Plant KASH proteins SINE1 and SINE2 have synergistic and antagonistic interactions with actin-branching and actin-bundling factors.

This article focuses on the genetic interactions of the Arabidopsis linker of nucleoskeleton and cytoskeleton (LINC) complex KASH proteins SINE1 and SINE2 with the actin-remodeling ARP2/3 complex and the actin-bundling factor SCAB1 during stomatal dynamics and plant development. The study demonstrates that SINE1 and the ARP2/3 complex function in the same pathway to regulate actin repolymerization during abscisic acid (ABA)-induced stomatal closure, whereas SINE2 and ARP2/3 have opposing roles, with SINE2 influencing actin depolymerization. Additionally, SINE1 and ARP2/3 act synergistically in lateral root development, while the absence of SINE2 renders trichome development independent of ARP2/3, partially rescuing trichome branching defects. These findings reveal distinct and complex roles for SINE1 and SINE2 in actin cytoskeleton remodeling linked to nuclear envelope-associated processes affecting stomatal function, root growth, and trichome morphology.