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The Interactome of Palmitoyl-Protein Thioesterase 1 (PPT1) Affects Neuronal Morphology and Function.

ABSTRACT: Palmitoyl-protein thioesterase 1 (PPT1) is a depalmitoylation enzyme that is mutated in cases of neuronal ceroid lipofuscinosis (NCL). The hallmarks of the disease include progressive neurodegeneration and blindness, as well as seizures. In the current study, we identified 62 high-confident PPT1-binding proteins. These proteins included a self-interaction of PPT1, two V-type ATPases, calcium voltage-gated channels, cytoskeletal proteins and others. Pathway analysis suggested their involvement in seizures and neuronal morphology. We then proceeded to demonstrate that hippocampal neurons from Ppt1-/- mice exhibit structural deficits, and further investigated electrophysiology parameters in the hippocampi of mutant mice, both in brain slices and dissociated postnatal primary cultures. Our studies reveal new mechanistic features involved in the pathophysiology of this devastating neurodegenerative disease.

SUBMITTER: Sapir T

PROVIDER: S-EPMC6424868 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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The Interactome of Palmitoyl-Protein Thioesterase 1 (PPT1) Affects Neuronal Morphology and Function.

Sapir Tamar T Segal Michal M Grigoryan Gayane G Hansson Karin M KM James Peter P Segal Menahem M Reiner Orly O

Frontiers in cellular neuroscience 20190313

Palmitoyl-protein thioesterase 1 (PPT1) is a depalmitoylation enzyme that is mutated in cases of neuronal ceroid lipofuscinosis (NCL). The hallmarks of the disease include progressive neurodegeneration and blindness, as well as seizures. In the current study, we identified 62 high-confident PPT1-binding proteins. These proteins included a self-interaction of PPT1, two V-type ATPases, calcium voltage-gated channels, cytoskeletal proteins and others. Pathway analysis suggested their involvement in ...[more]

PMID: 30918483

Similar Datasets

PPT1 binding proteins - The Interactome of Palmitoyl-Protein Thioesterase 1 (PPT1) Affects Neuronal Morphology and Function

Project description:Binding of proteins from mouse brain lysates to GFP-PPT1

2019-11-08 | PXD006429 | Pride

Reversible Cysteine Acylation Regulates the Activity of Human Palmitoyl-Protein Thioesterase 1 (PPT1).

Project description:Mutations in the depalmitoylating enzyme gene, PPT1, cause the infantile form of Neuronal Ceroid Lipofuscinosis (NCL), an early onset neurodegenerative disease. During recent years there have been different therapeutic attempts including enzyme replacement. Here we show that PPT1 is palmitoylated in vivo and is a substrate for two palmitoylating enzymes, DHHC3 and DHHC7. The palmitoylated protein is detected in both cell lysates and medium. The presence of PPT1 with palmitoylated signal peptide in the cell medium suggests that a subset of the protein is secreted by a nonconventional mechanism. Using a mutant form of PPT1, C6S, which was not palmitoylated, we further demonstrate that palmitoylation does not affect intracellular localization but rather that the unpalmitoylated form enhanced the depalmitoylation activity of the protein. The calculated Vmax of the enzyme was significantly affected by the palmitoylation, suggesting that the addition of a palmitate group is reminiscent of adding a noncompetitive inhibitor. Thus, we reveal the existence of a positive feedback loop, where palmitoylation of PPT1 results in decreased activity and subsequent elevation in the amount of palmitoylated proteins. This positive feedback loop is likely to initiate a vicious cycle, which will enhance disease progression. The understanding of this process may facilitate enzyme replacement strategies.

| S-EPMC4701722 | biostudies-literature

Human recombinant palmitoyl-protein thioesterase-1 (PPT1) for preclinical evaluation of enzyme replacement therapy for infantile neuronal ceroid lipofuscinosis.

Project description:Infantile neuronal ceroid lipofuscinosis (INCL, also known as Haltia-Santavuori disease) is a lysosomal storage disorder of infants and children characterized by blindness, seizures and a progressive neurodegenerative course. Recent clinical trials have involved neural stem cells and gene therapy directed to the central nervous system; however, enzyme replacement therapy has never been addressed. In the current paper, we describe the production of human recombinant PPT1 (the defective enzyme in INCL) by standard methods in Chinese Hamster Ovary (CHO) cells. The enzyme is largely mannose 6-phosphorylated as assessed by mannose 6-phosphate receptor binding (80% bound) and taken up rapidly by immortalized patient lymphoblasts, where clearance of PPT substrates was demonstrated (EC(50) of 0.25 nM after overnight incubation). When injected intravenously into PPT1-deficient mice, the clearance of recombinant human PPT1 from plasma was rapid, with a half-life of 10 min. Most of the injected dose was distributed to the kidney and liver and potentially corrective levels were also observed in heart, lung and spleen. Brain uptake was minimal, as expected based on experience with other intravenously administered lysosomal enzymes. The enzyme may be useful as an adjunct to central nervous system-directed therapies and could be used as a starting point for modifications designed to improve brain delivery.

| S-EPMC2839016 | biostudies-literature

Palmitoyl:protein thioesterase (PPT1) inhibitors can act as pharmacological chaperones in infantile Batten disease.

Project description:Competitive inhibitors of lysosomal hydrolases (pharmacological chaperones) have been used to treat some lysosomal storage diseases which result from mis-sense mutations and mis-folded protein but have not been tried in Batten disease, for which there is no current therapy. We synthesized a large number of novel, non-hydrolyzable competitive inhibitors of palmitoyl:protein thioesterase (PPT1) and showed that some could act as chemical chaperones. One inhibitor (CS38: betaAGDap(Pal)VKIKK) was taken up by lymphoblasts from patients with mutations leading to the T75P/R151X substitutions and enhanced PPT1 activity 2-fold. A similar 2-fold stimulation with another inhibitor (AcGDap(Palm)GG(R)(7)) was observed in patients with a G108R amino acid substitution in PPT1. Residual PPT1 activity in both was thermally unstable at pH 7.4 (but not at 4.7) consistent with a mis-folded, unstable PPT1 degraded by the ER stress response. Patients with null mutations did not respond to the pharmacological chaperones.

| S-EPMC2881699 | biostudies-literature

Mice deficient in the lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1) display a complex retinal phenotype.

Project description:Neuronal ceroid lipofuscinosis (NCL) type 1 (CLN1) is a neurodegenerative storage disorder caused by mutations in the gene encoding the lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1). CLN1 patients suffer from brain atrophy, mental and motor retardation, seizures, and retinal degeneration ultimately resulting in blindness. Here, we performed an in-depth analysis of the retinal phenotype of a PPT1-deficient mouse, an animal model of this condition. Reactive astrogliosis and microgliosis were evident in mutant retinas prior to the onset of retinal cell loss. Progressive accumulation of storage material, a pronounced dysregulation of various lysosomal proteins, and accumulation of sequestosome/p62-positive aggregates in the inner nuclear layer also preceded retinal degeneration. At advanced stages of the disease, the mutant retina was characterized by a significant loss of ganglion cells, rod and cone photoreceptor cells, and rod and cone bipolar cells. Results demonstrate that PPT1 dysfunction results in early-onset pathological alterations in the mutant retina, followed by a progressive degeneration of various retinal cell types at relatively late stages of the disease. Data will serve as a reference for future work aimed at developing therapeutic strategies for the treatment of retinal degeneration in CLN1 disease.

| S-EPMC6775149 | biostudies-literature

Identifying cellular pathways modulated by Drosophila palmitoyl-protein thioesterase 1 function.

Project description:Infantile-onset Neuronal Ceroid Lipofuscinosis (INCL) is a severe pediatric neurodegenerative disorder produced by mutations in the gene encoding palmitoyl-protein thioesterase 1 (Ppt1). This enzyme is responsible for the removal of a palmitate post-translational modification from an unknown set of substrate proteins. To better understand the function of Ppt1 in neurons, we performed an unbiased dominant loss-of-function genetic modifier screen in Drosophila using a previously characterized Ppt1 gain-of-function system. The enhancers and suppressors identified in our screen make novel connections between Ppt1 and genes involved in cellular trafficking and the modulation of synaptic growth. We further support the relevance of our screen by demonstrating that Garland cells from Ppt1 loss-of-function mutants have defects in endocytic trafficking. Endocytic tracer uptake and ultrastructural analysis of these non-neuronal cells points to Ppt1 playing a role in modulating the early stages of vesicle formation. This work lays the groundwork for further experimental exploration of these processes to better understand their contributions to the INCL disease process.

| S-EPMC2914843 | biostudies-literature

Cln3-mutations underlying juvenile neuronal ceroid lipofuscinosis cause significantly reduced levels of Palmitoyl-protein thioesterases-1 (Ppt1)-protein and Ppt1-enzyme activity in the lysosome.

Project description:Mutations in at least 13 different genes (called CLNs) underlie various forms of neuronal ceroid lipofuscinoses (NCLs), a group of the most common neurodegenerative lysosomal storage diseases. While inactivating mutations in the CLN1 gene, encoding palmitoyl-protein thioesterases-1 (PPT1), cause infantile NCL (INCL), those in the CLN3 gene, encoding a protein of unknown function, underlie juvenile NCL (JNCL). PPT1 depalmitoylates S-palmitoylated proteins (constituents of ceroid) required for their degradation by lysosomal hydrolases and PPT1-deficiency causes lysosomal accumulation of autofluorescent ceroid leading to INCL. Because intracellular accumulation of ceroid is a characteristic of all NCLs, a common pathogenic link for these diseases has been suggested. It has been reported that CLN3-mutations suppress the exit of cation-independent mannose 6-phosphate receptor (CI-M6PR) from the trans Golgi network (TGN). Because CI-M6PR transports soluble proteins such as PPT1 from the TGN to the lysosome, we hypothesized that CLN3-mutations may cause lysosomal PPT1-insufficiency contributing to JNCL pathogenesis. Here, we report that the lysosomes in Cln3-mutant mice, which mimic JNCL, and those in cultured cells from JNCL patients, contain significantly reduced levels of Ppt1-protein and Ppt1-enzyme activity and progressively accumulate autofluorescent ceroid. Furthermore, in JNCL fibroblasts the V0a1 subunit of v-ATPase, which regulates lysosomal acidification, is mislocalized to the plasma membrane instead of its normal location on lysosomal membrane. This defect dysregulates lysosomal acidification, as we previously reported in Cln1 -/- mice, which mimic INCL. Our findings uncover a previously unrecognized role of CLN3 in lysosomal homeostasis and suggest that CLN3-mutations causing lysosomal Ppt1-insuffiiciency may at least in part contribute to JNCL pathogenesis.

| S-EPMC6739123 | biostudies-literature

Transcription profiling of palmitoyl protein thioesterase-1 knockout mice

Project description:Infantile neuronal ceroid lipofuscinosis (aka infantile Batten disease) is a severe neurodegenerative disorder of early childhood characterized by cortical atrophy, blindness and seizures, leading to premature death in the first decade. The disorder is caused by deficiency in a soluble lysosomal enzyme, palmitoyl protein thioesterase-1 (PPT1). PPT1 knockout mice faithfully reproduce the features of the human disease, with motor deterioration, blindness, seizures, and death before 10 months of age. The progression of events leading from enzyme deficiency to organ failure is poorly defined. The neuronal ceroid lipofuscinoses are of particular interest because of the similarities between the accumulated material and lipofuscin that is associated with normal aging. We will determine changes in gene expression that occur during the course of neurodegeneration in PPT1 knockout as compared to control mice. Gene expression profiling of brain tissue from PPT1 knockout mice as compared to normal controls will provide insights into the mechanism of neurodegeneration. Comparison of this profile with gene expression profiles associated with normal aging may provide insights into the contribution of lipofuscin to aging and neurodegeneration. PPT1 knockout mice on a C57BL/6 background will be sacrificed under CO2 and whole brains removed and frozen under liquid nitrogen. Three mice will be used for each time point. Data points will be collected at 3 months, 5 months and 8 months of age. Normal age- and sex-matched C57BL/6 mice will be used as controls.

2008-06-15 | E-GEOD-6678 | biostudies-arrayexpress

Palmitoyl protein thioesterase-1 knockout mice hofma-affy-mouse-370000

2007-01-09 | GSE6678 | GEO

The crystal structure of palmitoyl protein thioesterase 1 and the molecular basis of infantile neuronal ceroid lipofuscinosis.

Project description:Mutations in palmitoyl-protein thioesterase 1 (PPT1), a lysosomal enzyme that removes fatty acyl groups from cysteine residues in modified proteins, cause the fatal inherited neurodegenerative disorder infantile neuronal ceroid lipofuscinosis. The accumulation of undigested substrates leads to the formation of neuronal storage bodies that are associated with the clinical symptoms. Less severe forms of PPT1 deficiency have been found recently that are caused by a distinct set of PPT1 mutations, some of which retain a small amount of thioesterase activity. We have determined the crystal structure of PPT1 with and without bound palmitate by using multiwavelength anomalous diffraction phasing. The structure reveals an alpha/beta-hydrolase fold with a catalytic triad composed of Ser115-His289-Asp233 and provides insights into the structural basis for the phenotypes associated with PPT1 mutations.

| S-EPMC18274 | biostudies-literature

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