A transcriptome analysis identifies molecular effectors of unconjugated bilirubin in human neuroblastoma SH-SY5Y cells.
BACKGROUND
The deposition of unconjugated bilirubin (UCB) in selected regions of the brain results in irreversible neuronal damage, or Bilirubin Encephalopathy (BE). Although UCB impairs a large number of cellular functions in other tissues, the basic mechanisms of neurotoxicity have not yet been fully clarified. While cells can accumulate UCB by passive diffusion, cell protection may involve multiple mechanisms including the extrusion of the pigment as well as pro-survival homeostatic responses that are still unknown.


RESULTS
Transcriptome changes induced by UCB exposure in SH-SY5Y neuroblastoma cell line were examined by high density oligonucleotide microarrays. Two-hundred and thirty genes were induced after 24 hours. A Gene Ontology (GO) analysis showed that at least 50 genes were directly involved in the endoplasmic reticulum (ER) stress response. Validation of selected ER stress genes is shown by quantitative RT-PCR. Analysis of XBP1 splicing and DDIT3/CHOP subcellular localization is presented.


CONCLUSIONS
These results show for the first time that UCB exposure induces ER stress response as major intracellular homeostasis in surviving neuroblastoma cells in vitro.
Calligaris
Raffaella
R
International School for Advanced Studies, AREA Science Park, Trieste, Italy. calliga@sissa.it
Bellarosa
Cristina
C
Foti
Rossana
R
Roncaglia
Paola
P
Giraudi
Pablo
P
Krmac
Helena
H
Tiribelli
Claudio
C
Gustincich
Stefano
S
D000596:Amino Acids / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects / Q000235:genetics; D001663:Bilirubin / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D009447:Neuroblastoma / Q000473:pathology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics; D019154:Protein Splicing / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051742:Transcription Factor CHOP / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D056811:Unfolded Protein Response / Q000187:drug effects; D000071717:X-Box Binding Protein 1
D000596:Amino Acids; D004268:DNA-Binding Proteins; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D051742:Transcription Factor CHOP; D001663:Bilirubin