A peptide-linked recombinant glucocerebrosidase for targeted neuronal delivery: Design, production, and assessment

Therapeutic delivery of recombinant glucocerebrosidase enzyme-containing extracellular vesicles to human cells from Gaucher disease patients

BACKGROUND

Gaucher disease (GD) is one of the most common types of lysosomal storage diseases (LSDs) caused by pathogenic variants of lysosomal β-glucocerebrosidase gene (GBA1), resulting in the impairment of Glucocerebrosidase (GCase) enzyme function and the accumulation of a glycolipid substrate, glucosylceramide (GlcCer) within lysosomes. Current therapeutic approaches such as enzyme replacement therapy and substrate reduction therapy cannot fully rescue GD pathologies, especially neurological symptoms. Meanwhile, delivery of lysosomal enzymes to the endocytic compartment of affected human cells is a promising strategy for treating neuropathic LSDs.

RESULT

Here, we describe a novel approach to restore GCase enzyme in cells from neuropathic GD patients by producing extracellular vesicle (EVs)-containing GCase from cells overexpressing GBA1 gene. Lentiviral vectors containing modified GBA1 were introduced into HEK293T cells to produce a stable cell line that provides a sustainable source of functional GCase enzyme. The GBA1-overexpressing cells released EV-containing GCase enzyme, that is capable of entering into and localizing in the endocytic compartment of recipient cells, including THP-1 macrophage, SH-SY5Y neuroblastoma, and macrophages and neurons derived from induced pluripotent stem cells (iPSCs) of neuropathic GD patients. Importantly, the recipient cells exhibit higher GCase enzyme activity.

CONCLUSION

This study presents a promising therapeutic strategy to treat severe types of LSDs. It involves delivering lysosomal enzymes to the endocytic compartment of human cells affected by conditions such as GDs with neurological symptoms, as well as potentially other neurological disorders impacting lysosomes.

Activation and Purification of ß-Glucocerebrosidase by Exploiting its Transporter LIMP-2 - Implications for Novel Treatment Strategies in Gaucher's and Parkinson's Disease

Genetic variants of GBA1 can cause the lysosomal storage disorder Gaucher disease and are among the highest genetic risk factors for Parkinson's disease (PD). GBA1 encodes the lysosomal enzyme beta-glucocerebrosidase (GCase), which orchestrates the degradation of glucosylceramide (GluCer) in the lysosome. Recent studies have shown that GluCer accelerates α-synuclein aggregation, exposing GCase deficiency as a major risk factor in PD pathology and as a promising target for treatment. This study investigates the interaction of GCase and three disease-associated variants (p.E326K, p.N370S, p.L444P) with their transporter, the lysosomal integral membrane protein 2 (LIMP-2). Overexpression of LIMP-2 in HEK 293T cells boosts lysosomal abundance of wt, E326K, and N370S GCase and increases/rescues enzymatic activity of the wt and E326K variant. Using a novel purification approach, co-purification of untagged wt, E326K, and N370S GCase in complex with His-tagged LIMP-2 from cell supernatant of HEK 293F cells is achieved, confirming functional binding and trafficking for these variants. Furthermore, a single helix in the LIMP-2 ectodomain is exploited to design a lysosome-targeted peptide that enhances lysosomal GCase activity in PD patient-derived and control fibroblasts. These findings reveal LIMP-2 as an allosteric activator of GCase, suggesting a possible therapeutic potential of targeting this interaction.

Glucocerebrosidase mutations and Parkinson disease

The discovery of glucocerebrosidase (GBA1) mutations as the greatest numerical genetic risk factor for the development of Parkinson disease (PD) resulted in a paradigm shift within the research landscape. Efforts to elucidate the mechanisms behind GBA1-associated PD have highlighted shared pathways in idiopathic PD including the loss and gain-of-function hypotheses, endoplasmic reticulum stress, lipid metabolism, neuroinflammation, mitochondrial dysfunction and altered autophagy-lysosomal pathway responsible for degradation of aggregated and misfolded a-synuclein. GBA1-associated PD exhibits subtle differences in phenotype and disease progression compared to idiopathic counterparts notably an earlier age of onset, faster motor decline and greater frequency of non-motor symptoms (which also constitute a significant aspect of the prodromal phase of the disease). GBA1-targeted therapies have been developed and are being investigated in clinical trials. The most notable are Ambroxol, a small molecule chaperone, and Venglustat, a blood-brain-barrier-penetrant substrate reduction therapy agent. It is imperative that further studies clarify the aetiology of GBA1-associated PD, enabling the development of a greater abundance of targeted therapies in this new era of precision medicine.

Genetic variations in GBA1 and LRRK2 genes: Biochemical and clinical consequences in Parkinson disease

Variants in the GBA1 and LRRK2 genes are the most common genetic risk factors associated with Parkinson disease (PD). Both genes are associated with lysosomal and autophagic pathways, with the GBA1 gene encoding for the lysosomal enzyme, glucocerebrosidase (GCase) and the LRRK2 gene encoding for the leucine-rich repeat kinase 2 enzyme. GBA1-associated PD is characterized by earlier age at onset and more severe non-motor symptoms compared to sporadic PD. Mutations in the GBA1 gene can be stratified into severe, mild and risk variants depending on the clinical presentation of disease. Both a loss- and gain- of function hypothesis has been proposed for GBA1 variants and the functional consequences associated with each variant is often linked to mutation severity. On the other hand, LRRK2-associated PD is similar to sporadic PD, but with a more benign disease course. Mutations in the LRRK2 gene occur in several structural domains and affect phosphorylation of GTPases. Biochemical studies suggest a possible convergence of GBA1 and LRRK2 pathways, with double mutant carriers showing a milder phenotype compared to GBA1-associated PD. This review compares GBA1 and LRRK2-associated PD, and highlights possible genotype-phenotype associations for GBA1 and LRRK2 separately, based on biochemical consequences of single variants.

Establishment and characterization of a novel ovarian high-grade serous carcinoma cell line-IPO43

Background

Epithelial ovarian cancer (EOC) is an aggressive and lethal malignancy and novel EOC cell lines with detailed characterization are needed, to provide researchers with diverse helpful resources to study EOC biological processes and cancer experimental therapies.

Methods

The IPO43 cell line was established from the ascitic fluid of a patient with a diagnosis of high-grade serous carcinoma (HGSC) of the ovary, previously treated with chemotherapy.

Cell immortalization was achieved in 2D cell culture and growth obtained in 2D and 3D cell cultures. The characterization of immortalized cells was done by immunocytochemistry, flow cytometry, cell proliferation, chromosomal Comparative Genomic Hybridization (cCGH), STR profile and Next Generation Sequencing (NGS).

Results

Characterization studies confirmed that IPO43 cell line is of EOC origin and maintains morphological and molecular features of the primary tumor. cCGH analysis showed a complex profile with gains and losses of specific DNA regions in both primary ascitic fluid and cell line IPO43. The cell line was successfully grown in a 3D system which allows its future application in more complex assays than those performed in 2D models. IPO43 cell line is resistant to standard drug treatment in vitro.

Conclusions

IPO43 is available for public research and we hope it can contribute to enrich the in vitro models addressing EOC heterogeneity, being useful to investigate EOC and to develop new therapeutic modalities.

IPOLFG-SOC43 cell line represents the heterogeneity of Epithelial Ovarian Cancer

Genetic alterations in cancer cells confer a selective advantage

3D cultures preserve the phenotypical features of the original tumor

GBA Variants and Parkinson Disease: Mechanisms and Treatments

The GBA gene encodes for the lysosomal enzyme glucocerebrosidase (GCase), which maintains glycosphingolipid homeostasis. Approximately 5–15% of PD patients have mutations in the GBA gene, making it numerically the most important genetic risk factor for Parkinson disease (PD). Clinically, GBA-associated PD is identical to sporadic PD, aside from the earlier age at onset (AAO), more frequent cognitive impairment and more rapid progression. Mutations in GBA can be associated with loss- and gain-of-function mechanisms. A key hallmark of PD is the presence of intraneuronal proteinaceous inclusions named Lewy bodies, which are made up primarily of alpha-synuclein. Mutations in the GBA gene may lead to loss of GCase activity and lysosomal dysfunction, which may impair alpha-synuclein metabolism. Models of GCase deficiency demonstrate dysfunction of the autophagic-lysosomal pathway and subsequent accumulation of alpha-synuclein. This dysfunction can also lead to aberrant lipid metabolism, including the accumulation of glycosphingolipids, glucosylceramide and glucosylsphingosine. Certain mutations cause GCase to be misfolded and retained in the endoplasmic reticulum (ER), activating stress responses including the unfolded protein response (UPR), which may contribute to neurodegeneration. In addition to these mechanisms, a GCase deficiency has also been associated with mitochondrial dysfunction and neuroinflammation, which have been implicated in the pathogenesis of PD. This review discusses the pathways associated with GBA-PD and highlights potential treatments which may act to target GCase and prevent neurodegeneration.

Glucocerebrosidase Mutations Cause Mitochondrial and Lysosomal Dysfunction in Parkinson’s Disease: Pathogenesis and Therapeutic Implications

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by multiple motor and non-motor symptoms. Mutations in the glucocerebrosidase (GBA) gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase), which hydrolyzes glucosylceramide (GlcCer) to glucose and ceramide, are the most important and common genetic PD risk factors discovered to date. Homozygous GBA mutations result in the most common lysosomal storage disorder, Gaucher’s disease (GD), which is classified according to the presence (neuronopathic types, type 2 and 3 GD) or absence (non-neuronopathic type, type 1 GD) of neurological symptoms. The clinical manifestations of PD in patients with GBA mutations are indistinguishable from those of sporadic PD at the individual level. However, accumulating data have indicated that GBA-associated PD patients exhibit a younger age of onset and a greater risk for cognitive impairment and psychiatric symptoms. The mechanisms underlying the increased risk of developing PD in GBA mutant carriers are currently unclear. Contributors to GBA-PD pathogenesis may include mitochondrial dysfunction, autophagy-lysosomal dysfunction, altered lipid homeostasis and enhanced α-synuclein aggregation. Therapeutic strategies for PD and GD targeting mutant GCase mainly include enzyme replacement, substrate reduction, gene and pharmacological small-molecule chaperones. Emerging clinical, genetic and pathogenic studies on GBA mutations and PD are making significant contributions to our understanding of PD-associated pathogenetic pathways, and further elucidating the interactions between GCase activity and neurodegeneration may improve therapeutic approaches for slowing PD progression.

The neuroinflammatory role of glucocerebrosidase in Parkinson's disease

The lysosomal enzyme glucocerebrosidase (GCase), encoded by the GBA1 gene, is a membrane-associated protein catalyzing the cleavage of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Homologous GBA1 mutations cause Gaucher disease (GD) and heterologous mutations cause Parkinson's disease (PD). Importantly, heterologous GBA1 mutations are recognized as the second risk factor of PD. The pathological features of PD are Lewy neurites (LNs) and Lewy bodies (LBs) composed of pathological α-synuclein. Oxidative stress, inflammatory response, autophagic impairment, and α-synuclein accumulation play critical roles in PD pathogenic cascades, but the pathogenesis of PD has not yet been fully elucidated. What's more, PD treatment drugs can only relieve symptoms to a certain extent, but cannot alleviate neurodegenerative progression. Therefore, it's urgent to explore new targets that can alleviate the neurodegenerative process. Deficient GCase can cause lysosomal dysfunction, obstructing the metabolism of α-synuclein. Meanwhile, GCase dysfunction causes accumulation of its substrates, leading to lipid metabolism disorders. Subsequently, astrocytes and microglia are activated, releasing amounts of pro-inflammatory mediators and causing extensive neuroinflammation. All these cascades can induce neuron damage and death, eventually promoting PD pathology. This review aims to summarize these points and the potential of GCase as an original target to provide some ideas for elucidating the pathogenesis of PD.

The structure of myeloid cell-specific TNF inhibitors affects their biological properties

Spatial organization and conformational changes of antibodies may significantly affect their biological functions. We assessed the effect of mutual organization of the two V_H H domains within bispecific antibodies recognizing human TNF and the surface molecules of murine myeloid cells (F4/80 or CD11b) on TNF retention and inhibition. TNF-neutralizing properties in vitro and in vivo of MYSTI-2 and MYSTI-3 antibodies were compared with new variants with interchanged V_H H domains and different linker sequences. The most effective structure of MYSTI-2 and MYSTI-3 proteins required the Ser/Gly-containing 'superflexible' linker. The orientation of the modules was crucial for the activity of the proteins, but not for MYSTI-3 with the Pro/Gln-containing 'semi-rigid' linker. Our results may contribute toward the development of more effective drug prototypes.

Glucocerebrosidase as a therapeutic target for Parkinson's disease

Introduction: The association between Gaucher disease, caused by the inherited deficiency of glucocerebrosidase, and Parkinson's disease was first recognized in the clinic, noting that patients with Gaucher disease and their carrier relatives had an increased incidence of Parkinson's disease. Currently, mutations in glucocerebrosidase (GBA1) are the most common genetic risk factor for Parkinson's disease and dementia with Lewy bodies, with an inverse relationship between glucocerebrosidase and α-synuclein, a key factor in Parkinson pathogenesis. The hypothesis that therapeutic enhancement of brain glucocerebrosidase levels might reduce the aggregation, accumulation or spread of α-synuclein has spurred great interest in glucocerebrosidase as a novel therapeutic target.Area covered: This article explores the potential molecular mechanisms underlying the association between GBA1 mutations and Parkinson's disease and outlines therapeutic strategies to increase brain glucocerebrosidase, including gene therapy, targeted delivery of recombinant glucocerebrosidase to the brain, small-molecule chaperones to rescue mutant glucocerebrosidase, and small-molecule modulators to activate wild-type glucocerebrosidase.Expert opinion: Although an improved understanding of the mechanistic basis for GBA1-associated parkinsonism is essential, enhancing levels of brain glucocerebrosidase may have wide therapeutic implications. While gene therapy may ultimately be effective, less expensive and invasive small-molecule non-inhibitory chaperones or activators could significantly impact the disease course.

The biochemical basis of interactions between Glucocerebrosidase and alpha-synuclein in GBA1 mutation carriers

The discovery of genes involved in familial as well as sporadic forms of Parkinson disease (PD) constitutes an important milestone in understanding this disorder's pathophysiology and potential treatment. Among these genes, GBA1 is one of the most common and well-studied, but it is still unclear how mutations in GBA1 translate into an increased risk for developing PD. In this review, we provide an overview of the biochemical and structural relationship between GBA1 and PD to help understand the recent advances in the development of PD therapies intended to target this pathway.

Gaucher disease iPSC-derived osteoblasts have developmental and lysosomal defects that impair bone matrix deposition

Gaucher disease (GD) is caused by bi-allelic mutations in GBA1, the gene that encodes acid β-glucocerebrosidase (GCase). Individuals affected by GD have hematologic, visceral and bone abnormalities, and in severe cases there is also neurodegeneration. To shed light on the mechanisms by which mutant GBA1 causes bone disease, we examined the ability of human induced pluripotent stem cells (iPSC) derived from patients with Types 1, 2 and 3 GD, to differentiate to osteoblasts and carry out bone deposition. Differentiation of GD iPSC to osteoblasts revealed that these cells had developmental defects and lysosomal abnormalities that interfered with bone matrix deposition. Compared with controls, GD iPSC-derived osteoblasts exhibited reduced expression of osteoblast differentiation markers, and bone matrix protein and mineral deposition were defective. Concomitantly, canonical Wnt/β catenin signaling in the mutant osteoblasts was downregulated, whereas pharmacological Wnt activation with the GSK3β inhibitor CHIR99021 rescued GD osteoblast differentiation and bone matrix deposition. Importantly, incubation with recombinant GCase (rGCase) rescued the differentiation and bone-forming ability of GD osteoblasts, demonstrating that the abnormal GD phenotype was caused by GCase deficiency. GD osteoblasts were also defective in their ability to carry out Ca2+-dependent exocytosis, a lysosomal function that is necessary for bone matrix deposition. We conclude that normal GCase enzymatic activity is required for the differentiation and bone-forming activity of osteoblasts. Furthermore, the rescue of bone matrix deposition by pharmacological activation of Wnt/β catenin in GD osteoblasts uncovers a new therapeutic target for the treatment of bone abnormalities in GD.

New treatments for the mucopolysaccharidoses: from pathophysiology to therapy

Enzyme replacement therapy is currently considered the standard of care for the treatment of mucopolysaccharidoses (MPS) type I, II, VI, and IV. This approach has shown substantial efficacy mainly on somatic symptoms of the patients, but no benefit was found for other clinical manifestations, such as neurological involvement. New strategies are currently being tested to address these limitations, in particular to obtain sufficient therapeutic levels in the brain. Intrathecal delivery of recombinant enzymes or chimeric enzymes represent promising approaches in this respect. Further innovation will likely be introduced by the recent advancements in the knowledge of lysosomal biology and function. It is now clear that the clinical manifestations of MPS are not only the direct effects of storage, but also derive from a cascade of secondary events that lead to dysfunction of several cellular processes and pathways. Some of these pathways may represent novel therapeutic targets and allow for development of novel or adjunctive therapies for these disorders.

Targeted therapy of intracranial glioma model mice with curcumin nanoliposomes

Background

Glioma is the most aggressive and lethal brain tumor in humans, it comprises about 30 per cent of all brain tumors and central nervous system tumors.

Purpose

The objective of this study was to create novel brain-targeting nanoliposomes to encapsulate curcumin as a promising option for glioma therapy.

Patients and methods

Human glioma cells (U251MG) were used to determine cell uptake efficiency and possible internalization mechanism of the curcumin-loaded nanoliposomes modified by a brain-targeting peptide RDP. In addition, intracranial glioma mice model was prepared by transplantation of U251MG cells into the mice striatum, and then the liposomes were intravenously administered into the glioma-bearing mice to evaluate the anti-glioma activity.

Results

RDP-modified liposomes (RCL) could enter the brain and glioma region, and were internalized by the glioma cells perhaps through acetylcholine receptor-mediated endocytosis pathway. Furthermore, the RCL prolonged the survival time of the glioma-bearing mice from 23 to 33 days, and the inhibition mechanism of the RCL on glioma cell was partly due to cell cycle arrest at the S phase and induction of cell apoptosis.

Conclusion

This study would provide a potential approach for targeted delivery of drug-loaded liposomes for glioma treatment.

Glucocerebrosidase and Parkinson Disease: Molecular, Clinical, and Therapeutic Implications

Parkinson disease (PD) is a complex neurodegenerative disease characterised by multiple motor and non-motor symptoms. In the last 20 years, more than 20 genes have been identified as causes of parkinsonism. Following the observation of higher risk of PD in patients affected by Gaucher disease, a lysosomal disorder caused by mutations in the glucocerebrosidase (GBA) gene, it was discovered that mutations in this gene constitute the single largest risk factor for development of idiopathic PD. Patients with PD and GBA mutations are clinically indistinguishable from patients with idiopathic PD, although some characteristics emerge depending on the specific mutation, such as slightly earlier onset. The molecular mechanisms which lead to this increased PD risk in GBA mutation carriers are multiple and not yet fully elucidated, they include alpha-synuclein aggregation, lysosomal-autophagy dysfunction and endoplasmic reticulum stress. Moreover, dysfunction of glucocerebrosidase has also been demonstrated in non-GBA PD, suggesting its interaction with other pathogenic mechanisms. Therefore, GBA enzyme function represents an interesting pharmacological target for PD. Cell and animal models suggest that increasing GBA enzyme activity can reduce alpha-synuclein levels. Clinical trials of ambroxol, a glucocerebrosidase chaperone, are currently ongoing in PD and PD dementia, as is a trial of substrate reduction therapy. The aim of this review is to summarise the main features of GBA-PD and discuss the implications of glucocerebrosidase modulation on PD pathogenesis.

Promotion of SH-SY5Y Cell Growth by Gold Nanoparticles Modified with 6-Mercaptopurine and a Neuron-Penetrating Peptide

Much effort has been devoted to the discovery of effective biomaterials for nerve regeneration. Here, we reported a novel application of gold nanoparticles (AuNPs) modified with 6-mercaptopurine (6MP) and a neuron-penetrating peptide (RDP) as a neurophic agent to promote proliferation and neurite growth of human neuroblastoma (SH-SY5Y) cells. When the cells were treated with 6MP-AuNPs-RDP conjugates, they showed higher metabolic activity than the control. Moreover, SH-SY5Y cells were transplanted onto the surface coated with 6MP-AuNPs-RDP to examine the effect of neurite development. It can be concluded that 6MP-AuNPs-RDP attached to the cell surface and then internalized into cells, leading to a significant increase of neurite growth. Even though 6MP-AuNPs-RDP-treated cells were recovered from frozen storage, the cells still maintained constant growth, indicating that the cells have excellent tolerance to 6MP-AuNPs-RDP. The results suggested that the 6MP-AuNPs-RDP had promising potential to be developed as a neurophic nanomaterial for neuronal growth.

Tuning the Flexibility of Glycine-Serine Linkers To Allow Rational Design of Multidomain Proteins

Flexible polypeptide linkers composed of glycine and serine are important components of engineered multidomain proteins. We have previously shown that the conformational properties of Gly-Gly-Ser repeat linkers can be quantitatively understood by comparing experimentally determined Förster resonance energy transfer (FRET) efficiencies of ECFP-linker-EYFP proteins to theoretical FRET efficiencies calculated using wormlike chain and Gaussian chain models. Here we extend this analysis to include linkers with different glycine contents. We determined the FRET efficiencies of ECFP-linker-EYFP proteins with linkers ranging in length from 25 to 73 amino acids and with glycine contents of 33.3% (GSSGSS), 16.7% (GSSSSSS), and 0% (SSSSSSS). The FRET efficiency decreased with an increasing linker length and was overall lower for linkers with less glycine. Modeling the linkers using the WLC model revealed that the experimentally observed FRET efficiencies were consistent with persistence lengths of 4.5, 4.8, and 6.2 Å for the GSSGSS, GSSSSS, and SSSSSS linkers, respectively. The observed increase in linker stiffness with reduced glycine content is much less pronounced than that predicted by a classical model developed by Flory and co-workers. We discuss possible reasons for this discrepancy as well as implications for using the stiffer linkers to control the effective concentrations of connected domains in engineered multidomain proteins.

The Complicated Relationship between Gaucher Disease and Parkinsonism: Insights from a Rare Disease

The discovery of a link between mutations in GBA1, encoding the lysosomal enzyme glucocerebrosidase, and the synucleinopathies directly resulted from the clinical recognition of patients with Gaucher disease with parkinsonism. Mutations in GBA1 are now the most common known genetic risk factor for several Lewy body disorders, and an inverse relationship exists between levels of glucocerebrosidase and oligomeric α-synuclein. While the underlying mechanisms are still debated, this complicated association is shedding light on the role of lysosomes in neurodegenerative disorders, demonstrating how insights from a rare disorder can direct research into the pathogenesis and therapy of seemingly unrelated common diseases.

The Spectrum of Neurological Manifestations Associated with Gaucher Disease

Gaucher disease, the most common lysosomal storage disorder, is due to a deficiency in the enzyme glucocerebrosidase. This leads to the accumulation of its normal substrate, glucocerebroside, in tissue macrophages, affecting the hematological, visceral, bone and neurologic systems. Gaucher disease is classified into three broad phenotypes based upon the presence or absence of neurological involvement: type 1 (non-neuronopathic), type 2 (acute neuronopathic), and type 3 (subacute neuronopathic). Phenotypically, there is a wide spectrum of visceral and neurological manifestations. Enzyme replacement is effective in managing the visceral disease; however, treating the neurological manifestations has proved to be more challenging. This review discusses the various neurological manifestations encountered in Gaucher disease, and provides a brief overview regarding the treatment and ongoing research challenges.

A new glucocerebrosidase-deficient neuronal cell model provides a tool to probe pathophysiology and therapeutics for Gaucher disease

Glucocerebrosidase is a lysosomal hydrolase involved in the breakdown of glucosylceramide. Gaucher disease, a recessive lysosomal storage disorder, is caused by mutations in the gene GBA1. Dysfunctional glucocerebrosidase leads to accumulation of glucosylceramide and glycosylsphingosine in various cell types and organs. Mutations in GBA1 are also a common genetic risk factor for Parkinson disease and related synucleinopathies. In recent years, research on the pathophysiology of Gaucher disease, the molecular link between Gaucher and Parkinson disease, and novel therapeutics, have accelerated the need for relevant cell models with GBA1 mutations. Although induced pluripotent stem cells, primary rodent neurons, and transfected neuroblastoma cell lines have been used to study the effect of glucocerebrosidase deficiency on neuronal function, these models have limitations because of challenges in culturing and propagating the cells, low yield, and the introduction of exogenous mutant GBA1. To address some of these difficulties, we established a high yield, easy-to-culture mouse neuronal cell model with nearly complete glucocerebrosidase deficiency representative of Gaucher disease. We successfully immortalized cortical neurons from embryonic null allele gba^−/− mice and the control littermate (gba^+/+) by infecting differentiated primary cortical neurons in culture with an EF1α-SV40T lentivirus. Immortalized gba^−/− neurons lack glucocerebrosidase protein and enzyme activity, and exhibit a dramatic increase in glucosylceramide and glucosylsphingosine accumulation, enlarged lysosomes, and an impaired ATP-dependent calcium-influx response; these phenotypical characteristics were absent in gba^+/+ neurons. This null allele gba^−/− mouse neuronal model provides a much-needed tool to study the pathophysiology of Gaucher disease and to evaluate new therapies.

Summary: This work describes the generation of a novel immortalized glucocerebrosidase-deficient neuronal cell model with utility for pathophysiology research and therapeutic development in Gaucher disease.

Progress and potential of non-inhibitory small molecule chaperones for the treatment of Gaucher disease and its implications for Parkinson disease

Gaucher disease, caused by pathological mutations GBA1, encodes the lysosome-resident enzyme glucocerebrosidase, which cleaves glucosylceramide into glucose and ceramide. In Gaucher disease, glucocerebrosidase deficiency leads to lysosomal accumulation of substrate, primarily in cells of the reticulo-endothelial system. Gaucher disease has broad clinical heterogeneity, and mutations in GBA1 are a risk factor for the development of different synucleinopathies. Insights into the cell biology and biochemistry of glucocerebrosidase have led to new therapeutic approaches for Gaucher disease including small chemical chaperones. Such chaperones facilitate proper enzyme folding and translocation to lysosomes, thereby preventing premature breakdown of the enzyme in the proteasome. This review discusses recent progress in developing chemical chaperones as a therapy for Gaucher disease, with implications for the treatment of synucleinopathies. It focuses on the development of non-inhibitory glucocerebrosidase chaperones and their therapeutic advantages over inhibitory chaperones, as well as the challenges involved in identifying and validating chemical chaperones.