TY - JOUR
T1 - Relationship of the Topological Distances and Activities between mPGES-1 and COX-2 versus COX-1
T2 - Implications of the Different Post-Translational Endoplasmic Reticulum Organizations of COX-1 and COX-2
AU - Akasaka, Hironari
AU - So, Shui Ping
AU - Ruan, Ke He
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/6/16
Y1 - 2015/6/16
N2 - In vascular inflammation, prostaglandin E2 (PGE2) is largely biosynthesized by microsomal PGE2 synthase-1 (mPGES-1), competing with other downstream eicosanoid-synthesizing enzymes, such as PGIS, a synthase of a vascular protector prostacyclin (PGI2), to isomerize the cyclooxygenase (COX)-2-derived prostaglandin H2 (PGH2). In this study, we found that a majority of the product from the cells co-expressing human COX-2, mPGES-1, and PGIS was PGE2. We hypothesize that the molecular and cellular mechanisms are related to the post-translational endoplasmic reticulum (ER) arrangement of those enzymes. A set of fusion enzymes, COX-2-linker [10 amino acids (aa)]-PGIS and COX-2-linker (22 amino acids)-PGIS, were created as "The Bioruler", in which the 10 and 22 amino acids are defined linkers with known helical structures and distances (14.4 and 30.8 Å, respectively). Our experiments have shown that the efficiency of PGI2 biosynthesis was reduced when the separation distance increased from 10 to 22 amino acids. When COX-2-10aa-PGIS (with a 14.4 Å separation) was co-expressed with mPGES-1 on the ER membrane, a major product was PGE2, but not PGI2. However, expression of COX-2-10aa-PGIS and mPGES-1 on a separated ER with a distance of 30.8 Å reduced the level of PGE2 production. These data indicated that the mPGES-1 is "complex-likely" colocalized with COX-2 within a distance of 14.4 Å. In addition, the cells co-expressing COX-1-10aa-PGIS and mPGES-1 produced PGI2 mainly, but not PGE2. This indicates that mPGES-1 is expressed much farther from COX-1. These findings have led to proposed models showing the different post-translational ER organization between COX-2 and COX-1 with respect to the topological arrangement of the mPGES-1 during vascular inflammation.
AB - In vascular inflammation, prostaglandin E2 (PGE2) is largely biosynthesized by microsomal PGE2 synthase-1 (mPGES-1), competing with other downstream eicosanoid-synthesizing enzymes, such as PGIS, a synthase of a vascular protector prostacyclin (PGI2), to isomerize the cyclooxygenase (COX)-2-derived prostaglandin H2 (PGH2). In this study, we found that a majority of the product from the cells co-expressing human COX-2, mPGES-1, and PGIS was PGE2. We hypothesize that the molecular and cellular mechanisms are related to the post-translational endoplasmic reticulum (ER) arrangement of those enzymes. A set of fusion enzymes, COX-2-linker [10 amino acids (aa)]-PGIS and COX-2-linker (22 amino acids)-PGIS, were created as "The Bioruler", in which the 10 and 22 amino acids are defined linkers with known helical structures and distances (14.4 and 30.8 Å, respectively). Our experiments have shown that the efficiency of PGI2 biosynthesis was reduced when the separation distance increased from 10 to 22 amino acids. When COX-2-10aa-PGIS (with a 14.4 Å separation) was co-expressed with mPGES-1 on the ER membrane, a major product was PGE2, but not PGI2. However, expression of COX-2-10aa-PGIS and mPGES-1 on a separated ER with a distance of 30.8 Å reduced the level of PGE2 production. These data indicated that the mPGES-1 is "complex-likely" colocalized with COX-2 within a distance of 14.4 Å. In addition, the cells co-expressing COX-1-10aa-PGIS and mPGES-1 produced PGI2 mainly, but not PGE2. This indicates that mPGES-1 is expressed much farther from COX-1. These findings have led to proposed models showing the different post-translational ER organization between COX-2 and COX-1 with respect to the topological arrangement of the mPGES-1 during vascular inflammation.
UR - http://www.scopus.com/inward/record.url?scp=84934937289&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84934937289&partnerID=8YFLogxK
U2 - 10.1021/acs.biochem.5b00339
DO - 10.1021/acs.biochem.5b00339
M3 - Article
C2 - 25988363
AN - SCOPUS:84934937289
SN - 0006-2960
VL - 54
SP - 3707
EP - 3715
JO - Biochemistry
JF - Biochemistry
IS - 23
ER -