Comparative study of somatostatin-human serum albumin fusion proteins and natural somatostatin on receptor binding, internalization and activation

PLoS One. 2014 Feb 27;9(2):e89932. doi: 10.1371/journal.pone.0089932. eCollection 2014.

Abstract

Albumin fusion technology, the combination of small molecular proteins or peptides with human serum albumin (HSA), is an effective method for improving the medicinal values of natural small molecular proteins or peptides. However, comparative studies between HSA-fusion proteins or peptides and the parent small molecules in biological and molecular mechanisms are less reported. In this study, we examined the binding property of two novel somatostatin-HSA fusion proteins, (SST14)2-HSA and (SST28)2-HSA, to human SSTRs in stably expressing SSTR1-5 HEK 293 cells; observed the regulation of receptor internalization and internalized receptor recycling; and detected the receptors activation of HSA fusion proteins in stably expressing SSTR2- and SSTR3-EGFP cells. We showed that both somatostatin-HSA fusion proteins had high affinity to all five SSTRs, stimulated the ERK1/2 phosphorylation and persistently inhibited the accumulation of forskolin-stimulated cAMP in SSTR2- and SSTR3-expressing cells; but were less potent than the synthetic somatostatin-14 (SST-14). Our experiments also showed that somatostatin-HSA fusion proteins did not induce the receptors internalization; rather, they accelerated the recycling of the internalized receptors induced by SST-14 to the plasma membrane. Our results indicated that somatostatin-HSA fusion proteins, different from SST-14, exhibit some particular properties in binding, regulating, and activating somatostatin receptors.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cyclic AMP / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression
  • Humans
  • Kinetics
  • Ligands
  • Phosphorylation
  • Protein Binding
  • Protein Transport
  • Receptors, Somatostatin / genetics
  • Receptors, Somatostatin / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Recombinant Fusion Proteins / pharmacology
  • Serum Albumin / genetics
  • Somatostatin / genetics
  • Somatostatin / metabolism*
  • Somatostatin / pharmacology

Substances

  • Ligands
  • Receptors, Somatostatin
  • Recombinant Fusion Proteins
  • Serum Albumin
  • somatostatin receptor 3
  • Somatostatin
  • somatostatin receptor 2
  • Cyclic AMP
  • Extracellular Signal-Regulated MAP Kinases

Grant support

This work was supported by the Ministry of Health of China grant LW201006, Department of Scientific and Technological of Jiangsu Province grant SBE201077641, Natural Science Foundation of Jiangsu Province BK2011165 and BK2012104, and Wuxi hospital administrative center grant YGZF1102. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.