Development of TDP-43 granule inhibitors as potential amyotrophic lateral sclerosis and frontotemporal lobar degeneration therapies

The 43 kDa TAR DNA binding protein (TDP-43) has been identified as one of the major proteins that accumulates in the cytoplasm of brain and spinal cord from the patients affected with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Under basal conditions, TDP-43 localizes in nucleus functioning as an RNA binding protein to regulate different aspects of RNA metabolism, such as alternative splicing of messenger RNA. In ALS/FTLD brains and spinal cords, TDP-43 forms well-defined cytoplasmic granules, the behavior very similar to stress granule (SG) proteins, but the mechanisms are poorly understood. To investigate the mechanism of TDP-43 granule formation and to identify potential therapeutic targets by inhibiting the granule formation, our laboratory screened a chemical library of 75,000 compounds using the inducible PC12 cells that express EGFP-tagged wild-type human TDP-43. We used the biological effect of cycloheximide on SGs as a basis for the screen, since it is known to prevent the formation of SGs and TDP-43 granules, pointing to a novel biological pathway that regulates TDP-43 granule formation. One of the candidate compounds, Compound 8 (C8) and its analog C8j dose- dependently decreased the arsenite-induced TDP-43 granules without cytotoxicity, and reduced the protein levels of full-length, truncated, high molecular weight and phosphorylated TDP-43. In addition, we found C8j reduced the phosphorylation at novel, previously unknown Thr103-Ser104 amino acid residues of human TDP-43 under arsenite stress. The phospho-mimetic mutations at these sites induced spontaneous intracellular TDP-43 granules, indicating their regulatory role in TDP-43 granule formation. We also performed a series of gene expression analysis combined with the systems biology algorithm, mode of action by network identification (MNI), to identify the mode of action of C8, and found C8 potentially targets protein metabolism and modification processes to reduce the TDP-43 granules. Our study identified a family of non-cytotoxic chemical compounds that reduces the formation of arsenite-induced TDP-43 granules and their potential mode of action. Furthermore, we identified previously unknown TDP-43 phosphorylation sites Thr103- Ser104 that are involved in the TDP-43 granule formation. We anticipate this study will elucidate the biological pathways regulating TDP-43 aggregation and potential therapeutics for ALS/FTLD-U

Non-Equilibrium Fluidization of Dense Active Suspension

We investigate dense suspensions of swimming bacteria prepared in a nutrient-exchange chamber. Near the pellet concentration, nonthermal fluctuations showed notable agreement between self and collective behaviors, a phenomenon not previously observed at equilibrium. The viscosity of active suspensions dramatically decreased compared to their inactive counterparts, where glassy features, such as non-Newtonian viscosity and dynamic heterogeneity, disappeared. Instead, the complex shear modulus showed a power-law rheology,$G^*(\omega)\propto\left(-i\omega\right)^\frac{1}{2}$, indicating the role of bacterial activity in driving the system towards a critical jamming state

Caenorhabditis elegans HCF-1 Functions in Longevity Maintenance as a DAF-16 Regulator

The transcription factor DAF-16/forkhead box O (FOXO) is a critical longevity determinant in diverse organisms, however the molecular basis of how its transcriptional activity is regulated remains largely unknown. We report that the Caenorhabditis elegans homolog of host cell factor 1 (HCF-1) represents a new longevity modulator and functions as a negative regulator of DAF-16. In C. elegans, hcf-1 inactivation caused a daf-16-dependent lifespan extension of up to 40% and heightened resistance to specific stress stimuli. HCF-1 showed ubiquitous nuclear localization and physically associated with DAF-16. Furthermore, loss of hcf-1 resulted in elevated DAF-16 recruitment to the promoters of its target genes and altered expression of a subset of DAF-16-regulated genes. We propose that HCF-1 modulates C. elegans longevity and stress response by forming a complex with DAF-16 and limiting a fraction of DAF-16 from accessing its target gene promoters, and thereby regulates DAF-16-mediated transcription of selective target genes. As HCF-1 is highly conserved, our findings have important implications for aging and FOXO regulation in mammals

An On-line Backup Function for a Clustered NAS System (X-NAS) _

An on-line backup function for X-NAS, a clustered NAS system designed for entry-level NAS, has been developed. The on-line backup function can replicate file objects on X-NAS to a remote NAS in real-time. It makes use of the virtualized global file system of X-NAS, and sends NFS write operations to both X-NAS and the remote backup NAS at the same time. The performance of the on-line backup function was evaluated and the evaluation results show that the on-line backup function of X-NAS improves the system reliability while maintaining 80 % of the throughput of the X-NAS without this function. 1