NEK9 regulates primary cilia formation by acting as a selective autophagy adaptor for MYH9/myosin IIA

Yasuhiro Yamamoto,Haruka Chino,Satoshi Tsukamoto,Noboru Mizushima,Hiroki R Ueda,Koji L Ode

doi:10.1038/s41467-021-23599-7

Abstract

Autophagy regulates primary cilia formation, but the underlying mechanism is not fully understood. In this study, we identify NIMA-related kinase 9 (NEK9) as a GABARAPs-interacting protein and find that NEK9 and its LC3-interacting region (LIR) are required for primary cilia formation. Mutation in the LIR of NEK9 in mice also impairs in vivo cilia formation in the kidneys. Mechanistically, NEK9 interacts with MYH9 (also known as myosin IIA), which has been implicated in inhibiting ciliogenesis through stabilization of the actin network. MYH9 accumulates in NEK9 LIR mutant cells and mice, and depletion of MYH9 restores ciliogenesis in NEK9 LIR mutant cells. These results suggest that NEK9 regulates ciliogenesis by acting as an autophagy adaptor for MYH9. Given that the LIR in NEK9 is conserved only in land vertebrates, the acquisition of the autophagic regulation of the NEK9–MYH9 axis in ciliogenesis may have possible adaptive implications for terrestrial life.

Highlights

Autophagy regulates primary cilia formation, but the underlying mechanism is not fully understood
Based on binding intensity and specificity to wild-type GABARAPL1 (Fig. 1b), we focused on NIMA-related kinase 9 (NEK9), because it was less characterized in the context of autophagy
How NEK9 is involved in primary cilia formation and whether its function relates to autophagy remain unknown

Summary

Introduction

Autophagy regulates primary cilia formation, but the underlying mechanism is not fully understood. Primary cilia sense and transduce various extracellular stimuli, such as signaling molecules (e.g., Hedgehog, Wnt, Notch, growth factors, and hormones), mechanical forces (e.g., fluid flow and tissue deformation), and environmental cues (e.g., light and odorants), depending on the cell type[2,3,4] They regulate diverse developmental and physiological processes, such as embryonic patterning, organogenesis, tissue homeostasis, and cell differentiation[2,5,6]. GABARAP (including GABARAP, GABARAPL1, and GABARAPL2) subfamilies They are covalently conjugated to phosphatidylethanolamine in the autophagic membrane and bind to selective cargos with a LC3-interacting region (LIR) motif[20,21]. Some LIR-containing soluble proteins, such as SQSTM1 (p62), NBR1, NDP52, OPTN, and TAX1BP1, work as selective autophagy adaptors to mediate binding between ATG8s and cargos[11,12]

Methods

Results

Conclusion