Quantitative Phenotyping of Cell Behavior

Micropatterns normalize cell polarity and internal organization. They also normalize cell behavior, for example during cell cycle progression or during symetric or asymmetric mitosis. They are therefore powerful tools to quantitatively phenotype cells when screening drugs or gene inactivations or to phenotype tumour cells

Example of TTL-null versus WT Mouse Embryonic Fibroblasts (MEF)

In both animal models and human cancers, TTL (tubulin-tyrosine ligase) is often suppressed during tumor growth, indicating that TTL suppression and resulting tubulin detyrosination represent a strong selective advantage for proliferating transformed cells. In a recent JCB paper, Peris et al. used micropatterns to provide evidence that TTL suppression induces abnormalities in spindle positioning.

Independently, impaired control of spindle positioning has been proposed as one factor favoring tumor invasiveness.

Mitotic spindle orientation in WT or TTL-null fibroblasts. (from Peris et al JCB)

Similar organization of actin assemblies and of cell adhesions were observed in TTL-null cells and WT cells placed on micropatterns. However, whereas the majority of mitotic spindles of WT cells grown on L-shaped patterns were oriented along the hypotenuse (see figure), there was a wide dispersion of spindle orientations in TTL-null cells with 70% of spindles deviating by >15° from the median angle compared with only 30% in WT cells (Fig. 8 B), indicating an impaired control of spindle positioning in TTL-null cells.