Microtubule minus-end regulation at a glance

Abstract

Microtubules are cytoskeletal filaments essential for numerous aspects of cell physiology. They are polarized polymeric tubes with a fast growing plus end and a slow growing minus end. In this Cell Science at a Glance article and the accompanying poster, we review the current knowledge on the dynamics and organization of microtubule minus ends. Several factors, including the γ-tubulin ring complex, CAMSAP/Patronin, ASPM/Asp, SPIRAL2 (in plants) and the KANSL complex recognize microtubule minus ends and regulate their nucleation, stability and interactions with partners, such as microtubule severing enzymes, microtubule depolymerases and protein scaffolds. Together with minus-end-directed motors, these microtubule minus-end targeting proteins (−TIPs) also control the formation of microtubule-organizing centers, such as centrosomes and spindle poles, and mediate microtubule attachment to cellular membrane structures, including the cell cortex, Golgi complex and the cell nucleus. Structural and functional studies are starting to reveal the molecular mechanisms by which dynamic −TIP networks control microtubule minus ends.

Endosomal Wnt signaling proteins control microtubule nucleation in dendrites

“…For example, microtubule severing can be used to generate new plus and minus ends and amplify microtubule number [44,73]. In many cell types, minus ends generated when a microtubule is severed are recognized by minus-end binding proteins in the calmodulin-regulated spectrin-associated protein (CAM-SAP)/Patronin family [74,75]. In C. elegans, γTub-mediated microtubule nucleation has been Refer to S1 Table for all genotypes and S1 Data for data used to generate graphs in (E), (F), (K), (L), and (M).…”

The Mechanism of Tubulin Assembly into Microtubules: Insights from Structural Studies

“…These include “defects” in the microtubule lattice, which may be involved in rescue events ( Aumeier et al., 2016 ; de Forges et al., 2016 ), and also tubulin in a curved-to-straight intermediate conformation, be it before microtubule incorporation or at microtubule ends. These last structures are the binding site of various MAPs targeting one or the other end of the microtubule ( Akhmanova and Steinmetz, 2019 ). Although the binding mode of some of them has been determined from decorated microtubules, as in the case of CAMSAP ( Atherton et al., 2017a ) and EBs ( Maurer et al., 2012 ), the end-binding preference remains poorly understood in most cases.…”

Microtubule Organization in Striated Muscle Cells

“…Controlling microtubule dynamics is pivotal for cells, as microtubules serve as tracks for intracellular transport and contribute to cellular organization and plasticity by providing scaffolds for and exerting forces on subcellular structures. While plus ends mainly contribute to microtubule mass and dynamic interactions of microtubules with other subcellular structures, nucleation and stable anchoring of minus ends determines microtubule network organization [21]. A key factor for microtubule nucleation is the γ-tubulin ring complex (γTuRC) which is formed from γ-tubulin and several γ-tubulin ring complex proteins (GCPs) [22].…”