In vitro and in vivo induction of heme oxygenase 1 in mouse macrophages following melanocortin receptor activation.
RAW264.7 cell incubation with adrenocorticotrophin (ACTH) led to a time-dependent (4-24 h) and concentration-related (1-100 ng/ml) induction of heme oxygenase (HO)-1, and this was a specific effect, because the pattern of expression of other cellular proteins (HO-2, heat shock proteins 70 and 90) was not modified by ACTH. Combined RT-PCR and Western blot analyses revealed expression of the melanocortin receptor (MC-R) types 1 and 3, but not 4, in these cells. However, use of more selective agonists (including melanotan (MTII)) indicated a predominant role for MC3-R in the induction of HO-1 expression and activity. Relevantly, ACTH and MTII incubation with primary peritoneal macrophages (Mphi) also induced HO-1 expression. The potential link between MC3-R dependent cAMP formation and HO-1 induction was ascertained by the following: 1) ACTH and MTII produced a concentration-dependent accumulation of cAMP in RAW264.7 cells, and 2) whereas a selective inhibitor of cAMP-dependent protein kinase A abrogated ACTH- and MTII-induced HO-1 expression, a soluble cAMP derivative promoted HO-1 induction both in RAW264.7 cells and primary Mphi. HO-1 induction in peritoneal Mphi was also detected following in vivo administration of MTII, and appeared to be functionally related to the antimigratory effect of this melanocortin, as determined with a specific inhibitor (zinc protoporphyrin IX). In conclusion, this study highlights a biochemical link between MC-R activation and HO-1 induction in the Mphi, and proposes that this may be of functional relevance in determining MC-R-dependent control of the host inflammatory response.
Lam
Connie W
CW
The William Harvey Research Institute, Bart's and the London, Queen Mary School of Medicine and Dentistry, London, United Kingdom.
Getting
Stephen J
SJ
Perretti
Mauro
M
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004790:Enzyme Induction / Q000276:immunology; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis* / Q000502:physiology; D051547:Heme Oxygenase-1; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology; D008264:Macrophages / Q000201:enzymology* / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000008:administration & dosage; D044104:Receptor, Melanocortin, Type 3 / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology; D000521:alpha-MSH / Q000008:administration & dosage / Q000031:analogs & derivatives*
D018836:Inflammation Mediators; D008565:Membrane Proteins; D010456:Peptides, Cyclic; D044104:Receptor, Melanocortin, Type 3; C079282:melanotan-II; D000521:alpha-MSH; D000242:Cyclic AMP; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse