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In this thread, I'm unloading the results of a few tools I've run on three microarray datasets. The first, from Chew et. al, compares static measurements of dermal papilla cell gene expression in balding vs. non-balding scalp (GSE66663). The second, again from Chew et. al, is time series data from balding and non-balding DPCs treated with 1nM or 10nM DHT (GSE66664). And the third, from Cotsarelis et. al, is a comparison of bald scalp vs. haired scalp as a whole (GSE36169). I won't go into much depth in this post (there's too much information, so an in depth analysis would be a dissertation and not a forum post ), but instead will mostly throw the results out there for discussion by the community.
Analysis of Static DP Expression
First, I filtered out all probesets with detection less than 1 in either all bald replicates or all non-bald replicates. I aggregated the probesets corresponding to the same gene and normalized for total mRNA signal for each replicate. Then I calculated average fold change between balding and non-balding DPCs for each gene as well as log2 average fold change.
First we can run gene ontology (GO) on the upregulated and downregulated genes to find biological processes overrepresented in the upregulated and downregulated genes.
List of major categories associated with upregulated genes (log2 fold change of 0.5 or more, i.e. genes expressed at ~1.41x or higher):
A lot of categories related to cell cycle and DNA damage/repair, as you can see. A few studies find that balding DPCs are more prone to cellular senescence than non-balding cells(1)(2). One study finds expression of DNA damage markers in balding DPCs(3).
List of major categories associated with downregulated genes (log2 fold change of -0.5 or less, i.e. genes expressed at ~0.71x or lower):
Many immune system categories among the downregulated genes, such as those related to the interferon pathway and histocompatibility/antigen processing. As you'll see later, immune-related categories are actually upregulated in balding scalp as a whole according to the Cotsarelis data. In particular, we run into the interferon pathway again and again through several separate analyses.
Next we'll use TFactS to infer transcription factors that may be responsible for changes in gene expression in balding DPCs, which performs extremely well compared to other methods(4):
There's both a signed mode, which specifies higher vs. lower activity of the transcription factor, and an unsigned mode which has a larger dataset but does not specify direction.
The unsigned analysis (statistically significant results after multi-testing correction shown):
The signed analysis (p < 0.05 shown):
TFs predicted to be more active:
TFs predicted to be less active:
Keep in mind that for the signed lists, I've bolded all results with p < 0.05 with no multi-testing correction. Therefore, probability of false positives is higher in these lists. We see CTNNB1 (beta-catenin) in both the activated and inhibited lists, which indicates that its target genes may be altered, perhaps through binding to AR, which one study has shown to be enhanced in Androgenetic Alopecia (5). We also see different subunits of NFkB (REL, NFKB1) in both groups. Others:
Gli2 – mediator of hedgehog signaling
MYC is upregulated 1.55x at the transcriptional level.
In the repressed list:
SREBF1 (a.k.a. SREBP1) and SREBF2 (a.k.a. SREBP2), which are involved in lipid and sterol synthesis.
CREBBP – acetyltransferase which acts as a general coactivator, is downregulated at the transcriptional level.
BRCA1 – involved in DNA repair (actually upregulated at transcriptional level).
SMAD4 – mediator of TGFbeta/BMP signaling
CDKN1A (a.k.a. p21) – cell cycle inhibitor, highly downregulated at transcriptional level
FOXO1 – regulates metabolism, resistance to stress, longevity
SP1 – wide variety of functions
Lastly for the static data, we can run SDREM(6) to attempt to reverse-engineer upstream signaling pathways that may account for changes in gene expression. SDREM is intended for time-series data, but we'll just treat it like the dermal papilla cells went from the non-balding state to the balding state all in one step.
Red = source node (which I specified as AR), green = target nodes (inferred downstream transcription factors), blue = internal nodes connecting the sources to the targets
There's a lot going on here, so it's helpful to break the nodes into rough categories:
Immune system – IRF9, TBK1, IRF8, IRF2, IRF3, IRF4, IRF5, IRF6, IRF7, RELA, SPI1, STAT1, STAT3, TAL1, XBP1
Development – CDX2, CTNNB1, EGFR, SOX8, ONECUT1, SMAD3, SMAD4, SOX18, PRDM1, SOX2, SOX4, TCF3, ALX1
Histone acetyltransferases – NCOA2, CREBBP, EP300, NCOA3, NCOA1, KAT2B
Histone deacetylases – HDAC1, HDAC2, HDAC4
Nuclear corepressors – NCOR1, NCOR2
Nuclear receptors – ESR1, NR5A2, NR6A1, NR3C1, AR (source), PPARG, RARA, VDR
Stress response/resistance – FOXO1, HIF1A
Chaperones – HSP90AA1
Cell Cycle – JUN, RB1, TP53, CDK1
Ubiquitination/proteasome – MDM2, UBC
Sumoylation – PIAS4, UBE2I, SUMO1, PIAS1
Kinases – SRC
DNA Repair – BRCA1
Other – DAXX, SIN3A, PML, SMARCA4, SP1, ZBTB16
(continued in next post)
Analysis of Static DP Expression
First, I filtered out all probesets with detection less than 1 in either all bald replicates or all non-bald replicates. I aggregated the probesets corresponding to the same gene and normalized for total mRNA signal for each replicate. Then I calculated average fold change between balding and non-balding DPCs for each gene as well as log2 average fold change.
First we can run gene ontology (GO) on the upregulated and downregulated genes to find biological processes overrepresented in the upregulated and downregulated genes.
List of major categories associated with upregulated genes (log2 fold change of 0.5 or more, i.e. genes expressed at ~1.41x or higher):
- DNA strand elongation involved in DNA replication
- DNA replication initiation
- telomere maintenance via recombination
- metaphase plate congression
- mitotic prometaphase
- spindle assembly
- G1/S transition of mitotic cell cycle
- DNA synthesis involved in DNA repair
- mitotic sister chromatid segregation
- sister chromatic cohesion
- regulation of mitotic nuclear division
- mitotic cell cycle checkpoint
- double-strand break repair
- regulation of microtubule cytoskeleton organization
- mitotic anaphase
- regulation of response to DNA damage stimulus
- cell division
- DNA damage checkpoint
- G2/M transition of mitotic cell cycle
- negative regulation of mitotic cell cycle phase transition
- regulation of signal transduction by p53 class mediator
- response to ionizing radiation
- DNA packaging
- positive regulation of cell cycle process
- regulation of cysteine-type endopeptidase activity involved in apoptotic process
- apoptotic signaling pathway
- angiogenesis
- urogenital system development
- morphogenesis of an epithelium
- tube morphogenesis
- regulation of DNA metabolic process
- reproductive structure development
- cellular response to lipid
- negative regulation of cellular component organization
- regulation of cellular protein localization
- single organism reproductive process
- regulation of cellular component biogenesis
- positive regulation of developmental process
- positive regulation of cellular component organization
- organonitrogen compound biosynthetic process
- movement of cell or subcellular component
- protein complex assembly
- regulation of cell proliferation
- generation of neurons
- positive regulation of signal transduction
- cell development
- regulation of phosphorylation
- positive regulation of molecular function
- animal organ development
- positive regulation of nucleobase-containing compound metabolic process
- positive regulation of gene expression
- regulation of multicellular organismal development
- regulation of protein modification process
- multi-organism process
- cellular protein metabolic process
- DNA replication initiation
- telomere maintenance via recombination
- metaphase plate congression
- mitotic prometaphase
- spindle assembly
- G1/S transition of mitotic cell cycle
- DNA synthesis involved in DNA repair
- mitotic sister chromatid segregation
- sister chromatic cohesion
- regulation of mitotic nuclear division
- mitotic cell cycle checkpoint
- double-strand break repair
- regulation of microtubule cytoskeleton organization
- mitotic anaphase
- regulation of response to DNA damage stimulus
- cell division
- DNA damage checkpoint
- G2/M transition of mitotic cell cycle
- negative regulation of mitotic cell cycle phase transition
- regulation of signal transduction by p53 class mediator
- response to ionizing radiation
- DNA packaging
- positive regulation of cell cycle process
- regulation of cysteine-type endopeptidase activity involved in apoptotic process
- apoptotic signaling pathway
- angiogenesis
- urogenital system development
- morphogenesis of an epithelium
- tube morphogenesis
- regulation of DNA metabolic process
- reproductive structure development
- cellular response to lipid
- negative regulation of cellular component organization
- regulation of cellular protein localization
- single organism reproductive process
- regulation of cellular component biogenesis
- positive regulation of developmental process
- positive regulation of cellular component organization
- organonitrogen compound biosynthetic process
- movement of cell or subcellular component
- protein complex assembly
- regulation of cell proliferation
- generation of neurons
- positive regulation of signal transduction
- cell development
- regulation of phosphorylation
- positive regulation of molecular function
- animal organ development
- positive regulation of nucleobase-containing compound metabolic process
- positive regulation of gene expression
- regulation of multicellular organismal development
- regulation of protein modification process
- multi-organism process
- cellular protein metabolic process
A lot of categories related to cell cycle and DNA damage/repair, as you can see. A few studies find that balding DPCs are more prone to cellular senescence than non-balding cells(1)(2). One study finds expression of DNA damage markers in balding DPCs(3).
List of major categories associated with downregulated genes (log2 fold change of -0.5 or less, i.e. genes expressed at ~0.71x or lower):
- response to interferon-beta
- phagosome acidification
- type I interferon signaling pathway
- cholesterol biosynthetic process
- negative regulation of viral genome replication
- antigen processing and presentation of exogenous peptide antigen via MHC class I
- regulation of macroautophagy
- multicellular organismal macromolecule metabolic process
- defense response to virus
- transition metal ion transport
- vacuole organization
- response to interferon-gamma
- carboxylic acid catabolic process
- cellular lipid catabolic process
- cellular response to insulin stimulus
- cellular response to nutrient levels
- membrane lipid metabolic process
- extracellular matrix organization
- positive regulation of innate immune response
- vacuolar transport
- organonitrogen compound catabolic process
- response to oxygen levels
- negative regulation of immune system process
- oxidation-reduction process
- monocarboxylic acid metabolic process
- regulation of cell migration
- positive regulation of apoptotic process
- negative regulation of cell proliferation
- organophosphate metabolic process
- positive regulation of signal transduction
- negative regulation of cell death
- apoptotic process
- protein transport
- vesicle-mediated transport
- negative regulation of multicellular organismal process
- negative regulation of cellular protein metabolic process
- negative regulation of signal transduction
- positive regulation of cellular protein metabolic process
- cellular protein localization
- protein complex subunit organization
- phosphate-containing compound metabolic process
- regulation of protein modification process
- intracellular signal transduction
- regulation of catalytic activity
- regulation of cellular component organization
- regulation of development process
- single-organism localization
- developmental process
- phagosome acidification
- type I interferon signaling pathway
- cholesterol biosynthetic process
- negative regulation of viral genome replication
- antigen processing and presentation of exogenous peptide antigen via MHC class I
- regulation of macroautophagy
- multicellular organismal macromolecule metabolic process
- defense response to virus
- transition metal ion transport
- vacuole organization
- response to interferon-gamma
- carboxylic acid catabolic process
- cellular lipid catabolic process
- cellular response to insulin stimulus
- cellular response to nutrient levels
- membrane lipid metabolic process
- extracellular matrix organization
- positive regulation of innate immune response
- vacuolar transport
- organonitrogen compound catabolic process
- response to oxygen levels
- negative regulation of immune system process
- oxidation-reduction process
- monocarboxylic acid metabolic process
- regulation of cell migration
- positive regulation of apoptotic process
- negative regulation of cell proliferation
- organophosphate metabolic process
- positive regulation of signal transduction
- negative regulation of cell death
- apoptotic process
- protein transport
- vesicle-mediated transport
- negative regulation of multicellular organismal process
- negative regulation of cellular protein metabolic process
- negative regulation of signal transduction
- positive regulation of cellular protein metabolic process
- cellular protein localization
- protein complex subunit organization
- phosphate-containing compound metabolic process
- regulation of protein modification process
- intracellular signal transduction
- regulation of catalytic activity
- regulation of cellular component organization
- regulation of development process
- single-organism localization
- developmental process
Many immune system categories among the downregulated genes, such as those related to the interferon pathway and histocompatibility/antigen processing. As you'll see later, immune-related categories are actually upregulated in balding scalp as a whole according to the Cotsarelis data. In particular, we run into the interferon pathway again and again through several separate analyses.
Next we'll use TFactS to infer transcription factors that may be responsible for changes in gene expression in balding DPCs, which performs extremely well compared to other methods(4):
To evaluate the ability of TFactS to detect the relevant TFs, we submitted the genes reported by the authors as showing a significant response in their respective microarray analysis. When regulated genes were not listed in the paper, we reanalyzed the raw data obtained from GEO database and we selected genes significantly regulated >2-fold.
Even though these studies were based on very different biological systems, the results summarized in Table 1 (details in Supplementary Data in supplementary file 1) show that TFactS identified all (18/18) of the relevant TFs. For example, Terragni et al. (32) showed that inhibition of the AKT pathway provokes the activation of FOXO3 and the inhibition of NF-κB. Consistently, TFactS identified FOXO3 as regulated (Pval≃0.00e+0) and activated (Pval = 1.40e−4) and NF-κB as regulated (Pval≃0.00e+0) and inhibited (Pval=1.16e−3).
…
To compare the different tools, we have used similar settings for all of them in terms of statistical cutoff and promoter length. Lists of enriched transcription factors generated using these tools were ranked according to P-values or FWER P-value (GSEA). We considered only significant results (nominal P-value) and limited the number of TFs in the output lists to maximum 100, even though such long lists are not suitable for experimental validation. Using these parameters, CRSD and CORE_TF found 12 out of 18 expected TFs, TFM-Explorer 8, oPOSSUM 7 and GSEA 2. Three TFs were absent from JASPAR profiles used by oPOSSUM. When used with TFactS sign-less catalog instead of ‘c3' signatures, GSEA performed better (5/18). We did not use other GSEA gene set signatures as they are not centered on TFs. Detailed results and methods are shown in Supplementary Data supplementary file 2. Compared to TFactS, these tools produced much longer lists of regulated TFs, but it is not clear whether these represent background or previously unrecognized regulations. In summary, TFactS was able to identify expected transcription factor regulations, which, at least in some cases, were not found by tools based on PWM or consensus motifs, using standard settings.
There's both a signed mode, which specifies higher vs. lower activity of the transcription factor, and an unsigned mode which has a larger dataset but does not specify direction.
The unsigned analysis (statistically significant results after multi-testing correction shown):
regulated TFs
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
MYC 0.000e+0 0.000e+0 0.000e+0 2.976e-4 121 553 100
TFAP2A 0.000e+0 0.000e+0 0.000e+0 5.952e-4 34 115 71
TCF7L2 0.000e+0 0.000e+0 0.000e+0 8.929e-4 20 61 31
NFKB1 0.000e+0 0.000e+0 0.000e+0 1.190e-3 38 141 88
JUN 0.000e+0 0.000e+0 0.000e+0 1.488e-3 28 131 85
USF1 0.000e+0 0.000e+0 0.000e+0 1.786e-3 25 108 64
FOXO1 0.000e+0 0.000e+0 0.000e+0 2.083e-3 39 161 88
GLI1 0.000e+0 0.000e+0 0.000e+0 2.381e-3 29 124 69
GLI2 0.000e+0 0.000e+0 0.000e+0 2.679e-3 31 107 62
AR 0.000e+0 0.000e+0 0.000e+0 2.976e-3 17 60 31
STAT3 0.000e+0 0.000e+0 0.000e+0 3.274e-3 19 69 48
SMAD3 0.000e+0 0.000e+0 0.000e+0 3.571e-3 18 63 37
SMAD4 0.000e+0 0.000e+0 0.000e+0 3.869e-3 14 45 15
SP3 0.000e+0 0.000e+0 0.000e+0 4.167e-3 29 132 77
SP1 0.000e+0 0.000e+0 0.000e+0 4.464e-3 112 428 100
SMAD1 0.000e+0 0.000e+0 0.000e+0 4.762e-3 10 22 5
RELA 0.000e+0 0.000e+0 0.000e+0 5.060e-3 26 84 52
STAT1 0.000e+0 0.000e+0 0.000e+0 5.357e-3 23 61 36
SREBF1 0.000e+0 0.000e+0 0.000e+0 5.655e-3 22 51 16
REL 0.000e+0 0.000e+0 0.000e+0 5.952e-3 11 23 10
FLI1 0.000e+0 0.000e+0 0.000e+0 6.250e-3 11 28 10
TP53 0.000e+0 0.000e+0 0.000e+0 6.548e-3 34 148 89
CTNNB1 0.000e+0 0.000e+0 0.000e+0 6.845e-3 86 306 100
CREB1 0.000e+0 0.000e+0 0.000e+0 7.143e-3 38 211 97
ETS1 1.000e-5 1.680e-3 3.339e-7 7.440e-3 26 136 87
ATF1 1.000e-5 1.680e-3 3.339e-7 7.738e-3 16 59 32
SREBF2 1.000e-5 1.680e-3 3.339e-7 8.036e-3 12 35 10
RARA 1.000e-5 1.680e-3 3.339e-7 8.333e-3 16 60 25
EGR1 1.000e-5 1.680e-3 3.339e-7 8.631e-3 20 91 58
USF2 2.000e-5 3.360e-3 6.247e-7 8.929e-3 19 86 47
NFIC 2.000e-5 3.360e-3 6.247e-7 9.226e-3 13 45 15
FOXO3 6.000e-5 1.008e-2 1.709e-6 9.524e-3 17 78 49
ETV4 6.000e-5 1.008e-2 1.709e-6 9.821e-3 10 31 9
ATF2 6.000e-5 1.008e-2 1.709e-6 1.012e-2 11 37 8
HIF1A 1.000e-4 1.680e-2 2.766e-6 1.042e-2 12 45 15
YY1 1.200e-4 2.016e-2 3.227e-6 1.071e-2 12 46 17
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
MYC 0.000e+0 0.000e+0 0.000e+0 2.976e-4 121 553 100
TFAP2A 0.000e+0 0.000e+0 0.000e+0 5.952e-4 34 115 71
TCF7L2 0.000e+0 0.000e+0 0.000e+0 8.929e-4 20 61 31
NFKB1 0.000e+0 0.000e+0 0.000e+0 1.190e-3 38 141 88
JUN 0.000e+0 0.000e+0 0.000e+0 1.488e-3 28 131 85
USF1 0.000e+0 0.000e+0 0.000e+0 1.786e-3 25 108 64
FOXO1 0.000e+0 0.000e+0 0.000e+0 2.083e-3 39 161 88
GLI1 0.000e+0 0.000e+0 0.000e+0 2.381e-3 29 124 69
GLI2 0.000e+0 0.000e+0 0.000e+0 2.679e-3 31 107 62
AR 0.000e+0 0.000e+0 0.000e+0 2.976e-3 17 60 31
STAT3 0.000e+0 0.000e+0 0.000e+0 3.274e-3 19 69 48
SMAD3 0.000e+0 0.000e+0 0.000e+0 3.571e-3 18 63 37
SMAD4 0.000e+0 0.000e+0 0.000e+0 3.869e-3 14 45 15
SP3 0.000e+0 0.000e+0 0.000e+0 4.167e-3 29 132 77
SP1 0.000e+0 0.000e+0 0.000e+0 4.464e-3 112 428 100
SMAD1 0.000e+0 0.000e+0 0.000e+0 4.762e-3 10 22 5
RELA 0.000e+0 0.000e+0 0.000e+0 5.060e-3 26 84 52
STAT1 0.000e+0 0.000e+0 0.000e+0 5.357e-3 23 61 36
SREBF1 0.000e+0 0.000e+0 0.000e+0 5.655e-3 22 51 16
REL 0.000e+0 0.000e+0 0.000e+0 5.952e-3 11 23 10
FLI1 0.000e+0 0.000e+0 0.000e+0 6.250e-3 11 28 10
TP53 0.000e+0 0.000e+0 0.000e+0 6.548e-3 34 148 89
CTNNB1 0.000e+0 0.000e+0 0.000e+0 6.845e-3 86 306 100
CREB1 0.000e+0 0.000e+0 0.000e+0 7.143e-3 38 211 97
ETS1 1.000e-5 1.680e-3 3.339e-7 7.440e-3 26 136 87
ATF1 1.000e-5 1.680e-3 3.339e-7 7.738e-3 16 59 32
SREBF2 1.000e-5 1.680e-3 3.339e-7 8.036e-3 12 35 10
RARA 1.000e-5 1.680e-3 3.339e-7 8.333e-3 16 60 25
EGR1 1.000e-5 1.680e-3 3.339e-7 8.631e-3 20 91 58
USF2 2.000e-5 3.360e-3 6.247e-7 8.929e-3 19 86 47
NFIC 2.000e-5 3.360e-3 6.247e-7 9.226e-3 13 45 15
FOXO3 6.000e-5 1.008e-2 1.709e-6 9.524e-3 17 78 49
ETV4 6.000e-5 1.008e-2 1.709e-6 9.821e-3 10 31 9
ATF2 6.000e-5 1.008e-2 1.709e-6 1.012e-2 11 37 8
HIF1A 1.000e-4 1.680e-2 2.766e-6 1.042e-2 12 45 15
YY1 1.200e-4 2.016e-2 3.227e-6 1.071e-2 12 46 17
The signed analysis (p < 0.05 shown):
TFs predicted to be more active:
activated TFs
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
CTNNB1 2.190e-3 1.971e-1 1.107e-1 5.556e-4 45 300 0
GLI2 2.460e-3 2.214e-1 1.107e-1 1.111e-3 20 104 0
MYC 9.760e-3 8.784e-1 2.928e-1 1.667e-3 30 197 0
REL 2.747e-2 2.472e+0 6.181e-1 2.222e-3 2 3 0
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
CTNNB1 2.190e-3 1.971e-1 1.107e-1 5.556e-4 45 300 0
GLI2 2.460e-3 2.214e-1 1.107e-1 1.111e-3 20 104 0
MYC 9.760e-3 8.784e-1 2.928e-1 1.667e-3 30 197 0
REL 2.747e-2 2.472e+0 6.181e-1 2.222e-3 2 3 0
TFs predicted to be less active:
inhibited TFs
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
SREBF1 0.000e+0 0.000e+0 0.000e+0 5.556e-4 17 50 0
SREBF2 4.610e-3 4.149e-1 2.074e-1 1.111e-3 9 34 0
CREBBP 8.290e-3 7.461e-1 2.205e-1 1.667e-3 3 5 0
BRCA1 9.800e-3 8.820e-1 2.205e-1 2.222e-3 2 2 0
CTNNB1 1.738e-2 1.564e+0 3.128e-1 2.778e-3 41 300 0
SMAD4 2.177e-2 1.959e+0 3.266e-1 3.333e-3 8 36 0
CDKN1A 2.747e-2 2.472e+0 3.532e-1 3.889e-3 2 3 0
FOXO1 4.085e-2 3.676e+0 3.893e-1 4.444e-3 23 160 0
NFKB1 4.275e-2 3.848e+0 3.893e-1 5.000e-3 11 63 0
SP1 4.326e-2 3.893e+0 3.893e-1 5.556e-3 25 178 0
Transcription Factor P.value E.value Q.value FDR control (B-H) Intersection Target genes Random Control(%)
SREBF1 0.000e+0 0.000e+0 0.000e+0 5.556e-4 17 50 0
SREBF2 4.610e-3 4.149e-1 2.074e-1 1.111e-3 9 34 0
CREBBP 8.290e-3 7.461e-1 2.205e-1 1.667e-3 3 5 0
BRCA1 9.800e-3 8.820e-1 2.205e-1 2.222e-3 2 2 0
CTNNB1 1.738e-2 1.564e+0 3.128e-1 2.778e-3 41 300 0
SMAD4 2.177e-2 1.959e+0 3.266e-1 3.333e-3 8 36 0
CDKN1A 2.747e-2 2.472e+0 3.532e-1 3.889e-3 2 3 0
FOXO1 4.085e-2 3.676e+0 3.893e-1 4.444e-3 23 160 0
NFKB1 4.275e-2 3.848e+0 3.893e-1 5.000e-3 11 63 0
SP1 4.326e-2 3.893e+0 3.893e-1 5.556e-3 25 178 0
Keep in mind that for the signed lists, I've bolded all results with p < 0.05 with no multi-testing correction. Therefore, probability of false positives is higher in these lists. We see CTNNB1 (beta-catenin) in both the activated and inhibited lists, which indicates that its target genes may be altered, perhaps through binding to AR, which one study has shown to be enhanced in Androgenetic Alopecia (5). We also see different subunits of NFkB (REL, NFKB1) in both groups. Others:
Gli2 – mediator of hedgehog signaling
MYC is upregulated 1.55x at the transcriptional level.
In the repressed list:
SREBF1 (a.k.a. SREBP1) and SREBF2 (a.k.a. SREBP2), which are involved in lipid and sterol synthesis.
CREBBP – acetyltransferase which acts as a general coactivator, is downregulated at the transcriptional level.
BRCA1 – involved in DNA repair (actually upregulated at transcriptional level).
SMAD4 – mediator of TGFbeta/BMP signaling
CDKN1A (a.k.a. p21) – cell cycle inhibitor, highly downregulated at transcriptional level
FOXO1 – regulates metabolism, resistance to stress, longevity
SP1 – wide variety of functions
Lastly for the static data, we can run SDREM(6) to attempt to reverse-engineer upstream signaling pathways that may account for changes in gene expression. SDREM is intended for time-series data, but we'll just treat it like the dermal papilla cells went from the non-balding state to the balding state all in one step.
Red = source node (which I specified as AR), green = target nodes (inferred downstream transcription factors), blue = internal nodes connecting the sources to the targets
There's a lot going on here, so it's helpful to break the nodes into rough categories:
Immune system – IRF9, TBK1, IRF8, IRF2, IRF3, IRF4, IRF5, IRF6, IRF7, RELA, SPI1, STAT1, STAT3, TAL1, XBP1
Development – CDX2, CTNNB1, EGFR, SOX8, ONECUT1, SMAD3, SMAD4, SOX18, PRDM1, SOX2, SOX4, TCF3, ALX1
Histone acetyltransferases – NCOA2, CREBBP, EP300, NCOA3, NCOA1, KAT2B
Histone deacetylases – HDAC1, HDAC2, HDAC4
Nuclear corepressors – NCOR1, NCOR2
Nuclear receptors – ESR1, NR5A2, NR6A1, NR3C1, AR (source), PPARG, RARA, VDR
Stress response/resistance – FOXO1, HIF1A
Chaperones – HSP90AA1
Cell Cycle – JUN, RB1, TP53, CDK1
Ubiquitination/proteasome – MDM2, UBC
Sumoylation – PIAS4, UBE2I, SUMO1, PIAS1
Kinases – SRC
DNA Repair – BRCA1
Other – DAXX, SIN3A, PML, SMARCA4, SP1, ZBTB16
(continued in next post)