Research Projects

Amyloid aggregates are hallmark of age-related neurodegenerative diseases (NDDs)¹-⁴. Multiple mechanisms including the presence of pre-formed amyloid seeds from other proteins, oxidative stress, genetic mutations, disruption of cellular protein quality control, interactions with gut bacteria and their amyloidogenic proteins; etc. are known to trigger misfolding and amyloidogenesis of disease-related proteins⁵-¹¹. Viral infections are also long associated with increased risk of age-related amyloid diseases. For example, viral encephalitis is associated with Alzheimer’s disease and influenza infection significantly increases the risk of Parkinson’s disease (PD)¹². However, mechanistic connections between viral infection and amyloid formation are not fully understood and important to investigate to prevent increased load of NDDs in tropical countries like India where viral-infections represent regular health-setbacks. This is particularly important in the background of neurological concerns of the SARS-CoV-2 pandemic. α-Synuclein is an amyloidogenic protein that shuttles between the nucleus, cytoplasm, cell organelles, and the cell membrane¹³-⁸. Amyloid aggregates of this protein are associated with many Synucleopathies including PD¹⁵,¹⁹,²⁰. Marreiros et al. in 2020 showed that H1N1 influenza infection promote α-Synuclein aggregation in mouse primary neurons²¹. Our recent unpublished results using mitotic cell culture and mouse primary neuron models illustrate that H1N1 influenza RNA expedites amyloid formation by α-Synuclein (Fig. 1-2). We identified specific G-quadruplexes in H1N1 genome that interact with α-Synuclein to trigger rapid amyloidosis (Fig. 2C-D). Importantly, SARS-CoV-2 genome also contain G-quadruplexes that potentiate α-Synuclein amyloidogenesis in primary neurons (Fig. 2E-F). Indeed, a recent study reports that SARS-CoV-2 infection exacerbates the cellular pathology of PD in human dopaminergic neurons and mouse models²². We also found that ATP-dependent DExD-Box Helicase 39A (DDX39A) opens up these viral RNA G-quadruplex structures to limit the phase separation of α-Synuclein and consequent amyloidogenesis (Fig. 3). α-Synuclein is not a bona fide RNA binding protein (RBP). How viral RNA G-quadruplexes interact with α-Synuclein to expedite amyloid fibril formation is not understood at the atomic level. We find DDX39A as a novel interactor of α-Synuclein. It is also not known how it interferes with the RNA binding of α-Synuclein to alleviate amyloidogenesis. In this work, we propose to elucidate the molecular details of the α-Synuclein-viral RNA G-quadruplex-DDX39A interaction triad using spectroscopy, mass spectrometry, and cryo-electron microscopy (cryo-EM) followed by validations using mitotic cell and primary neuron models (Fig. 4-5). The specific questions will include: 1) which residues constitute the viral RNA G-quadruplex binding sites of α-Synuclein? 2) How do viral RNA G-quadruplexes facilitate α-Synuclein amyloidogenesis? 3) What specific interactions with DDX39A deters α-Synuclein amyloid formation? Answers to these questions will offer information towards designing structure-based chemical intervention of α-Synuclein amyloidogenesis.