Expression of apoptosis-related genes in the organ of Corti, modiolus and stria vascularis of newborn rats.
Cell death in the inner ear tissues is an important mechanism leading to hearing impairment. Here, using microarrays and real-time RT-PCR we analyzed expression of selected apoptosis-related genes in rat's inner ear. We determined the gene expression in tissues freshly isolated from neonatal rats (3-5 days old) and compared it to that of explants cultured for 24 h under normoxic or hypoxic conditions. For the analyses, we used pooled samples of the organ of Corti (OC), modiolus (MOD) and stria vascularis (SV), respectively. We observed region-specific changes in gene expression between the fresh tissues and the normoxic culture. In the OC, expression of the proapoptotic genes caspase-2, caspase-3, caspase-6 and calpain-1 was downregulated. In the MOD, the antioxidative defense SOD-2 and SOD-3 were upregulated. In the SV, caspase-2, caspase-6, calpain-1 and SOD-3 were downregulated and SOD-2 upregulated. We speculate that these changes could reflect survival shift in transcriptome of inner ear explants tissues under in vitro conditions. With the exception of SOD-2, hypoxic culture conditions induced the same changes in gene expression as the normoxic conditions indicating that culture preparation is likely the dominating factor, which modifies the gene expression pattern. We conclude that various culture conditions induce different expression pattern of apoptosis-related genes in the organotypic cochlear cultures, as compared to fresh tissues. This transcriptional pattern may reflect the survival ability of specific tissues and could become a tempting target for a pharmacological intervention in inner ear diseases.
Gross
Johann
J
Dept. Othorhinolaryngology, Charité-Universitätsmedizin Berlin, Molecular Biology Research Laboratory, Charitéplatz 1, 10117-Berlin, Germany. johann.gross@charite.de
Machulik
Astrid
A
Amarjargal
Nyamaa
N
Moller
Renate
R
Ungethüm
Ute
U
Kuban
Ralf-Jürgen
RJ
Fuchs
Frank-Uwe
FU
Andreeva
Nadezhda
N
Fuchs
Julia
J
Henke
Wolfgang
W
Pohl
Elena E
EE
Szczepek
Agnieszka J
AJ
Haupt
Heidemarie
H
Mazurek
Birgit
B
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D003051:Cochlea / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D009924:Organ Culture Techniques; D009925:Organ of Corti / Q000254:growth & development; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013316:Stria Vascularis / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D012333:RNA, Messenger