Cell micropatterning reveals the modulatory effect of cell shape on proliferation through intracellular calcium transients

https://doi.org/10.1016/j.bbamcr.2017.09.015Get rights and content
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Highlights

  • Cell shape affects its proliferation through modulating the intracellular calcium transients.

  • The patterns of intracellular Ca2 + transients are related to the expressions of IP3R1 and SERCA2 in osteoblasts.

  • The expressions of IP3R1 and SERCA2 are determined by NSI as a result of nuclear volume changes in different shaped cells.

Abstract

The mechanism by which cell shape regulates the function of the cell is one of the most important biological issues, but it remains unclear. Here, we investigated the effect of the regulation of cell shape on proliferation by using a micropatterning approach to confine MC3T3-E1 cells into specific shapes. Our results show that the proliferation rate for rectangle-, triangle-, square- and circle-shaped osteoblasts increased sequentially and was related to the nuclear shape index (NSI) but not the cell shape index (CSI). Interestingly, intracellular calcium transients also displayed different patterns, with the number of Ca2 + peaks increasing with the NSI in shaped cells. Further causal investigation revealed that the gene expression levels of the inositol 1,4,5-triphosphate receptor 1 (IP3R1) and sarco/endoplasmic reticulum Ca2 +-ATPase 2 (SERCA2), two major calcium cycling proteins in the endoplasmic reticulum (ER), were increased with an increase in NSI as a result of nuclear volume changes. Moreover, the down-regulation of IP3R1 and/or SERCA2 using shRNAs in circle-shaped or control osteoblasts resulted in changes in intracellular calcium transient patterns and cell proliferation rates towards that of smaller-NSI-shaped cells. Our results indicate that changes in cell shape changed nuclear morphology and then the gene expression of IP3R1 and SERCA2, which produced different intracellular calcium transient patterns. The patterns of intracellular calcium transients then determined the proliferation rate of the shaped osteoblasts.

Keywords

Micropatterning
Calcium transient
ER
Nuclear shape index
Shape

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