Splice-specific deficiency of the PTSD-associated gene PAC1 leads to a paradoxical age-dependent stress behavior

Jakob Biran,Lior Appelbaum,Amrutha Swaminathan,Ido Shirat,Gil Levkowitz,Michael Gliksberg,Talia Levitas-Djerbi

doi:10.1038/s41598-020-66447-2

Abstract

The pituitary adenylate cyclase-activating polypeptide receptor (PAC1, also known as ADCYAP1R1) is associated with post-traumatic stress disorder and modulation of stress response in general. Alternative splicing of PAC1 results in multiple gene products, which differ in their mode of signalling and tissue distribution. However, the roles of distinct splice variants in the regulation of stress behavior is poorly understood. Alternative splicing of a short exon, which is known as the “hop cassette”, occurs during brain development and in response to stressful challenges. To examine the function of this variant, we generated a splice-specific zebrafish mutant lacking the hop cassette, which we designated ‘hopless’. We show that hopless mutant larvae display increased anxiety-like behavior, including reduced dark exploration and impaired habituation to dark exposure. Conversely, adult hopless mutants displayed superior ability to rebound from an acute stressor, as they exhibited reduced anxiety-like responses to an ensuing novelty stress. We propose that the developmental loss of a specific PAC1 splice variant mimics prolonged mild stress exposure, which in the long term, predisposes the organism’s stress response towards a resilient phenotype. Our study presents a unique genetic model demonstrating how early-life state of anxiety paradoxically correlates with reduced stress susceptibility in adulthood.

Highlights

The pituitary adenylate cyclase-activating polypeptide receptor (PAC1, known as ADCYAP1R1) is associated with post-traumatic stress disorder and modulation of stress response in general
The same PAC1 single-nucleotide polymorphism (SNP) was associated with post-traumatic stress disorder (PTSD) in African-American females, emotional numbing in traumatized earthquake Chinese survivors, dark-enhanced startle response in children[14,15,16], and with impaired hippocampal and amygdalar activation in response to fearful stimuli and contextual fear conditioning in non-traumatized individuals[17,18]
We further demonstrated that zebrafish larvae injected with an antisense oligonucleotide that prevents the inclusion of the hop cassette displayed prolonged increase of crh transcription and impaired anxiety-like dark avoidance behavior[4]

Summary

Introduction

The pituitary adenylate cyclase-activating polypeptide receptor (PAC1, known as ADCYAP1R1) is associated with post-traumatic stress disorder and modulation of stress response in general. We have previously demonstrated that alternative splicing of PAC1 is induced by an acute stress challenge to mice, which suggested that the ratio between PAC1-hop and PAC1-short isoforms may be involved in the adaptive response to stress[4]. We further demonstrated that zebrafish larvae injected with an antisense oligonucleotide that prevents the inclusion of the hop cassette displayed prolonged increase of crh transcription and impaired anxiety-like dark avoidance behavior[4]. We examined the short- and long-term behavioral consequences of this splice-specific PAC1 deficiency by generating a germline-transmitted zebrafish mutant lacking the hop cassette, which we designated ‘hopless’. We show that while hopless larvae display increased anxiety-like and stress related behaviors, adult hopless mutants exhibit increased resilience to acute stress These findings suggest that PAC1-hop splice isoform is involved in the developmental establishment of stress responsiveness

Methods

Results

Conclusion