Overview of structure and function of mammalian cilia.
Cilia are membrane-bounded, centriole-derived projections from the cell surface that contain a microtubule cytoskeleton, the ciliary axoneme, surrounded by a ciliary membrane. Axonemes in multiciliated cells of mammalian epithelia are 9 + 2, possess dynein arms, and are motile. In contrast, single nonmotile 9 + 0 primary cilia are found on epithelial cells, such as those of the kidney tubule, but also on nonepithelial cells, such as chondrocytes, fibroblasts, and neurons. The ciliary membranes of all cilia contain specific receptors and ion channel proteins that initiate signaling pathways controlling motility and/or linking mechanical or chemical stimuli, including sonic hedgehog and growth factors, to intracellular transduction cascades regulating differentiation, migration, and cell growth during development and in adulthood. Unique motile 9 + 0 cilia, found during development at the embryonic node, determine left-right asymmetry of the body.
Satir
Peter
P
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA. satir@aecom.yu.edu
Christensen
Søren Tvorup
ST
D000818:Animals; D002923:Cilia / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure*; D003238:Connective Tissue / Q000502:physiology / Q000648:ultrastructure; D053823:Hedgehog Proteins / Q000502:physiology; D006801:Humans; D008322:Mammals / Q000502:physiology*; D009068:Movement / Q000502:physiology; D051153:Wnt Proteins / Q000502:physiology
D053823:Hedgehog Proteins; D051153:Wnt Proteins