Combinatorial treatment increases IKAP levels in human cells generated from Familial Dysautonomia patients.

Sivan Yannai,Maya Donyo,Gil Ast,Jonathan Zonszain,Emanuele Buratti

doi:10.1371/journal.pone.0211602

Abstract

Familial Dysautonomia (FD) is an autosomal recessive congenital neuropathy that results from a point mutation at the 5’ splice site of intron 20 in the IKBKAP gene. This mutation decreases production of the IKAP protein, and treatments that increase the level of the full-length IKBKAP transcript are likely to be of therapeutic value. We previously found that phosphatidylserine (PS), an FDA-approved food supplement, elevates IKAP levels in cells generated from FD patients. Here we demonstrate that combined treatment of cells generated from FD patients with PS and kinetin or PS and the histone deacetylase inhibitor trichostatin A (TSA) resulted in an additive elevation of IKAP compared to each drug alone. This indicates that the compounds influence different pathways. We also found that pridopidine enhances production of IKAP in cells generated from FD patients. Pridopidine has an additive effect on IKAP levels when used in combination with kinetin or TSA, but not with PS; suggesting that PS and pridopidine influence IKBKAP levels through the same mechanism. Indeed, we demonstrate that the effect of PS and pridopidine is through sigma-1 receptor-mediated activation of the BDNF signaling pathway. A combination treatment with any of these drugs with different mechanisms has potential to benefit FD patients.

Highlights

Familial Dysautonomia (FD) is an autosomal recessive congenital neuropathy that is characterized by abnormal development and progressive degeneration of the sensory and autonomic nervous systems [1,2,3]
We previously demonstrated that phosphatidylserine (PS) elevates IKBKAP transcription and, as consequence, IκB kinase complex-associated protein (IKAP) protein levels in cells generated from FD patients (FD cells) and in humanized FD mice [30,31]
In FD cells, the combination of PS and kinetin led to elevation in IKAP protein level by 3.33 and 1.56 fold compared to PS and kinetin alone, respectively (Fig 1A, p 0.005 and p 0.05)

Summary

Introduction

Familial Dysautonomia (FD) is an autosomal recessive congenital neuropathy that is characterized by abnormal development and progressive degeneration of the sensory and autonomic nervous systems [1,2,3]. The mutation observed in 99.5% of FD patients is a transition from T to C at position 6 of the 5’ splice site of intron 20 [1,6]. This mutation occurs almost exclusively in the Ashkenazi Jewish population, with carrier frequency ranging from 1 in 32 to as high as 1 in 18 in those of Polish descent [1,7]. The mutation causes a shift in the splicing pattern of the IKBKAP pre-mRNA. Exon 20 is constitutively included in the mature mRNA, but in the nervous systems of FD patients exon 20 is mainly skipped [4,8].

Objectives

Methods

Results

Conclusion