Human basal body basics

Abstract

In human cells, the basal body (BB) core comprises a ninefold microtubule-triplet cylindrical structure. Distal and subdistal appendages are located at the distal end of BB, where they play indispensable roles in cilium formation and function. Most cells that arrest in the G0 stage of the cell cycle initiate BB docking at the plasma membrane followed by BB-mediated growth of a solitary primary cilium, a structure required for sensing the extracellular environment and cell signaling. In addition to the primary cilium, motile cilia are present in specialized cells, such as sperm and airway epithelium. Mutations that affect BB function result in cilia dysfunction. This can generate syndromic disorders, collectively called ciliopathies, for which there are no effective treatments. In this review, we focus on the features and functions of BBs and centrosomes in Homo sapiens.

Keywords: Basal body; Centrosome; Ciliopathy; Cilium; Human.

Fig. 1

Structure of the human basal body (BB) at initial step of ciliogenesis. a Side view of the BB. DAP/TF, distal appendages/transition fibers, SAP/BF, sub-distal appendages/basal feet, CV, ciliary vesicle. b Cross section of the BB with SAS protein-containing central hub, attached to Cep135 and MT triplets. c. Primary ciliogenesis progresses through five morphologically distinct stages in human astrocytes. Stage 1: lateral vesicles are at the distal end of the BB. Stage 2: the lateral vesicles fuse and become a vesicular cap. Stage 3–4: stretch of vesicular cap and outgrowth of primary cilium. Stage 5: mature primary cilium surrounded with cilium pit [64]. Used with permission from [64]