- to 4-fold. Sephadex G-75 chromatography showed that the activity of high molecular weight ZPA hydrolase, which was initially predominant in fibroblasts, decreased markedly during their culture with leupeptin, while the activities of lower molecular weight ZPA hydrolase and cathepsin B increased about 5-fold. These results suggest that high molecular weight ZPA hydrolase, which is presumably cathepsin J, degrades beta-galactosidase, and that the defect in galactosialidosis is impaired protection of beta-galactosidase from degradation.
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PMID:Involvement of thiol proteases in galactosialidosis. 308 37

Cathepsins B and D, beta-galactosidase, and acid phosphatase activities were found to be decreased in the regenerating rat liver, the reduction being maximal around the peak of hepatocyte mitoses (30 h). To investigate whether these changes could be heterogeneously distributed among hepatic cells, total cell populations from control or two-thirds hepatectomized rat livers were dissociated by the collagenase perfusion technique and analysed by different procedures. Isopycnic centrifugation in a Metrizamide gradient satisfactorily resolved hepatocytes and non-parenchymal cells from control animals but was not adequate when applied to 30-h regenerating liver cells. Colchicine treatment of the hepatectomized animals, resulted in substantial accumulation of phase M-hepatocytes. Subpopulations considerably enriched in fast-sedimenting phase M-cells were obtained by sedimentation at 1 g of the total liver cell population, and subsequently analysed by isopycnic equilibration. Phase M-hepatocytes were shown to have markedly reduced levels of beta-galactosidase, acid phosphatase, and cathepsin B activities in comparison, not only with control hepatocytes, but also with those parenchymal cells which were not metaphase-arrested in the same regenerating livers. Therefore, in partially-hepatectomized rats, hepatocytes progressing up to metaphase in the first mitotic cycle exhibited a selective depletion of lysosomal enzyme activities. The mechanism(s) underlying this change remain(s) presently unknown.
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PMID:Cellular distribution of lysosomal hydrolase activities in the regenerating rat liver. 308 41

We have employed colloidal silica (Percoll) density-gradient subcellular fractionation technique to examine the distribution of lysosomal hydrolases between intermediate vesicles (primary lysosomes) and secondary lysosomes in contact-inhibited non-proliferating vs proliferating chicken embryo fibroblasts. We find that the activities of lysosomal specific enzymes from both phases of growth are distributed within two peaks; however, the relative amounts differ markedly. In normal, non-proliferating cells approx. 60% of the total activities of cathepsin B, beta-mannosidase, alpha-fucosidase, beta-galactosidase and hexosaminidase is recovered in the heavier density fraction corresponding to secondary lysosomes, while less than 9% of the enzyme activities are recovered in the light-density peak. With transformed cells, between 16 and 22% of activity for these enzymes are recovered in the lighter density intermediate vesicle fraction, when less than 40% of the enzyme activities recovered in the heavy density fraction. beta-Glucuronidase distribution was different from that of the above enzymes. First, a more even distribution between the two lysosomal fractions was found with non-proliferating normal cells (33% in heavy-density fraction and 21% in light-density fraction), whereas more than 40% of the total enzyme activity was recovered in the lighter density fraction from transformed cells. Also, the amount of cathepsin B contained in the vesicle fractions is increased severalfold relative to that of contact-inhibited normal cells. However, the apparent differences in enzyme distribution between confluent normal and transformed cells are not found when vesicles are prepared from subconfluent, actively proliferating cultures. We have also compared the Percoll density gradient patterns of membrane vesicles from proliferating and non-proliferating human fibroblasts, since most earlier studies utilized this system. Again, we find that the majority of beta-hexosaminidase activity (41%) of contact-inhibited, confluent cells is recovered in the heavier density fraction with less than 15% in the lighter density fraction. Also, the distribution of beta-hexosaminidase between the heavy density and light density vesicle fractions is altered in homogenates from exponentially growing cells, being 22% and 26% respectively. We conclude that the distribution of lysosomal hydrolases between the two vesicle populations is growth-phase dependent and is markedly heterogeneous in proliferating cells.
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PMID:Distribution of acid hydrolases in subcellular fractions of proliferating vs non-proliferating fibroblasts. 609 Jan 91

In the newborn lamb, activities of lysosomal enzymes are lower in the duodenum and jejunum than in the ileum. In contrast, there are only minor differences, if any, in activities of lysosomal enzymes between the regions of the small intestine of 5-day-old lambs. In the duodenum, jejunum and ileum, activities of hexosaminidase, alpha-mannosidase, beta-mannosidase, alpha-L-fucosidase and phosphodiesterase are greater in newborn than in 5-day-old lambs. Only in the distal part of the small intestine are activities of beta-glucuronidase, alpha-glucosidase, alpha-galactosidase, beta-galactosidase, acid phosphatase and cathepsin B higher in the newborn than in 5-day-old lambs. Cathepsin B activity is lower in the duodenum and jejunum of the newborn than in 5-day-old lambs.
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PMID:Lysosomal enzymes in the intestine of the newborn lamb. 609 93


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