Posttranscriptional gene regulation under hypoxia

Aim of this work is the analysis of posttranscriptional gene regulation under hypoxic conditions. Oxygen deprivation is the physiological signal for the sprouting of new blood vessels and therefore important during development and wound healing. Further on, misregulation in hypoxia adaptation is implicated in several diseases as well as tumor growth and metastasis.

Up to 95% of all human genes undergo alternative splicing (AS) and aberrant splicing can be the causative agent of diseases. In addition, 5' and 3' ends of mRNAs vary due to alternative promoter selection (APS) and polyadenylation, leading to different protein isoforms and untranslated regions (UTRs). We investigate posttranscriptional gene regulation mechanisms in endothelial cells (HUVEC) upon adaptation to oxygen deprivation using two different approaches. We analyzed changes in splicing pattern upon oxygen shortage (1% O2) using the Affymetrix exon array. We confirmed 10 AS and APS events, 8 of them coding for different protein isoforms and 1 leading to nonsense mediated decay. Furthermore, using a bioinformatic approach, we predicted regulatory RNA elements in the 5' and 3' UTRs of all human genes. Using the program Dynalign we compared the UTRs of human and mouse genes with respect to structure conservation. We are currently focusing on elements predicted in the UTRs of genes known to be related to hypoxia adaptation. For initial tests we have chosen 15 UTRs and are analyzing their function under hypoxic and normoxic conditions.