Kir4.1-dependent astrocyte-fast motor neuron interactions are required for peak strength
journal contributionposted on 20.08.2020, 16:22 by Kevin W Kelley, Lucile Ben Haim, Lucas Schirmer, Giulia E Tyzack, Michaela Tolman, John G Miller, Hui-Hsin Tsai, Sandra M Chang, Anna V Molofsky, Yongjie Yang, Rickie Patani, Andras Lakatos, Erik M Ullian, David H Rowitch
Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) around MNs in a VGLUT1-dependent manner. Loss of astrocyte-encoded Kir4.1 selectively altered FαMN size and function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation might uncouple symptoms of muscle weakness from MN cell death in diseases like ALS.
Kir4.1amyotrophic lateral sclerosisastrocyte diversityfast-twitch musclemotor neuronneurodegenerationpeak strengthspinal cord developmentAmyotrophic Lateral SclerosisAnimalsAnimals, NewbornAstrocytesCells, CulturedFemaleHumansInduced Pluripotent Stem CellsMaleMiceMice, TransgenicMotor NeuronsOrgan Culture TechniquesPotassium Channels, Inwardly RectifyingPatani - sec1109 Neurosciences1702 Cognitive Sciences1701 PsychologyNeurology & Neurosurgery