Kinetic analysis of de novo centriole assembly in heat‐shocked mammalian cells

Abstract

Mammalian cells are capable of de novo centriole formation after the removal of existing centrioles. This suggests that de novo centriole assembly is repressed in normally duplicating cells to maintain a constant number of centrioles in the cells. However, neither the mechanism of de novo centriole assembly nor that of its hypothesized repression is understood due to the lack of an experimental system. We found that the heat shock (HS; 42°C, 2 h) of mouse embryonic fibroblasts caused the separation of centriole pairs, a transient increase in polo-like kinase (Plk) 4 expression, and the formation of a complex containing γ-tubulin, pericentrin, HS protein (Hsp) 90, and Plk4, in approximately half of the cells. Subsequently, spindle-assembly abnormal protein (Sas) 6, centrosomal protein (Cep) 135, and centrin localized to the complex, and tubulin consequently became polyglutamylated, indicating de novo centriole assembly in the heat-shocked cells. These results suggested that HS-induced de novo centriole assembly could provide an experimental system for further elucidating the regulation of centrosome number in mammalian cells. © 2016 Wiley Periodicals, Inc.

Heat Stress-Induced Multiple Multipolar Divisions of Human Cancer Cells

“…Heat stress can induce both structural and numerical aberrations of centrosomes in human cancer cells [15,17,20]. In our experiments, we first found that heat stress alters centrosome organization.…”

“…Heat stress is another kind of mechanical factor that can induce multipolar cell divisions [14,15,16,17,18,19,20]. For example, by immunofluorescence assay, Nakahata [17] et al demonstrated the percentage of metaphases with multiple spindles of MCF-7 cells with about 3% in control and 71.0% in heat-shocked group.…”

“…In particular, the PCM provides a scaffold for γ-tubulin ring complexes that play a key role in microtubule nucleation. By using γ-tubulin antibodies, Baek et al [20] found that 85.7% of HeLa cells and 47.7% of NIH3T3 cells had no γ-tubulin spots after heat shock. During the recovery period, they found that γ-tubulin spots began to reappear and the percentage of cells with extra γ-tubulin spots increased.…”

“…Multipolar cell division can be promoted by polyploid cells [7], and various treatments by paclitaxel [8], colchicine [9], carboplatin [10], confined microenvironment [11,12], UV- and X-radiation [13], and even heat stress [14,15,16,17,18,19,20]. Through time lapse observation, Temme et al [14] found that the fraction of dividing cells that exhibited multipolar divisions was elevated to about 50% in the heated Chinese hamster ovary (CHO) cells.…”

“…Meanwhile, Zhang et al [19] demonstrated that heat stress can also drive fish embryonic cells to form multipolar spindles in their mitosis, which was assumed to be caused by insufficient disorganization of daughter centrioles and splitting from the mother centriole by heat shock. Baek et al [20] concluded that heat shock can induce de novo centriole assembly in mammalian cells, thus causing centrosome amplification. These previous studies showed that subcellular mechanisms underlying heat stress-induced multipolar divisions can be attributed to the structural or numerical aberrations in centrosomes directly stemming from heat stress.…”