Prostaglandin-endoperoxide synthase 2

An enzyme involved in the biosynthesis of prostaglandins

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Identifiers
EC number	1.14.99.1
CAS number	9007-92-5
Alt. names
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway

Prostaglandin-endoperoxide synthase 2 (PTGS2), also known as cyclooxygenase-2 (COX-2), is an enzyme that plays a crucial role in the biosynthesis of prostaglandins, which are lipid compounds that perform a variety of hormone-like actions in the body. PTGS2 is one of two cyclooxygenase enzymes, the other being COX-1.

Function

PTGS2 is an inducible enzyme, meaning its expression is increased in response to certain stimuli, such as inflammatory cytokines, growth factors, and tumor promoters. This enzyme is primarily involved in the conversion of arachidonic acid to prostaglandin H2 (PGH2), the precursor of other prostaglandins and thromboxanes. Unlike COX-1, which is constitutively expressed in most tissues and involved in maintaining physiological functions such as gastric mucosal protection and platelet aggregation, COX-2 is mainly expressed at sites of inflammation and is associated with the inflammatory response.

Clinical significance

The overexpression of PTGS2 has been linked to various pathological conditions, including inflammation, arthritis, and certain types of cancer. As a result, COX-2 inhibitors, a class of nonsteroidal anti-inflammatory drugs (NSAIDs), have been developed to selectively inhibit this enzyme, thereby reducing inflammation and pain without affecting COX-1 activity. However, the use of COX-2 inhibitors has been associated with an increased risk of cardiovascular events, which has led to the withdrawal of some of these drugs from the market.

Regulation

The expression of PTGS2 is tightly regulated at the transcriptional level by various factors, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), cyclic AMP response element-binding protein (CREB), and peroxisome proliferator-activated receptor gamma (PPARγ). Post-transcriptional regulation also plays a role, with microRNAs and RNA-binding proteins influencing the stability and translation of PTGS2 mRNA.

Structure

PTGS2 is a homodimeric enzyme, with each monomer consisting of three domains: an epidermal growth factor (EGF) domain, a membrane-binding domain, and a catalytic domain. The catalytic domain contains the active site where the conversion of arachidonic acid to PGH2 occurs. The enzyme is anchored to the endoplasmic reticulum and nuclear envelope membranes, which facilitates its access to arachidonic acid.

Also see

• Prostaglandin-endoperoxide synthase 1
• Arachidonic acid
• Nonsteroidal anti-inflammatory drug
• Inflammation
• Cancer