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Cyclooxygenase in normal human tissues--is COX-1 really a constitutive isoform, and COX-2 an inducible isoform?

Zidar N, Odar K, Glavac D, Jerse M, Zupanc T, Stajer D - J. Cell. Mol. Med. (2008)

Bottom Line: COX-1 was found in blood vessels, interstitial cells, smooth muscle cells, platelets and mesothelial cells.In contrast, COX-2 was found predominantly in the parenchymal cells of many tissues, with few exceptions, for example the heart.Our results confirm the hypothesis that the distribution of COX isoforms in healthy tissues is much more complex than generally believed.

View Article: PubMed Central - PubMed

Affiliation: Medical Faculty, Institute of Pathology, University of Ljubljana, Ljubljana, Slovenia. nina.zidar@mf.uni-lj.si

ABSTRACT
Cyclooxygenase (COX) is a key enzyme in prostanoid synthesis. It exists in two isoforms, COX-1 and COX-2. COX-1 is referred to as a 'constitutive isoform', and is considered to be expressed in most tissues under basal conditions. In contrast, COX-2 is referred to as an 'inducible isoform', which is believed to be undetectable in most normal tissues, but can be up-regulated during various conditions, many of them pathological. Even though the role of COX in homeostasis and disease in now well appreciated, controversial information is available concerning the distribution of COX isoforms in normal human tissues. There is mounting evidence that it is much more complex than generally believed. Our aim was therefore to analyse the expression and distribution of COX isoforms in normal human tissues, using immunohistochemistry, Western blotting and real-time RT-PCR. Autopsy samples from 20 healthy trauma victims and samples from 48 biopsy surgical specimens were included. COX-1 was found in blood vessels, interstitial cells, smooth muscle cells, platelets and mesothelial cells. In contrast, COX-2 was found predominantly in the parenchymal cells of many tissues, with few exceptions, for example the heart. Our results confirm the hypothesis that the distribution of COX isoforms in healthy tissues is much more complex than generally believed. This and previous studies indicate that both isoforms, not only COX-1, are present in many normal human tissues, and that both isoforms, not only COX-2, are up-regulated in various pathological conditions. We may have to revise the concept of 'constitutive' and 'inducible' COX isoforms.

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Related in: MedlinePlus

COX in the brain. Positive immunohistochemical reaction for COX-1 in the glial cells (A), and for COX-2 in the neurons (B).
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fig01: COX in the brain. Positive immunohistochemical reaction for COX-1 in the glial cells (A), and for COX-2 in the neurons (B).

Mentions: Immunohistochemical results are summarized in Table 1, and some examples, representative of all tested samples, are shown in Figs 1–5. COX-1 expression was fairly constant and did not vary significantly between cases. It was found in blood vessels (constantly in endothelial cells and often in smooth muscle cells), platelets, scattered interstitial and supportive cells, resident inflammatory cells, smooth muscle cells and mesothelial cells of all tested organs (Figs. 1A–5A). COX-1 expression was observed in the parenchymal cells in a few organs, for example in the kidney (in collecting ducts), diffuse neuroendocrine system (Fig. 4A), reproductive system (Fig. 5A), and occasionally in endocrine glands and neurons.


Cyclooxygenase in normal human tissues--is COX-1 really a constitutive isoform, and COX-2 an inducible isoform?

Zidar N, Odar K, Glavac D, Jerse M, Zupanc T, Stajer D - J. Cell. Mol. Med. (2008)

COX in the brain. Positive immunohistochemical reaction for COX-1 in the glial cells (A), and for COX-2 in the neurons (B).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4516524&req=5

fig01: COX in the brain. Positive immunohistochemical reaction for COX-1 in the glial cells (A), and for COX-2 in the neurons (B).
Mentions: Immunohistochemical results are summarized in Table 1, and some examples, representative of all tested samples, are shown in Figs 1–5. COX-1 expression was fairly constant and did not vary significantly between cases. It was found in blood vessels (constantly in endothelial cells and often in smooth muscle cells), platelets, scattered interstitial and supportive cells, resident inflammatory cells, smooth muscle cells and mesothelial cells of all tested organs (Figs. 1A–5A). COX-1 expression was observed in the parenchymal cells in a few organs, for example in the kidney (in collecting ducts), diffuse neuroendocrine system (Fig. 4A), reproductive system (Fig. 5A), and occasionally in endocrine glands and neurons.

Bottom Line: COX-1 was found in blood vessels, interstitial cells, smooth muscle cells, platelets and mesothelial cells.In contrast, COX-2 was found predominantly in the parenchymal cells of many tissues, with few exceptions, for example the heart.Our results confirm the hypothesis that the distribution of COX isoforms in healthy tissues is much more complex than generally believed.

View Article: PubMed Central - PubMed

Affiliation: Medical Faculty, Institute of Pathology, University of Ljubljana, Ljubljana, Slovenia. nina.zidar@mf.uni-lj.si

ABSTRACT
Cyclooxygenase (COX) is a key enzyme in prostanoid synthesis. It exists in two isoforms, COX-1 and COX-2. COX-1 is referred to as a 'constitutive isoform', and is considered to be expressed in most tissues under basal conditions. In contrast, COX-2 is referred to as an 'inducible isoform', which is believed to be undetectable in most normal tissues, but can be up-regulated during various conditions, many of them pathological. Even though the role of COX in homeostasis and disease in now well appreciated, controversial information is available concerning the distribution of COX isoforms in normal human tissues. There is mounting evidence that it is much more complex than generally believed. Our aim was therefore to analyse the expression and distribution of COX isoforms in normal human tissues, using immunohistochemistry, Western blotting and real-time RT-PCR. Autopsy samples from 20 healthy trauma victims and samples from 48 biopsy surgical specimens were included. COX-1 was found in blood vessels, interstitial cells, smooth muscle cells, platelets and mesothelial cells. In contrast, COX-2 was found predominantly in the parenchymal cells of many tissues, with few exceptions, for example the heart. Our results confirm the hypothesis that the distribution of COX isoforms in healthy tissues is much more complex than generally believed. This and previous studies indicate that both isoforms, not only COX-1, are present in many normal human tissues, and that both isoforms, not only COX-2, are up-regulated in various pathological conditions. We may have to revise the concept of 'constitutive' and 'inducible' COX isoforms.

Show MeSH
Related in: MedlinePlus