Linked Life Data

1921761

Source:http://linkedlifedata.com/resource/pubmed/id/1921761

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1991-11-14
pubmed:abstractText
CKS-17, an immunosuppressive peptide homologous to certain retroviral transmembrane envelope protein, has been shown to inhibit lymphocyte proliferation in response to mitogens or alloantigens when covalently attached to bovine serum albumin (CKS-17-BSA). To define its site of action, we determined if CKS-17 conjugated to human serum albumin (CKS-17-HSA) could block the direct activation of lymphocytes by phorbol-12-myristate-13-acetate (PMA) or by a synthetic diacylglycerol, dioctanoylglycerol (DiC8). CKS-17-HSA inhibited lymphocyte proliferation in response to PMA and ionomycin in a dose-dependent manner with up to 88% inhibition occurring with 15 microM CKS-17-HSA. The conjugated peptide also inhibited the proliferation of lymphocytes in response to DiC8 and ionomycin by up to 57% at 15 microM CKS-17-HSA. Based on these findings we investigated the effect of CKS-17-HSA on the activity of protein kinase C (PKC), an enzyme directly activated by PMA and DiC8. PKC was isolated chromatographically from the cytosol of human neutrophils or the human lymphoblastoid cell line Jurkat. CKS-17-HSA caused a dose-dependent enzyme inhibition with a concentration giving half-maximal inhibition (IC50) of ca.3 microM and greater than 95% inhibition at 15 microM CKS-17-HSA. Inhibition of PKC by the conjugated peptide was not reversed by increasing concentrations of Ca2+, Mg2+, phosphatidylserine, diolein, or adenosine triphosphate (ATP), indicating that the conjugated peptide did not function as a chelator or competitive inhibitor. In contrast to its effects on PKC, CKS-17-HSA did not inhibit the activity of adenosine 3':5'-cyclic monophosphate (cyclic AMP)-dependent protein kinase (PK-A) nor the calcium and phospholipid-independent form of PKC (PK-M). Moreover the peptide inhibited in vivo PKC activity in cytosol of intact cells and in membrane of PMA-stimulated cells. These results suggest that the inhibition of lymphocyte proliferation by CKS-17-HSA may be due to the direct inactivation of PKC.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0385-5600
pubmed:author
pubmed:issnType
Print
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
443-59
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
A synthetic peptide homologous to retroviral transmembrane envelope proteins depresses protein kinase C mediated lymphocyte proliferation and directly inactivated protein kinase C: a potential mechanism for immunosuppression.
pubmed:affiliation
Second Department of Internal Medicine, Nagasaki University School of Medicine.
pubmed:publicationType
Journal Article