Therapeutic targeting of Lyn kinase to treat chorea-acanthocytosis

Physiological and Pathogenesis Significance of Chorein in Health and Disease

This comprehensive review explores the physiological and pathophysiological significance of VPS13A, a protein encoded by the VPS13A gene. The VPS13A gene is associated with Chorea-acanthocytosis (ChAc), a rare hereditary neurodegenerative disorder. The review covers essential aspects, beginning with the genetics of VPS13A, highlighting its role in the pathogenesis of ChAc, and addressing the spectrum of genetic variants involved. It delves into the structure and function of the VPS13A protein, emphasizing its presence in various tissues and its potential involvement in protein trafficking and lipid homeostasis. Molecular functions of VPS13A in the brain tissue and other cell types or tissues with respect to their role in cytoskeletal regulation and autophagy are explored. Finally, it explores the intriguing link between VPS13A mutations, lipid imbalances, and neurodegeneration, shedding light on future research directions. Overall, this review serves as a comprehensive resource for understanding the pivotal role of VPS13A in health and disease, particularly in the context of ChAc. Key words: Chorein , Tumor, Actin, Microfilament, Gene expression, Chorea-acanthocytosis.

An Autopsy Series of Seven Cases of VPS13A Disease (Chorea-Acanthocytosis)

BACKGROUND

Vacuolar protein sorting 13 homolog A (VPS13A) disease, historically known as chorea-acanthocytosis, is a rare neurodegenerative disorder caused by biallelic mutations in VPS13A, usually resulting in reduced or absent levels of its protein product, VPS13A. VPS13A localizes to contact sites between subcellular organelles, consistent with its recently identified role in lipid transfer between membranes. Mutations are associated with neuronal loss in the striatum, most prominently in the caudate nucleus, and associated marked astrogliosis. There are no other known disease-specific cellular changes (eg, protein aggregation), but autopsy reports to date have been limited, often lacking genetic or biochemical diagnostic confirmation.

OBJECTIVE

The goal of this study was to characterize neuropathological findings in the brains of seven patients with VPS13A disease (chorea-acanthocytosis).

METHODS

In this study, we collected brain tissues and clinical data from seven cases of VPS13A for neuropathological analysis. The clinical diagnosis was confirmed by the presence of VPS13A mutations and/or immunoblot showing the loss or reduction of VPS13A protein. Tissues underwent routine, special, and immunohistochemical staining focused on neurodegeneration. Electron microscopy was performed in one case.

RESULTS

Gross examination showed severe striatal atrophy. Microscopically, there was neuronal loss and astrogliosis in affected regions. Luxol fast blue staining showed variable lipid accumulation with diverse morphology, which was further characterized by electron microscopy. In some cases, rare degenerating p62- and ubiquitin-positive cells were present in affected regions. Calcifications were present in four cases, being extensive in one.

CONCLUSIONS

We present the largest autopsy series of biochemically and genetically confirmed VPS13A disease and identify novel histopathological findings implicating abnormal lipid accumulation. © 2023 International Parkinson and Movement Disorder Society.

Nilotinib alleviates paraquat-induced hepatic and pulmonary injury in rats via the Nrf2/Nf-kB axis

BACKGROUND

Paraquat (PQ, 1,1'-dimethyl-4-4'-bipyridinium dichloride) is a highly toxic quaternary ammonium herbicide widely used in agriculture. It exerts its toxic effects mainly as a result of its redox cycle via the production of superoxide anions in organisms, leading to an imbalance in the redox state of the cell causing oxidative damage and finally cell death. The aim of this study was to estimate the beneficial protective role of nilotinib (NIL) on PQ-induced hepatic and pulmonary toxicity in rats.

METHODS

Male wistar rats were randomly divided into four groups, namely control, PQ (15 mg/kg), PQ plus NIL (5 mg/kg) and PQ plus NIL (10 mg/kg). NIL (5 and 10 mg/kg/day) was taken by oral syringe for five days followed by a single intra-peritoneal administration of PQ (15 mg/kg) on sixth day.

RESULTS

Pretreatment with NIL relieved the histological damage in liver and lung tissues and improved hepatic biochemical markers. It significantly (p < 0.05) reduced serum levels of ALT, AST, ALP, Y-GT and total bilirubin while increased that of albumin. Meanwhile, NIL significantly (p < 0.05) reduced oxidative stress markers via reduction of malondialdhyde (MDA) and elevation of glutathione (GSH) contents in liver and lung tissues. In addition, it significantly (p < 0.05) decreased the inflammation by reducing hepatic and pulmonary tumor necrosis factor alpha (TNF-α) and nuclear transcription factor kappa B (NF-KB/p65) contents. Nilotinib also down-regulated apoptosis by reducing cysteinyl aspartate-specific proteinase-3 (caspase-3). Furthermore, it upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and microtubule-associated protein 1A/1B-light chain 3 II (LC3II) in liver and lung tissues.

SIGNIFICANCE

NIL suppressed PQ-induced inflammation, oxidative stress and apoptosis in liver and lung tissues by modulating Nrf2/Nf-kB axis.

VPS13A knockdown impairs corticostriatal synaptic plasticity and locomotor behavior in a new mouse model of chorea-acanthocytosis

Chorea-acanthocytosis (ChAc) is an inherited neurodegenerative movement disorder caused by VPS13A gene mutations leading to the absence of protein expression. The striatum is the most affected brain region in ChAc patients. However, the study of the VPS13A function in the brain has been poorly addressed. Here we generated a VPS13A knockdown (KD) model and aimed to elucidate the contribution of VPS13A to synaptic plasticity and neuronal communication in the corticostriatal circuit. First, we infected primary cortical neurons with miR30-shRNA against VPS13A and analyzed its effects on neuronal plasticity. VPS13A-KD neurons showed a higher degree of branching than controls, accompanied by decreased BDNF and PSD-95 levels, indicative of synaptic alterations. We then injected AAV-KD bilaterally in the frontal cortex and two different regions of the striatum of mice and analyzed the effects of VPS13A-KD on animal behavior and synaptic plasticity. VPS13A-KD mice showed modification of the locomotor behavior pattern, with increased exploratory behavior and hyperlocomotion. Corticostriatal dysfunction in VPS13A-KD mice was evidenced by impaired striatal long-term depression (LTD) after stimulation of cortical afferents, which was partially recovered by BDNF administration. VPS13A-KD did not lead to neuronal loss in the cortex or the striatum but induced a decrease in the neuronal release of CX3CL1 and triggered a microglial reaction, especially in the striatum. Notably, CX3CL1 administration partially restored the impaired corticostriatal LTD in VPS13A-KD mice. Our results unveil the involvement of VPS13A in neuronal connectivity modifying BDNF and CX3CL1 release. Moreover, the involvement of VPS13A in synaptic plasticity and motor behavior provides key information to further understand not only ChAc pathophysiology but also other neurological disorders.

Sphingolipid and Phospholipid Levels Are Altered in Human Brain in Chorea-Acanthocytosis

BACKGROUND

Chorea-acanthocytosis (ChAc) is associated with mutations of VPS13A, which encodes for chorein, a protein implicated in lipid transport at intracellular membrane contact sites.

OBJECTIVES

The goal of this study was to establish the lipidomic profile of patients with ChAc.

METHODS

We analyzed 593 lipid species in the caudate nucleus (CN), putamen, and dorsolateral prefrontal cortex (DLPFC) from postmortem tissues of four patients with ChAc and six patients without ChAc.

RESULTS

We found increased levels of bis(monoacylglycerol)phosphate, sulfatide, lysophosphatidylserine, and phosphatidylcholine ether in the CN and putamen, but not in the DLPFC, of patients with ChAc. Phosphatidylserine and monoacylglycerol were increased in the CN and N-acyl phosphatidylserine in the putamen. N-acyl serine was decreased in the CN and DLPFC, whereas lysophosphatidylinositol was decreased in the DLPFC.

CONCLUSIONS

We present the first evidence of altered sphingolipid and phospholipid levels in the brains of patients with ChAc. Our observations are congruent with recent findings in cellular and animal models, and implicate defects of lipid processing in VPS13A disease pathophysiology. © 2023 International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Duality of Nrf2 in iron-overload cardiomyopathy

Cardiomyopathy deeply affects quality of life and mortality of patients with b-thalassemia or with transfusion-dependent myelodysplastic syndromes. Recently, a link between Nrf2 activity and iron metabolism has been reported in liver ironoverload murine models. Here, we studied C57B6 mice as healthy control and nuclear erythroid factor-2 knockout (Nrf2-/-) male mice aged 4 and 12 months. Eleven-month-old wild-type and Nrf2-/- mice were fed with either standard diet or a diet containing 2.5% carbonyl-iron (iron overload [IO]) for 4 weeks. We show that Nrf2-/- mice develop an age-dependent cardiomyopathy, characterized by severe oxidation, degradation of SERCA2A and iron accumulation. This was associated with local hepcidin expression and increased serum non-transferrin-bound iron, which promotes maladaptive cardiac remodeling and interstitial fibrosis related to overactivation of the TGF-b pathway. When mice were exposed to IO diet, the absence of Nrf2 was paradoxically protective against further heart iron accumulation. Indeed, the combination of prolonged oxidation and the burst induced by IO diet resulted in activation of the unfolded protein response (UPR) system, which in turn promotes hepcidin expression independently from heart iron accumulation. In the heart of Hbbth3/+ mice, a model of b-thalassemia intermedia, despite the activation of Nrf2 pathway, we found severe protein oxidation, activation of UPR system and cardiac fibrosis independently from heart iron content. We describe the dual role of Nrf2 when aging is combined with IO and its novel interrelation with UPR system to ensure cell survival. We open a new perspective for early and intense treatment of cardiomyopathy in patients with b-thalassemia before the appearance of heart iron accumulation.

Neuroacanthocytosis Syndromes: The Clinical Perspective

The two very rare neurodegenerative diseases historically known as the "neuroacanthocytosis syndromes" are due to mutations of either VPS13A or XK. These are phenotypically similar disorders that affect primarily the basal ganglia and hence result in involuntary abnormal movements as well as neuropsychiatric and cognitive alterations. There are other shared features such as abnormalities of red cell membranes which result in acanthocytes, whose relationship to neurodegeneration is not yet known. Recent insights into the functions of these two proteins suggest dysfunction of lipid processing and trafficking at the subcellular level and may provide a mechanism for neuronal dysfunction and death, and potentially a target for therapeutic interventions.

VPS13 Forum Proceedings: XK, XK-Related and VPS13 Proteins in Membrane Lipid Dynamics

In 2020, the pandemic interrupted the series of biannual International Neuroacanthocytosis Meetings that brought together clinicians, scientists, and patient groups to share research into a small group of devastating genetic diseases that combine both acanthocytosis (deformed red blood cells) and neurodegeneration with movement disorders. This Meeting Report describes talks at the 5th VPS13 Forum in January 2022, one of a series of online meetings held to fill the gap. The meeting addressed the basic biology of two key proteins implicated in chorea-acanthocytosis (mutations in VPS13A) and McLeod syndrome (mutations in XK). In a remarkable confluence of ideas, the speakers described different aspects of a single functional unit that comprises of VPS13A and XK proteins working together. Conditions caused by VPS13 (A-D) gene family mutations and related genes, such as XK, previously footnote knowledge, seem to turn central for a novel disease paradigm: bulk lipid transfer disorders.

FDA-Approved Kinase Inhibitors in Preclinical and Clinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases. We previously developed a new concept termed "Aberrant Cell Cycle Diseases" (ACCD), revealing that these two diseases share a common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncogene activation and tumor suppressor inactivation, which are hallmarks of both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase inhibition, tumor suppressor elevation) can be leveraged for neurological treatments. The United States Food and Drug Administration (US FDA) has so far approved 74 kinase inhibitors, with numerous other kinase inhibitors in clinical trials, mostly for the treatment of cancers. In contrast, there are dire unmet needs of FDA-approved drugs for neurological treatments, such as Alzheimer's disease (AD), intracerebral hemorrhage (ICH), ischemic stroke (IS), traumatic brain injury (TBI), and others. In this review, we list these 74 FDA-approved kinase-targeted drugs and identify those that have been reported in preclinical and/or clinical trials for neurological disorders, with a purpose of discussing the feasibility and applicability of leveraging these cancer drugs (FDA-approved kinase inhibitors) for neurological treatments.

A partnership between the lipid scramblase XK and the lipid transfer protein VPS13A at the plasma membrane

Chorea-acanthocytosis (ChAc) and McLeod syndrome are diseases with shared clinical manifestations caused by mutations in VPS13A and XK, respectively. Key features of these conditions are the degeneration of caudate neurons and the presence of abnormally shaped erythrocytes. XK belongs to a family of plasma membrane (PM) lipid scramblases whose action results in exposure of PtdSer at the cell surface. VPS13A is an endoplasmic reticulum (ER)-anchored lipid transfer protein with a putative role in the transport of lipids at contacts of the ER with other membranes. Recently VPS13A and XK were reported to interact by still unknown mechanisms. So far, however, there is no evidence for a colocalization of the two proteins at contacts of the ER with the PM, where XK resides, as VPS13A was shown to be localized at contacts between the ER and either mitochondria or lipid droplets. Here we show that VPS13A can also localize at ER-PM contacts via the binding of its PH domain to a cytosolic loop of XK, that such interaction is regulated by an intramolecular interaction within XK, and that both VPS13A and XK are highly expressed in the caudate neurons. Binding of the PH domain of VPS13A to XK is competitive with its binding to intracellular membranes that mediate other tethering functions of VPS13A. Our findings support a model according to which VPS13A-dependent lipid transfer between the ER and the PM is coupled to lipid scrambling within the PM. They raise the possibility that defective cell surface exposure of PtdSer may be responsible for neurodegeneration.

An Endemic Plant of the Mediterranean Area: Phytochemical Characterization of Strawberry Tree (Arbutus unedo L.) Fruits Extracts at Different Ripening Stages

This work focused on the extraction, quantification, and characterization of bioactive compounds of Arbutus unedo L. fruits, comparing the results obtained from the different ripening states. Extractions were performed by different methods (such as maceration extraction and ultrasonic extraction) and food grade solvents (aqueous and hydroalcoholic solvents) in each of the all ripening states (four states considered, associated with four different colors, i.e., green, yellow, orange, and red). The presence of (poly)phenols was quantified and characterized, and scavenging activity was determined by the Folin–Ciocâlteu reagent and the DPPH method, respectively. The content of bioactive compounds was characterized by LC-MS/MS, such as multiple reaction monitoring (MRM) mass spectrometry. The results showed that ultrasound-assisted extraction (UAE) performed better than maceration extraction; ethanol–water mixture extracts showed a more positive effect than the use of aqueous extracts regarding the content of total phenolic compounds. Overall, the total phenolic compounds in the EtOH:H₂O mixture at a ratio of 7:3 (v:v) were higher than that of the other solvents for both extraction methods. Some bioactive molecules were characterized for the first time in the extracts of A. unedo. The chemical profile of the strawberry tree extracts depended on the degree of fruit ripeness. The results suggest that A. unedo fruits may be of great interest for food and nutraceutical applications.

Yeast as a Model to Find New Drugs and Drug Targets for VPS13-Dependent Neurodegenerative Diseases

Mutations in human VPS13A-D genes result in rare neurological diseases, including chorea-acanthocytosis. The pathogenesis of these diseases is poorly understood, and no effective treatment is available. As VPS13 genes are evolutionarily conserved, the effects of the pathogenic mutations could be studied in model organisms, including yeast, where one VPS13 gene is present. In this review, we summarize advancements obtained using yeast. In recent studies, vps13Δ and vps13-I2749 yeast mutants, which are models of chorea-acanthocytosis, were used to screen for multicopy and chemical suppressors. Two of the suppressors, a fragment of the MYO3 and RCN2 genes, act by downregulating calcineurin activity. In addition, vps13Δ suppression was achieved by using calcineurin inhibitors. The other group of multicopy suppressors were genes: FET4, encoding iron transporter, and CTR1, CTR3 and CCC2, encoding copper transporters. Mechanisms of their suppression rely on causing an increase in the intracellular iron content. Moreover, among the identified chemical suppressors were copper ionophores, which require a functional iron uptake system for activity, and flavonoids, which bind iron. These findings point at areas for further investigation in a higher eukaryotic model of VPS13-related diseases and to new therapeutic targets: calcium signalling and copper and iron homeostasis. Furthermore, the identified drugs are interesting candidates for drug repurposing for these diseases.

Changes in Blood Cell Deformability in Chorea-Acanthocytosis and Effects of Treatment With Dasatinib or Lithium

Misshaped red blood cells (RBCs), characterized by thorn-like protrusions known as acanthocytes, are a key diagnostic feature in Chorea-Acanthocytosis (ChAc), a rare neurodegenerative disorder. The altered RBC morphology likely influences their biomechanical properties which are crucial for the cells to pass the microvasculature. Here, we investigated blood cell deformability of five ChAc patients compared to healthy controls during up to 1-year individual off-label treatment with the tyrosine kinase inhibitor dasatinib or several weeks with lithium. Measurements with two microfluidic techniques allowed us to assess RBC deformability under different shear stresses. Furthermore, we characterized leukocyte stiffness at high shear stresses. The results showed that blood cell deformability–including both RBCs and leukocytes - in general was altered in ChAc patients compared to healthy donors. Therefore, this study shows for the first time an impairment of leukocyte properties in ChAc. During treatment with dasatinib or lithium, we observed alterations in RBC deformability and a stiffness increase for leukocytes. The hematological phenotype of ChAc patients hinted at a reorganization of the cytoskeleton in blood cells which partly explains the altered mechanical properties observed here. These findings highlight the need for a systematic assessment of the contribution of impaired blood cell mechanics to the clinical manifestation of ChAc.

XK-Associated McLeod Syndrome: Nonhematological Manifestations and Relation to VPS13A Disease

BACKGROUND

McLeod syndrome (MLS) is an X-linked multisystemic progressive disorder caused by loss of function mutations in the XK gene. The rare blood group phenotype of MLS patients with absent Kx antigen requires the support of specialized transfusion institutions because of the risk of transfusion complications. Acanthocytosis of red blood cells occurs in almost all patients. Nonhematological manifestations of MLS are very similar to those of VPS13A disease (chorea-acanthocytosis), an autosomal-recessive condition. Their shared phenotype apart from acanthocytosis includes movement disorders such as chorea and dystonia, epilepsy, peripheral neuropathy, and muscle involvement, typically with creatine kinase (CK) elevation, cardiomyopathy included.

SUMMARY

In this review, we describe the nonhematological manifestations of MLS in comparison with those of VPS13A disease. While there are many similarities, differences such as mode of inheritance, sex distribution, age at manifestation, severity of heart involvement, frequency of feeding dystonia or of involuntary head drops may help to distinguish these disorders in the clinic. Immunohematological demonstration of the McLeod-Kell phenotype or detection of pathogenic mutations of XK (or VPS13A, respectively) is the gold standard for distinction. "Neuroacanthocytosis" was often used as an overarching term, but is potentially misleading, as the term does not refer to a defined disease entity. Its use, if continued, must not prevent clinicians to seek a final diagnosis on the basis of molecular findings. The clinical similarity of MLS and VPS13A disease has long suggested some shared pathophysiology. Evidence for molecular interaction between XK, the McLeod protein, and chorein, the VPS13A gene product, has recently been put forward: XK forms a complex with chorein/VPS13A, a bulk lipid transporter located at various membrane contact sites. The exact role of XK in this complex needs to be further elucidated. Impairment of bulk lipid transport appears as the common denominator of both MLS and VPS13A disease. A variety of further conditions may in time be added to the "bulk lipid transport diseases," such as the recently recognized disorders caused by mutations in the VPS13B, VPS13C, and VPS13D genes.

KEY MESSAGES

(1) Patients diagnosed with the rare red cell McLeod phenotype (McLeod syndrome, MLS) require interdisciplinary collaboration of transfusion medicine specialists, neurologists, and cardiologists for both their hematological and nonhematological disease manifestations. (2) The phenotypical similarity of MLS and VPS13A disease, often leading to either confusion or insufficient diagnostic depth (under the label of "neuroacanthocytosis"), is based on interaction of the respective proteins, XK and chorein, within the cellular machinery for bulk lipid transport. (3) Overall, the term "bulk lipid transport diseases" seems useful for further research on a group of conditions that may not only share pathophysiology, but may also share treatment approaches.

Adaptative Up-Regulation of PRX2 and PRX5 Expression Characterizes Brain from a Mouse Model of Chorea-Acanthocytosis

The peroxiredoxins (PRXs) constitute a ubiquitous antioxidant. Growing evidence in neurodegenerative disorders such as Parkinson’s disease (PD) or Alzheimer’s disease (AD) has highlighted a crucial role for PRXs against neuro-oxidation. Chorea-acanthocytosis/Vps13A disease (ChAc) is a devastating, life-shortening disorder characterized by acanthocytosis, neurodegeneration and abnormal proteostasis. We recently developed a Vps13a^−/− ChAc-mouse model, showing acanthocytosis, neurodegeneration and neuroinflammation which could be restored by LYN inactivation. Here, we show in our Vps13a^−/− mice protein oxidation, NRF2 activation and upregulation of downstream cytoprotective systems NQO1, SRXN1 and TRXR in basal ganglia. This was associated with upregulation of PRX2/5 expression compared to wild-type mice. PRX2 expression was age-dependent in both mouse strains, whereas only Vps13a^−/− PRX5 expression was increased independent of age. LYN deficiency or nilotinib-mediated LYN inhibition improved autophagy in Vps13a^−/− mice. In Vps13a^−/−; Lyn^−/− basal ganglia, absence of LYN resulted in reduced NRF2 activation and down-regulated expression of PRX2/5, SRXN1 and TRXR. Nilotinib treatment of Vps13a^−/− mice reduced basal ganglia oxidation, and plasma PRX5 levels, suggesting plasma PRX5 as a possible ChAc biomarker. Our data support initiation of therapeutic Lyn inhibition as promptly as possible after ChAc diagnosis to minimize development of irreversible neuronal damage during otherwise inevitable ChAc progression.

The Erythrocyte Sedimentation Rate and Its Relation to Cell Shape and Rigidity of Red Blood Cells from Chorea-Acanthocytosis Patients in an Off-Label Treatment with Dasatinib

Background: Chorea-acanthocytosis (ChAc) is a rare hereditary neurodegenerative disease with deformed red blood cells (RBCs), so-called acanthocytes, as a typical marker of the disease. Erythrocyte sedimentation rate (ESR) was recently proposed as a diagnostic biomarker. To date, there is no treatment option for affected patients, but promising therapy candidates, such as dasatinib, a Lyn-kinase inhibitor, have been identified. Methods: RBCs of two ChAc patients during and after dasatinib treatment were characterized by the ESR, clinical hematology parameters and the 3D shape classification in stasis based on an artificial neural network. Furthermore, mathematical modeling was performed to understand the contribution of cell morphology and cell rigidity to the ESR. Microfluidic measurements were used to compare the RBC rigidity between ChAc patients and healthy controls. Results: The mechano-morphological characterization of RBCs from two ChAc patients in an off-label treatment with dasatinib revealed differences in the ESR and the acanthocyte count during and after the treatment period, which could not directly be related to each other. Clinical hematology parameters were in the normal range. Mathematical modeling indicated that RBC rigidity is more important for delayed ESR than cell shape. Microfluidic experiments confirmed a higher rigidity in the normocytes of ChAc patients compared to healthy controls. Conclusions: The results increase our understanding of the role of acanthocytes and their associated properties in the ESR, but the data are too sparse to answer the question of whether the ESR is a suitable biomarker for treatment success, whereas a correlation between hematological and neuronal phenotype is still subject to verification.