CILIA: before and after

This is a history of cilia research before and after the discovery of intraflagellar transport (IFT) and the link between primary cilia ciliogenesis and polycystic kidney disease (PKD). Before IFT, ca. the beginning of the new millennium, although sensory and primary cilia were well described, research was largely focused on motile cilia, their structure, movement, and biogenesis. After IFT and the link to PKD, although work on motile cilia has continued to progress, research on primary cilia has exploded, leading to new insights into the role of cilia in cell signaling and development. Genomics, proteomics, and new imaging techniques have unified the field and pointed out the critical role of cilia as a restricted cell organellar compartment, functionally integrated with other cell organelles including the autophagosome and the nucleus.

Methods for Studying Movement of Molecules Within Cilia

The assembly of cilia and eukaryotic flagella (interchangeable terms) requires the import of numerous proteins from the cell body into the growing organelle. Proteins move into and inside cilia by diffusion and by motor-based intraflagellar transport (IFT). Many aspects of ciliary protein transport such as the distribution of unloading sites and the frequency of transport can be analyzed using direct in vivo imaging of fluorescently tagged proteins. Here, we will describe how to use total internal reflection fluorescence microcopy (TIRFM) to analyze protein transport in the flagella of the unicellular alga Chlamydomonas reinhardtii, a widely used model for cilia and cilia-related disease.

Intraflagellar Transport Complex B Proteins Regulate the Hippo Effector Yap1 during Cardiogenesis

Cilia and the intraflagellar transport (IFT) proteins involved in ciliogenesis are associated with congenital heart diseases (CHDs). However, the molecular links between cilia, IFT proteins, and cardiogenesis are yet to be established. Using a combination of biochemistry, genetics, and live-imaging methods, we show that IFT complex B proteins (Ift88, Ift54, and Ift20) modulate the Hippo pathway effector YAP1 in zebrafish and mouse. We demonstrate that this interaction is key to restrict the formation of the proepicardium and the myocardium. In cellulo experiments suggest that IFT88 and IFT20 interact with YAP1 in the cytoplasm and functionally modulate its activity, identifying a molecular link between cilia-related proteins and the Hippo pathway. Taken together, our results highlight a noncanonical role for IFT complex B proteins during cardiogenesis and shed light on a mechanism of action for ciliary proteins in YAP1 regulation.

The Role of Intraflagellar Transport in the Photoreceptor Sensory Cilium

The photoreceptor is a complex specialized cell in which a major component responsible for visual transduction is the photoreceptor sensory cilium (PSC). Building and maintenance of the PSC requires the transport of large proteins along microtubules that extend from the inner segments to the outer segments. A key process, termed intraflagellar transport (IFT), has been recognized as an essential phenomenon for photoreceptor development and maintenance, and exciting new studies have highlighted its importance in retinal and cilia related diseases. This review focuses on the important roles of IFT players, including motor proteins, IFT proteins, and photoreceptor-specific cargos in photoreceptor sensory cilium. In addition, specific IFT components that are involved in inherited human diseases are discussed.

An age of enlightenment for cilia: The FASEB summer research conference on the "Biology of Cilia and Flagella"

From July 19-24, 2015, 169 clinicians and basic scientists gathered in the vertiginous heights of Snowmass, Colorado (2502 m) for the fourth FASEB summer research conference on the 'Biology of Cilia and Flagella'. Organizers Maureen Barr (Rutgers University), Iain Drummond (Massachusetts General Hospital/Harvard Medical School), and Jagesh Shah (Brigham and Women's Hospital/Harvard Medical School) assembled a program filled with new data and forward-thinking ideas documenting the ongoing growth of the field. Sixty oral presentations and 77 posters covered novel aspects of cilia structure, ciliogenesis, cilia motility, cilia-mediated signaling, and cilia-related disease. In this report, we summarize the meeting, highlight exciting developments and discuss open questions.