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2017.07.11 Press Release

Tctex-1 controls ciliary resorption by regulating branched actin polymerization and endocytosis

The primary cilium is a plasma membrane-protruding sensory
organelle that undergoes regulated assembly and resorption. While
the assembly process has been studied extensively, the cellular
machinery that governs ciliary resorption is less well understood.
Previous studies showed that the ciliary pocket membrane is an
actin-rich, endocytosis-active periciliary subdomain. Furthermore,
Tctex-1, originally identified as a cytoplasmic dynein light chain,
has a dynein-independent role in ciliary resorption upon phosphorylation
at Thr94. Here, we show that the remodeling and endocytosis
of the ciliary pocket membrane are accelerated during
ciliary resorption. This process depends on phospho(T94)Tctex-1,
actin, and dynamin. Mechanistically, Tctex-1 physically and functionally
interacts with the actin dynamics regulators annexin A2,
Arp2/3 complex, and Cdc42. Phospho(T94)Tctex-1 is required for
Cdc42 activation before the onset of ciliary resorption. Moreover,
inhibiting clathrin-dependent endocytosis or suppressing Rab5GTPase
on early endosomes effectively abrogates ciliary resorption.
Taken together with the epistasis functional assays, our results
support a model in which phospho(T94)Tctex-1-regulated actin
polymerization and periciliary endocytosis play an active role in
orchestrating the initial phase of ciliary resorption.
Keywords branched actin dynamics; Cdc42; clathrin-dependent endocytosis

Publication Details:
Title:Tctex-1 controls ciliary resorption by regulating
branched actin polymerization and endocytosis
Authors:Masaki Saito*, Wataru Otsu, Kuo-Shun Hsu, Jen-Zen Chuang, Teruyuki Yanagisawa, Vincent Shieh, Taku Kaitsuka, Fan-Yan Wei, Kazuhito Tomizawa, Ching-Hwa Sung* (*; corresponding authors)
Journal:EMBO Reports

For enquiries about this research:
Masaki Saito
Department of Molecular Pharmacology, Tohoku University Graduate School of Medicine
Email: saimasa@med.tohoku.ac.jp

For media enquiries:
Hitoshi Inada
Public Relations Office
Tohoku University Graduate School of Medicine
Tel: +81-22-717-7891
E-mail: hinada@med.tohoku.ac.jp