Role Of SPIN90 (SH3 Protein Interacting With Nck, 90kda) In The Formation Of Endocytic Vesicle And Its Movement In Receptor-mediated Endocytosis

Abstract

Endocytosis is a key mechanism for mediating diverse cellular functions, like uptake of nutrients, recycling of synaptic vesicles and intracellular signaling. The formation and targeting of vesicles to their acceptor compartment from the plasma membrane are tightly controlled for regulating tissue homeostasis. To gain insight into the effect of SPIN90 in the formation of vesicles, we measured the interaction between syndapin and dynamin in SPIN90 overexpressed and deficient fibroblasts. It is reported that syndapin is the phophorylation-regulated dynamin I partner in vivo and its interaction is crucial for SVE. SPIN90-SH3 domain binds with dynamin I-PRD in synapses and PRD domain of SPIN90 interacts to syndapin-SH3 in fibroblasts are already reported. Here, we show that the syndapin-dynamin interaction is maintained in SPIN90-N terminal (SH3 and PRD domain containing part) overexpressed cells comparing to that in mock overexpressed cells. In addition, SPIN90 C terminus (642–722aa) interacts with Rab5a small GTPase which has a role for early endosome movement and fusion were found. For verifying this, immuno-fluorescence and live cell imaging technique were used. We examined that SPIN90 is co-localized with Rab5 in fibroblast, and the movement of gfp-Rab5 positive endosome is delayed when the SPIN90-CC (Rab5 binding) part is overexpressed. From these results, we proposed that SPIN90 has a role in the formation and movement of early endosome.