Loss of <i>ap4s1</i> in zebrafish leads to neurodevelopmental defects resembling spastic paraplegia 52

D’Amore, Angelica; Tessa, Alessandra; Naef, Valentina; Bassi, Maria Teresa; Citterio, Andrea; Romaniello, Romina; Fichi, Gianluca; Galatolo, Daniele; Mero, Serena; Battini, Roberta; Bertocci, Giulia; Baldacci, Jacopo; Sicca, Federico; Gemignani, Federica; Ricca, Ivana; Rubegni, Anna; Hirst, Jennifer; Marchese, Maria; Şahin, Mustafa; Ebrahimi‐Fakhari, Darius; Santorelli, Filippo M.

doi:10.1002/acn3.51018

Cited by 18 publications

(20 citation statements)

References 20 publications

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“…It is orally available and CNS penetrant, with a reported IC50 of 14 nM, and in clinical trials for several neurological disorders, including phase I trials for neuropathic pain and inflammatory CNS disorders as well as a phase II trial for Tourette syndrome 32 . It will now be important to assess the efficacy of ABX-1431 in further pre-clinical models of AP-4 deficiency syndrome, for example, AP-4-deficient zebrafish, which also exhibit an axon growth defect 39 . Our data suggest that the level of MGLL inhibition must be finely tuned, as complete rescue of neurite length only occurred at lower concentrations of ABX-1431 (Fig.…”

Section: Resultsmentioning

confidence: 99%

AP-4-mediated axonal transport controls endocannabinoid production in neurons

et al. 2022

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The adaptor protein complex AP-4 mediates anterograde axonal transport and is essential for axon health. AP-4-deficient patients suffer from a severe neurodevelopmental and neurodegenerative disorder. Here we identify DAGLB (diacylglycerol lipase-beta), a key enzyme for generation of the endocannabinoid 2-AG (2-arachidonoylglycerol), as a cargo of AP-4 vesicles. During normal development, DAGLB is targeted to the axon, where 2-AG signalling drives axonal growth. We show that DAGLB accumulates at the trans-Golgi network of AP-4-deficient cells, that axonal DAGLB levels are reduced in neurons from a patient with AP-4 deficiency, and that 2-AG levels are reduced in the brains of AP-4 knockout mice. Importantly, we demonstrate that neurite growth defects of AP-4-deficient neurons are rescued by inhibition of MGLL (monoacylglycerol lipase), the enzyme responsible for 2-AG hydrolysis. Our study supports a new model for AP-4 deficiency syndrome in which axon growth defects arise through spatial dysregulation of endocannabinoid signalling.

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Section: Resultsmentioning

confidence: 99%

AP-4-mediated axonal transport controls endocannabinoid production in neurons

et al. 2022

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“…5C and D ). Since these proteins are known to change with the loss of AP-4 function, including in AP-4 knockout cells, AP-4 knockout mice and cells from AP-4-HSP patients, 9–11 , 40 , 41 the absence of change argues against a functionally-relevant impact of the novel missense variants in P VUS/VUS _01 .…”

Section: Resultsmentioning

confidence: 99%

High-throughput imaging of ATG9A distribution as a diagnostic functional assay for adaptor protein complex 4-associated hereditary spastic paraplegia

Ebrahimi‐Fakhari

Alecu

Brechmann

et al. 2021

Brain Communications

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Adaptor protein complex 4 (AP-4)-associated hereditary spastic paraplegia is caused by biallelic loss-of-function variants in AP4B1, AP4M1, AP4E1 or AP4S1, which constitute the four subunits of this obligate complex. While the diagnosis of AP-4-associated hereditary spastic paraplegia relies on molecular testing, the interpretation of novel missense variants remains challenging. Here we address this diagnostic gap by using patient-derived fibroblasts to establish a functional assay that measures the subcellular localization of ATG9A, a transmembrane protein that is sorted by AP-4. Using automated high-throughput microscopy, we determine the ratio of the ATG9A fluorescence in the trans-Golgi-network versus cytoplasm and ascertain that this metric meets standards for screening assays (Z’-factor robust > 0.3, strictly standardized mean difference > 3). The ‘ATG9A ratio’ is increased in fibroblasts of 18 well-characterized AP-4-associated hereditary spastic paraplegia patients (mean: 1.54 ± 0.13 vs. 1.21 ± 0.05 (standard deviation) in controls) and receiver-operating-characteristic analysis demonstrates robust diagnostic power (area under the curve: 0.85, 95% confidence interval: 0.849–0.852). Using fibroblasts from two individuals with atypical clinical features and novel biallelic missense variants of unknown significance in AP4B1, we show that our assay can reliably detect AP-4 function. Our findings establish the ‘ATG9A ratio’ as a diagnostic marker of AP-4-associated hereditary spastic paraplegia.

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“…To quantify possible eye abnormalities, we measured the eye size using Danioscope software (Noldus). Electrophysiological forebrain recordings were performed in 120 hpf larval zebrafish, as described [ 30 ]. The whole-mount immunohistochemistry staining was performed as reported [ 29 ] utilizing anti-ATP synthase subunit C (SCMAS) antibody (1:100; Abcam, Cambridge, UK).…”

Section: Methodsmentioning

confidence: 99%

Lysosomal Proteomics Links Disturbances in Lipid Homeostasis and Sphingolipid Metabolism to CLN5 Disease

Doccini

Marchese

Morani

et al. 2022

Cells

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CLN5 disease (MIM: 256731) represents a rare late-infantile form of neuronal ceroid lipofuscinosis (NCL), caused by mutations in the CLN5 gene that encodes the CLN5 protein (CLN5p), whose physiological roles stay unanswered. No cure is currently available for CLN5 patients and the opportunities for therapies are lagging. The role of lysosomes in the neuro-pathophysiology of CLN5 disease represents an important topic since lysosomal proteins are directly involved in the primary mechanisms of neuronal injury occurring in various NCL forms. We developed and implemented a lysosome-focused, label-free quantitative proteomics approach, followed by functional validations in both CLN5-knockout neuronal-like cell lines and Cln5−/− mice, to unravel affected pathways and modifying factors involved in this disease scenario. Our results revealed a key role of CLN5p in lipid homeostasis and sphingolipid metabolism and highlighted mutual NCL biomarkers scored with high lysosomal confidence. A newly generated cln5 knockdown zebrafish model recapitulated most of the pathological features seen in NCL disease. To translate the findings from in-vitro and preclinical models to patients, we evaluated whether two FDA-approved drugs promoting autophagy via TFEB activation or inhibition of the glucosylceramide synthase could modulate in-vitro ROS and lipid overproduction, as well as alter the locomotor phenotype in zebrafish. In summary, our data advance the general understanding of disease mechanisms and modifying factors in CLN5 disease, which are recurring in other NCL forms, also stimulating new pharmacological treatments.

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Loss of ap4s1 in zebrafish leads to neurodevelopmental defects resembling spastic paraplegia 52

Cited by 18 publications

References 20 publications

AP-4-mediated axonal transport controls endocannabinoid production in neurons

AP-4-mediated axonal transport controls endocannabinoid production in neurons

High-throughput imaging of ATG9A distribution as a diagnostic functional assay for adaptor protein complex 4-associated hereditary spastic paraplegia

Lysosomal Proteomics Links Disturbances in Lipid Homeostasis and Sphingolipid Metabolism to CLN5 Disease

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