Yadav, E. | bioRxiv Science

bioRxiv2024

Optogenetically Induced Microtubule Acetylation Unveils the Molecular Dynamics of Actin-Microtubule Crosstalk in Directed Cell Migration

Microtubule acetylation is implicated in regulating cell motility, yet its physiological role in directional migration and the underlying molecular mechanisms have remained unclear. This knowledge gap has persisted primarily due to a lack of tools capable of rapidly manipulating microtubule acetylation in actively migrating cells. To overcome this limitation and elucidate the causal relationship between microtubule acetylation and cell migration, we developed a novel optogenetic actuator, optoTAT, which enables precise and rapid induction of microtubule acetylation within minutes in live cells. Using optoTAT, we observed striking and rapid responses at both molecular and cellular level. First, microtubule acetylation triggers release of the RhoA activator GEF-H1 from sequestration on microtubules. This release subsequently enhances actomyosin contractility and drives focal adhesion maturation. These subcellular processes collectively promote sustained directional cell migration. Our findings position GEF-H1 as a critical molecular responder to microtubule acetylation in the regulation of directed cell migration, revealing a dynamic crosstalk between the actin and microtubule cytoskeletal networks.

cell biology↗

bioRxiv2023

Activity of brain stem glucagon neurons are modulated by energy state and encode sex and frequency-dependent negative valence and anxiety.

The glucagon-like peptide 1 (GLP-1) system has emerged as an important drug target for the treatment of obesity and diabetes. Preclinical and clinical studies demonstrate that the activation of GLP-1 receptors (GLP-1Rs) directly in the brain through overexpression of GLP-1 or GLP-1R agonists produces potent anorexigenic effects, yet the behavioral role and modulation of the endogenous GLP-1 producing system in the brain by energy status is unclear. In this study, we examined the anatomical, physiological, and behavioral properties of preproglucagon-expressing neurons in the nucleus of the solitary tract, GcgNTS neurons, which serve as the primary source of GLP-1 in the brain. Using transgenic laboratory mice, we observed no sex differences in the density and distribution of GcgNTS neurons in male and female mice. Fos immunolabeling experiments show that GcgNTS neurons are not significantly activated after intermittent access to palatable food, but the magnitude of Fos activation was linearly related to the amount of food intake in mice provided with ad libitum intermittent access to palatable food. Electrophysiological examination of GcgNTS neurons revealed that these neurons show energy-status and sex-dependent changes in neuronal firing and intrinsic excitability. Twenty-four hour food deprivation produced a significant reduction in excitability and firing in male, but not female mice. We then used optogenetics to investigate the causal behavioral role of GcgNTS neurons. High frequency optogenetic activation of GcgNTS neurons using the red light-gated opsin ChrimsonR produced female-specific anxiety-like behavior and real-time place aversion. For feeding, we observed that reversible optogenetic stimulation at high frequencies produced a significant reduction in homeostatic refeeding that did not differ by sex. Using operant conditioning, we found that reversible optogenetic activation of GcgNTS neurons at 20 Hz, but not 5, also reduces appetitive behavior. These data demonstrate that GcgNTS neurons exert control over motivation and food-seeking behavior in addition to consumption.

neuroscience↗