Key Avasthi Lab Contributions

Initial ciliary assembly in Chlamydomonas requires Arp2/3 complex-dependent endocytosis Bigge BM, Rosenthal NE, Avasthi P.
Why it’s cool: We found many interesting functions for actin in various stages of cilium assembly but how do we tease apart those functions? Actin binding proteins! They dictate when, where, and for what purpose actin filaments form. We studied the Arp2/3 complex, an actin binding complex that makes branched networks and proposed a new model for ciliary membrane protein targeting in which ciliary membrane proteins can stored in a reservoir in the plasma membrane and reclaimed by Arp2/3 dependent endocytosis for early ciliogenesis.

Chlamydomonas reinhardtii formin FOR1 and profilin PRF1 are optimized for acute rapid actin filament assembly Christensen JR, Craig EW, Glista MJ, Mueller DM, Li Y, Sees JA, Huang S, Suarez C, Mets LJ, Kovar DR, Avasthi P.
Why it’s cool: This collaborative paper with the Kovar Lab is the first biochemical and cellular characterization of a Chlamydomonas formin (there are 4 of them!) and profilin, actin binding proteins that dictate when, where, and how actin filaments assemble. Broadly, it helps us understand how properties of these actin binding proteins tune cellular functions.

The elusive actin cytoskeleton of a green alga expressing both conventional and divergent actins Craig EW, Mueller DM, Bigge BM, Schaffer M, Engel BD, Avasthi P.
Why it’s cool: The function of a fundamental cytoskeletal component, the actin network, in the green alga Chlamydomonas reinhardtii has been obscured in large part because actin filaments have been difficult to visualize. In this work we overcame these challenges and produced the first visual characterization of actin filaments in fixed Chlamydomonas cells using fluorescence microscopy and in situ cryo-electron tomography in collaboration with Ben Engel and his team. This opens the door for understanding the function of actin filaments in a broad range of cellular processes for which Chlamydomonas is a leading model system: photosynthesis, cilia, biofuels, the evolution of multicellularity and beyond.

Partially Redundant Actin Genes in Chlamydomonas Control Transition Zone Organization and Flagellum-Directed Traffic Jack B, Mueller DM, Fee AC, Tetlow AL, Avasthi P.
Why it’s cool: We previously identified a role for the actin cytoskeleton in trafficking needed to build the ubiquitous microtubule-based sensory organelle, the cilium. This new work identified specific cellular mechanisms by which actin regulates ciliary assembly. Mechanisms include controlling ciliary protein synthesis, post-Golgi traffic, and organization of the ciliary gate, a region housing many proteins mutated in ciliary diseases. We provided new clues about how one major cytoskeletal component (actin) regulates another (microtubules) for organelle (cilium) biogenesis.

Flagellar Synchronization Is a Simple Alternative to Cell Cycle Synchronization for Ciliary and Flagellar Studies Dutta S, Avasthi P.
Why it’s cool: Cell size and organelle size are often linked and the cell size/ciliary length relationship is no exception. Here we were able to break the cell and cilium size scaling to synchronize ciliary length without synchronizing cell size, limiting variation in cilium length despite large variation in cell size. This work provides a useful framework for ciliary length screening for the discovery of ciliary regulatory mechanisms and ciliary disease therapeutics.

Separable roles for RanGTP in nuclear and ciliary trafficking of a kinesin-2 subunit. Huang S, Dogherty LL, Avasthi P.
Why it’s cool: Nuclear transport and ciliary transport share some important features and regulatory proteins but it has been difficult to tease apart whether perturbations of nuclear transport affect ciliary trafficking directly or indirectly. We used the power of the Chlamydomonas model system to show there is direct small GTPase-dependent regulation of cilia independent of nuclear roles.

Complete List of Publications by Prachee Avasthi 

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