Biology subjects

Ho, W.-L.

Publications and source records attributed to Ho, W.-L..

3 recordsLinked to original sources

bioRxiv2022

Phase separation driven by interchangeable properties in the intrinsically disordered regions of protein paralogs

Paralogs, arising from gene duplications, increase the functional diversity of proteins. Protein functions in paralog families have been extensively studied, but little is known about the roles of intrinsically disordered regions (IDRs), even though more than half of eukaryotic proteins have them. Using the RNA-binding protein Musashi family as an example, we applied multiple structural techniques and phylogenetic analysis to show how members in a paralog family have evolved their IDRs to different physicochemical properties but converge to the same function. In this example, the lower prion-like tendency of Musashi-1s IDRs, rather than Musashi-2s, is compensated by its higher -helical propensity to assist their assembly. Without a folded structure to restraint, IDRs sequences mutate faster along with evolution. No matter how fast they change, our work suggests that IDRs evolve different traits to a converged function, such as liquid-liquid phase separation.

biophysics↗

bioRxiv2021

The return of the rings: evolutionary role of aromatic residues in liquid-liquid phase separation

Aromatic residues appeared relatively late in the evolution of protein sequences. They stabilize the hydrophobic core of globular proteins and are typically absent from intrinsically disordered regions (IDRs). However, recent advances in protein liquid-liquid phase separation (LLPS) studies have shown that aromatic residues in IDRs often act as important "stickers", promoting multivalent interactions and the formation of higher-order oligomers. To reconcile this apparent contradiction, we compared levels of sequence disorder in RNA binding proteins and the human proteome and found that aromatic residues appear more frequently than expected in the IDRs of RNA binding proteins, which are often found to undergo LLPS. Phylogenetic analysis shows that aromatic residues are highly conserved among chordates, highlighting their importance in LLPS-driven functional assembly. These results suggest therefore that aromatic residues have contributed twice to evolution: in stabilizing structured proteins and in the assembly of biomolecular condensates.

molecular biology↗

bioRxiv2021

Biphasic roles of hedgehog signaling in the production and self-renewal of outerradial glia in the ferret cerebral cortex

The neocortex, the center for higher brain function, emerged in mammals and expanded in the course of evolution. The expansion of outer radial glia (oRGs) and intermediate progenitor cells (IPCs) plays key roles in the expansion and consequential folding of the neocortex. Therefore, understanding the mechanisms of oRG and IPC expansion is important for understanding neocortical development and evolution. By using mice and human cerebral organoids, we previously revealed that hedgehog (HH) signaling expands oRGs and IPCs. Nevertheless, it remained to be determined whether HH signaling expanded oRGs and IPCs in vivo in gyrencephalic species, in which oRGs and IPCs are naturally expanded. Here, we show that HH signaling is necessary and sufficient to expand oRGs and IPCs in ferrets, a gyrencephalic species, through conserved cellular mechanisms. HH signaling increases oRG-producing division modes of ventricular radial glia (vRGs), oRG self-renewal, and IPC proliferation. Notably, HH signaling affects vRG division modes only in an early restricted phase before superficial-layer neuron production peaks. Beyond this restricted phase, HH signaling promotes oRG self-renewal. Thus, HH signaling expands oRGs and IPCs in two distinct but continuous phases during cortical development.

developmental biology↗