The scaffolding protein IQGAP1 co-localizes with actin at the cytoplasmic face of the nuclear envelope: implications for cytoskeletal regulation

Abstract

IQGAP1 is an important cytoskeletal regulator, known to act at the plasma membrane to bundle and cap actin filaments, and to tether the cortical actin meshwork to microtubules via plus-end binding proteins. Here we describe the novel subcellular localization of IQGAP1 at the cytoplasmic face of the nuclear envelope, where it co-located with F-actin. The IQGAP1 and F-actin staining overlapped that of microtubules at the nuclear envelope, revealing a pattern strikingly similar to that observed at the plasma membrane. In detergent-extracted cells IQGAP1 was retained at cytoskeletal structures at the nuclear envelope. This finding has new implications for involvement of IQGAP1 in cell polarization and migration events and potentially in cell cycle-associated nuclear envelope assembly/disassembly.

Keywords: :

• Cdc42
• IQGAP1
• Rac1
• actin
• cell polarization
• nuclear envelope

Disclosure of Potential Conflicts of Interest

No potential conflict of interest was disclosed.

Acknowledgments

The authors wish to thank members of the Henderson lab for helpful comments and discussions, and give particular appreciation to Emma Kettle and Ross Boadle (Institute for Clinical Pathology and Medical Research, Westmead, Sydney) for their assistance with electron microscopy. This work was funded by grants to B.R.H. from the National Health and Medical Research Council (NH&MRC) of Australia and the Cancer Council of New South Wales. B.R.H. is a Senior Research Fellow of the NH&MRC.