Biology subjects

Verhey, K.

Publications and source records attributed to Verhey, K..

4 recordsLinked to original sources

bioRxiv2023

Kif6 regulates cilia motility and polarity in brain ependymal cells

Ependymal cells, lining brain ventricular walls, display tufts of cilia that beat in concert promoting laminar Cerebrospinal fluid (CSF) flow within brain ventricles. The ciliary axonemes of multiciliated ependymal cells display a 9+2 microtubule array common to motile cilia. Dyneins and kinesins are ATPase microtubule motor proteins that promote the rhythmic beating of cilia axonemes. Despite common consensus about the importance of axonemal dynein motor proteins, little is known about how Kinesin motors contribute to cilia motility. Here, we define the function of Kinesin family member 6 (Kif6) using a mutation that lacks a highly conserved C-terminal tail domain (Kif6p.G555fs) and which displays progressive hydrocephalus in mice. An analogous mutation was isolated in a proband displaying macrocephaly, hypotonia, and seizures implicating an evolutionarily conserved function for Kif6 in neurodevelopment. We find that loss of Kif6 function caused decreased ependymal cilia motility and subsequently decreased fluid flow on the surface of brain ventricular walls. Kif6 protein was localized at ependymal cilia and displayed processive motor movement (676 nm/s) on microtubules in vitro. Loss of the Kif6 C-terminal tail domain did not affect the initial ciliogenesis in vivo, but did result in defects in cilia orientation, the formation of robust apical actin networks, and stabilization of basal bodies at the apical surface. This suggests a novel role for the Kif6 motor in maintenance of ciliary homeostasis of ependymal cells. Summary statementWe found that Kif6 is localized to the axonemes of ependymal cells. In vitro analysis shows that Kif6 moves on microtubules and that its loss mice decrease cilia motility and cilia-driven flow, resulting in hydrocephalus.

developmental biology↗

bioRxiv2022

Dual and Opposing Roles for the Kinesin-2 Motor, KIF17, in Hedgehog-dependent Cerebellar Development

While the kinesin-2 motors KIF3A and KIF3B have essential roles in ciliogenesis and Hedgehog (HH) signal transduction, potential role(s) for another kinesin-2 motor, KIF17, in HH signaling have yet to be explored. Here, we investigated the contribution of KIF17 to HH-dependent cerebellar development, where Kif17 is expressed in both HH-producing Purkinje cells and HH-responding cerebellar granule neuron progenitors (CGNPs). Germline Kif17 deletion in mice results in cerebellar hypoplasia due to reduced CGNP proliferation, a consequence of decreased HH pathway activity mediated through decreased Sonic HH (SHH) protein. Notably, Purkinje cell-specific Kif17 deletion phenocopies Kif17 germline mutants. Surprisingly, CGNP-specific Kif17 deletion results in the opposite phenotype- increased CGNP proliferation and HH target gene expression due to altered GLI transcription factor processing. Together these data identify KIF17 as a key regulator of HH-dependent cerebellar development, with dual and opposing roles in HH-producing Purkinje cells and HH-responding CGNPS. TeaserDuring cerebellar development, the KIF17 microtubule motor performs opposing roles in HH-producing and HH-responding cells.

developmental biology↗

bioRxiv2021

Zn2+ acts as a brake signal for axonal transport by directly inhibiting motor protein progression

Accurate delivery of cargo over long distances through axonal transport requires precise spatiotemporal regulation and relies on microtubule function. Here we discover that Zn2+ influx via depolarization inhibits axonal transport. Zn2+-mediated inhibition is nonselective for cargo. Elevated Zn2+ (IC50 >> 5-10 nM) reduces both lysosomal and mitochondrial motility in primary rat hippocampal neurons and HeLa cells. We further reveal that Zn2+ directly binds to microtubules, inhibiting movement of motor proteins (kinesin and dynein) and promoting detachment of neuronal-specific MAPs (Tau, DCX, and MAP2C). We finally provide a detailed model of microtubule interactions with Tau, DCX, dynein, kinesin, and predict microtubule Zn2+ binding sites. Our results reveal that Zn2+ acts to inhibit the microtubule binding of tau, DCX, and MAP2C and can directly block the progression of motor proteins on microtubules. Intraneuronal Zn2+, therefore, is a critical signal for regulating axonal transport and microtubulebased processes.

cell biology↗

bioRxiv2020

Pathogenic Mutations in the Kinesin-3 Motor KIF1A Diminish Force Generation and Movement Through Allosteric Mechanisms

The kinesin-3 motor KIF1A functions in neurons where its fast and superprocessive motility is thought to be critical for long-distance transport. However, little is known about the force-generating properties of kinesin-3 motors. Using optical tweezers, we demonstrate that KIF1A and its C. elegans homolog UNC-104 undergo force-dependent detachments at ~3 pN and then rapidly reattach to the microtubule to resume motion, resulting in a sawtooth pattern of clustered force generation events that is unique among the kinesin superfamily. Whereas UNC-104 motors stall before detaching, KIF1A motors do not. To examine the mechanism of KIF1A force generation, we introduced mutations linked to human neurodevelopmental disorders, V8M and Y89D, based on their location in structural elements required for force generation in kinesin-1. Molecular dynamics simulations predict that the V8M and Y89D mutations impair docking of the N-terminal ({beta}9) or C-terminal ({beta}10) portions of the neck linker, respectively, to the KIF1A motor domain. Indeed, both mutations dramatically impair force generation of KIF1A but not the motors ability to rapidly reattach to the microtubule track. Homodimeric and heterodimeric mutant motors also display decreased velocities, run lengths, and landing rates and homodimeric Y89D motors exhibit a higher frequency of non-productive, diffusive events along the microtubule. In cells, cargo transport by the mutant motors is delayed. Our work demonstrates the importance of the neck linker in the force generation of kinesin-3 motors and advances our understanding of how mutations in the kinesin motor domain can manifest in disease.

biophysics↗