Chlamydomonas: Cilia and Ciliopathies

Abstract

Cilia and flagella are evolutionally conserved microtubule-based cellular protrusions that are present from organisms ranging from protozoan and algae to human. In the human body and embryo, motile cilia have been found in embryonic node, ventricles of the brain, respiratory ducts, fallopian tube, and sperm. Cilia motility provides cell movement, movement of fluids surrounding the ciliated cells and fluid-flow-generated signaling. Immotile primary cilia exist in almost every cell in the human body and during embryonic development. The presence of various receptors and ion channels on the ciliary membrane enables the cilia as a signaling center to perceive extracellular inputs. The signals generated will be transduced into the cell to control proper human development and physiology. A well-known example is that hedgehog signaling is indispensable for cilia in mammals. Thus, it is not surprising that defects in ciliary structure, assembly, and signaling have been linked with a cohort of human diseases, called ciliopathies. Chlamydomonas is one of the widely used organisms to study ciliary biology, and the research involving this organism has been playing a leading role in our understanding of ciliary biology and ciliopathies.