Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Short-term vasectomy was studied in adult male rats in order to ascertain whether cytosolic or lysosomal hydrolases were differently affected 100 days after vas ligation. The secretory form of alpha-1,4-glucosidase remained unchanged while the lysosomal form of the enzyme and also cathepsin D increased in the cytosol of both caput and cauda epididymis. This set of data demonstrates for the first time that a triggering mechanism which stimulates lysosomal activity is present all along the rat epididymis. Disposal of the continuous influx of spermatozoa from the testis could therefore require both an active and a passive process.
 ...
PMID:Fate of alpha-1,4-glucosidases and cathepsin D in the rat epididymis after vasectomy. 210 99

Procathepsin L, the precursor to a powerful lysosomal cysteine proteinase, has been purified to apparent homogeneity from guinea pig spermatozoa, a novel and previously unrecognized source of this catalytically active zymogen. In the range of pH 5.0, procathepsin L (39,000 M(r)) readily self-processed yielding a mature, single-chain proteinase (29,000 M(r)) and an intact propeptide (10,000 M(r)) by what appeared kinetically to be an intramolecular reaction mechanism. These characteristics resembled those reported for the "major excreted protein" (MEP) of malignantly transformed mouse fibroblasts-a protein that has been characterized as the precursor to the mouse analog of human cathepsin L (B. R. Troen, S. Gal, and M. M. Gottesman (1987) Biochem. J. 246, 731-735). Other characteristics shared by the guinea pig and mouse zymogens included proteolytic activity at pH 5.0, homologous N-terminal amino acid sequences, and immunological relatedness. It was thus concluded that acrosomal procathepsin L is the guinea pig analog of MEP. Acrosomal procathepsin L had a specific activity on benzyloxy-carbonyl-Phe-Arg-7-(4-methyl)coumarylamide (Z-Phe-Arg-NMec) of 30 mumol min-1 mg-1 enzyme at pH 3.2 and 37 degrees C. Relative to the assay substrate, rates on other fluorogenic substrates were 90% for Z-Phe-Cit-NMec, 63% for Z-Leu-Leu-Arg-NMec, 43% for D-Phe-Ser(Bzl)-Phe-Phe-Ala-Ala-p-aminobenzoate (a "specific" cathepsin D assay substrate), and 32% for Z-Val-Val-Arg-NMec. No action was detected on Z-Arg-Arg-NMec or Arg-NMec. Mature cathepsin L showed the same relative order of substrate specificity as its proenzyme form, but the absolute rates were about 5-fold greater. Additionally, the mature (single-chain) form of cathepsin L displayed Km and kcat values on Z-Phe-Arg-NMec that yielded an exceptionally high catalytic coefficient (11,600 s-1 mM-1) compared to values reported for two-chain forms of cathepsin L. Self-processing by acrosomal procathepsin L at pH 5.5 was totally inhibited by leupeptin, cystatin C, Ep-475, and Z-Phe-Phe-CHN2 at 1 microM levels. Gossypol (0.1 mM) gave 94% inhibition. Interestingly, dextran sulfate (100 micrograms ml-1) gave a 3.6-fold increase in the rate of self-processing seen at pH 5.5--a phenomenon of potential physiological relevance in view of the high-negative-charge density present within the hyaluronic acid-rich outer layer (cumulus oophorus) of the ovum.
 ...
PMID:Purification and characterization of procathepsin L, a self-processing zymogen of guinea pig spermatozoa that acts on a cathepsin D assay substrate. 748 6

The way in which the human epididymis modifies spermatozoa during their sojourn in this structure might be clarified by knowledge of the nature of its secretions. We have examined the presence of several lysosomal hydrolases in human epididymal tissue and fluids, and their synthesis and secretion by monolayer cultures. Tissues were obtained from men undergoing orchidectomy for prostatic carcinoma. The enzymes cathepsin D and acid alpha-glucosidase were localised in the lysosomes of epithelial cells from the corpus epididymidis, by an immunocytochemical technique. Cathepsin D was also found in epithelial cells of the efferent ducts within lysosomes, apical vesicles and multivesicular bodies. No immunolocalisation of acid glucosidase in the efferent ducts or on the microvilli of the corpus was demonstrable. Cathepsin D, beta-hexosaminidase (N-acetylglucosaminidase) and alpha-glucosidase were measurable in the luminal fluid from the human corpus epididymidis; beta-hexosaminidase was secreted into the culture medium by confluent monolayers of epididymal and efferent duct cells. Immunoprecipitation of cell extracts and culture medium of these cultures incubated with 35S-methionine revealed that the precursors of cathepsin D and beta-hexosaminidase were synthesized and secreted by such monolayers. Thus, active lytic enzymes are secreted by the human epididymis and could modify sperm membranes.
 ...
PMID:Immunocytochemical localisation of some lysosomal hydrolases, their presence in luminal fluid and their directional secretion by human epididymal cells in culture. 778 Oct 38

Apical and narrow cells of the initial segment and intermediate zone of the adult rat epididymis were glutaraldehyde fixed and Epon embedded for routine light (LM) and electron (EM) microscopic analysis and Bouin fixed and paraffin embedded for LM immunocytochemical analysis in order to examine their structural features, distribution, and functions. The goblet-shaped apical cells comprised 10.7 +/- 1.0% of the total epithelial population in the proximal initial segment but only 1.3 +/- 0.5% in the intermediate zone. In the EM, these cells presented numerous mitochondria, few C-shaped vesicles, and a pale round or oblong nucleus located in the upper half of their cytoplasm. The slender elongated narrow cells increased from 2.8 +/- 0.3% in the proximal initial segment to 6.3 +/- 0.4% in the intermediate zone. In an EM analysis, these cells presented numerous C-shaped vesicles and mitochondria and a small flattened nucleus located in the upper half of their cytoplasm. The structural features of both these cell types differed not only from each other but also from the neighboring principal and basal cells of each region. Of the various antibodies examined to lysosomal proteins, narrow and apical cells expressed high levels of cathepsin D, while beta-hexosaminidase A was expressed at high levels in narrow cells but only moderately in apical cells. Apical cells were intensely reactive for the Yf subunit of glutathione S-transferase (GST)-P, whereas no reaction was seen in narrow cells; the Yo subunit of GST was localized within both cell types but only in the proximal initial segment. Narrow cells exclusively expressed carbonic anhydrase II. Selective differences in the immunolocalization of these various proteins were also noted between these two cell types and principal and basal cells. The localization of cathepsin D and beta-hexosaminidase A within narrow and apical cells suggests these cells may be involved in the degradation of specific proteins within their lysosomes, whereas the presence of GSTs may aid in protecting spermatozoa from a changing environment of harmful electrophiles. Localization of carbonic anhydrase II exclusively within narrow cells suggests that these cells may modify the pH of the lumen resulting in the quiescence of sperm motility in the proximal end of the epididymis. Together, the data indicate that apical and narrow cells differ not only from each other but also from principal and basal cells in their structure and relative distribution. They also express different proteins within the distinct epididymal regions, indicating that they perform different functions.
 ...
PMID:Apical and narrow cells are distinct cell types differing in their structure, distribution, and functions in the adult rat epididymis. 879 11

As a new approach, various synthetic fluorogenic substrates, the CellProbe reagents, were applied to examine the topography of their cleavage in vital human spermatozoa. These substrates are able to enter the cells without requiring previous cell permeabilization and can produce a fluorescent dye after cleavage, depending on enzyme activity. Vital spermatozoa from samples with normal spermiogram parameters showed fluorescence in different areas and intensity after incubation with a variety of substrates for aminopeptidase A, peroxides, subtilisin, dipeptidylpeptidase IV (DPP IV), cathepsin D, glucosidase and glucuronidase, but not with the substrate for galactosidase. Fluorescence was mainly located in the acrosomal cap (substrates for DPP IV, subtilisin, cathepsin D, glucosidase and glucuronidase) in the middle piece and head (substrates for peroxides, glucosidase), in the sperm head (substrates for aminopeptidase A) and occasionally in the tail (substrate for glucosidase). The substrate for subtilisin may play a role in andrology, because subtilisin is a serine protease like acrosin. This substrate may possibly be used to determine the acrosin activity in vital spermatozoa. The CellProbe reagents for fluorescence cytoenzymology may serve advanced methods in both clinical andrology and spermiological research, presuming that the characteristics and qualities of the synthetic substrates are correct. Therefore, more extended studies will be necessary to determine their clinical utility and significance under physiological and pathological conditions.
 ...
PMID:Localisation of enzymes in live spermatozoa by CellProbe reagents (preliminary results). 994 87