ABSTRACT
VPAC2P-PEG is a VPAC2 receptor agonist peptide that acts as a glucose-dependent insulin secretagogue. Proteolysis by DPPIV may contribute to the in vivo clearance of VPAC2P-PEG. Here, the N-terminus of VPAC2P-PEG is modified by N-terminal acetylation to impart DPPIV resistance. The acetylated peptide, Ac-VPAC2P-PEG, is a selective and potent VPAC2 agonist, resistant to DPPIV proteolysis, and exhibits substantially improved half-life and glucose disposal in rodents. Ac-VPAC2P-PEG has therapeutic potential for diabetes management.
Subject(s)
Dipeptidyl Peptidase 4/metabolism , Glucose/metabolism , Hypoglycemic Agents/chemical synthesis , Insulin/metabolism , Peptides/chemical synthesis , Receptors, Vasoactive Intestinal Peptide, Type II/agonists , Acetylation , Animals , CHO Cells , Cricetinae , Cricetulus , Half-Life , Humans , Hydrolysis , Hypoglycemic Agents/chemistry , Hypoglycemic Agents/pharmacology , Insulin Secretion , Male , Peptides/chemistry , Peptides/pharmacology , Radioligand Assay , Rats , Rats, Wistar , Receptors, Vasoactive Intestinal Peptide, Type II/metabolismABSTRACT
Elevation of plasma free fatty acids has been linked with insulin resistance and diabetes. Inhibition of lipolysis may provide a mechanism to decrease plasma fatty acids, thereby improving insulin sensitivity. Hormone-sensitive lipase (HSL) is a critical enzyme involved in the hormonally regulated release of fatty acids and glycerol from adipocyte lipid stores, and its inhibition may thus improve insulin sensitivity and blood glucose handling in type 2 diabetes. In rat adipocytes, forskolin-activated lipolysis was blocked by in vitro addition of a potent and selective HSL inhibitor or by prior treatment of the animals themselves. Antilipolytic effects also were demonstrated in overnight-fasted mice, rats, and dogs with species-dependent effects on plasma free fatty acid levels but with similar reductions in plasma glycerol being observed in all species. Inhibition of HSL also reduced hyperglycemia in streptozotocin-induced diabetic rats. The data support a connection between adipose tissue lipolysis and plasma glucose levels.
Subject(s)
Blood Glucose/metabolism , Lipids/blood , Sterol Esterase/antagonists & inhibitors , 3T3-L1 Cells , Adipocytes/metabolism , Animals , Diabetes Mellitus, Experimental/blood , Diabetes Mellitus, Experimental/metabolism , Dogs , Fasting , Fatty Acids/analysis , Fatty Acids/metabolism , Glycerol/analysis , Glycerol/metabolism , Humans , Insulin/analysis , Insulin/metabolism , Insulin Secretion , Islets of Langerhans/metabolism , Lipolysis , Male , Mice , Mice, Inbred BALB C , Rats , Rats, Sprague-Dawley , Rats, Wistar , Species Specificity , Sterol Esterase/genetics , Time FactorsABSTRACT
The effects of PEGylation of glucose-dependent insulinotropic polypeptide (GIP) on potency and dipeptidyl peptidase IV (DPPIV) stability are reported. N-terminal modification of GIP(1-30) with 40 kDa polyethylene glycol (PEG) abrogates functional activity. In contrast, C-terminal PEGylation of GIP(1-30) maintains full agonism and reasonable potency at the GIP receptor and confers a high level of DPPIV resistance. Moreover, the dual modification of N-terminal palmitoylation and C-terminal PEGylation results in a full agonist of comparable potency to native GIP that is stable to DPPIV cleavage. The results provide the basis for the development of long acting, PEGylated GIP, GIP variants, or GIP-based hybrid peptide therapeutics.
Subject(s)
Dipeptidyl Peptidase 4/chemistry , Dipeptidyl Peptidase 4/metabolism , Glucose/metabolism , Insulin/metabolism , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Polyethylene Glycols/chemistry , Amino Acid Sequence , Animals , CHO Cells , Cricetinae , Cyclic AMP/metabolism , Enzyme Stability , Glucose/pharmacology , Molecular Sequence DataABSTRACT
A series of (5-(2H)-isoxazolonyl) ureas were developed as nanomolar inhibitors of hormone-sensitive lipase, an enzyme of potential importance in the treatment of diabetes.
