No abstract

Misfolding, abnormal accumulation, and secretion of α-Synuclein (α-Syn) are closely associated with synucleinopathies, including Parkinson’s disease (PD). VH14 is a human single domain intrabody selected against the non-amyloid component (NAC) hydrophobic interaction region of α-Syn, which is critical for initial aggregation. Using neuronal cell lines, we show that as a bifunctional nanobody fused to a proteasome targeting signal, VH14PEST can counteract heterologous proteostatic effects of mutant α-Syn on mutant huntingtin Exon1 and protect against α-Syn toxicity using propidium iodide or Annexin V readouts. We compared this anti-NAC candidate to NbSyn87, which binds to the C-terminus of α-Syn. NbSyn87PEST degrades α-Syn as well or better than VH14PEST. However, while both candidates reduced toxicity, VH14PEST appears more effective in both proteostatic stress and toxicity assays. These results show that the approach of reducing intracellular monomeric targets with novel antibody engineering technology should allow in vivo modulation of proteostatic pathologies.

Summary The nascent polypeptide-associated complex (NAC) is a conserved ribosome-associated protein biogenesis factor. Whether NAC exerts chaperone activity and whether this function is restricted to de novo protein synthesis is unknown. Here, we demonstrate that NAC directly exerts chaperone activity toward structurally diverse model substrates including polyglutamine (PolyQ) proteins, firefly luciferase, and Aβ40. Strikingly, we identified the positively charged ribosome-binding domain in the N terminus of the βNAC subunit (N-βNAC) as a major chaperone entity of NAC. N-βNAC by itself suppressed aggregation of PolyQ-expanded proteins in vitro , and the positive charge of this domain was critical for this activity. Moreover, we found that NAC also exerts a ribosome-independent chaperone function in vivo . Consistently, we found that a substantial fraction of NAC is non-ribosomal bound in higher eukaryotes. In sum, NAC is a potent suppressor of aggregation and proteotoxicity of mutant PolyQ-expanded proteins associated with human diseases like Huntington’s disease and spinocerebellar ataxias.

The rapid emergence of large-scale atlas-level single-cell RNA-seq datasets presents remarkable opportunities for broad and deep biological investigations through integrative analyses. However, harmonizing such datasets requires integration approaches to be not only computationally scalable, but also capable of preserving a wide range of fine-grained cell populations. We created Portal, a unified framework of adversarial domain translation to learn harmonized representations of datasets. With innovation in model and algorithm designs, Portal achieves superior performance in preserving biological variation during integration, while achieving integration of millions of cells in minutes with low memory consumption. We show that Portal