Activity Suppression Behavior Phenotype in SULT4A1 Frameshift Mutant Zebrafish

Evolution and multiple functions of sulfonation and cytosolic sulfotransferases across species

Organisms have conversion systems for sulfate ion to take advantage of the chemical features. The use of biologically converted sulfonucleotides varies in an evolutionary manner, with the universal use being that of sulfonate donors. Sulfotransferases have the ability to transfer the sulfonate group of 3'-phosphoadenosine 5'-phosphosulfate to a variety of molecules. Cytosolic sulfotransferases (SULTs) play a role in the metabolism of low-molecular-weight compounds in response to the host organism's living environment. This review will address the diverse functions of the SULT in evolution, including recent findings. In addition to the diversity of vertebrate sulfotransferases, the molecular aspects and recent studies on bacterial and plant sulfotransferases are also addressed.

Pharmacodynamic Material Basis and Potential Mechanism Study of Spatholobi Caulis in Reversing Osteoporosis

Objective

To elucidate the mechanism of Spatholobi Caulis (SC) in treating osteoporosis (OP) integrated zebrafish model and bioinformatics.

Methods

Skeleton staining coupled with image quantification was performed to evaluate the effects of SC on skeleton mineralization area (SSA) and total optical density (TOD). Zebrafish locomotor activity was monitored using the EthoVision XT. Bioactive compounds of SC and their corresponding protein targets were acquired from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Potential therapeutic targets for OP were summarized through retrieving 5 databases, and then, the overlapping genes between SC and OP were acquired. The core genes were selected by CytoHubba. Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) functional analysis of the intersection target genes were carried out by R software. Finally, the molecular docking simulation was manipulated between the ingredients and the hub genes.

Results

Compared with the model group, SC significantly increased the SSA and TOD at 10 mg/mL and improved the locomotor activity in a dose-dependent manner (p < 0.001). 33 components of SC were associated with 72 OP-related genes including 10 core genes (MAPK1, VEGFA, MMP9, AKT1, AR, IL6, CALM3, TP53, EGFR, and CAT). Advanced Glycation End Product (AGE) Receptor for AGE (RAGE) signaling pathway was screened out as the principal pathway of SC in anti-OP. The bioactive components (Aloe-emodin, Emodin, Formononetin, Licochalcone A, Luteolin, and Lopac-I-3766) have excellent affinity to core genes (MAPK1, VEGFA, MMP9, AKT1, and IL6).

Conclusion

SC had the hierarchical network characteristics of "multicomponents/multitargets/multifunctions/multipathways" in reversing OP, but AGE-RAGE signaling pathway may be the main regulatory mechanism.

Sulfotransferase 4A1 activity facilitates sulfate-dependent cellular protection to oxidative stress

Sulfotransferase 4A1 (SULT4A1) is an orphan member of the cytosolic SULT superfamily that contains enzymes that catalyze the sulfonation of hydrophobic drugs and hormones. SULT4A1 has been assessed through all classical SULT approaches yet no SULT activity has been reported. To ascertain SULT4A1 function and activity, we utilized Saccharomyces cerevisiae as a model system, which exhibits no endogenous SULT activity nor possesses SULT-related genes. We observed that ectopic SULT4A1 expression in yeast displays similar subcellular localization as reported in mouse neurons and observed that SULT4A1 is associated with the outer mitochondria membrane. SULT4A1 expression stimulates colony formation and protects these cells from hydrogen peroxide and metabolism-associated oxidative stress. These SULT4A1-mediated phenotypes are dependent on extracellular sulfate that is converted in yeast to PAPS, the universal sulfonate donor for SULT activity. Thus, heterologous SULT4A1 expression in yeast is correctly distributed and functional, and SULT4A1 antioxidant activity is sulfate dependent supporting the concept that SULT4A1 has sulfate-associated activity.

Sulfation modification of dopamine in brain regulates aggregative behavior of animals

Behavioral plasticity and the underlying neuronal plasticity represent a fundamental capacity of animals to cope with environmental stimuli. Behavioral plasticity is controlled by complex molecular networks that act under different layers of regulation. While various molecules have been found to be involved in the regulation of plastic behaviors across species, less is known about how organisms orchestrate the activity of these molecules as part of a coherent behavioral response to varying environments. Here we discover a mechanism for the regulation of animal behavioral plasticity involving molecular sulfation in the brain, a modification of substrate molecules by sulfotransferase (ST)-catalyzed addition of a sulfonate group (SO₃) from an obligate donor, 3^′-phosphoadenosine 5^′-phosphosulfate (PAPS) to the substrates. We investigated aggregation behaviors of migratory locusts, which are well-known for extreme phase change plasticity triggered by population density. The processes of PAPS biosynthesis acted efficiently on induction of locust behavioral transition: Inhibition of PAPS synthesis solicited a behavioral shift from gregarious to solitarious states; external PAPS dosage, by contrast, promoted aggregation in solitarious locusts. Genetic or pharmacological intervention in the sulfation catalyzation resulted into pronounced solitarizing effects. Analysis of substrate-specific STs suggests a widespread involvement of sulfated neurotransmitters in the behavioral response. Dopamine in the brain was finally identified to be actively sulfate conjugated, and the sulfate conjugation enhanced the free DA-mediated behavioral aggregation. Similar results in Caenorhabditis elegans and mice indicate that sulfation may be involved more broadly in the modulation of animal aggregation. These findings reveal a general mechanism that effectively regulates animal social-like behavioral plasticity, possibly through sulfation-mediated modification of neural networks.

SULT genetic polymorphisms: physiological, pharmacological and clinical implications

INTRODUCTION

Cytosolic sulfotransferases (SULTs)-mediated sulfation is critically involved in the metabolism of key endogenous compounds, such as catecholamines and thyroid/steroid hormones, as well as a variety of drugs and other xenobiotics. Studies performed in the past three decades have yielded a good understanding about the enzymology of the SULTs and their structural biology, phylogenetic relationships, tissue/organ-specific/developmental expression, as well as the regulation of the SULT gene expression. An emerging area is related to the functional impact of the SULT genetic polymorphisms.

AREAS COVERED

The current review aims to summarize our current knowledge about the above-mentioned aspects of the SULT research. An emphasis is on the information concerning the effects of the polymorphisms of the SULT genes on the functional activity of the SULT allozymes and the associated physiological, pharmacological, and clinical implications.

EXPERT OPINION

Elucidation of how SULT SNPs may influence the drug-sulfating activity of SULT allozymes will help understand the differential drug metabolism and eventually aid in formulating personalized drug regimens. Moreover, the information concerning the differential sulfating activities of SULT allozymes toward endogenous compounds may allow for the development of strategies for mitigating anomalies in the metabolism of these endogenous compounds in individuals with certain SULT genotypes.

SULT4A1 Modulates Synaptic Development and Function by Promoting the Formation of PSD-95/NMDAR Complex

Sulfotransferase 4A1 (SULT4A1) is a cytosolic sulfotransferase that is highly conserved across species and extensively expressed in the brain. However, the biological function of SULT4A1 is unclear. SULT4A1 has been implicated in several neuropsychiatric disorders, such as Phelan-McDermid syndrome and schizophrenia. Here, we investigate the role of SULT4A1 within neuron development and function. Our data demonstrate that SULT4A1 modulates neuronal branching complexity and dendritic spines formation. Moreover, we show that SULT4A1, by negatively regulating the catalytic activity of Pin1 toward PSD-95, facilitates NMDAR synaptic expression and function. Finally, we demonstrate that the pharmacological inhibition of Pin1 reverses the pathologic phenotypes of neurons knocked down by SULT4A1 by specifically restoring dendritic spine density and rescuing NMDAR-mediated synaptic transmission. Together, these findings identify SULT4A1 as a novel player in neuron development and function by modulating dendritic morphology and synaptic activity.SIGNIFICANCE STATEMENT Sulfotransferase 4A1 (SULT4A1) is a brain-specific sulfotransferase highly expressed in neurons. Different evidence has suggested that SULT4A1 has an important role in neuronal function and that SULT4A1 altered expression might represent a contributing factor in multiple neurodevelopmental disorders. However, the function of SULT4A1 in the mammalian brain is still unclear. Here, we demonstrate that SULT4A1 is highly expressed at postsynaptic sites where it sequesters Pin1, preventing its negative action on synaptic transmission. This study reveals a novel role of SULT4A1 in the modulation of NMDA receptor activity and strongly contributes to explaining the neuronal dysfunction observed in patients carrying deletions of SULTA41 gene.

Interaction of the Brain-Selective Sulfotransferase SULT4A1 with Other Cytosolic Sulfotransferases: Effects on Protein Expression and Function

Sulfotransferase (SULT) 4A1 is a brain-selective sulfotransferase-like protein that has recently been shown to be essential for normal neuronal development in mice. In the present study, SULT4A1 was found to colocalize with SULT1A1/3 in human brain neurons. Using immunoprecipitation, SULT4A1 was shown to interact with both SULT1A1 and SULT1A3 when expressed in human cells. Mutation of the conserved dimerization motif located in the C terminus of the sulfotransferases prevented this interaction. Both ectopically expressed and endogenous SULT4A1 decreased SULT1A1/3 protein levels in neuronal cells, and this was also prevented by mutation of the dimerization motif. During differentiation of neuronal SH-SY5Y cells, there was a loss in SULT1A1/3 protein but an increase in SULT4A1 protein. This resulted in an increase in the toxicity of dopamine, a substrate for SULT1A3. Inhibition of SULT4A1 using small interference RNA abrogated the loss in SULT1A1/3 and reversed dopamine toxicity. These results show a reciprocal relationship between SULT4A1 and the other sulfotransferases, suggesting that it may act as a chaperone to control the expression of SULT1A1/3 in neuronal cells. SIGNIFICANCE STATEMENT: The catalytically inactive sulfotransferase (SULT) 4A1 may regulate the function of other SULTs by interacting with them via a conserved dimerization motif. In neuron-like cells, SULT4A1 is able to modulate dopamine toxicity by interacting with SULT1A3, potentially decreasing the metabolism of dopamine.

Acute toxic effects of polyethylene microplastic on adult zebrafish

To identify the physical effects, behavioral changes, and gene expression profiles of the phase 1 detoxification-related gene (cyp 1a) and oogenesis-related gene (vtg 1) induced by microplastics, high-density polyethylene microplastics of various sizes were used because of their dominance in coastal areas and effluent samples in Hong Kong. Adult zebrafish were used as the model organism to identify the upper and lower boundaries of microplastics ingestion and were exposed to individual polyethylene microplastics in five size ranges (10-22 μm, 45-53 μm, 90-106 μm, 212-250 μm, and 500-600 μm) at a concentration of 2 mg/L for 96 h. To study behavioral changes and targeted gene expression profiles via real-time PCR (qPCR), a mixture of microplastics in three size ranges at effluent-related (11 particles/L), moderate (110 particles/L), and high concentrations (1,100 particles/L) were applied for 96 h. The zebrafish behavior was recorded by a video camera and by two observers (interrater reliability, >85%). The results implied that the upper and lower size boundaries for microplastic ingestion were 558.4 ± 26.2 μm (yellow) and 19.7 ± 3.1 μm (red), respectively. In addition, 61 ± 10% of fish in medium concentration treatments and 61 ± 10% of fish in high concentration treatments were found with the microplastic ingestion and remaining in their intestine. In addition, 28 ± 10% of fish in high concentration treatments were found with microplastic retaining in their gills (No. of fishes = 18 in each treatment). The presence of microplastics, which occupied 89 ± 6% of intestine area, reduced the voids inside the intestine for feed. The expression of cyp1a in the intestine (medium concentration) and vtg1 in the liver (medium and high concentration) showed significant up-regulation, and abnormal behavior (i.e., seizures and tail bent downward) was observed (medium and high concentration). In summary, the effects on the aryl hydrocarbon receptor (AHR) pathway, disruption of the oogenesis process, and neurotoxicity could be caused by acute exposure of adult zebrafish to microplastics.

Behavioral toxicity of tannery effluent in zebrafish (Danio rerio) used as model system

The ecotoxicity of untreated tannery effluent (UTE) in several animal models has been reported; however, its effects on fish behavior, and neurotoxicity, remain unknown. Thus, the hypothesis that the chronic exposure to UTE can induce behavioral changes in adult zebrafish (Danio rerio) representatives, even when it is highly diluted in water, was tested. Animals exposed to 0.1% and 0.3% UTE for 30 days showed behavioral changes in visual social preference tests through their co-specific and antipredator defensive responses, which had indicated neurotoxic actions. Zebrafish exposed to UTE appeared to have not co-specific preference when it is paired with Poecilia sphrenops. In addition, only animals in the control group showed aversive behavior in the presence of the herein used predatory stimulus (Oreochromis niloticus). However, Cr, Na and Mg bioaccumulation was higher in zebrafish exposed to 0.1% and 0.3% UTE, although anxiogenic and anxiolytic effects were not observed in the models exposed to UTE in the novel tank diving or aggressiveness-increase-in-the-mirror tests. This outcome allowed associating the exposure to the pollutant and bioaccumulation with the observed behavioral changes. The present study is pioneer in scientifically evidencing the sublethal impact caused by chronic exposure to UTE in experimental environment simulating realistic aquatic pollution conditions. Accordingly, results in the current research should motivate further investigations to broaden the knowledge about the real magnitude of UTE biological impacts on the aquatic biota.

SULT4A1 Protects Against Oxidative-Stress Induced Mitochondrial Dysfunction in Neuronal Cells

Sulfotransferase 4A1 (SULT4A1), a member of cytosolic sulfotransferases (SULT), is exclusively expressed in neurons with no known function. Severe phenotype and early postnatal death in SULT4A1 knockout mice revealed that SULT4A1 is an essential neuronal protein. Localization of SULT4A1 in different cytosolic compartments, including mitochondria, suggests multiple roles for this protein. We observed that knockdown of SULT4A1 results in the accumulation of reactive oxygen species in primary cortical neurons, suggesting a potential role of SULT4A1 in regulating redox homeostasis. Expression of SULT4A1 in the human neuroblastoma SH-SY5Y cells revealed a defused but nonuniform staining pattern in the cytoplasm, with increased density around mitochondria. Subcellular fractionation of SULT4A1 expressing SH-SY5Y cells confirms the presence of SULT4A1 in mitochondrial fractions. SULT4A1 expressing cells display significant protection against H₂O₂-mediated defects in mitochondrial function and loss of mitochondrial membrane potential. Expression of SULT4A1 in SH-SY5Y cells also protects against H₂O₂-induced cell death. These data indicate that SULT4A1 protects mitochondria against oxidative damage and may serve as a potential pharmacological target in neural diseases involving mitochondrial dysfunction and oxidative stress. SIGNIFICANCE STATEMENT: Studies on SULT4A1 knockout mice suggest that SULT4A1 plays a vital role in neuronal function and survival via yet undefined mechanisms. Our data demonstrate that depletion of SULT4A1 induces oxidative stress in neurons and expression of SULT4A1 in SH-SY5Y cells protects against oxidative-stress-induced mitochondrial dysfunction and cell death. These results suggest that SULT4A1 may have a crucial protective function against mitochondrial dysfunction and oxidative stress, and may serve a potential therapeutic target in different neurological diseases involving mitochondrial dysfunction and oxidative stress.

Generation and Characterization of SULT4A1 Mutant Mouse Models

Sulfotransferase 4A1 (SULT4A1) belongs to the cytosolic sulfotransferase (SULT) superfamily of enzymes that catalyze sulfonation reactions with a variety of endogenous and exogenous substrates. Of the SULTs, SULT4A1 was shown to have the highest sequence homology between vertebrate species, yet no known function or enzymatic activity has been identified for this orphan SULT. To better understand SULT4A1 function in mammalian brain, two mutant SULT4A1 mouse strains were generated utilizing clustered regulatory interspaced short palindromic repeats (CRISPR)-content-addressable storage (Cas) 9 technology. The first strain possessed a 28-base pair (bp) deletion (Δ28) in exon 1 that resulted in a frameshift mutation with premature termination. The second strain possessed a 12-bp in-frame deletion (Δ12) immediately preceding an active site histidine¹¹¹ common to the SULT family. Homozygous pups of both strains present with severe and progressive neurologic symptoms, including tremor, absence seizures, abnormal gait, ataxia, decreased weight gain compared with littermates, and death around postnatal days 21-25. SULT4A1 immunostaining was decreased in brains of heterozygous pups and not detectable in homozygous pups of both SULT4A1 mutants. SULT4A1 localization in subcellular fractions of mouse brain showed SULT4A1 associated with mitochondrial, cytosolic, and microsomal fractions, a novel localization pattern for SULTs. Finally, primary cortical neurons derived from embryonic (E15) CD-1 mice expressed high levels of SULT4A1 throughout the cell except in nuclei. Taken together, SULT4A1 appears to be an essential neuronal protein required for normal brain function, at least in mammals. Mouse models will be valuable in future studies to investigate the regulation and functions of SULT4A1 in the mammalian brain.

Identification and characterization of 5α-cyprinol-sulfating cytosolic sulfotransferases (Sults) in the zebrafish (Danio rerio)

5α-Cyprinol 27-sulfate is the major biliary bile salt present in cypriniform fish including the zebrafish (Danio rerio). The current study was designed to identify the zebrafish cytosolic sulfotransferase (Sult) enzyme(s) capable of sulfating 5α-cyprinol and to characterize the zebrafish 5α-cyprinol-sulfating Sults in comparison with human SULT2A1. Enzymatic assays using zebrafish homogenates showed 5α-cyprinol-sulfating activity. A systematic analysis, using a panel of recombinant zebrafish Sults, revealed two Sult2 subfamily members, Sult2st2 and Sult2st3, as major 5α-cyprinol-sulfating Sults. Both enzymes showed higher activities using 5α-cyprinol as the substrate, compared to their activity with DHEA, a representative substrate for mammalian SULT2 family members, particularly SULT2A1. pH-Dependence and kinetics experiments indicated that the catalytic properties of zebrafish Sult2 family members in mediating the sulfation of 5α-cyprinol were different from those of either zebrafish Sult3st4 or human SULT2A1. Collectively, these results imply that both Sult2st2 and Sult2st3 have evolved to sulfate specifically C₂₇-bile alcohol, 5α-cyprinol, in Cypriniform fish, whereas the enzymatic characteristics of zebrafish Sult3 members, particularly Sult3st4, correlated with those of human SULT2A1.

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

Phelan-McDermid syndrome (PMS) is characterized by a variety of clinical symptoms with heterogeneous degrees of severity, including intellectual disability (ID), absent or delayed speech, and autism spectrum disorders (ASD). It results from a deletion of the distal part of chromosome 22q13 that in most cases includes the SHANK3 gene. SHANK3 is considered a major gene for PMS, but the factors that modulate the severity of the syndrome remain largely unknown. In this study, we investigated 85 patients with different 22q13 rearrangements (78 deletions and 7 duplications). We first explored the clinical features associated with PMS, and provide evidence for frequent corpus callosum abnormalities in 28% of 35 patients with brain imaging data. We then mapped several candidate genomic regions at the 22q13 region associated with high risk of clinical features, and suggest a second locus at 22q13 associated with absence of speech. Finally, in some cases, we identified additional clinically relevant copy-number variants (CNVs) at loci associated with ASD, such as 16p11.2 and 15q11q13, which could modulate the severity of the syndrome. We also report an inherited SHANK3 deletion transmitted to five affected daughters by a mother without ID nor ASD, suggesting that some individuals could compensate for such mutations. In summary, we shed light on the genotype-phenotype relationship of patients with PMS, a step towards the identification of compensatory mechanisms for a better prognosis and possibly treatments of patients with neurodevelopmental disorders.

Updated perspectives on the cytosolic sulfotransferases (SULTs) and SULT-mediated sulfation

The cytosolic sulfotransferases (SULTs) are Phase II detoxifying enzymes that mediate the sulfate conjugation of numerous xenobiotic molecules. While the research on the SULTs has lagged behind the research on Phase I cytochrome P-450 enzymes and other Phase II conjugating enzymes, it has gained more momentum in recent years. This review aims to summarize information obtained in several fronts of the research on the SULTs, including the range of the SULTs in different life forms, concerted actions of the SULTs and other Phase II enzymes, insights into the structure-function relationships of the SULTs, regulation of SULT expression and activity, developmental expression of SULTs, as well as the use of a zebrafish model for studying the developmental pharmacology/toxicology.