Cell polarity: keeping worms LeGaL

Spying on the Polarity Dynamics during Wound Healing of Zebrafish by Using Rationally Designed Carbon Dots

Wound healing is an essential and complex biological process. Research into its mechanism and factors that influence its effectiveness has led to better treatments. Changes in the microenvironment are demonstrated to affect wound healing. Cell polarity is a significant microenvironment-related parameter that is associated with many physiological and pathological activities. However, dynamic changes in polarity during wound healing have not been investigated. Monitoring cell polarity during wound healing may open up a new avenue for developing better treatments. Here, a method is developed to monitor cell polarity that involved taking advantage of the fascinating optical properties and biocompatibility of carbon dots (CDs). Specifically, near-infrared (NIR) polarity-sensitive N-phenyl-p-phenylenediamine (PPh-CDs) are successfully prepared, which exhibit high sensitivity to polarity, with 509-fold stronger fluorescence in dioxane than in water. The PPh-CDs are successfully applied to monitor the changes of lysosomal polarity during starvation conditions. Using this method, dynamic changes of polarity during wound healing of zebrafish are monitored for the first time. Upon an amputation performed at the zebrafish tail, stronger PPh-CDs fluorescence appeared at the wound sites, and the intensity increased for 25 min and then gradually decreased. This report provides an important experimental basis for investigating wound healing by employing polarity-sensitive CDs.

Influence of cell polarity on early development of the sea urchin embryo

BACKGROUND

Establishment and maintenance of cell polarity is critical for normal embryonic development. Previously, it was thought that the echinoderm embryo remained relatively unpolarized until the first asymmetric division at the 16-cell stage. Here, we analyzed roles of the cell polarity regulators, the PAR complex proteins, and how their disruption in early development affects later developmental milestones.

RESULTS

We found that PAR6, aPKC, and CDC42 localize to the apical cortex as early as the 2-cell stage and that this localization is retained through the gastrula stage. Of interest, PAR1 also colocalizes with these apical markers through the gastrula stage. Additionally, PAR1 was found to be in complex with aPKC, but not PAR6. PAR6, aPKC, and CDC42 are anchored in the cortical actin cytoskeleton by assembled myosin. Furthermore, assembled myosin was found to be necessary to maintain proper PAR6 localization through subsequent cleavage divisions. Interference with myosin assembly prevented the embryos from reaching the blastula stage, while transient disruptions of either actin or microtubules did not have this effect.

CONCLUSIONS

These observations suggest that disruptions of the polarity in the early embryo can have a significant impact on the ability of the embryo to reach later critical stages in development.