Effect of N-acetyl-seryl-aspartyl-lysyl-proline on DNA and collagen synthesis in rat cardiac fibroblasts.
N:-Acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a natural inhibitor of pluripotent hematopoietic stem cell entry into the S phase of the cell cycle and is normally present in human plasma. Ac-SDKP is exclusively hydrolyzed by ACE, and its plasma concentration is increased 5-fold after ACE inhibition in humans. We examined the effect of 0.05 to 100 nmol/L Ac-SDKP on 24-hour (3)H-thymidine incorporation (DNA synthesis) by cardiac fibroblasts both in the absence and presence of 5% FCS. Captopril (1 micromol/L) was added in all cases to prevent the degradation of Ac-SDKP. Treatment of cardiac fibroblasts with 5% FCS increased thymidine incorporation from a control value of 12 469+/-594 to 24 598+/-1051 cpm (P:<0.001). Cotreatment with 1 nmol/L Ac-SDKP reduced stimulation to control levels (10 373+/-200 cpm, P:<0.001). We measured hydroxyproline content and incorporation of (3)H-proline into collagenous fibroblast proteins and found that Ac-SDKP blocked endothelin-1 (10(-8) mol/L)-induced collagen synthesis in a biphasic and dose-dependent manner, causing inhibition at low doses, whereas high doses had little or no effect. It also blunted the activity of p44/p42 mitogen-activated protein kinase in a biphasic and dose-dependent manner in serum-stimulated fibroblasts, suggesting that the inhibitory effect of DNA and collagen synthesis may depend in part on blocking mitogen-activated protein kinase activity. Participation of p44/p42 in collagen synthesis was confirmed, because a specific inhibitor for p44/p42 activation (PD 98059, 25 micromol/L) was able to block endothelin-1-induced collagen synthesis, similar to the effect of Ac-SDKP. The fact that Ac-SDKP inhibits DNA and collagen synthesis in cardiac fibroblasts suggests that it may be an important endogenous regulator of fibroblast proliferation and collagen synthesis in the heart. Ac-SDKP may participate in the cardioprotective effect of ACE inhibitors by limiting fibroblast proliferation (and hence collagen production), and therefore it would reduce fibrosis in patients with hypertension.
Rhaleb
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Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, MI 48202-2689, USA. nrhaleb1@hfhs.org
Peng
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Harding
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Tayeh
M
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LaPointe
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MC
Carretero
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OA
D000804:Angiotensin II / Q000502:physiology*; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000378:metabolism / Q000627:therapeutic use; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000037:antagonists & inhibitors; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005355:Fibrosis / Q000188:drug therapy; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009842:Oligopeptides / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000378:metabolism; D012084:Renin-Angiotensin System
D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D009842:Oligopeptides; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D003094:Collagen; D004247:DNA; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D007703:Peptidyl-Dipeptidase A; C058504:goralatide