A bioactive peptide amidating enzyme is required for ciliogenesis.

Dhivya Kumar,Betty A Eipper,Sabeeha S Merchant,Ramila S Patel-King,Daniela Strenkert,Stephen M King,Michael T Leonard,Richard E Mains

doi:10.7554/elife.25728

Abstract

The pathways controlling cilium biogenesis in different cell types have not been fully elucidated. We recently identified peptidylglycine α-amidating monooxygenase (PAM), an enzyme required for generating amidated bioactive signaling peptides, in Chlamydomonas and mammalian cilia. Here, we show that PAM is required for the normal assembly of motile and primary cilia in Chlamydomonas, planaria and mice. Chlamydomonas PAM knockdown lines failed to assemble cilia beyond the transition zone, had abnormal Golgi architecture and altered levels of cilia assembly components. Decreased PAM gene expression reduced motile ciliary density on the ventral surface of planaria and resulted in the appearance of cytosolic axonemes lacking a ciliary membrane. The architecture of primary cilia on neuroepithelial cells in Pam-/- mouse embryos was also aberrant. Our data suggest that PAM activity and alterations in post-Golgi trafficking contribute to the observed ciliogenesis defects and provide an unanticipated, highly conserved link between PAM, amidation and ciliary assembly.

Highlights

Cilia are ancient microtubule-based organelles derived from the basal body, and were present in the last common ancestor of eukaryotes (Carvalho-Santos et al, 2011)
Our work has identified peptidylglycine a-amidating monooxygenase (PAM) as a crucial, evolutionarily conserved factor that is required for ciliogenesis in multiple cell types
PAM is important for the biogenesis of the motile cilia present in C. reinhardtii and on the ventral epithelium of planaria, as well as the normal assembly of the primary cilia of neuroepithelial cells in mammals

Summary

Introduction

Cilia are ancient microtubule-based organelles derived from the basal body, and were present in the last common ancestor of eukaryotes (Carvalho-Santos et al, 2011). The protein and lipid complements of the cilium are distinct from the rest of the cell; more than 700 proteins and specific lipids such as sterols are enriched in this intricate structure. The roles of microtubule motors and intraflagellar transport (IFT) proteins in trafficking the cargo proteins required to build and maintain ciliary architecture have been well described. The growing cilium relies on the delivery of membrane vesicles and proteins derived from the Golgi, and disruption of the secretory pathway by brefeldin A inhibits ciliogenesis (Dentler, 2013; Haller and Fabry, 1998). Proteins and complexes involved in polarized vesicular trafficking such as the clathrin adaptor protein-1 complex (AP1), Rabs and Arf/Arl proteins, the exocyst and BBS

Methods

Results

Conclusion