Transcriptional Program of Ciliated Epithelial Cells Reveals New Cilium and Centrosome Components and Links to Human Disease

Ramona A Hoh,Erin Turk,Timothy R Stowe,Tim Stearns,Panayiotis V Benos

doi:10.1371/journal.pone.0052166

Abstract

Defects in the centrosome and cilium are associated with a set of human diseases having diverse phenotypes. To further characterize the components that define the function of these organelles we determined the transcriptional profile of multiciliated tracheal epithelial cells. Cultures of mouse tracheal epithelial cells undergoing differentiation in vitro were derived from mice expressing GFP from the ciliated-cell specific FOXJ1 promoter (FOXJ1:GFP). The transcriptional profile of ciliating GFP+ cells from these cultures was defined at an early and a late time point during differentiation and was refined by subtraction of the profile of the non-ciliated GFP- cells. We identified 649 genes upregulated early, when most cells were forming basal bodies, and 73 genes genes upregulated late, when most cells were fully ciliated. Most, but not all, of known centrosome proteins are transcriptionally upregulated early, particularly Plk4, a master regulator of centriole formation. We found that three genes associated with human disease states, Mdm1, Mlf1, and Dyx1c1, are upregulated during ciliogenesis and localize to centrioles and cilia. This transcriptome for mammalian multiciliated epithelial cells identifies new candidate centrosome and cilia proteins, highlights similarities between components of motile and primary cilia, and identifies new links between cilia proteins and human disease.

Highlights

Cilia are highly conserved microtubule-based structures that are found in all branches of the eukaryotic tree [1]
The two time points chosen were based on previous analysis of landmark events in these cultures [17]; four days after air-liquid interface (ALI) (ALI+4) to enrich for genes involved in initial steps of centriole duplication, and ALI+12 to enrich for genes expressed when cilia are mature (Figure 1A)
Our results show that the core set of proteins required for centriole duplication in cycling cells is upregulated during basal body formation in ciliated multiciliated tracheal epithelial cells (MTECs)

Summary

Introduction

Cilia are highly conserved microtubule-based structures that are found in all branches of the eukaryotic tree [1]. There are several types of cilia, differing in the specifics of their structure and function. The primary cilium, present in one copy on many cell types in the body, has a 9+0 axonemal structure and is important for sensing chemical and mechanical stimuli. Important developmental signaling pathways such as hedgehog and non-canonical Wnt are transduced through primary cilia [2,3]. Motile cilia usually have an additional central pair of microtubules in the axoneme (9+2), as well as accessory structures including dynein arms and radial spokes associated with ciliary beating [4]. In addition to generating force, motile cilia have sensory functions [5,6,7,8]

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Results

Conclusion