Disease relevance of THOP1

• A phosphonamide peptide, N-(phenylethylphosphonyl)-Gly-L-Pro-L-aminohexanoic acid, previously shown to block Clostridium histolyticum collagenases, was examined as a putative inhibitor of endopeptidase 24.16 and endopeptidase 24.15 [1].
• Furthermore, immunoneutralization of EP24.15 resulted in the inhibition of the LHRH-facilitated lordosis but had no inhibitory effects on LHRH-(1-5)-facilitated lordosis [2].
• The gluzincins, defined by the HEXXH motif and a glutamic acid as the third zinc ligand, include the thermolysin, endopeptidase-24.11, aminopeptidase, angiotensin converting enzyme, endopeptidase-24.15, and tetanus and botulinum neurotoxin families [3].
• In addition, recombinant h-MP78 purified from E. coli cleaved an APP-derived substrate spanning the beta-secretase site (ISEVKMD1AEFRHDS) at multiple sites, but the beta-site cleavage was only a minor one; cleavage occurred predominantly at K-M and E-F bonds [4].
• It is suggested that elevated plasma nociceptin level found in Wilson disease patients is due to inhibition of nociceptin-inactivating Zn-metallopeptidases (aminopeptidase N (APN) and endopeptidase 24.15) by the toxic copper deposits in liver and/or brain [5].

High impact information on THOP1

• This review will focus on the biochemistry, cell biology, and physiology of the soluble metalloendopeptidases EC 3.4.24.15 (thimet oligopeptidase) and EC 3.4.24.16 (neurolysin), as well as presenting evidence that both peptidases play an important role in such diverse functions as reproduction, nociception, and cardiovascular homeostasis [6].
• The cytosolic endopeptidase, thimet oligopeptidase, destroys antigenic peptides and limits the extent of MHC class I antigen presentation [7].
• In the cytosol, endopeptidases, especially thimet oligopeptidase, and aminopeptidases degrade many proteasomal products, thereby limiting the supply of many antigenic peptides [8].
• If only either one of the two sites is mutated in thimet oligopeptidase, then the enzyme cleaves almost equally at the two hydrolysis positions [9].
• Thimet oligopeptidase mutated so that neurolysin residues are at all four positions cleaves neurotensin at the neurolysin site, and the reverse mutations in neurolysin switch hydrolysis to the thimet oligopeptidase site [9].

Chemical compound and disease context of THOP1

• EP24.15 actions are increased in androgen-dependent prostate cancer compared to androgen-independent; augmented by androgen treatment, and inhibited by clinical GnRH analogs [10].

Biological context of THOP1

• Results of the hybridization and FISH mapping of positive clones indicated localization of THOP1 to chromosome 19p13.3 and not 19q13 [11].
• 3. After localizing THOP1 to the high-resolution cosmid contig map of human chromosome 19, we found that the previous report was incorrect [11].
• In addition, EP24.15 was previously identified as a putative soluble angiotensin II binding protein [12].
• Major histocompatibility complex class I-presented antigenic peptides are degraded in cytosolic extracts primarily by thimet oligopeptidase [13].
• In discussing the results, we consider the determinants of the complex substrate specificity of thimet oligopeptidase [14].

Anatomical context of THOP1

• One such endopeptidase, thimet oligopeptidase (TOP), which was recently shown to degrade many antigenic precursors in the cytosol, was found to play a major role in degrading proteasome products [15].
• Distribution of thimet oligopeptidase (E.C. 3.4.24.15) in human and rat testes [16].
• We have purified human thimet oligopeptidase to homogeneity from erythrocytes, and compared it with the enzyme from rat testis and chicken liver [14].
• To ascertain whether EP24.15 is associated with the extracellular surface of plasma membrane, two sets of experiments were carried out [17].
• These results suggest that the EP24.15 is associated with the extracellular surface of the AtT-20 cell plasma membrane and is enzymatically active [17].

Associations of THOP1 with chemical compounds

• EP24.15 is widely distributed and is known to degrade bioactive peptides such as angiotensin I and II and bradykinin [12].
• Additionally, drugs which disrupt the classical secretory pathway, such as Brefeldin A and nocodazole, blocked A23187-stimulated EP24.15 release yet had no effect on basal EP24.15 release, suggesting differences in the basal and stimulated pathways of secretion for EP24.15 [18].
• Experiments with isoleucine-containing analogues of (Gly-Hyp-Leu)4 showed that thimet oligopeptidase preferred to cleave these peptides near the C-terminus [19].
• EP24.15/16 inhibition by N-[1(R,S)-carboxy-3-phenylpropyl]-Ala-AlalTyr-p-aminobenzoate (cFP) resulted in a 1000-fold increase in B2R sensitivity to BK as measured by inositol phosphate accumulation [20].
• In addition, the phosphonamide peptide inhibited the hydrolysis of benzoyl (Bz)-Gly-Ala-Ala-Phe-(pAB) p-aminobenzoate and neurotensin by endopeptidase 24.15 with about a 10-fold lower potency (KI values of 5 and 7.5 nM respectively) [1].

Enzymatic interactions of THOP1

• Thimet oligopeptidase cleaves the full-length Alzheimer amyloid precursor protein at a beta-secretase cleavage site in COS cells [21].

Regulatory relationships of THOP1

• Furthermore, the treatment of primary cultures of trigeminal ganglia with inhibitors of EP24.15/16 led to the potentiation of several bradykinin-induced events that occur downstream of B2R activation [20].

Other interactions of THOP1

• 3. This localization is a correction of wrong chromosomal delegation and excludes THOP1 from the region that shows evidence of linkage to late-onset familial Alzheimer disease [11].
• Thimet oligopeptidase EC 3.4.24.15 is a major liver kininase [22].
• Potentially, the colocalization of EP24.15/16 and B2R at plasma membrane microdomains known as lipid rafts in a physiologically relevant nociceptive system would allow for discrete, peptidase regulation of BK signaling [20].
• Like cFP, JA-2 inhibited the closely related endopeptidase EC 3.4.24.16 1/20 to 1/30 as potently as it did EP24.15, and did not inhibit the other thermolysin-like endopeptidases angiotensin-converting enzyme, endothelin-converting enzyme and neutral endopeptidase [23].
• Both neprilysin and thimet oligopeptidase are also involved in the metabolism of bradykinin and the atrial natriuretic peptide [24].

Analytical, diagnostic and therapeutic context of THOP1

• Analysis of endosomal fractions following immunoprecipitation with AT1 or B2 antibodies detected strong association of EP24.15 with the receptors in both light and heavy endosomal populations [12].
• Fluorescence in situ hybridization on human metaphase chromosomes localized the human endopeptidase 24.15 to 19q13.3 [25].
• Western immunoblot analyses of crude cytosolic and post-nuclear membrane fractions prepared by differential centrifugation revealed a slightly smaller molecular mass ( approximately 2 kDa) for EP24.15 in the post-nuclear membrane fraction [17].
• Using a combination of PCR and hybridization screening, we have isolated a cDNA clone for a metalloendopeptidase (h-MP78) from a human temporal cortex library [26].
• Western blot analysis of crude subcellular fractions and lipid raft preparations of cultured rat trigeminal ganglia demonstrate similar expression profiles between EP24.15/16 and B2R on a subcellular level [20].

References