Tracing the dynamic recruitment trajectory of Optineurin between the centrosome and other macromolecular assemblies, signifying its role in cell cycle progression

Spatiotemporal allocation and dynamic redistribution of centrosomal proteins are critical for coordinating the structural and molecular events that ensure successful cell division. While depletion of the multifunctional protein Optineurin (OPTN) impairs cell-cycle progression, our previous report of the presence of OPTN at key cell-division assemblies raised the question of how its trafficking is coordinated during cell division. In this study, using cell-cycle synchronisation coupled with flow cytometric analysis and confocal microscopy, we report that OPTN progressively dissociates from centrosomes during mitosis, redistributes to cytokinetic structures, accumulates at the spindle midzone, and then concentrates at the midbody during cytokinesis. Moreover, following this transition, OPTN progressively re-emerges at centrosomes during G1 of the subsequent cell cycle. Further, microtubule perturbation and regrowth assays provide evidence that OPTN recruitment and retention at the pericentriolar matrix (PCM) can occur independently of microtubules, whereas its exit is microtubule-dependent. Collectively, this study depicts, for the first time, a detailed movement trail of OPTN, highlighting its centrosome-linked redistribution and microtubule dependency. This context-dependent localisation and trafficking of OPTN across the centrosome-midbody axis establish a definitive spatiotemporal roadmap that can be strategically utilised to study its functional role in cell division.