Submitted on July 10, 2007
Accepted on December 3, 2007
Gene Expression in Mouse Brain Following Chronic Hypoxia: Role of Sarcospan in Glial Cell Death
Dan Zhou1, Jiyi Wang1, Matthew A Zapala2, Jin Xue1, Nicholas J Schork2, and Gabriel G. Haddad3*
1 Pediatrics, University of California San Diego, La Jolla, California, United States
2 Psychiatry, University of California San Diego, La Jolla, California, United States
3 Pediatrics, University of California San Diego, La Jolla, California, United States; Neurosciences, University of California San Diego, La Jolla, California, United States; The Rady Children's Hospital - San Diego, San Diego, California, United States
* To whom correspondence should be addressed. E-mail: ghaddad{at}ucsd.edu.
Hypoxia is a hallmark of respiratory, neurological or hematological diseases as well as life at high altitude. For example, chronic constant hypoxia (CCH) occurs in chronic lung diseases or at high altitude, whereas chronic intermittent hypoxia (CIH) occurs in diseases such as sleep apnea or sickle cell disease. In spite of the fact that such conditions are frequent, the cellular and molecular mechanisms underlying the effect of hypoxia, whether constant or intermittent, are not well understood. In this study, we first determined the effect of CCH and CIH on global gene expression in different regions of mouse brain using microarrays and then investigated the biological role of genes of interest. We found that: 1) in the cortical region, the expression level of 80 genes was significantly altered by CIH (16 up- and 64 down-regulated) and this number increased to 137 genes following CCH (34 up- and 103 down-regulated); 2) a similar number of gene alterations was identified in the hippocampal area, and the majority of the changes in this region were up-regulations; 3) two genes (Sspn and Ttc27) were down-regulated in both brain regions and following both treatments; and 4) RNAi-mediated knockdown of Sspn increased cell death in hypoxia in a cell culture system. We conclude that CIH or CCH induced significant and distinguishable alterations in gene expression in cortex and hippocampus and that Sspn seems to play a critical role in inducing cell death under hypoxic conditions.
