Distribution of the serine protease HtrA1 in normal human tissues

Antonio De Luca, Maria De Falco, Anna Severino, Mara Campioni, Daniele Santini, Feliciano Baldi, Marco G. Paggi, Alfonso Baldi

Research output: Contribution to journalArticlepeer-review


The human HtrA family of proteases consists of three members: HtrA1, HtrA2, and HtrA3. In bacteria, the chief role of HtrA is recognition and degradation of misfolded proteins in the periplasm, combining a dual activity of chaperone and protease. In humans, the three HtrA homologues appear to be involved in diverse functions such as cell growth, apoptosis, allergic reactions, fertilization, control of blood pressure, and blood clotting. Previous studies using RNA blot hybridization have shown that the expression of HtrA1 is ubiquitous in normal human tissues. Here we show by immunohistochemistry (IHC) that HtrA1 is widely expressed, although different tissue distributions and/or levels of expression were detected in the different tissues examined. In particular, high to medium HtrA1 expression was detected in mature layers of epidermis, in secretory breast epithelium, in liver, and in kidney tubules of cortex, in concordance with its secretory properties. Furthermore, we show a higher protein expression level in the epithelium of proliferative endometrium, in contrast to epithelium of secretory endometrium, which is almost completely negative for this protein. This suggests a possible role for HtrA1 in the modulation of tissue activity in this organ. The various expression levels in human tissues indicate several possible roles for HtrA1 in different cell types.

Original languageEnglish
Pages (from-to)1279-1284
Number of pages6
JournalJournal of Histochemistry and Cytochemistry
Issue number10
Publication statusPublished - Oct 1 2003


  • Endometrium
  • HtrA1
  • Human tissues
  • Immunohistochemistry

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology


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