α-Fodrin is required for the organization of functional microtubules during mitosis

Abstract

The cytoskeleton protein α-fodrin plays a major role in maintaining structural stability of membranes. It was also identified as part of the brain γ-tubulin ring complex, the major microtubule nucleator. Here, we investigated the requirement of α-fodrin for microtubule spindle assembly during mitotic progression. We found that α-fodrin depletion results in abnormal mitosis with uncongressed chromosomes, leading to prolonged activation of the spindle assembly checkpoint and a severe mitotic delay. Further, α-fodrin repression led to the formation of shortened spindles with unstable kinetochore-microtubule attachments. We also found that the mitotic kinesin CENP-E had reduced levels at kinetochores to likely account for the chromosome misalignment defects in α-fodrin-depleted cells. Importantly, we showed these cells to exhibit reduced levels of detyrosinated α-tubulin, which primarily drives CENP-E localization. Since proper microtubule dynamics and chromosome alignment are required for completion of normal mitosis, this study reveals an unforeseen role of α-fodrin in regulating mitotic progression. Future studies on these lines of observations should reveal important mechanistic insight for fodrin's involvement in cancer.

A Fresh Look at the Structure, Regulation, and Functions of Fodrin

“…CENP-E, a mitotic motor, carries chromosomes through the spindle with help from detyrosinated tubulin. We reported that ␣-fodrin-deficient cells displayed reduced detyrosinated tubulin (58). This could have important implications for the involvement of ␣-fodrin in the progression of cancer.…”

α-Fodrin in Cytoskeletal Organization and the Activity of Certain Key Microtubule Kinesins

“…U-251 MG cells were treated with control shRNA/α-fodrin shRNA for 96 h to achieve appreciable downregulation of α-fodrin expression. The shRNA used for these experiments has beendetailed in our previous publication [ 5 ]. The cells were then harvested and total protein was extracted using RapiGest TM SF (Waters Corporation, Milford, MA, USA).…”

“…The literature survey also revealed diverse functions of this protein. Further, we have been able to show that α-fodrin is important in chromosome congression and mitotic progression in cells [ 5 ]. It is also important in calcium-based signaling, especially in neuronal cells [ 6 ].…”

“…We chose to work with glioblastoma cells because of the abundant presence of α-fodrin. Additionally, through our previous studies, we have been able to understand that α-fodrin is significant in microtubule formation (unpublished results) and organization in these cells [ 4 , 5 , 8 ].…”

Near-Dead Cells to Special Tetraploidy to First Cells to Cancer Diagnostic Morphology: Unlikely Therapy-Gain from For-Profit Industrial Goliath

“…To replace the dicey SMG-based therapy, there are numerous works citing or implicating cytoskeleton perpendicular move relative to the cell polarity axial orientation [49] [50] [51]. These works showed that the resultant cells in such orientations relative to surrounding cells had attained movability which has had special attention in metastasis [6] [7] [52] [53].…”