The SH3 domain distinguishes the role of I-BAR proteins IRTKS and MIM in chemotactic response to serum

Abstract

The family of inverse BAR (I-BAR) domain proteins participates in a range of cellular processes associated with membrane dynamics and consists of five distinct members. Three of the I-BAR proteins, including insulin receptor tyrosine kinase substrate (IRTKS), contain an SH3 domain near their C-termini. Yet, the function of the SH3 domain of IRTKS remains uncharacterized. Here we report that in contrast to MIM, which is a prototype of I-BAR proteins and does not contain an SH3 domain, IRTKS promoted serum-induced cell migration along with enhanced phosphorylation of mitogen activated kinases Erk1/2 and p38, and activation of small GTPases Rac1 and Cdc42. In addition, cells overexpressing IRTKS exhibited an increased polarity characterized by elongated cytoplasm and extensive lamellipodia at leading edges. However, a mutant with deletion of the SH3 domain attenuated both cellular motility and p38 phosphorylation but had little effect on Erk1/2 phosphorylation. Also, a chimeric mutant in which the N-terminal portion of MIM is fused with the C-terminal IRTKS, including the SH3 domain, was able to promote chemotactic response to serum and cellular polarity. In contrast, a chimeric mutant in which the N-terminal IRTKS is fused with the C-terminal MIM failed to do so. Furthermore, treatment of cells with SB203580, a selective inhibitor of p38, also neutralized the effect of IRTKS on cell migration. These data indicate that the SH3 domain distinguishes the function of IRTKS in promoting cell migration and inducing signal transduction from those of SH3-less I-BAR proteins.

IRTKS Promotes Insulin Signaling Transduction through Inhibiting SHIP2 Phosphatase Activity

“…The I-BAR domain is a common structure of I-BAR superfamily members, and can induce plasma membrane protrusion formation [12]. The SH3 domain, known as a protein recognition module, could serve as a docking harbor [13]. Here, we found that the SH3 domain mediates the binding of IRTKS to SHIP2.…”

Differential interactions of missing in metastasis and insulin receptor tyrosine kinase substrate with RAB proteins in the endocytosis of CXCR4

“…We were interested in whether interaction with RABs is a common property of I-BAR domain proteins and thus analyzed HeLa cells expressing GFP-conjugated IRTKS (IRTKS-GFP). We chose IRTKS because we had found previously that it regulates cellular motility differently than MIM does (29) and that it is structurally distinct from MIM by having an internal SH3 domain ( Fig. 4A).…”

“…PBS was from Corning. The plasmids encoding MIM-GFP, IRTKS-GFP, IRTKS⌬SH3-GFP, IRTKS-IBAR-MIM-GFP, and MIM-IBAR-IRTKS-GFP have been described previously (29).…”

CRY–BARs: Versatile light-gated molecular tools for the remodeling of membrane architectures

“…The MTSS1 (Missing in Metastasis 1) protein is considered the prototype of I-BAR proteins (Li et al, 2016), but, to the best of our knowledge, has not previously been applied in an optogenetic context. In this work, we investigated the potential of the MTSS1 I-BAR domain to serve as an actuator of membrane architecture and plasma membrane dynamics.…”