Adducin‐1 is essential for spindle pole integrity through its interaction with TPX2

Abstract

Bipolar spindle assembly is necessary to ensure the proper progression of cell division. Loss of spindle pole integrity leads to multipolar spindles and aberrant chromosomal segregation. However, the mechanism underlying the maintenance of spindle pole integrity remains unclear. In this study, we show that the actin‐binding protein adducin‐1 (ADD1) is phosphorylated at S726 during mitosis. S726‐phosphorylated ADD1 localizes to centrosomes, wherein it organizes into a rosette‐like structure at the pericentriolar material. ADD1 depletion causes centriole splitting and therefore results in multipolar spindles during mitosis, which can be restored by re‐expression of ADD1 and the phosphomimetic S726D mutant but not by the S726A mutant. Moreover, the phosphorylation of ADD1 at S726 is crucial for its interaction with TPX2, which is essential for spindle pole integrity. Together, our findings unveil a novel function of ADD1 in maintaining spindle pole integrity through its interaction with TPX2.

Excess TPX2 Interferes with Microtubule Disassembly and Nuclei Reformation at Mitotic Exit

“…However, we cannot exclude that actin, the cyto B primary target, contributes to the phenotype. Emerging evidence showing that TPX2 interacts with components of the actin-myosin network makes this possibility worthy of further investigation [55,56]. We show that the presence of reassembling Golgi cisternae, associated to the centrosome, inside the doughnut also contributes to the physical hindrance and abolishing its reassembly partially rescues the phenotype; whether Golgi trapping inside the doughnuts also results in its impaired functionality is an open question to be explored.…”

The Aurora-A/TPX2 Axis Directs Spindle Orientation in Adherent Human Cells by Regulating NuMA and Microtubule Stability

“…Although we did not observe any major changes in the length or number of growing EB1-labeled astral MTs or in the number of astral MTs reaching the cortex in the TPX2-overexpressing metaphases (Figures 3G and 3H), we cannot rule out that subtle changes in MT dynamics parameters in specific MT populations are present. It is also possible that TPX2 overexpression impacts on the TPX2 interaction with spindle-associated, actin-binding proteins, such as myosin 10 28 and adducin-1, 29 that stabilize the connection between astral MTs and the acto-myosin cortex, which is key for spindle-placement mechanisms. 3…”

Phosphorylation of adducin-1 by cyclin-dependent kinase 5 is important for epidermal growth factor-induced cell migration

“…To prepare whole-cell lysates, cells were lysed with 1% NP-40 lysis buffer (1% NP-40, 20 mM Tris-HCl pH 8.0, 137 mM NaCl, 10% glycerol, and 1 mM Na 3 VO 4 ) containing protease inhibitor cocktail (Roche). Immunoblotting and immunoprecipitation were performed as described previously 33 .…”

“…Adducin has multiple cellular functions, which plays important roles in establishing erythrocyte membrane-skeleton 17 , stabilizing cell-cell junctions 28,29 , regulating neuronal synapse plasticity 30,31 , maintaining proper mitotic spindle apparatus during mitosis 32,33 , and facilitating cell migration 34,35 . Adducin has also been implicated in cancer cell migration and metastasis 36–38 .…”