Cell division: kinetochores SKAdaddle

SKA3 targeted therapies in cancer precision surgery: bridging bench discoveries to clinical applications - review article

Spindle and kinetochore-associated complex subunit 3 (SKA3) is a microtubule-binding subcomplex of the outer kinetochore, which plays a vital role in proper chromosomal segregation and cell division. Recently, SKA3 have been demonstrated its oncogenic role of tumorigenesis and development in cancers. In this review, the authors comprehensively deciphered SKA3 in human cancer from various aspects, including bibliometrics, pan-cancer analysis, and narrative summary. The authors also provided the top 10 predicted drugs targeting SKA3. The authors proposed that SKA3 was a potential target and brought new therapeutic opportunities for cancer patients.

Multisite phosphorylation determines the formation of Ska-Ndc80 macro-complexes that are essential for chromosome segregation during mitosis

The human Ska complex (Ska) localizing to both spindle microtubules and kinetochores is essential for proper chromosome segregation during mitosis. Although several mechanisms have been proposed to explain how Ska is recruited to kinetochores, it is still not fully understood. By analyzing Ska3 phosphorylation, we identified six critical Cdk1 sites, including the previously identified Thr358 and Thr360. Mutations of these sites to phospho-deficient alanine (6A) in cells completely abolished Ska3 localization to kinetochores and Ska functions in chromosome segregation. In vitro, Cdk1 phosphorylation on Ska enhanced WT, not phospho-deficient 6A, binding to Ndc80C. Strikingly, the phosphomimetic Ska 6D complex formed a stable macro-complex with Ndc80C, but Ska WT failed to do so. These results suggest that multisite Cdk1 phosphorylation-enabled Ska–Ndc80 binding is decisive for Ska localization to kinetochores and its functions. Moreover, we found that Ska decrease at kinetochores triggered by the microtubule-depolymerizing drug nocodazole is independent of Aurora B but can be overridden by Ska3 overexpression, suggestive of a role of spindle microtubules in promoting Ska kinetochore recruitment. Thus, based on the current and previous results, we propose that multisite Cdk1 phosphorylation is critical for the formation of Ska–Ndc80 macro-complexes that are essential for chromosome segregation.

High expression of spindle and kinetochore- associated protein 1 predicts early recurrence and progression of non-muscle invasive bladder cancer

BACKGROUND

Spindle and kinetochore-associated protein 1 (SKA1) is a component of SKA, which is essential for proper chromosome segregation. Recently, SKA1 was found to be over-expressed in several types of human cancers. However, reports on the relationship between SKA1 expression and the prognosis of bladder cancer, in particular, are lacking.

OBJECTIVES

To clarify the clinical significance of SKA1 as a prognostic biomarker for early recurrence and progression of patients with non-muscle invasive bladder cancer (NMIBC).

METHODS

The differential expression levels of SKA1 of 148 NMIBC tissues were determined by immunohistochemical staining. Quantitative real-time PCR and western blot analysis were further performed to confirm the immunohistochemistry results. Recurrence and progression free interval were assessed by Kaplan-Meier method and differences between groups calculated by log-rank statistics. The prognostic value of SKA1 for early recurrence and progression was analyzed by multivariate Cox proportional hazard regression models.

RESULTS

SKA1 expression was significantly different in various NMIBC tissues. Kaplan-Meier analysis revealed that patients with high SKA1 expression showed high early recurrence (p< 0.001) and progression (p< 0.05) rates. Although univariate Cox regression analysis revealed that several other factors had an impact on recurrence and progression, upon multivariate analysis, high SKA1expression was the only independent predictor for early recurrence (hazards ratio [HR], 0.246; 95% confidence interval [CI], 0.131-0.461; p= 0.000) and progression (HR, 0.194; 95% CI, 0.052-0.715; p= 0.014).

CONCLUSIONS

High SKA1 expression is associated with early recurrence and progression in patients with NMIBC, indicating SKA1 may serve as a promising prognostic biomarker for this disease.

Comparative Microarray Analysis of Proliferating and Differentiating Murine ENS Progenitor Cells

Postnatal neural progenitor cells of the enteric nervous system are a potential source for future cell replacement therapies of developmental dysplasia like Hirschsprung's disease. However, little is known about the molecular mechanisms driving the homeostasis and differentiation of this cell pool. In this work, we conducted Affymetrix GeneChip experiments to identify differences in gene regulation between proliferation and early differentiation of enteric neural progenitors from neonatal mice. We detected a total of 1333 regulated genes that were linked to different groups of cellular mechanisms involved in cell cycle, apoptosis, neural proliferation, and differentiation. As expected, we found an augmented inhibition in the gene expression of cell cycle progression as well as an enhanced mRNA expression of neuronal and glial differentiation markers. We further found a marked inactivation of the canonical Wnt pathway after the induction of cellular differentiation. Taken together, these data demonstrate the various molecular mechanisms taking place during the proliferation and early differentiation of enteric neural progenitor cells.