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Myosin 18Aα targets the guanine nucleotide exchange factor β‐Pix to the dendritic spines of cerebellar Purkinje neurons and promotes spine maturation
Author(s) -
Alexander Christopher J.,
Barzik Melanie,
Fujiwara Ikuko,
Remmert Kirsten,
Wang YaXian,
Petralia Ronald S.,
Friedman Thomas B.,
Hammer John A.
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.202001449r
Subject(s) - myosin , guanine nucleotide exchange factor , actin , dendritic spine , microbiology and biotechnology , biology , gene knockdown , chemistry , biochemistry , gtpase , neuroscience , hippocampal formation , apoptosis
Abstract Myosin 18Aα is a myosin 2‐like protein containing unique N‐ and C‐terminal protein interaction domains that co‐assembles with myosin 2. One protein known to bind to myosin 18Aα is β‐Pix, a guanine nucleotide exchange factor (GEF) for Rac1 and Cdc42 that has been shown to promote dendritic spine maturation by activating the assembly of actin and myosin filaments in spines. Here, we show that myosin 18A⍺ concentrates in the spines of cerebellar Purkinje neurons via co‐assembly with myosin 2 and through an actin binding site 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, β‐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 argue that mixed filaments of myosin 2 and myosin 18A⍺ form a complex with β‐Pix in Purkinje neuron spines that promotes spine maturation by enhancing the assembly of actin and myosin filaments downstream of β‐Pix's GEF activity.