Human Somatostatin SST4 Receptor Transgenic Mice: Construction and Brain Expression Pattern Characterization.

Balázs Nemes,Dániel Hegedüs,Angéla Kecskés,Erika Pintér,Balázs Gaszner,Timea Aczél,Zoltán Sándor,Zsuzsanna Helyes,Kata Bölcskei,Viktória Kormos

doi:10.3390/ijms22073758

Balázs Nemes, Dániel Hegedüs + Show 8 more

Open Access

https://doi.org/10.3390/ijms22073758

Copy DOI

Abstract

Somatostatin receptor subtype 4 (SST4) has been shown to mediate analgesic, antidepressant and anti-inflammatory functions without endocrine actions; therefore, it is proposed to be a novel target for drug development. To overcome the species differences of SST4 receptor expression and function between humans and mice, we generated an SST4 humanized mouse line to serve as a translational animal model for preclinical research. A transposon vector containing the hSSTR4 and reporter gene construct driven by the hSSTR4 regulatory elements were created. The vector was randomly inserted in Sstr4-deficient mice. hSSTR4 expression was detected by bioluminescent in vivo imaging of the luciferase reporter predominantly in the brain. RT-qPCR confirmed the expression of the human gene in the brain and various peripheral tissues consistent with the in vivo imaging. RNAscope in situ hybridization revealed the presence of hSSTR4 transcripts in glutamatergic excitatory neurons in the CA1 and CA2 regions of the hippocampus; in the GABAergic interneurons in the granular layer of the olfactory bulb and in both types of neurons in the primary somatosensory cortex, piriform cortex, prelimbic cortex and amygdala. This novel SST4 humanized mouse line might enable us to investigate the differences of human and mouse SST4 receptor expression and function and assess the effects of SST4 receptor agonist drug candidates.

Highlights

Somatostatin is a cyclic neuropeptide, which inhibits the secretion of several excitatory and inhibitory mediators, such as somatotropin, glucagon, insulin, acetylcholine, glutamate and gamma-aminobutyric acid (GABA) [1]
The entire transgene cassette was flanked at both ends by Lox2272 Cre recombinase recognition sites as an option for conditional KO by insulators to inhibit position effects and by PiggyBac (PB) transposon inverted terminal repeats (ITR) as specific recognition sites for the PB transposase enzyme (Figure 1B)
The PB transposon integration sites were located by ligation‐mediated polymerase chain reaction (LM‐PCR) (Figure 2E)

Summary

Introduction

Somatostatin is a cyclic neuropeptide, which inhibits the secretion of several excitatory and inhibitory mediators, such as somatotropin, glucagon, insulin, acetylcholine, glutamate and gamma-aminobutyric acid (GABA) [1]. It regulates a range of physiological functions like sleep, motor activity, sensory functions, emotions, learning and memory, as well as different pathological conditions like pain, inflammation [2,3,4,5], neurodegeneration [6,7,8,9], anxiety and depression [10,11,12,13]. Previous work provided evidence that the SST4 receptor activation produces analgesic, anti-inflammatory, anti-amyloid, anti-anxiety and antidepressant effects without influencing hormone secretion [2,19,20,21,22,23]

Objectives

Methods

Results

Conclusion