Wong, D. C. P. | bioRxiv Science

bioRxiv2023

Coordination of focal adhesion nanostructure and mechano-signaling drives cardiomyocyte differentiation

Focal adhesion (FA) organization and signaling are essential for cell growth and differentiation. However, the molecular mechanism that coordinates the FA signaling with cardiomyocyte differentiation has not been fully understood. Here, we provide empirical evidence that BNIP-2, a BCH-domain-containing protein, is the organizer of FA nanostructure that potentiates FA signaling and cell traction force transmission. Mechanistically, BNIP-2 serves as a scaffold for focal adhesion kinase (FAK), paxillin and vinculin to control their molecular organization and assembly/disassembly within FAs. Constitutively active phosphomimetic mutant FAK Y397D shows enhanced binding to BNIP-2, whereas the depletion of BNIP-2 reduces FAK phosphorylation and interaction between FAK and paxillin. Using H9c2 myoblasts and human embryonic stem cells as model systems, we show that BNIP-2 depletion results in aberrant FA dynamics with impairment of traction force, and changes in signature target genes, hereby impeding cardiomyocyte differentiation. BNIP-2 regulation of FA organization and dynamic is therefore pivotal to the mechanotransduction in cardiomyocyte differentiation, shedding new light to how FA-transduced force modulates cell growth and differentiation.

cell biology↗

bioRxiv2023

Natural Killer cell contractility and cytotoxicity is driven by TLR3 agonist-mediated TAZ cytoplasmic sequestration

The evolutionarily conserved YAP/TAZ mechano-responsive transcription cofactors regulate development and tumorigenesis. Here, we show for the first time that human natural killer (NK) cells specifically express TAZ but not YAP, and TAZ serves to limit NK cytotoxicity. The TLR3 agonist, hiltonol, was able to trigger cytoplasmic sequestration of TAZ, which increased NK cytotoxicity. Mechanistically, a low dose of hiltonol enhanced the intracellular contractility of NK cells accompanied by an increase in active RhoA and myosin light chain phosphorylation, conceivably through an increase in ERK1/2 activation-dependent ROS production. Importantly, we showed that the dissociation of LATS1 from actin upon activation of contractility, is required to sequester TAZ in the cytoplasm. Functionally, hiltonol also reduced the NK cell surface inhibitory receptors, KIR3DL1 through c-Myc inhibition and PD-1 through enhanced contractility. Direct inhibition of c-Myc promoted NK cytotoxicity against K562 lymphoblast. We corroborated our findings by coculturing hiltonol-pretreated NK cells with breast and lung cancer cells, and demonstrated increased NK-mediated cancer killing, which conceivably occurred via sequestration of TAZ to the cytoplasm which facilitated NK cytotoxicity. Our findings pave the way for ex vivo rejuvenation of NK cells for in vivo immunotherapies, which could involve a cocktail of hiltonol and c-Myc inhibitor.

cell biology↗