Saunders, H. A. J. | bioRxiv Science

bioRxiv2017

Effects of mutating α-tubulin lysine 40 on sensory dendrite development

Microtubules are essential to neuronal structure and function. Axonal and dendritic microtubules are enriched in post-translational modifications that impact microtubule dynamics, transport, and microtubule-associated proteins. Acetylation of -tubulin lysine 40 (K40) is a prominent, conserved modification of neuronal microtubules. However, the cellular role of microtubule acetylation remains controversial. To resolve how microtubule acetylation might affect neuronal morphogenesis we mutated endogenous -tubulin in vivo using a new fly strain that facilitates the rapid knock-in of designer -tubulin alleles. Leveraging our new strain, we found that microtubule acetylation, as well as polyglutamylation and (de)tyrosination, is not essential for survival. However, we found that dendrite branch refinement in sensory neurons relies on -tubulin K40. Mutagenesis of K40 reveals moderate yet significant changes in dendritic lysosome transport, microtubule polymerization, and Futsch distribution in dendrites but not axons. Our studies point to an unappreciated role for -tubulin K40 and acetylation in dendrite morphogenesis. While our results are consistent with the idea that microtubule acetylation patterns microtubule function within neurons, they also suggest there may be a structural requirement for -tubulin K40.\n\nSummary StatementNeurons are enriched in post-translationally modified microtubules. Targeted mutagenesis of endogenous -tubulin in flies reveals that dendrite branch refinement is altered by acetylation-blocking mutations.

cell biology↗

bioRxiv2017

Architecture and dynamics of overlapped RNA regulatory networks

A single protein can bind and regulate many mRNAs. Multiple proteins with similar specificities often bind and control overlapping sets of mRNAs. Yet, little is known about the architecture or dynamics of overlapped networks. We focused on three proteins with similar structures and related RNA-binding specificities - Puf3p, Puf4p, and Puf5p of S. cerevisiae. Using RNA Tagging, we identified a \"super-network\" comprised of four sub-networks: Puf3p, Puf4p, and Puf5p sub-networks, and one controlled by both Puf4p and Puf5p. The architecture of individual subnetworks, and thus the super-network, are determined by competition among particular PUF proteins to bind mRNAs, their affinities for binding elements, and the abundances of the proteins. The super-network responds dramatically: the remaining network can either expand or contract. These strikingly opposite outcomes are determined by an interplay between the relative abundance of the RNAs and proteins, and their affinities for one another. The diverse interplay between overlapping RNA-protein networks provides versatile opportunities for regulation and evolution.

molecular biology↗