PQN-75 is expressed in the pharyngeal gland cells of Caenorhabditiselegans and is dispensable for germline development.

Catherine S Sharp,Karolina M Andralojc,Paige C Tanner,Jesse D Rochester,Dustin L Updike

doi:10.1242/bio.027987

Catherine S Sharp, Karolina M Andralojc + Show 3 more

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https://doi.org/10.1242/bio.027987

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Journal: Biology open	Publication Date: Sep 15, 2017
Citations: 3	License type: CC BY 3.0

Affiliation: Mount Desert Island Biological Laboratory

Abstract

ABSTRACTIn Caenorhabditis elegans, five pharyngeal gland cells reside in the terminal bulb of the pharynx and extend anterior processes to five contact points in the pharyngeal lumen. Pharyngeal gland cells secrete mucin-like proteins thought to facilitate digestion, hatching, molting and assembly of the surface coat of the cuticle, but supporting evidence has been sparse. Here we show pharyngeal gland cell expression of PQN-75, a unique protein containing an N-terminal signal peptide, nucleoporin (Nup)-like phenylalanine/glycine (FG) repeats, and an extensive polyproline repeat domain with similarities to human basic salivary proline-rich pre-protein PRB2. Imaging of C-terminal tagged PQN-75 shows localization throughout pharyngeal gland cell processes but not the pharyngeal lumen; instead, aggregates of PQN-75 are occasionally found throughout the pharynx, suggesting secretion from pharyngeal gland cells into the surrounding pharyngeal muscle. PQN-75 does not affect fertility and brood size in C. elegans but confers some degree of stress resistance and thermotolerance through unknown mechanisms.

Highlights

Phenylalanine/glycine (FG) repeats create intrinsically disordered protein domains and are common in the nuclear pore complex (NPC) where FG-nucleoporin (Nups) constitute the permeability barrier of the pore and facilitate transport between the nucleus and cytoplasm
Unlike the majority of FG-repeat proteins, which associate with the nuclear pore complex or germline P granules, PQN-75 aggregates disperse throughout the cytosol of pharyngeal gland cells and appear to be secreted into surrounding pharyngeal muscle, the function of PQN-75 aggregates in these cells remains unclear
We have demonstrated that PQN-75 does not affect brood size or growth rate, and minimally impacts osmotic stress and innate immunity

Summary

Introduction

Phenylalanine/glycine (FG) repeats create intrinsically disordered protein domains and are common in the nuclear pore complex (NPC) where FG-nucleoporin (Nups) constitute the permeability barrier of the pore and facilitate transport between the nucleus and cytoplasm (reviewed in Beck and Hurt, 2016). In Caenorhabditis elegans, FG-repeat domains are found outside the periphery of NPCs in the core P-granule proteins GLH-1, GLH-2, GLH-4, DDX19, and RDE-12 (Sheth et al, 2010). These P-granule proteins extend the permeability barrier of NPCs into the cytoplasm of germ cells (Updike et al, 2011). In addition to FGNups and the five P-granule FG-repeat proteins above, FG-repeats

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