IISc's light-based LISA technique switches Aurora A kinase on and off
IISc researchers have developed LISA, a blue-light technique that reversibly activates Aurora A kinase and can rescue cell division defects caused by centrosome loss.
Researchers at the Indian Institute of Science (IISc) have devised a technique that uses blue light to switch a key cell-division enzyme on and off at will. Named Light-Induced Spindle Activation (LISA), the method reversibly activates Aurora A kinase, a centrosomal enzyme central to the assembly of the mitotic spindle.
Aurora A is believed to be switched on through clustering, a process that in cells is aided by Cep192, an evolutionarily conserved scaffold. Earlier experiments showed that Aurora A-coated beads could set off microtubule nucleation in frog egg extracts, but only when Cep192 was present. LISA sidesteps that requirement, allowing researchers to induce and study Aurora A clustering reversibly with blue light across a range of cell types. Unlike the bead-based approach, which is largely confined to cell extracts, LISA can be used directly in living cells.
The method grew out of LARIAT, an existing technique normally used to inhibit proteins by clustering them with light. Sachin Kotak, associate professor in the Department of Microbiology and Cell Biology, and his team recognised that the same light-driven clustering could instead be turned to activating Aurora A. LARIAT relies on the plant proteins CRY2 and CIB1, which cluster when exposed to blue light.
The team engineered human cells to produce a fusion protein linking Aurora A kinase to CRY2. Blue light triggers a conformational change in CRY2 that promotes its interaction with CIB1, driving multiple Aurora A assemblies to cluster. Vignesh Olakkal, a PhD student and first author of the study, said this offers a new way to trigger and activate an artificial Aurora A kinase complex, sufficient to induce microtubule nucleation.
Because cells lacking centrosomes often falter in spindle assembly and divide incorrectly, the team tested whether LISA could compensate. After chemically removing centrosomes from human cells and introducing the engineered clustering system, they found that applying blue light during mitosis stimulated microtubule nucleation efficiently. The light-induced activation was enough to restore spindle assembly and rescue the division defects caused by centrosome loss.
The approach may also have therapeutic implications. Aurora A is overexpressed in many solid tumours, making it a drug target, but the enzyme acts on multiple targets. Kotak said the strategy could help identify Aurora A-specific targets involved in microtubule nucleation independently of the centrosome, which may aid the design of new drugs.