Nephronophthisis gene products display RNA-binding properties and are recruited to stress granules

Luisa Estrada Mallarino,İbrahim Avşar Ilık,Christina Engel,Gerd Walz,Florian Heyl,Asifa Akhtar,Jörn Dengjel,Toma A Yakulov,Rolf Backofen,Barbara Müller,Daniel Maticzka

doi:10.1038/s41598-020-72905-8

Abstract

Mutations of cilia-associated molecules cause multiple developmental defects that are collectively termed ciliopathies. However, several ciliary proteins, involved in gating access to the cilium, also assume localizations at other cellular sites including the nucleus, where they participate in DNA damage responses to maintain tissue integrity. Molecular insight into how these molecules execute such diverse functions remains limited. A mass spectrometry screen for ANKS6-interacting proteins suggested an involvement of ANKS6 in RNA processing and/or binding. Comparing the RNA-binding properties of the known RNA-binding protein BICC1 with the three ankyrin-repeat proteins ANKS3, ANKS6 (NPHP16) and INVERSIN (NPHP2) confirmed that certain nephronophthisis (NPH) family members can interact with RNA molecules. We also observed that BICC1 and INVERSIN associate with stress granules in response to translational inhibition. Furthermore, BICC1 recruits ANKS3 and ANKS6 into TIA-1-positive stress granules after exposure to hippuristanol. Our findings uncover a novel function of NPH family members, and provide further evidence that NPH family members together with BICC1 are involved in stress responses to maintain tissue and organ integrity.

Highlights

Mutations of cilia-associated molecules cause multiple developmental defects that are collectively termed ciliopathies
While only few RNA molecules interacted with either ARL13B or BBS3, likely representing non-specific interactions, this approach identified a total of 1518 RNA molecules for BICC1, 603 RNA molecules for INVERSIN, 524 RNA molecules for ANKS6, and 290 RNA molecules for ANKS3 not found in the ARL13B and BBS3 controls
The Pearson correlation revealed a closer relation between BICC1, ANKS6 and INVS than to ANKS3; similar results were observed in the Venn diagram (Fig. 1a), suggesting similar biological functions between BICC1, ANKS6 and INVS

Summary

Introduction

Mutations of cilia-associated molecules cause multiple developmental defects that are collectively termed ciliopathies. Several ciliary proteins, involved in gating access to the cilium, assume localizations at other cellular sites including the nucleus, where they participate in DNA damage responses to maintain tissue integrity. Several NPH gene products (NPHPs) localize to subcellular compartments outside of the cilium, including cell–cell junctions[4], the secretory p athway[5] and the n ucleus[6] It is unclear whether NPHPs at these sites participate in specific cellular functions independent of the cilium. Several NPHPs with nuclear localization have been implicated in DNA damage r esponses[7,8,9], suggesting that cilia-associated NPHPs participate in developmental programs, while NPHPs outside of the cilium are involved in maintaining cellular homeostasis[10]. ANKS6 was identified as a NPHP9/NEK8-interacting protein, and a subsequent screen for ANKS6-interacting proteins identified ANKS3, an ankyrin-repeat protein that likely plays a role in N PH15–18

Methods

Results

Conclusion