Prominin-1 controls stem cell activation by orchestrating ciliary dynamics.

Donald R J Singer ,Dongmei Lu,Xiangnan Wu,Portia Rebecca Clare Grayson,Jana Karbanová,Heng Jin,Jemma Victoria Walker,Heng Zhuang,Stefano Ardu,Denis Corbeil,Pauline Marangoni,Kristina Thamm,Shouqing Luo,Yan Gao,Bing Hu,Massimo Attanasio,Christopher Tredwin,Peter Carmeliet,Alexander C Zambon ,Karen Liu ,A.k Wann ,Clarissa Coveney ,Ophir D Klein ,Anton M Jetten ,Wieland B Huttner ,Tülay Gülşen

doi:10.15252/embj.201899845

Abstract

Proper temporal and spatial activation of stem cells relies on highly coordinated cell signaling. The primary cilium is the sensory organelle that is responsible for transmitting extracellular signals into a cell. Primary cilium size, architecture, and assembly–disassembly dynamics are under rigid cell cycle‐dependent control. Using mouse incisor tooth epithelia as a model, we show that ciliary dynamics in stem cells require the proper functions of a cholesterol‐binding membrane glycoprotein, Prominin‐1 (Prom1/CD133), which controls sequential recruitment of ciliary membrane components, histone deacetylase, and transcription factors. Nuclear translocation of Prom1 and these molecules is particularly evident in transit amplifying cells, the immediate derivatives of stem cells. The absence of Prom1 impairs ciliary dynamics and abolishes the growth stimulation effects of sonic hedgehog (SHH) treatment, resulting in the disruption of stem cell quiescence maintenance and activation. We propose that Prom1 is a key regulator ensuring appropriate response of stem cells to extracellular signals, with important implications for development, regeneration, and diseases.

Highlights

Tissue homeostasis depends on proper stem cell maintenance and activation to guarantee that balanced cell lineages can be produced upon necessity (Li & Clevers, 2010; Cheung & Rando, 2013)
The two cell populations could be distinguished for instance, at postnatal day 7 (P7) lower incisor cervical loop epithelium (CLE) by immunofluorescence (IF) using markers Sox2 and Bmi1 for stem cells, and Ki67 for transit amplifying cells (Fig 1A and Appendix Fig S1B) or upon laser capture microdissection followed by real-time room temperature (RT)–PCR profiling using markers such as Sox2, Bmi1, CDKn1c, CDKn2b, and p16 for stem cells, and CDK5r1, c-Myc, and Sonic Hedgehog (SHH) for transit amplifying cells (Fig 1B and C)
To validate the primary cilium profiles in the CLE, we performed immunostaining on the primary cilium axoneme using anti-acetylated a-tubulin (AcTub) antibodies followed by threedimensional (3D) measurements to determine whether cilium size and integrity were linked to the stem cell status in vivo (Appendix Fig S1C)

Summary

Introduction

Tissue homeostasis depends on proper stem cell maintenance and activation to guarantee that balanced cell lineages can be produced upon necessity (Li & Clevers, 2010; Cheung & Rando, 2013). Stem cells produce long primary cilia that are responsible for sensing and transmitting signals into the cells (Izawa et al, 2015; Sanchez & Dynlacht, 2016). Stem cell activation is accompanied by dynamic primary cilium size, architecture, and assembly–disassembly modifications (Izawa et al, 2015; Sanchez & Dynlacht, 2016) and release of factors from primary cilium to cytoplasm to trigger downstream cascades that are responsible for cell lineage differentiation (Berbari et al, 2009; Goetz & Anderson, 2010). We use continuously growing mouse incisor as a model where epithelial stem cells represent a large proportion of cells at the distal end of the tooth epithelium named cervical loop (CL) (Jussila & Thesleff, 2012; Biehs et al, 2013) that provides a dynamic system in which we are able to profile the functional associations between primary cilia and stem cells

Methods

Results

Conclusion