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A meta-analysis of differential coexpression across age
Jesse Gillis
Expression Analysis
Interpretations• Differential Expression
– Functional: Tissue differences– Dysfunctional: Disease expression profiling
• Coexpression– GO groups
• Differential Coexpression– If functional association indicates coexpression then change
in functional association would indicate change in coexpression
– Tumor network vs normal network – Ageing involves many coordinated changes (functional and
dysfunctional)
Differential Coexpression
Theories of aging
• Antagonistic pleiotropy – Early and late effects– P53 suppresses tumors and stem cells
• Mutation accumulation– Decreased selection, extrinsic mortality predicting lifespan– cancer
• Fetal programming– Maternal stress, cardiovascular risks
• Senescence versus development– Often both
Background• Differential coexpression across age• Human microarray studies from Gemma’s database were
categorized by their subject’s ages into the four groups– “prenatal”– “child/young adult” (0-18 years) – “adult” (19-54)– “older adult” (55+)
• 8 to 13 studies for each age group• 2803 individual microarrays (repurposed)
• Problem: How to generalize taking a difference to multiple conditions?
Sorting Data
Wavelets and Differential Coexpression
Separates Data into:
Lifelong coexpression
Lifelong change in coexpression
Early life change in coexpression
Late life change in coexpression
Basis Set
Sample Results
GO group Validation
Differential coexpression AUC 0.77
Coexpression values AUC 0.65
Random gene sets AUC 0.49
GO groups 25-30 genes
leave-one-out-validation
Take home message: Patterns of differential coexpression predict related fuction
SIRT1-Longevity interest
-Gene silencing in yeast
-Unusual but repeated pattern
-Early changes determine lifelong state
Ongoing Work
• Disease groupings– Alzheimer’s– Schizophrenia
• Aging patterns– Specific genes and theories
• Finer aging gradations– Year by year
Acknowledgments
Paul Pavlidis and the Pavlidis lab
Support from NIH and the Michael Smith Foundation for Health Research
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