NudCL2 is an autophagy receptor that mediates selective autophagic degradation of CP110 at mother centrioles to promote ciliogenesis

Min Liu,Tianhua Zhou,Qiang Sun,Yuehong Yang,Zhangqi Xu,Wei Liu,Qiang Shu,Xiying Chen,Jianfeng Hua,Chunxia Yang,Wen Zhang,Shanshan Xie,Min Li,Feng Yang,Jiaxing Feng,Wenjun Kuang

doi:10.1038/s41422-021-00560-3

Abstract

Primary cilia extending from mother centrioles are essential for vertebrate development and homeostasis maintenance. Centriolar coiled-coil protein 110 (CP110) has been reported to suppress ciliogenesis initiation by capping the distal ends of mother centrioles. However, the mechanism underlying the specific degradation of mother centriole-capping CP110 to promote cilia initiation remains unknown. Here, we find that autophagy is crucial for CP110 degradation at mother centrioles after serum starvation in MEF cells. We further identify NudC-like protein 2 (NudCL2) as a novel selective autophagy receptor at mother centrioles, which contains an LC3-interacting region (LIR) motif mediating the association of CP110 and the autophagosome marker LC3. Knockout of NudCL2 induces defects in the removal of CP110 from mother centrioles and ciliogenesis, which are rescued by wild-type NudCL2 but not its LIR motif mutant. Knockdown of CP110 significantly attenuates ciliogenesis defects in NudCL2-deficient cells. In addition, NudCL2 morphants exhibit ciliation-related phenotypes in zebrafish, which are reversed by wild-type NudCL2, but not its LIR motif mutant. Importantly, CP110 depletion significantly reverses these ciliary phenotypes in NudCL2 morphants. Taken together, our data suggest that NudCL2 functions as an autophagy receptor mediating the selective degradation of mother centriole-capping CP110 to promote ciliogenesis, which is indispensable for embryo development in vertebrates.

Highlights

Since proteins fated for ubiquitin-proteasomal degradation are usually conjugated to ubiquitin, we examined whether coil protein 110 (CP110) is ubiquitylated in cultured mouse embryonic fibroblast (MEF) cells at different time points after serum starvation
Our results revealed that the ubiquitination level of CP110 did not obviously change, whereas the ubiquitination level of centrosomal protein 97 (CEP97) was dramatically increased during ciliogenesis initiation induced by serum starvation (Supplementary information, Fig. S2), suggesting that the ubiquitin-proteasome pathway may not be directly involved in CP110 degradation during ciliogenesis
In this study, we provide evidence that nuclear distribution gene C (NudC)-like protein 2 (NudCL2) serves as a hitherto unrecognized autophagy receptor mediating CP110 removal from mother centrioles, which is crucial for ciliogenesis initiation (Fig. 7i)

Summary

Introduction

Primary cilia are microtubule-based organelles that project from the surface of vertebrate cells to transduce extracellular signals into intracellular responses,[1,2] and are of crucial importance in vertebrate development and homeostasis maintenance.[3,4,5,6,7] Defects in cilia function are involved in multiple human syndromes that are collectively called ciliopathies, including situs inversus, congenital heart defects, cystic kidney disease and so on.[8,9,10,11,12] Primary cilia form in the interphase, and are resorbed prior to mitosis.[13,14,15] In G0 or early G1 phase, mother centrioles convert into basal bodies, dock to the plasma membrane through their distal appendages, and nucleate ciliary axonemes to form primary cilia.[16]. The mechanism by which mother centriole-localized CP110 is degraded to promote ciliogenesis remains unknown

Methods

Results

Conclusion