The identification of protein kinase C iota as a regulator of the Mammalian heat shock response using functional genomic screens.
BACKGROUND
The heat shock response is widely used as a surrogate of the general protein quality control system within the cell. This system plays a significant role in aging and many protein folding diseases as well as the responses to other physical and chemical stressors.


RESULTS
In this study, a broad-based functional genomics approach was taken to identify potential regulators of the mammalian heat shock response. In the primary screen, a total of 13724 full-length genes in mammalian expression vectors were individually co-transfected into human embryonic kidney cells together with a human HSP70B promoter driving firefly luciferase. A subset of the full-length genes that showed significant activation in the primary screen were then evaluated for their ability to hyper-activate the HSP70B under heat shock conditions. Based on the results from the secondary assay and gene expression microarray analyses, eight genes were chosen for validation using siRNA knockdown. Of the eight genes, only PRKCI showed a statistically significant reduction in the heat shock response in two independent siRNA duplexes compared to scrambled controls. Knockdown of the PRKCI mRNA was confirmed using quantitative RT-PCR. Additional studies did not show a direct physical interaction between PRKCI and HSF1.


CONCLUSIONS
The results suggest that PRKCI is an indirect co-regulator of HSF1 activity and the heat shock response. Given the underlying role of HSF1 in many human diseases and the response to environmental stressors, PRKCI represents a potentially new candidate for gene-environment interactions and therapeutic intervention.
Boellmann
Frank
F
Center for Genomic Biology and Bioinformatics, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina, United States of America.
Thomas
Russell S
RS
D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D015894:Genome, Human / Q000235:genetics*; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D000099293:Protein Kinase C-lambda
D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D007527:Isoenzymes; D011493:Protein Kinase C; D014157:Transcription Factors; D000099293:Protein Kinase C-lambda; C000619706:HSF1 protein, human