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.

Ayyadevara, Haarika et al. (2021) International Worm Meeting "C. elegans precision AD models confirm transcriptional disruption of autophagy by APOE4 but not APOE3, and help to characterize E4-specific drugs"

Shmookler Reis, Robert, Ganne, Akshatha, Griffin, Sue, Balasubramaniam, Meenakshisundaram, Ayyadevara, Haarika

[International Worm Meeting, 2021]

Apolipoprotein E (APOE) is a multifunctional protein that transports lipids and also helps to repair brain injuries. By far the strongest genetic risk factor for late-onset Alzheimer's disease (AD) is the inheritance of APOE epsilon4 alleles (APOE4), increasing AD likelihood by at least 4-fold per epsilon4 copy - a risk elevation for which mechanisms remain unclear. The APOE genotype influences clearance of protein aggregates from the brain, in particular peri-neuronal aggregates containing amyloid-beta and intra-neuronal tau aggregates - two hallmark aggregates for AD. We found that under neuronal stress, APOE4 protein translocates to the nucleus and competes with the transcription factor EB (TFEB) for binding to CLEAR enhancer sites in DNA, thus impeding transcription of TFEB targets, many of which are part of the lysosomal/ autophagy pathway. APOE4, but not APOE3, binds to CLEAR sites and prevents transcription of key autophagy proteins p62/SQSTM1, LAMP2, and LC3B. In the absence of these gene products, the autophagic aggregate-clearance response to starvation/neuronal stress is blunted, resulting in an APOE4-specific increase in protein aggregation. Although C. elegans lacks an APOE ortholog, it expresses the hlh-30 ortholog of TFEB for which the CLEAR binding-motif targets are almost perfectly conserved. It therefore provides a model in which APOE4 may compete for CLEAR sites free of any lipid-transport or other function. We devised a novel protocol to introduce human APOE4 protein directly into transgenic C. elegans models of AD. In adult worms expressing human Abeta42 in muscle, beta-amyloid accumulation is increased by APOE4 relative to E3; whereas worms expressing Abeta42 in neurons showed less chemotaxis after E4. We also identified a novel therapeutic small molecule targeting APOE4 protein preferentially over APOE3, which alleviates the age- and aggregation-mediated chemotactic decline in worms expressing neuronal Abeta42.

ayyadevara, srinivas et al. (2019) International Worm Meeting "A novel microtubule-binding drug attenuates and reverses protein aggregation in animal models of Alzheimer's disease."

Kakraba, Samuel, Alla, Ramani, Penthala, Narsimha Reddy, Griffin, Sue, Ganne, Akshatha, Barger, Steven, Ayyadevara, Srinivas, Liu , Ling, Shmookler Reis, Robert, Balasubramaniam, Meenakshisundaram, Bommagani, Shoban Babu, Crooks, Peter

[International Worm Meeting, 2019]

Age-progressive neurodegenerative pathologies, including Alzheimer's disease, are distinguished and diagnosed by disease-specific components of intra- or extra-cellular aggregates. Increasing evidence suggests that neuroinflammation promotes protein aggregation, and is involved in the etiology of neurological diseases. We synthesized and tested analogues of the naturally occurring tubulin-binding compound, combretastatin A-4. One such analogue, PNR502, markedly reduced the quantity of Alzheimer-associated amyloid aggregates in the BRI-A?1-42 mouse model of Alzheimer's disease, while blunting the ability of the pro-inflammatory cytokine IL-1? to raise levels of amyloid plaque and its protein precursors in a neuronal cell-culture model. In transgenic C. elegans strains that express human A?1-42 in muscle or neurons, PNR502 rescued A?-induced disruption of motility (3.8-fold, p<0.0001) or chemotaxis (1.8-fold, p<0.05), respectively. Moreover, in C. elegans with neuronal expression of A?1-42, a single day of PNR502 exposure reverses the chemotaxis deficit by 54% (p<0.01), actually exceeding the protection from longer exposure. Moreover, continuous PNR502 treatment also extends nematode lifespan 23% (p?0.001). Given that PNR502 can slow, prevent, or reverse Alzheimer-like protein aggregation in human-cell-culture and animal models, and that its principal predicted and observed binding targets are proteins previously implicated in Alzheimer's, we propose that PNR502 has therapeutic potential to inhibit cerebral A?1-42 aggregation and prevent or reverse neurodegeneration.