Thimet Oligopeptidase and the Stability of MHC Class I Epitopes in Macrophage Cytosol

Portaro, Fernanda Calheta Vieira; Gomes, Marcelo D.; Cabrera, Adriana; Fernandes, Beatriz Lieblich; Silva, Célio Lopes; Ferro, Emer S.; Juliano, Luis; Camargo, Antônio Carlos Martins de

doi:10.1006/bbrc.1999.0251

Cited by 58 publications

(55 citation statements)

References 33 publications

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“…Moreover, related studies by our group (15) and others (16) have shown that in cultured cells TOP destroys antigenic peptides in the cytosol, limiting their presentation to the immune system. These findings are not consistent with the proposal that cytosolic TOP binds antigenic peptides but is unable to digest them and can even protect them from cytosolic degradation (53,54).…”

Section: Discussioncontrasting

confidence: 98%

Pathway for Degradation of Peptides Generated by Proteasomes

Šarić¹,

Graef²,

Goldberg

2004

Journal of Biological Chemistry

170

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The degradation of cellular proteins by proteasomes generates peptides 2-24 residues long, which are hydrolyzed rapidly to amino acids. To define the final steps in this pathway and the responsible peptidases, we fractionated by size the peptides generated by proteasomes from ␤-[ 14 C]casein and studied in HeLa cell extracts the degradation of the 9 -17 residue fraction and also of synthetic deca-and dodecapeptide libraries, because peptides of this size serve as precursors to MHC class I antigenic peptides. Their hydrolysis was followed by measuring the generation of smaller peptides or of new amino groups using fluorescamine. The 14 C-labeled peptides released by 20 S proteasomes could not be degraded further by proteasomes. However, their degradation in the extracts and that of the peptide libraries was completely blocked by o-phenanthroline and thus required metallopeptidases. 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. Inhibition or immunodepletion of TOP decreased their degradation and that of the peptide libraries by 30 -50%. Pure TOP failed to degrade proteasome products 18 -24 residues long but degraded the 9 -17 residue fraction to peptides of 6 -9 residues. When aminopeptidases in the cell extract were inhibited with bestatin, the 9 -17 residue proteasome products were also converted to peptides of 6 -9 residues, instead of smaller products. Accordingly, the cytosolic aminopeptidase, leucine aminopeptidase, could not degrade the 9 -17 residue fraction but hydrolyzed the peptides generated by TOP to smaller products, recapitulating the process in cell extracts. Inactivation of both TOP and aminopeptidases blocked the degradation of proteasome products and peptide libraries nearly completely. Thus, degradation of most 9 -17 residue proteasome products is initiated by endoproteolytic cleavages, primarily by TOP, and the resulting 6 -9 residue fragments are further digested to amino acids by aminopeptidases.

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Section: Discussioncontrasting

confidence: 98%

Pathway for Degradation of Peptides Generated by Proteasomes

Šarić¹,

Graef²,

Goldberg

2004

Journal of Biological Chemistry

170

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“…Additionally, accumulating evidence indicates the role of these peptidases in the intracellular metabolism of peptides (41,42). Functional studies revealed the role of both peptidases in neurotensin- related nociception (43,44), bradykinin-mediated regulation of blood pressure and microvascular permeability (45,46), and antigen presentation through major histocompatibility complex class I (MHC-I) (47)(48)(49). Cell type-dependent membrane association of neurolysin, constituting ϳ10% of total activity of this peptidase, was documented in several studies (31, 32, 34, 50 -53).…”

Section: Discussionmentioning

confidence: 99%

Identification of Membrane-bound Variant of Metalloendopeptidase Neurolysin (EC 3.4.24.16) as the Non-angiotensin Type 1 (Non-AT1), Non-AT2 Angiotensin Binding Site

Wangler

Santos

Schadock

et al. 2012

Journal of Biological Chemistry

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Background: Angiotensin II, the renin-angiotensin system effector peptide, interacts with a recently discovered binding site that is distinctly different from its classic receptors. Results: A radioiodinated angiotensin II photoprobe bound to a ϳ75-kDa membrane protein, enabling its isolation and identification. Conclusion: Membrane-bound metalloendopeptidase neurolysin (EC 3.4.24.16) is the novel angiotensin-binding protein.Significance: This metalloendopeptidase may be a crucial component of the renin-angiotensin system.

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“…These include at least two enzymes, PSA and BH, that have been reported to be inhibited by AAF-cmk (32,36). In addition, TO and the IFN-␥-inducible LA have been proposed to act as either productive or destructive postproteasomal trimming enzymes (33)(34)(35)49). To test whether any of these proteases contributes to productive NP 147-155 generation, recombinant vacs expressing each of the four proteases were constructed.…”

Section: Overexpression Of Other Proteasesmentioning

confidence: 99%

“…In addition to TPP II, several reports have demonstrated that other nonproteasomal cytosolic proteases may contribute to the generation or destruction of antigenic peptides via post proteasomal trimming. These include LA (33), thymet oligopeptidase (TO) (34,35), bleomycin hydrolase (BH), and puromycin-sensitive aminopeptidase (PSA) (32,36). In addition to these cytosolic proteases, ER-resident amino peptidase (ERAAP or ERAP1 in the mouse, ERAP1/2 complex in the human) can further trim peptides at the N terminus once they have been transported via TAP (10 -13).…”

mentioning

confidence: 99%

Re-evaluating the Generation of a “Proteasome-Independent” MHC Class I-Restricted CD8 T Cell Epitope

Wherry

Golovina

Morrison

et al. 2006

The Journal of Immunology

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The proteasome is primarily responsible for the generation of MHC class I-restricted CTL epitopes. However, some epitopes, such as NP147–155 of the influenza nucleoprotein (NP), are presented efficiently in the presence of proteasome inhibitors. The pathways used to generate such apparently “proteasome-independent” epitopes remain poorly defined. We have examined the generation of NP147–155 and a second proteasome-dependent NP epitope, NP50–57, using cells adapted to growth in the presence of proteasome inhibitors and also through protease overexpression. We observed that: 1) Ag processing and presentation proceeds in proteasome-inhibitor adapted cells but may become more dependent, at least in part, on nonproteasomal protease(s), 2) tripeptidyl peptidase II does not substitute for the proteasome in the generation of NP147–155, 3) overexpression of leucine aminopeptidase, thymet oligopeptidase, puromycin-sensitive aminopeptidase, and bleomycin hydrolase, has little impact on the processing and presentation of NP50–57 or NP147–155, and 4) proteasome-inhibitor treatment altered the specificity of substrate cleavage by the proteasome using cell-free digests favoring NP147–155 epitope preservation. Based on these results, we propose a central role for the proteasome in epitope generation even in the presence of proteasome inhibitors, although such inhibitors will likely alter cleavage patterns and may increase the dependence of the processing pathway on postproteasomal enzymes.

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Thimet Oligopeptidase and the Stability of MHC Class I Epitopes in Macrophage Cytosol

Cited by 58 publications

References 33 publications

Pathway for Degradation of Peptides Generated by Proteasomes

Pathway for Degradation of Peptides Generated by Proteasomes

Identification of Membrane-bound Variant of Metalloendopeptidase Neurolysin (EC 3.4.24.16) as the Non-angiotensin Type 1 (Non-AT1), Non-AT2 Angiotensin Binding Site

Re-evaluating the Generation of a “Proteasome-Independent” MHC Class I-Restricted CD8 T Cell Epitope

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