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Binding of proteins to the PDZ domain regulates proteolytic activity of HtrA1 serine protease.

ABSTRACT: HtrA1, a member of the mammalian HtrA (high temperature requirement A) serine protease family, has a highly conserved protease domain followed by a PDZ domain. Accumulating evidence has indicated that PDZ domains regulate protease activity of HtrA proteins. We searched for binding partners of the PDZ domain of mouse HtrA1 by yeast two-hybrid screening, and isolated proteins that were recognized by the HtrA1 PDZ domain through their C-terminal ends with a core consensus Phi-X-Phi-[V/L/F/A]-COOH sequence (where Phi is a hydrophobic/non-polar amino acid). C-propeptides of fibrillar collagens were most frequently isolated. Type III procollagen alpha1 C-propeptide, which was used as a model protein, was digested by HtrA1. HtrA1 cleavage of the collagen C-propeptide was enhanced by reductive denaturation of the C-propeptide and partly inhibited by removal of the C-terminal four amino acids from the C-propeptide, suggesting that the substrate recognition was facilitated by the binding of the free C-terminal ends of substrates to the PDZ domain of HtrA1. The synthetic oligopeptide (GM130Pep) that fitted the consensus recognition sequence bound to HtrA1 with a high affinity (K(d)=6.0 nM). GM130Pep stimulated HtrA1 protease activity 3- to 4-fold, but did not efficiently stimulate the activity of an HtrA1 mutant lacking the PDZ domain, supporting the notion that the PDZ domain enhances protease activity upon ligand binding. The peptide derived from Type III collagen alpha1 C-propeptide specifically stimulated protease activity of HtrA1, but did not stimulate nor significantly bind to HtrA2, suggesting that the collagen C-propeptide is a specific physiological regulator of HtrA1.

SUBMITTER: Murwantoko

PROVIDER: S-EPMC1133901 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature

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Binding of proteins to the PDZ domain regulates proteolytic activity of HtrA1 serine protease.

Murwantoko Yano Masato M Ueta Yoshifumi Y Murasaki Ai A Kanda Hidenobu H Oka Chio C Kawaichi Masashi M

The Biochemical journal 20040801 Pt 3

HtrA1, a member of the mammalian HtrA (high temperature requirement A) serine protease family, has a highly conserved protease domain followed by a PDZ domain. Accumulating evidence has indicated that PDZ domains regulate protease activity of HtrA proteins. We searched for binding partners of the PDZ domain of mouse HtrA1 by yeast two-hybrid screening, and isolated proteins that were recognized by the HtrA1 PDZ domain through their C-terminal ends with a core consensus Phi-X-Phi-[V/L/F/A]-COOH s ...[more]

PMID: 15101818

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Project description:HTRA1 is a highly conserved serine protease which has been implicated in suppression of epithelial-to-mesenchymal-transition (EMT) and cell motility in breast cancer. Its prognostic relevance for breast cancer is unclear so far. Therefore, we evaluated the impact of HTRA1 mRNA expression on patient outcome using a cohort of 131 breast cancer patients as well as a validation cohort including 2809 publically available data sets. Additionally, we aimed at investigating for the presence of promoter hypermethylation as a mechanism for silencing the HTRA1 gene in breast tumors. HTRA1 downregulation was detected in more than 50% of the breast cancer specimens and was associated with higher tumor stage (p?=?0.025). By applying Cox proportional hazard models, we observed favorable overall (OS) and disease-free survival (DFS) related to high HTRA1 expression (HR?=?0.45 [CI 0.23-0.90], p?=?0.023; HR?=?0.55 [CI 0.32-0.94], p?=?0.028, respectively), with even more pronounced impact in node-positive patients (HR?=?0.21 [CI 0.07-0.63], p?=?0.006; HR?=?0.29 [CI 0.13-0.65], p?=?0.002, respectively). Moreover, HTRA1 remained a statistically significant factor predicting DFS among established clinical parameters in the multivariable analysis. Its impact on patient outcome was independently confirmed in the validation set (for relapse-free survival (n?=?2809): HR?=?0.79 [CI 0.7-0.9], log-rank p?=?0.0003; for OS (n?=?971): HR?=?0.63 [CI 0.48-0.83], log-rank p?=?0.0009). In promoter analyses, we in fact detected methylation of HTRA1 in a small subset of breast cancer specimens (two out of a series of 12), and in MCF-7 breast cancer cells which exhibited 22-fold lower HTRA1 mRNA expression levels compared to unmethylated MDA-MB-231 cells. In conclusion, we show that downregulation of HTRA1 is associated with shorter patient survival, particularly in node-positive breast cancer. Since HTRA1 loss was demonstrated to induce EMT and cancer cell invasion, these patients might benefit from demethylating agents or histone deacetylase inhibitors previously reported to lead to HTRA1 upregulation, or from novel small-molecule inhibitors targeting EMT-related processes.

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Dataset Information

Binding of proteins to the PDZ domain regulates proteolytic activity of HtrA1 serine protease.

Publications

Binding of proteins to the PDZ domain regulates proteolytic activity of HtrA1 serine protease.

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