Illuminating the phosphatidylinositol 3-kinase/Akt pathway

Qiang Ni, Matthew Fosbrink, Jin Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Genetically encodable fluorescent biosensors based on fluorescence resonance energy transfer (FRET) are being developed for analyzing spatiotemporal dynamics of various signaling events in living cells, as these events are often dynamically regulated and spatially compartmentalized within specific signaling context. In particular, to investigate the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in the cellular context, we have developed a series of such biosensors that enable dynamic visualization of several key signaling events in this pathway, namely InPAkt for lipid second messenger dynamics, BAKR for Akt activity, and ReAktion for the action of Akt during its multi-step activation process. Discussed here are several studies that have been carried out with these novel biosensors. First, we examined nuclear phosphatidylinositol-3,4,5-triphosphate (PIP3) in living cells using nucleus-targeted InPAkt. Second, we analyzed signal propagation from the plasma membrane to the nucleus by using plasma membrane-targeted InPAkt and nucleus-targeted BKAR to simultaneously monitor PIP3 dynamics and Akt activity in the same cell. Of note, results from these co-imaging experiments suggest that active Akt can dissociate from the plasma membrane and translocate into the nucleus in the presence of high levels of PIP3 at the plasma membrane. This finding has led to a further study of the action of Akt during its activation process, particularly focusing on how Akt dissociates from the membrane. In this regard, a live-cell molecular analysis using ReAktion reveals a conformational change in Akt that is critically dependent on the existence of a phosphorylatable T308 in the activation loop. Subsequently this has led to the discovery of new regulatory roles of this critical phosphorylation event of Akt for ensuring its proper activation and function.

Original languageEnglish (US)
Title of host publicationSmall Animal Whole-Body Optical Imaging Based on Genetically Engineered Probes
DOIs
StatePublished - Apr 21 2008
EventSmall Animal Whole-Body Optical Imaging Based on Genetically Engineered Probes - San Jose, CA, United States
Duration: Jan 21 2008Jan 22 2008

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume6868
ISSN (Print)1605-7422

Other

OtherSmall Animal Whole-Body Optical Imaging Based on Genetically Engineered Probes
CountryUnited States
CitySan Jose, CA
Period1/21/081/22/08

Keywords

  • Akt
  • Fluorescence resonance energy transfer
  • Fluorescent biosensor
  • Fluorescent protein
  • Live-cell imaging
  • Phosphatidylinositol 3-kinase
  • Phosphatidylinositol- 3,4,5-triphosphate

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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