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Novel Role for Matrix Metalloproteinase 9 in Modulation of Cholesterol Metabolism

View Article: PubMed Central - PubMed

ABSTRACT

Background: The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown.

Methods and results: We examined MMP‐9–deficient (Mmp9−/−) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9+/+ (wild‐type) mice, Mmp9−/− mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9−/− mice failed to increase the expression of genes encoding the rate‐limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP‐9 deficiency did not impair intestinal cholesterol absorption, as shown by the 14C‐cholesterol and 3H‐sitostanol absorption assay. Similar to our earlier study on Mmp2−/− mice, we observed that Mmp9−/− mice had elevated plasma secreted phospholipase A2 activity. Pharmacological inhibition of systemic circulating secreted phospholipase A2 activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9−/− mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism.

Conclusions: Our results show that MMP‐9 modulates cholesterol metabolism, at least in part, through a novel MMP‐9–plasma secreted phospholipase A2 axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.

No MeSH data available.


Related in: MedlinePlus

Plasma sPLA2 activity is elevated by MMP‐9 deficiency. A, sPLA2 activity in the plasma, liver, and heart of Mmp9−/− mice (n=4 mice per genotype). *P<0.05 vs WT, t test. B, The elevated plasma PLA2 activity in Mmp9−/− mice (compared to WT) was confirmed using 2 unrelated assays: the Cayman sPLA2 assay kit (substrate: di‐heptanoyl‐thio‐PC; n=4 per genotype; *P<0.05 vs WT, t test) and the 3H‐oleate E coli membrane assay (data are representative of technical duplicates for a pool of 5 mice per genotype). C, EGTA and varespladib inhibition profiles for the sPLA2 from Mmp9−/− plasma vs heart and plasma from Mmp2−/− mice. The analysis was performed in duplicate using samples from pools of 4 mice per genotype using the 3H‐oleate E coli membrane assay. Similar results were obtained using the Cayman assay kit (data not shown). D, Profiling of PLA2 activity inhibition demonstrates that the plasma sPLA2 that is present in Mmp2−/− and Mmp9−/− mice is the same enzyme or very similar enzymes (pools of plasma: n=5 for Mmp2−/− and n=5 for Mmp9−/−). Data are representative of technical duplicates. For comparison, the activity of cardiac sPLA2 from an Mmp2−/− mouse (mouse “E” in figure S3 of Hernandez‐Anzaldo et al2) is presented. *P<0.05 vs Mmp2−/− plasma, t test. The x‐axis values indicate (0) no inhibitor; (1) EDTA, inhibits Ca2+‐dependent PLA2s; (2) dithiothreitol, sulfhydryl redox agent; (3) MJ33, active site‐directed PLA2 inhibitor; (4) KH064, sPLA2 inhibitor; (5) YM 26734, sPLA2 (PLAG2A, PLA2G5) inhibitor; (6) arachidonyl trifluoromethyl ketone, cytosolic PLA2 and iPLA2 inhibitor; (7) N‐(p‐amylcinnamoyl) anthranilic acid, PLA2 inhibitor; (8) bromoenol lactone, iPLA2 inhibitor; and (9) heparin, inhibits some sPLA2s. AACOCF3 indicates arachidonyl trifluoromethyl ketone; ACA, N‐(p‐Amylcinnamoyl) anthranilic acid; BEL, bromoenol lactone; cPLA2, cytosolic phospholipase A2; DTT, dithiothreitol; E. coli, Escherichia coli; EDTA, ethylenediaminetetraacetic acid (divalent metal ion chelator); EGTA, ethylene glycol‐bis(?‐aminoethyl ether)‐tetraacetic acid (Ca2+ chelator); iPLA2, calcium‐independent phospholipase A2; MJ33, 1‐hexadecyl‐3‐trifluoroethylglycero‐sn‐2‐phosphomethanol; Mmp, matrix metalloproteinase gene; MMP, matrix metalloproteinase; MMP‐2, matrix metalloproteinase‐2; MMP‐9, matrix metalloproteinase‐9; PC, phosphatidylcholine; SH, sulfhydryl; sPLA2, secreted phospholipase A2; WT, wild type; YM 26734, 1,1?‐[5‐[3,4‐dihydro‐7‐hydroxy‐2‐(4‐hydroxyphenyl)‐2H‐1‐benzopyran‐4‐yl]‐2,4,6‐trihydroxy‐1,3‐phenylene]bis‐1‐dodecanone.
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jah31792-fig-0004: Plasma sPLA2 activity is elevated by MMP‐9 deficiency. A, sPLA2 activity in the plasma, liver, and heart of Mmp9−/− mice (n=4 mice per genotype). *P<0.05 vs WT, t test. B, The elevated plasma PLA2 activity in Mmp9−/− mice (compared to WT) was confirmed using 2 unrelated assays: the Cayman sPLA2 assay kit (substrate: di‐heptanoyl‐thio‐PC; n=4 per genotype; *P<0.05 vs WT, t test) and the 3H‐oleate E coli membrane assay (data are representative of technical duplicates for a pool of 5 mice per genotype). C, EGTA and varespladib inhibition profiles for the sPLA2 from Mmp9−/− plasma vs heart and plasma from Mmp2−/− mice. The analysis was performed in duplicate using samples from pools of 4 mice per genotype using the 3H‐oleate E coli membrane assay. Similar results were obtained using the Cayman assay kit (data not shown). D, Profiling of PLA2 activity inhibition demonstrates that the plasma sPLA2 that is present in Mmp2−/− and Mmp9−/− mice is the same enzyme or very similar enzymes (pools of plasma: n=5 for Mmp2−/− and n=5 for Mmp9−/−). Data are representative of technical duplicates. For comparison, the activity of cardiac sPLA2 from an Mmp2−/− mouse (mouse “E” in figure S3 of Hernandez‐Anzaldo et al2) is presented. *P<0.05 vs Mmp2−/− plasma, t test. The x‐axis values indicate (0) no inhibitor; (1) EDTA, inhibits Ca2+‐dependent PLA2s; (2) dithiothreitol, sulfhydryl redox agent; (3) MJ33, active site‐directed PLA2 inhibitor; (4) KH064, sPLA2 inhibitor; (5) YM 26734, sPLA2 (PLAG2A, PLA2G5) inhibitor; (6) arachidonyl trifluoromethyl ketone, cytosolic PLA2 and iPLA2 inhibitor; (7) N‐(p‐amylcinnamoyl) anthranilic acid, PLA2 inhibitor; (8) bromoenol lactone, iPLA2 inhibitor; and (9) heparin, inhibits some sPLA2s. AACOCF3 indicates arachidonyl trifluoromethyl ketone; ACA, N‐(p‐Amylcinnamoyl) anthranilic acid; BEL, bromoenol lactone; cPLA2, cytosolic phospholipase A2; DTT, dithiothreitol; E. coli, Escherichia coli; EDTA, ethylenediaminetetraacetic acid (divalent metal ion chelator); EGTA, ethylene glycol‐bis(?‐aminoethyl ether)‐tetraacetic acid (Ca2+ chelator); iPLA2, calcium‐independent phospholipase A2; MJ33, 1‐hexadecyl‐3‐trifluoroethylglycero‐sn‐2‐phosphomethanol; Mmp, matrix metalloproteinase gene; MMP, matrix metalloproteinase; MMP‐2, matrix metalloproteinase‐2; MMP‐9, matrix metalloproteinase‐9; PC, phosphatidylcholine; SH, sulfhydryl; sPLA2, secreted phospholipase A2; WT, wild type; YM 26734, 1,1?‐[5‐[3,4‐dihydro‐7‐hydroxy‐2‐(4‐hydroxyphenyl)‐2H‐1‐benzopyran‐4‐yl]‐2,4,6‐trihydroxy‐1,3‐phenylene]bis‐1‐dodecanone.

Mentions: We recently found that in Mmp2−/− mice, the heart secretes an as yet unidentified PLA2 (cardiac sPLA2), which circulates in plasma, acting as a signal that is governed by MMP‐2 and that modulates lipid metabolism in the liver.2, 3 In Mmp9−/− mice, plasma sPLA2 activity was significantly higher than in WT plasma but otherwise was normal in the heart, as demonstrated by assaying the generation of free thiol from di‐heptanoyl‐thio‐phosphatidylcholine (substrate) (Figure 4A). The elevated sPLA2 activity in the Mmp9−/− plasma was confirmed using a highly sensitive (3H)‐oleic acid radiolabeled E coli membranes assay (Figure 4B).


Novel Role for Matrix Metalloproteinase 9 in Modulation of Cholesterol Metabolism
Plasma sPLA2 activity is elevated by MMP‐9 deficiency. A, sPLA2 activity in the plasma, liver, and heart of Mmp9−/− mice (n=4 mice per genotype). *P<0.05 vs WT, t test. B, The elevated plasma PLA2 activity in Mmp9−/− mice (compared to WT) was confirmed using 2 unrelated assays: the Cayman sPLA2 assay kit (substrate: di‐heptanoyl‐thio‐PC; n=4 per genotype; *P<0.05 vs WT, t test) and the 3H‐oleate E coli membrane assay (data are representative of technical duplicates for a pool of 5 mice per genotype). C, EGTA and varespladib inhibition profiles for the sPLA2 from Mmp9−/− plasma vs heart and plasma from Mmp2−/− mice. The analysis was performed in duplicate using samples from pools of 4 mice per genotype using the 3H‐oleate E coli membrane assay. Similar results were obtained using the Cayman assay kit (data not shown). D, Profiling of PLA2 activity inhibition demonstrates that the plasma sPLA2 that is present in Mmp2−/− and Mmp9−/− mice is the same enzyme or very similar enzymes (pools of plasma: n=5 for Mmp2−/− and n=5 for Mmp9−/−). Data are representative of technical duplicates. For comparison, the activity of cardiac sPLA2 from an Mmp2−/− mouse (mouse “E” in figure S3 of Hernandez‐Anzaldo et al2) is presented. *P<0.05 vs Mmp2−/− plasma, t test. The x‐axis values indicate (0) no inhibitor; (1) EDTA, inhibits Ca2+‐dependent PLA2s; (2) dithiothreitol, sulfhydryl redox agent; (3) MJ33, active site‐directed PLA2 inhibitor; (4) KH064, sPLA2 inhibitor; (5) YM 26734, sPLA2 (PLAG2A, PLA2G5) inhibitor; (6) arachidonyl trifluoromethyl ketone, cytosolic PLA2 and iPLA2 inhibitor; (7) N‐(p‐amylcinnamoyl) anthranilic acid, PLA2 inhibitor; (8) bromoenol lactone, iPLA2 inhibitor; and (9) heparin, inhibits some sPLA2s. AACOCF3 indicates arachidonyl trifluoromethyl ketone; ACA, N‐(p‐Amylcinnamoyl) anthranilic acid; BEL, bromoenol lactone; cPLA2, cytosolic phospholipase A2; DTT, dithiothreitol; E. coli, Escherichia coli; EDTA, ethylenediaminetetraacetic acid (divalent metal ion chelator); EGTA, ethylene glycol‐bis(?‐aminoethyl ether)‐tetraacetic acid (Ca2+ chelator); iPLA2, calcium‐independent phospholipase A2; MJ33, 1‐hexadecyl‐3‐trifluoroethylglycero‐sn‐2‐phosphomethanol; Mmp, matrix metalloproteinase gene; MMP, matrix metalloproteinase; MMP‐2, matrix metalloproteinase‐2; MMP‐9, matrix metalloproteinase‐9; PC, phosphatidylcholine; SH, sulfhydryl; sPLA2, secreted phospholipase A2; WT, wild type; YM 26734, 1,1?‐[5‐[3,4‐dihydro‐7‐hydroxy‐2‐(4‐hydroxyphenyl)‐2H‐1‐benzopyran‐4‐yl]‐2,4,6‐trihydroxy‐1,3‐phenylene]bis‐1‐dodecanone.
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jah31792-fig-0004: Plasma sPLA2 activity is elevated by MMP‐9 deficiency. A, sPLA2 activity in the plasma, liver, and heart of Mmp9−/− mice (n=4 mice per genotype). *P<0.05 vs WT, t test. B, The elevated plasma PLA2 activity in Mmp9−/− mice (compared to WT) was confirmed using 2 unrelated assays: the Cayman sPLA2 assay kit (substrate: di‐heptanoyl‐thio‐PC; n=4 per genotype; *P<0.05 vs WT, t test) and the 3H‐oleate E coli membrane assay (data are representative of technical duplicates for a pool of 5 mice per genotype). C, EGTA and varespladib inhibition profiles for the sPLA2 from Mmp9−/− plasma vs heart and plasma from Mmp2−/− mice. The analysis was performed in duplicate using samples from pools of 4 mice per genotype using the 3H‐oleate E coli membrane assay. Similar results were obtained using the Cayman assay kit (data not shown). D, Profiling of PLA2 activity inhibition demonstrates that the plasma sPLA2 that is present in Mmp2−/− and Mmp9−/− mice is the same enzyme or very similar enzymes (pools of plasma: n=5 for Mmp2−/− and n=5 for Mmp9−/−). Data are representative of technical duplicates. For comparison, the activity of cardiac sPLA2 from an Mmp2−/− mouse (mouse “E” in figure S3 of Hernandez‐Anzaldo et al2) is presented. *P<0.05 vs Mmp2−/− plasma, t test. The x‐axis values indicate (0) no inhibitor; (1) EDTA, inhibits Ca2+‐dependent PLA2s; (2) dithiothreitol, sulfhydryl redox agent; (3) MJ33, active site‐directed PLA2 inhibitor; (4) KH064, sPLA2 inhibitor; (5) YM 26734, sPLA2 (PLAG2A, PLA2G5) inhibitor; (6) arachidonyl trifluoromethyl ketone, cytosolic PLA2 and iPLA2 inhibitor; (7) N‐(p‐amylcinnamoyl) anthranilic acid, PLA2 inhibitor; (8) bromoenol lactone, iPLA2 inhibitor; and (9) heparin, inhibits some sPLA2s. AACOCF3 indicates arachidonyl trifluoromethyl ketone; ACA, N‐(p‐Amylcinnamoyl) anthranilic acid; BEL, bromoenol lactone; cPLA2, cytosolic phospholipase A2; DTT, dithiothreitol; E. coli, Escherichia coli; EDTA, ethylenediaminetetraacetic acid (divalent metal ion chelator); EGTA, ethylene glycol‐bis(?‐aminoethyl ether)‐tetraacetic acid (Ca2+ chelator); iPLA2, calcium‐independent phospholipase A2; MJ33, 1‐hexadecyl‐3‐trifluoroethylglycero‐sn‐2‐phosphomethanol; Mmp, matrix metalloproteinase gene; MMP, matrix metalloproteinase; MMP‐2, matrix metalloproteinase‐2; MMP‐9, matrix metalloproteinase‐9; PC, phosphatidylcholine; SH, sulfhydryl; sPLA2, secreted phospholipase A2; WT, wild type; YM 26734, 1,1?‐[5‐[3,4‐dihydro‐7‐hydroxy‐2‐(4‐hydroxyphenyl)‐2H‐1‐benzopyran‐4‐yl]‐2,4,6‐trihydroxy‐1,3‐phenylene]bis‐1‐dodecanone.
Mentions: We recently found that in Mmp2−/− mice, the heart secretes an as yet unidentified PLA2 (cardiac sPLA2), which circulates in plasma, acting as a signal that is governed by MMP‐2 and that modulates lipid metabolism in the liver.2, 3 In Mmp9−/− mice, plasma sPLA2 activity was significantly higher than in WT plasma but otherwise was normal in the heart, as demonstrated by assaying the generation of free thiol from di‐heptanoyl‐thio‐phosphatidylcholine (substrate) (Figure 4A). The elevated sPLA2 activity in the Mmp9−/− plasma was confirmed using a highly sensitive (3H)‐oleic acid radiolabeled E coli membranes assay (Figure 4B).

View Article: PubMed Central - PubMed

ABSTRACT

Background: The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown.

Methods and results: We examined MMP&#8208;9&ndash;deficient (Mmp9&minus;/&minus;) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9+/+ (wild&#8208;type) mice, Mmp9&minus;/&minus; mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9&minus;/&minus; mice failed to increase the expression of genes encoding the rate&#8208;limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP&#8208;9 deficiency did not impair intestinal cholesterol absorption, as shown by the 14C&#8208;cholesterol and 3H&#8208;sitostanol absorption assay. Similar to our earlier study on Mmp2&minus;/&minus; mice, we observed that Mmp9&minus;/&minus; mice had elevated plasma secreted phospholipase A2 activity. Pharmacological inhibition of systemic circulating secreted phospholipase A2 activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9&minus;/&minus; mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism.

Conclusions: Our results show that MMP&#8208;9 modulates cholesterol metabolism, at least in part, through a novel MMP&#8208;9&ndash;plasma secreted phospholipase A2 axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.

No MeSH data available.


Related in: MedlinePlus