Activity Suppression Behavior Phenotype in SULT4A1 Frameshift Mutant Zebrafish

Abstract

Since its identification in 2000, sulfotransferase (SULT) 4A1 has presented an enigma to the field of cytosolic SULT biology. SULT4A1 is exclusively expressed in neural tissue, is highly conserved, and has been identified in every vertebrate studied to date. Despite this singular level of conservation, no substrate or function for SULT4A1 has been identified. Previous studies demonstrated that SULT4A1 does not bind the obligate sulfate donor, 3'-phosphoadenosine-5'-phosphosulfate, yet SULT4A1 is classified as a SULT superfamily member based on sequence and structural similarities to the other SULTs. In this study, transcription activator-like effector nucleases were used to generate heritable mutations in the SULT4A1 gene of zebrafish. The mutation (SULT4A1(Δ8)) consists of an 8-nucleotide deletion within the second exon of the gene, resulting in a frameshift mutation and premature stop codon after 132 AA. During early adulthood, casual observations were made that mutant zebrafish were exhibiting excessively sedentary behavior during the day. These observations were inconsistent with published reports on activity in zebrafish that are largely diurnal organisms and are highly active during the day. Thus, a decrease in activity during the day represents an abnormal behavior and warranted further systematic analysis. EthoVision video tracking software was used to monitor activity levels in wild-type (WT) and SULT4A1(Δ8/Δ8) fish over 48 hours of a normal light/dark cycle. SULT4A1(Δ8/Δ8) fish were shown to exhibit increased inactivity bout length and frequency as well as a general decrease in daytime activity levels when compared with their WT counterparts.

Generation and Characterization of SULT4A1 Mutant Mouse Models

“…In zebrafish eyes, SULT4A1 mRNA was detected by real-time quantitative polymerase chain reaction in 72 hpf embryos, and morpholino-mediated SULT4A1 knockdown resulted in upregulation of phototransduction genes related to cone function (Crittenden et al, 2014). TALEN-induced SULT4A1-KO adult zebrafish were shown to be less active during daylight hours, yet appeared normal, reproduced, and thrived (Crittenden et al, 2015). To determine the function of SULT4A1 in a mammalian system, CRISPR-Cas9 was used to mutate/delete SULT4A1 in C57BL/6J mice.…”

“…These genes were related to cone function and were the first identified cellular process associated with SULT4A1. Subsequent studies using transcription activator-like effector nucleases (TALEN)-induced SULT4A1 knockout (KO) zebrafish models, homozygous SULT4A1-KO adult zebrafish were shown to have an activity suppression phenotype during daylight hours compared with wild-type (WT) zebrafish (Crittenden et al, 2015). The homozygous SULT4A1-KO zebrafish appeared normal, were able to readily reproduce and possessed normal lifespans (Crittenden et al, 2015).…”

SULTA4A1 modulates synaptic development and function by promoting the formation of PSD-95/NMDAR complex

“…These results support a role for 297 SULT4A1 in the regulation of PSD-95-targeted Pin1 activity, which in turn controls GluN1 298 synaptic levels and the formation or stability of dendritic spines. As NMDAR function is intricately 299 linked to synaptic maturation and activity, it is compelling to hypothesize a direct link between 300 GluN1 synaptic levels, dendritic spine density and the well characterized behavioral deficits within 301 SULT4A1 knockout models (Garcia et al, 2018, Crittenden et al, 2015. 302…”

A framework to identify modifier genes in patients with Phelan-McDermid syndrome

“…Interestingly, zebrafish carrying homozygous SULT4A1 mutations exhibit excessively sedentary behavior during the day, 35 suggesting a role of this gene in regulating behavior. The function of ATXN10 remains largely unknown, but expanded ATTCT pentanucleotide repeats in intron 9 of the gene cause a rare form of spinocerebellar ataxia (SCA10) characterized by cerebellar ataxia and epilepsy.…”