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)

The ADP-ribosylation site of histone H1 from calf thymus by purified hen liver nuclear ADP-ribosyltransferase was determined and effects of the ADP-ribose X histone-H1 adduct on cAMP-dependent phosphorylation of the histone H1 were investigated. ADP-ribosylated histone H1 was prepared by incubation of histone H1, 1 mM [adenylate-32P]NAD and the purified ADP-ribosyltransferase. N-Bromosuccinimide-directed bisection of ADP-ribosylated histone H1 showed that the NH2-terminal fragment (Mr = 6000) was modified and contained serine residue 38, the site of phosphorylation by cAMP-dependent protein kinase. Digestion of the NH2-terminal fragment with cathepsin D and trypsin, and purification of this fragment, using high-performance liquid chromatography, yielded a radiolabelled single peptide corresponding to residues 29-34 of histone H1, containing the arginine residue as the ADP-ribosylation site. These results indicate that ADP-ribosylation of histone H1 occurs at the arginine residue 34, sequenced at the NH2-terminal side of the phosphate-accepting serine residue 38. Phosphorylation of histone H1 from calf thymus by cAMP-dependent protein kinase was markedly reduced when histone H1 was ADP-ribosylated. Kinetic studies of phosphorylation revealed that ADP-ribosylated histone H1 was a linear competitive inhibitor of histone H1 and a linear non-competitive inhibitor of ATP.
 ...
PMID:Amino acid sequence of histone H1 at the ADP-ribose-accepting site and ADP-ribose X histone-H1 adduct as an inhibitor of cyclic-AMP-dependent phosphorylation. 299 55

We have identified a system in human lymphocytes which proteolytically cleaves poly(ADPribose) polymerase to specific fragments of molecular weight 96 000, 79 000 and 62 000-60 000. This proteolytic processing is dependent on two different classes of proteinase. One of these proteinases is a serine proteinase, since the processing is inhibited by phenylmethylsulfonyl fluoride, antipain, soybean trypsin inhibitor and diisopropylfluorophosphate, the other is a cathepsin D-like proteinase, since processing is also inhibited by pepstatin A. The processing that occurs in permeabilized cells can be simulated in vitro by treating purified poly(ADPribose) polymerase with trypsin, but not by treating the polymerase with cathepsin D. Since processing at the cellular level is blocked by inhibitors of either of the two proteinases, but only trypsin could cleave the purified polymerase, this suggests that in the cell the action of the cathepsin D-like proteinase is a prerequisite for cleavage of poly(ADPribose) polymerase by the serine proteinase. Thus, a pathway involving sequential action of these proteinases may exist. Proteolysis in permeabilized human lymphocytes is stimulated by nucleotides containing a pyrophosphate group, such as 5',5'''-P1,P4-tetraphosphate and ATP, or by pyrophosphate itself. In contrast, nucleotides containing only a single phosphate, such as AMP and cyclic AMP, or inorganic sodium phosphate, do not show this stimulation of proteolysis. These results suggest that a pyrophosphate linkage is the minimum molecular requirement for stimulation of proteolytic processing of poly(ADPribose) polymerase. Proteolytic processing of poly(ADPribose) polymerase is independent of ADPribosylation. Following proteolysis, specific fragments of the polymerase, particularly the 62 000-60 000 molecular weight fragment(s), are still capable of being ADPribosylated.
 ...
PMID:Proteolysis of poly(ADPribose) polymerase by a pyrophosphate- and nucleotide-stimulated system dependent on two different classes of proteinase. 299 8

Renatured, S-carboxymethylated subunit A1 of cholera toxin possess the ADP-ribose transferase activity (Lai, et.al., Biochem. Biophys. Res. Commun. 1981, 102, 1021). In the absence of acceptor self ADP-ribosylation of A1 subunit was observed. Stoicheometric incorporation of ADP-ribose moiety was achieved in 20 min at room temperature in a 0.1 - 0.2M PO4(Na) buffer, pH 6.6. On incubation of the complex with polyarginine, 75% of the enzyme-bound ADP-ribose moiety was transferred to the acceptor in 25 min. The ADP-ribosylated A1 was stable at low pH, and on cleavage with BrCN, the ADP-ribose moiety was found associated with peptide Cn I, the COOH-terminal fragment of A1 subunit. On further fragmentation with cathepsin D, a dodecapeptide containing ADP-ribose moiety was isolated whose structure was determined as: Asp-Glu-Glu-Leu-His-Arg-Gly-Tyr-Arg*-Asp-Arg-Tyr. The Arg* in the peptide was indicated to be the site of ADP-ribosylation.
 ...
PMID:Location and amino acid sequence around the ADP-ribosylation site in the cholera toxin active subunit A1. 631 8

The antitumor activity of spicatoside A (1), a steroidal saponin isolated from the tuber of Liriope platyphylla, and its underlying mechanisms were investigated in HCT116 human colorectal cancer cells. Compound 1 induced autophagy and apoptotic cell death and inhibited tumor growth in a nude mouse xenograft model implanted with HCT116 cells. Treatment with 1 for 24 h enhanced the formation of acidic vesicular organelles in the cytoplasm, indicating the induction of the onset of autophagy. This event was associated with the regulation of autophagic markers including microtubule-associated protein 1 light chain 3 (LC3)-II, p62, beclin 1, lysosomal-associated membrane protein 1 (LAMP 1), and cathepsin D by inhibiting the PI3K/Akt/mTOR signaling pathway, regulating mitogen-activated protein kinase (MAPK) signaling, and increasing p53 levels. However, a prolonged exposure to 1 resulted in apoptosis characterized by the accumulation of a sub-G1 cell population and an annexin V/propidium iodide (PI)-positive cell population. Apoptosis induced by 1 was associated with the regulation of apoptotic proteins including Bcl-2, Bax, and Bid, the release of cytochrome c into the cytosol, and the accumulation of cleaved poly-ADP-ribose polymerase (PARP). Further study revealed that cleavage of beclin 1 by caspases plays a critical role in the 1-mediated switch from autophagy to apoptosis. Taken together, these findings highlight the significance of 1 in the modulation of crosstalk between autophagy and apoptosis, as well as the potential use of 1 as a novel candidate in the treatment of human colorectal cancer cells.
...
PMID:Antitumor Activity of Spicatoside A by Modulation of Autophagy and Apoptosis in Human Colorectal Cancer Cells. 2706 30