Bizat N et al. (2021) Brain "An in vivo Caenorhabditis elegans model for therapeutic research in human prion diseases."

Ravassard P, Laplanche JL, Brandel JP, Beaudry P, Laoues S, Levavasseur E, Parrales V, Privat N, Bizat N, Haik S, Gougerot A, Normant S, Roussel J

[Brain, 2021]

Human prion diseases are fatal neurodegenerative disorders that include sporadic, infectious and genetic forms. Inherited Creutzfeldt-Jakob disease due to the E200K mutation of the prion protein-coding gene is the most common form of genetic prion disease. The phenotype resembles that of sporadic Creutzfeldt-Jakob disease at both the clinical and pathological levels, with a median disease duration of 4 months. To date, there is no available treatment for delaying the occurrence or slowing the progression of human prion diseases. Existing in vivo models do not allow high-throughput approaches that may facilitate the discovery of compounds targeting pathological assemblies of human prion protein or their effects on neuronal survival. Here, we generated a genetic model in the nematode Caenorhabditis elegans, which is devoid of any homologue of the prion protein, by expressing human prion protein with the E200K mutation in the mechanosensitive neuronal system. Expression of E200K prion protein induced a specific behavioural pattern and neurodegeneration of green fluorescent protein-expressing mechanosensitive neurons, in addition to the formation of intraneuronal inclusions associated with the accumulation of a protease-resistant form of the prion protein. We demonstrated that this experimental system is a powerful tool for investigating the efficacy of anti-prion compounds on both prion-induced neurodegeneration and prion protein misfolding, as well as in the context of human prion protein. Within a library of 320 compounds that have been approved for human use and cross the blood-brain barrier, we identified five molecules that were active against the aggregation of the E200K prion protein and the neurodegeneration it induced in transgenic animals. This model breaks a technological limitation in prion therapeutic research and provides a key tool to study the deleterious effects of misfolded prion protein in a well-described neuronal system.

Boland, Sebastian et al. (2017) International Worm Meeting "PEGCs: novel glycosphingolipids that mobilize cholesterol in Caenorhabditis elegans."

Boland, Sebastian, Sampaio, Julio, L., Zagoriy, Vyacheslav, Fritsche, Raphael, Reimann, Jakob, Lubken, Tilo, Knolker, Hans-Joachim, Penkov, Sider, Czerwonka, Regina, Schmidt, Ulrike, Kurzchalia, Teymuras, V.

[International Worm Meeting, 2017]

Caenorhabditis elegans (C. elegans) cannot synthesize cholesterol de novo, and requires exogenous cholesterol to progress through its four larval stages. Previously, we showed that worms grown for 2 generations in the absence of cholesterol arrest early in development. This suggests that maternal contributions of sterols are exploitable only in the first generation, but sterol reservoirs are either depleted or inaccessible by the second generation. Here, we present a novel class of phosphorylated glycosphingolipids, which we coined phosphoethanolamine glucosylceramides (PEGCs), that can overcome the sterol deprivation-induced larval arrest. However, they are not direct substitutes for cholesterol because they rescue larval arrest in only one additional generation. Instead, we propose a new model where larval arrest in the second generation of continious sterol deprivation is due not to depletion of internal reservoirs, but a failure to mobilize those reservoirs for promoting growth/development through PEGCs-induced mobilization of internal sterol pools. More precisely, we found that NPC1 and DAF-7 mutants, which display a Daf-c phenotype due to an impaired sterol transport to places of DA synthesis, are rescued by feeding PEGC. Moreover, the biosynthesis of PEGC depends on functional NPC1 and TGF- beta , indicating that these proteins control larval development at least partly through promoting increases in PEGC. Furthermore, glucosylceramide deficiency dramatically reduced PEGC amounts; however, the resulting developmental arrest could be rescued by over-saturation of food with cholesterol. This indicates that PEGC is a major regulator of cholesterol utilization in C. elegans and, thus, of development. The remarkable similarity in sterol trafficking between C. elegans and other metazoans, including mammals, suggests PEGCs might be conserved regulators of sterol transport.

Ganne, Akshatha et al. (2021) International Worm Meeting "14-3-3 and its interacting proteins in aging and neurodegeneration"

Ganne, Akshatha, Balasubramaniam, Meenakshisundaram, Reis, Robert Shmookler, Ayyadevara, Srinivas

[International Worm Meeting, 2021]

The 14-3-3 proteins are an evolutionarily conserved family of proteins that are ubiquitous from nematodes to humans. They are intrinsically unstructured proteins that bind to a diverse array of key regulatory-protein targets, modulating their functions. They were shown to bind to DAF-16 and SIR-2.1 proteins, with substantial effects on C.elegans lifespan. In mammals, these regulatory proteins are most highly expressed in brain/cerebral tissue, predominantly in neurons. Their presence in cerebrospinal fluid may serve as biomarkers of neuronal damage associated with Alzheimer's disease (AD), Creutzfeldt-Jakob disease (CJD), spongiform encephalitis, brain cancers, and stroke. We also observed a significant enrichment of specific 14-3-3 isoforms among the proteins we identified in neuropathy-associated protein aggregates. Intriguingly, the interacting partners of 14-3-3 isoforms are altered in AD. We pursued these observations in the present study, by immunoprecipitation to isolate specific aggregate types, followed by mass spectrometry to identify interacting protein partners of 14-3-3, and thus to gain insights into their roles in C.elegans aging and models of age- associated neurodegeneration.

Ganne A et al. (2022) Int J Mol Sci "Physiological Consequences of Targeting 14-3-3 and Its Interacting Partners in Neurodegenerative Diseases."

Ganne A, Balasubramaniam M, Shmookler Reis RJ, Mainali N, Ayyadevara S, Atluri P

[Int J Mol Sci, 2022]

The mammalian 14-3-3 family comprises seven intrinsically unstructured, evolutionarily conserved proteins that bind >200 protein targets, thereby modulating cell-signaling pathways. The presence of 14-3-3 proteins in cerebrospinal fluid provides a sensitive and specific biomarker of neuronal damage associated with Alzheimer's disease (AD), Creutzfeldt-Jakob disease (CJD), spongiform encephalitis, brain cancers, and stroke. We observed significant enrichment of 14-3-3 paralogs G, S, and Z in human brain aggregates diagnostic of AD. We used intra-aggregate crosslinking to identify 14-3-3 interaction partners, all of which were significantly enriched in AD brain aggregates relative to controls. We screened FDA-approved drugs in silico for structures that could target the 14-3-3G/hexokinase interface, an interaction specific to aggregates and AD. C. elegans possesses only two 14-3-3 orthologs, which bind diverse proteins including DAF-16 (a FOXO transcription factor) and SIR-2.1 (a sensor of nutrients and stress), influencing lifespan. Top drug candidates were tested in C. elegans models of neurodegeneration-associated aggregation and in a human neuroblastoma cell-culture model of AD-like amyloidosis. Several drugs opposed aggregation in all models assessed and rescued behavioral deficits in C. elegans AD-like neuropathy models, suggesting that 14-3-3 proteins are instrumental in aggregate accrual and supporting the advancement of drugs targeting 14-3-3 protein complexes with their partners.

Baker M et al. (2006) Nature "Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17."

Neary D, Robinson T, Mackenzie IR, Dickson D, Snowden J, Rollinson S, Pickering-Brown SM, Cannon A, Crook R, Boeve B, Melquist S, Berger Z, Dickey CA, Adamson J, Mann D, Rademakers R, Gass J, Dwosh E, Sadovnick AD, Zehr C, Baker M, Hutton M, Richardson A, Eriksen J, McGowan E, Feldman H, Lindholm C

[Nature, 2006]

Frontotemporal dementia (FTD) is the second most common cause of dementia in people under the age of 65 years. A large proportion of FTD patients (35-50%) have a family history of dementia, consistent with a strong genetic component to the disease. In 1998, mutations in the gene encoding the microtubule-associated protein tau (MAPT) were shown to cause familial FTD with parkinsonism linked to chromosome 17q21 (FTDP-17). The neuropathology of patients with defined MAPT mutations is characterized by cytoplasmic neurofibrillary inclusions composed of hyperphosphorylated tau. However, in multiple FTD families with significant evidence for linkage to the same region on chromosome 17q21 (D17S1787-D17S806), mutations in MAPT have not been found and the patients consistently lack tau-immunoreactive inclusion pathology. In contrast, these patients have ubiquitin (ub)-immunoreactive neuronal cytoplasmic inclusions and characteristic lentiform ub-immunoreactive neuronal intranuclear inclusions. Here we demonstrate that in these families, FTD is caused by mutations in progranulin (PGRN) that are likely to create null alleles. PGRN is located 1.7 Mb centromeric of MAPT on chromosome 17q21.31 and encodes a 68.5-kDa secreted growth factor involved in the regulation of multiple processes including development, wound repair and inflammation. PGRN has also been strongly linked to tumorigenesis. Moreover, PGRN expression is increased in activated microglia in many neurodegenerative diseases including Creutzfeldt-Jakob disease, motor neuron disease and Alzheimer''s disease. Our results identify mutations in PGRN as a cause of neurodegenerative disease and indicate the importance of PGRN function for neuronal survival.