Biology subjects

Petralia, R. S.

Publications and source records attributed to Petralia, R. S..

3 recordsLinked to original sources

bioRxiv2022

NudC regulated Lis1 stability is essential for maintenance of dynamic microtubule ends in the axon terminal

Axon terminal structure is critical for neuronal function. This cellular compartment houses synaptic terminals and is a site of high metabolic and functional demand. Axon terminals are also the site of a change in microtubule structure within the neuron. Microtubule stability is decreased relative to the axon shaft due to an enrichment of microtubule plus ends and increase in microtubule dynamics. These dynamic microtubule plus ends have many functions including serving as a docking site for the microtubule motor protein complex Cytoplasmic dynein. Here, we report an unexplored function of the dynein motor in axon terminals: regulation of microtubule stability. Using a forward genetic screen, we identified a mutant with abnormal axon terminal structure due to a loss of function mutation in the dynein interacting protein NudC. We show that the primary function of NudC in the axon terminal is as a chaperone for the protein Lis1. Loss of NudC results in decreased Lis1 protein in this neuronal compartment. Decreased Lis1 in nudc mutants causes dynein/dynactin accumulation and increased microtubule stability in axon terminals. Microtubules in the proximal axon are unaffected. Abnormal microtubule stability and structure can be suppressed by pharmacologically inhibiting dynein, implicating excess dynein motor activity as causal in the enhanced axon terminal microtubule stability. Together, our data support a model in which local NudC-Lis1 modulation of dynein motor activity is critical for regulation of microtubule stability in the axon terminal.

neuroscience↗

bioRxiv2020

Voltage-gated Ca2+ and K+ channel coupling regulates CA1 hippocampal synaptic filtering and spine excitability

The transient K+ current (IA) carried by pore forming Kv4.2 subunits regulates the propagation of synaptic input, dendritic excitability, and synaptic plasticity in CA1 pyramidal neuron dendrites of the hippocampus. We report that the Ca2+ channel subunit Cav2.3 regulates IA in this cell type. We first identified Cav2.3 as a Kv4.2 interacting protein in a proteomic screen and we confirmed Cav2.3-Kv4.2 complex association using multiple techniques. Functionally, Cav2.3 Ca2+-entry increases Kv4.2-mediated whole-cell current due to an increase in Kv4.2 surface expression. Using pharmacology and Cav2.3 knockout mice, Cav2.3 was found to promote whole-cell IA and the increasing gradient of IA in the apical dendrite distal to the neuronal soma. Furthermore, the loss of Cav2.3 function leads to enhancement of synaptic currents and spine Ca2+ influx. These results present Cav2.3 and Kv4.2 as integral constituents of an ion channel complex that impacts synaptic function in the hippocampus.

neuroscience↗

bioRxiv2020

Myosin 18Aα targets guanine nucleotide exchange factor β-Pix to dendritic spines of cerebellar Purkinje neurons to promote spine maturation

Dendritic spines are signaling microcompartments that serve as the primary site of synapse formation in neurons. Actin assembly and myosin 2 contractility play major roles in the maturation of spines from filopodial precursors, as well as in the subsequent, activity-dependent changes in spine morphology that underly learning and memory. Myosin 18A is a myosin 2-like protein conserved from flies to man that lacks motor activity, is sub-stochiometric to myosin 2, and co-assembles with myosin 2 to make mixed filaments. Myosin 18A is alternatively spliced to create multiple isoforms that contain unique N- and C-terminal extensions harboring both recognizable and uncharacterized protein: protein interaction domains. These observations suggest that myosin 18A serves to recruit proteins to mixed filaments of myosin 2 and myosin 18A. One protein known to bind to myosin 18A is {beta}-Pix, a guanine nucleotide exchange factor (GEF) for Rac1 and Cdc42. Notably, {beta}-Pix has been shown to promote spine maturation by activating both Arp2/3 complex-dependent branched actin filament assembly and myosin 2 contractility within spines. Here we show that myosin 18A is expressed in cerebellar Purkinje neurons and concentrates in spines along with myosin 2 and F-actin. Myosin 18A is targeted to spines by co-assembling with myosin 2 and by an actin binding site present in its N-terminal extension. miRNA-mediated knockdown of myosin 18A results in a significant defect in spine maturation that is rescued by an RNAi-immune version of myosin 18A. Importantly, {beta}-Pix co-localizes with myosin 18A in spines, and its spine localization is lost upon myosin 18A knockdown or when its myosin 18A binding site is deleted. Finally, we show that the spines of myosin 18A knockdown Purkinje neurons contain significantly less F-actin and myosin 2. Together, these data demonstrate that mixed filaments of myosin 2 and myosin 18A form a complex with {beta}-Pix in Purkinje neuron spines that promotes spine maturation by enhancing the assembly of actin and myosin filaments downstream of {beta}-Pixs GEF activity.

neuroscience↗