Systemic delivery of bioactive glucagon-like peptide 1 after adenoviral-mediated gene transfer in the murine salivary gland.
An adenoviral (Ad) vector that expresses bioactive glucagon-like peptide 1 (GLP-1) was generated, and its effectiveness at modulating glucose homeostasis was evaluated after transduction of murine salivary glands. The construct was engineered with the signal sequence of mouse GH to direct the peptide into the secretory pathway, followed by a furin cleavage site and the GLP-1(7-37) sequence encoding an Ala to Gly substitution at position 8 to achieve resistance to degradation. When expressed in Neuro2A and COS7 cells, an active form of GLP-1 was specifically detected by RIA in the conditioned medium of transduced cells, showed resistance to degradation by dipeptidyl-peptidase IV, and induced the secretion of insulin from NIT1 pancreatic beta-cells in vitro. In vivo studies demonstrated that healthy mice transduced with Ad-GLP-1 in both submandibular glands had serum GLP-1 levels approximately 3 times higher than mice transduced with the control Ad-luciferase vector. In fasted animals, serum glucose levels were similar between Ad-GLP-1 and Ad-luciferase transduced mice in keeping with GLP-1's glucose-dependent action. However, when challenged with glucose, Ad-GLP-1 transduced mice cleared the glucose significantly faster than control mice. In an animal model of diabetes induced by alloxan, progression of hyperglycemia was significantly attenuated in mice given the Ad-GLP-1 vector compared with control mice. These studies demonstrate that the bioactive peptide hormone, GLP-1, normally secreted from endocrine cells in the gut through the regulated secretory pathway, can be engineered for secretion into the circulatory system from exocrine cells of the salivary gland to affect glucose homeostasis.
Voutetakis
Antonis
A
Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.
Cotrim
Ana P
AP
Rowzee
Anne
A
Zheng
Changyu
C
Rathod
Trushar
T
Yanik
Tulin
T
Loh
Y Peng
YP
Baum
Bruce J
BJ
Cawley
Niamh X
NX
D000256:Adenoviridae / Q000235:genetics*; D000496:Alloxan; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000235:genetics / Q000628:therapy; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000235:genetics; D052216:Glucagon-Like Peptide 1 / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D012469:Salivary Glands / Q000378:metabolism*
D007328:Insulin; D000496:Alloxan; D052216:Glucagon-Like Peptide 1; D018819:Dipeptidyl Peptidase 4; D005947:Glucose