HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Permissions Request Permissions Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Berchner-Pfannschmidt, U. Articles by Fandrey, J. Search for Related Content PubMed PubMed Citation Articles by Berchner-Pfannschmidt, U. Articles by Fandrey, J.

Imaging of the hypoxia-inducible factor pathway: insights into oxygen sensing

Institut für Physiologie, Universität Duisburg-Essen, Essen, Germany.

CORRESPONDENCE: J. Fandrey, Institut für Physiologie, Universität Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany. Fax: 49 2017234648. E-mail: joachim.fandrey{at}uni-due.de

Keywords: Fluorescence recovery after photo-bleaching, fluorescence resonance energy transfer, green fluorescent protein fusion proteins, hypoxia-inducible factor-1, immunohistology, in vivo imaging

Received: January 28, 2008
Accepted January 31, 2008

The transcription factor complex hypoxia-inducible factor (HIF)-1 controls the expression of most genes involved in adaptation to hypoxic conditions. HIF-1 is a heterodimer composed of oxygen-labile HIF- and constitutively expressed HIF-β subunits. The oxygen-dependent regulation of HIF- is a multistep process that includes degradation under normoxia but stabilisation, translocation into the nucleus and activation under hypoxic conditions.

The present paper summarises the contributions of optical methods to the understanding of oxygen-dependent regulation of the HIF-1 pathway. The tissue- and cell-specific distribution of HIF- was visualised immunohistochemically and by immunofluorescence. Transcriptional activity of HIF-1 was monitored using green fluorescent protein as a reporter under control of hypoxia response elements in living cells, spheroids and tumour tissues in living mice. With cyan and yellow variants of green fluorescent protein fused to HIF subunits and regulatory proteins, subcellular distribution, migration and interaction were imaged in vivo by means of fluorescence recovery after photo-bleaching and fluorescence resonance energy transfer. Noninvasive imaging of these cellular and molecular processes by laser scanning microscopy complements ex vivo molecular biology assays and provides an additional spatial and temporal dimension to the understanding of the HIF-1 pathway.