A Synthetic Heterobivalent Ligand Composed of Glucagon-Like Peptide 1 and Yohimbine Specifically Targets β Cells Within the Pancreas

Leah V. Steyn, Kameswari Ananthakrishnan, Miranda J. Anderson, Renata Patek, Amy Kelly, Josef Vagner, Ronald M. Lynch, Sean W. Limesand

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Purpose: β Cell specificity for a heterobivalent ligand composed of glucagon-like peptide-1 (GLP-1) linked to yohimbine (GLP-1/Yhb) was evaluated to determine its utility as a noninvasive imaging agent. Procedures: Competition binding assays were performed on βTC3 cells and isolated rat islets. Immunostaining for insulin was used to co-localized intravenously injected Cy5-labeled GLP-1/Yhb in β cells of Sprague–Dawley rats. Rats were intravenously injected with In-111-labeled GLP-1/Yhb to determine clearance rates and tissue biodistribution. Tissue-specific binding was confirmed by competition with pre-administration of unlabeled GLP-1/Yhb and in Streptozotocin-induced diabetic rats. Results: In βTC3 cells, high affinity binding of GLP-1/Yhb required interactions with both receptors because monovalent competition or receptor knockdown with RNAi lowered specificity and avidity of the heterobivalent ligand. Binding specificity for isolated islets was 2.6-fold greater than that of acinar tissue or islets pre-incubated with excess unlabeled GLP-1/Yhb. Immunofluorescent localization of Cy5-labeled GLP-1/Yhb was restricted to pancreatic islets. Within 30 min, ~90 % of the In-111-labeled GLP-1/Yhb was cleared from blood. Tissue-specific accumulation of radiolabeled ligand was apparent in the pancreas, but not in other tissues within the abdominal imaging field. Pancreas specificity was lost in Streptozotocin-induced diabetic rats. Conclusions: The GLP-1/Yhb exhibits high specificity for β cells, rapid blood clearance rates, and low non-specific uptake by other tissues within the abdominal imaging field. These characteristics of GLP-1/Yhb are desirable for application to β cell imaging in vivo and provide a basis for developing additional multivalent β cell-specific targeting agents to aid in the management of type 1 diabetes.

Original languageEnglish (US)
Pages (from-to)461-470
Number of pages10
JournalMolecular Imaging and Biology
Volume17
Issue number4
DOIs
StatePublished - Aug 23 2015

Keywords

  • Adrenergic receptor
  • GLP-1
  • Imaging
  • Multivalency
  • β Cell mass

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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