Hypoxic regulation of secreted proteoglycans in macrophages.
Macrophages are prominent in hypoxic areas of atherosclerotic lesions, and their secreted proteoglycans (PG), such as versican, can modulate the retention of lipoproteins and the activity of enzymes, cytokines, and growth factors involved in atherogenesis. In this study, we report the effects of hypoxia on PG secreted by human monocyte-derived macrophages (HMDM) and the potential regulation by the transcription factor hypoxia-inducible factor (HIF-1alpha and HIF-2alpha). We found that versican co-localized with HIF-1alpha in macrophage-rich areas in human advanced atherosclerotic lesions. Versican and perlecan mRNA expression increased after exposure to 0.5% O(2) (hypoxia) compared with 21% O(2) (control cells). Using precursors to GAG biosynthesis combined with immunoabsorption with a versican antibody an increased versican synthesis was detected at hypoxia. Furthermore, siRNA knockdown of HIF-1alpha and HIF-2alpha in THP-1 cells showed that the hypoxic induction of versican and perlecan mRNA expression involved HIF signaling. Versican expression was co-regulated by HIF-1alpha and HIF-2alpha but expression of perlecan was influenced only by HIF-1alpha and not by HIF-2alpha knockdown. The results show that oxygen concentration is an important modulator of PG expression in macrophages. This may be a novel component of the complex role of macrophages in atherosclerosis.
Asplund
Annika
A
Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska Academy, Göteborg University, Göteborg.
Stillemark-Billton
Pia
P
Larsson
Erik
E
Rydberg
Ellen Knutsen
EK
Moses
Jonatan
J
Hultén
Lillemor Mattsson
LM
Fagerberg
Björn
B
Camejo
Germán
G
Bondjers
Göran
G
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D006025:Glycosaminoglycans / Q000737:chemistry; D019812:Heparan Sulfate Proteoglycans / Q000737:chemistry; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008264:Macrophages / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry; D011509:Proteoglycans / Q000378:metabolism*; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053675:Versicans / Q000737:chemistry; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D006025:Glycosaminoglycans; D019812:Heparan Sulfate Proteoglycans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010100:Oxygen; D011509:Proteoglycans; D053675:Versicans; D000099162:Endothelial PAS Domain-Containing Protein 1; C071927:perlecan