Last updated: 2022-08-13

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File Version Author Date Message
Rmd f1a7b55 Hillary Koch 2022-08-13 add DNase analysis
html f1a7b55 Hillary Koch 2022-08-13 add DNase analysis

This vignette walks through a lightweight version of the DNase-seq analysis discussed in the CLIMB paper. The purpose of the original analysis was to investigate patterns of chromatin accessibility across 38 hematopoietic cell populations, and how these relate to differential transcription factor binding across cell populations. While the complete analysis considered DNase-seq collected on all autosomes across these cell populations, and checked results against transcription factor footprinting signals and motif enrichment at DNase hypersensitive sites, this lightweight version will only consider the analysis of DNaseq-seq in 5 cell populations on 2 chromosomes. A figure akin to Fig. 5a from the CLIMB article is generated.

# load libraries
library(readxl)
suppressPackageStartupMessages(library(dplyr))
library(purrr)
library(readr)
library(stringr)
suppressPackageStartupMessages(library(magrittr))
suppressPackageStartupMessages(library(R.utils))
suppressWarnings(library(CLIMB))
suppressPackageStartupMessages(library(tidyr))
library(ggplot2)
library(cowplot)

Prepare data

First we download and process the data, made publicly available by Meuleman et al (2020).

Download DNase-seq data

if(!file.exists("data/dat_FDR01_hg38.RData")) {
  download.file(url = "https://zenodo.org/record/3838751/files/dat_FDR01_hg38.RData?download=1",
                destfile = "data/dat_FDR01_hg38.RData",
                method = "curl")
}

if (!file.exists("data/DHS_Index_and_Vocabulary_hg38_WM20190703.txt.gz")) {
  download.file(url = "https://zenodo.org/record/3838751/files/DHS_Index_and_Vocabulary_hg38_WM20190703.txt.gz?download=1",
                destfile = "data/DHS_Index_and_Vocabulary_hg38_WM20190703.txt.gz",
                method = "curl")
  R.utils::gunzip("data/DHS_Index_and_Vocabulary_hg38_WM20190703.txt.gz")
}

if (!file.exists("data/DHS_Index_and_Vocabulary_metadata.xlsx")) {
  download.file(url = "https://zenodo.org/record/3838751/files/DHS_Index_and_Vocabulary_metadata.xlsx?download=1",
                destfile = "data/DHS_Index_and_Vocabulary_metadata.xlsx",
                method = "curl")
}

Extract subset of data for this demonstration

We will only analyze 5 cell populations from this dataset. The selected cell populations are those whose transcription factor footprinting signals are visualized in Fig. 5b of the CLIMB paper.

# Extract sample metadata for samples to be used
sample_data <-
  read_xlsx("data/biosamples_used.xlsx",
            range = c("A1:M39"))

# Cell populations to be analyzeds
cell_pops_to_keep <-
  c(
    "CD4.DS17881",
    "CD34.DS12274",
    "CD34_T18.DS25969A",
    "CD14.DS17215",
    "K562.DS16924"
  )


# Join with the data from the source paper's supplement
all_sample_metadata <- 
    read_xlsx("data/DHS_Index_and_Vocabulary_metadata.xlsx") %>%
    right_join(
        sample_data,
        by = c("DCC Library ID" = "DCC_library_id", "DCC Biosample ID" = "DCC_biosample_id")
    )

# Get BED info
bed <- readr::read_tsv("data/DHS_Index_and_Vocabulary_hg38_WM20190703.txt")
Rows: 3591898 Columns: 10
── Column specification ────────────────────────────────────────────────────────
Delimiter: "\t"
chr (3): seqname, identifier, component
dbl (7): start, end, mean_signal, numsamples, summit, core_start, core_end

ℹ Use `spec()` to retrieve the full column specification for this data.
ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
# Load in and subset the normalized data (this object is called `dat`)
load("data/dat_FDR01_hg38.RData")

# Subset to selected hematopoietic columns, then filter out rows with 0 or 1 DHSs
my_dat <- dat %>%
    as_tibble() %>%
    dplyr::select(all_sample_metadata$`library order`) %>%
    bind_cols(dplyr::select(bed, seqname, start, end)) %>%
    relocate(seqname, start, end, .before = 1) %>%
    # subset to 5 samples as plotted in the CLIMB article
    dplyr::select(seqname, start, end, matches(cell_pops_to_keep)) %>%
    dplyr::filter(rowSums(across(all_of(4:last_col()), ~ .x != 0)) > 1) %>%
    rename("chr" = "seqname") %>%
    mutate(across(4:last_col(), ~ replace(.x, .x == 0, rnorm(sum(.x==0)))))

# clean large object from environment
rm(dat)

# this is to prevent some numerical issues due to extreme outliers
max_quant <- dplyr::select(my_dat, 4:last_col()) %>%
        map_dbl(~ quantile(.x, .999)) %>%
        max()
        
my_dat <- my_dat %>%
    mutate(across(4:last_col(), ~ replace(.x, .x >= max_quant, max_quant))) %>%
    # select only chromosomes 21 and 22
    filter(chr %in% c("chr21", "chr22")) %>%
    group_split(chr)

for(i in seq_along(my_dat)) {
    if(!dir.exists(paste0("data/DNase_", my_dat[[i]]$chr[1]))) {
        dir.create(paste0("data/DNase_", my_dat[[i]]$chr[1]))
    }
    saveRDS(object = my_dat[[i]], file = paste0("data/DNase_", my_dat[[i]]$chr[1], "/dat.rds"))
}

Run CLIMB

As in the other vignettes, we now implement CLIMB in 4 steps. Run locally, this should complete in ~30 minutes. The bottleneck is the MCMC on 2 chromosomes serially.

Step 1: Pairwise fitting

set.seed(217)

chr <- 21:22
z <- map(chr, ~ readRDS(paste0("data/DNase_chr", .x, "/dat.rds")) %>%
                 mutate(chr = NULL, start = NULL, end = NULL)) %>%
  set_names(paste0("chr", chr))

fits <- map(z, ~ CLIMB::get_pairwise_fits(z = .x, parallel = TRUE, ncores = 4))

if(!dir.exists("output/DNase")) {
  dir.create("output/DNase")
}

if(!dir.exists("output/DNase/pwfits")) {
  dir.create("output/DNase/pwfits")
}

walk(chr, ~ {
  if (!dir.exists(paste0("output/DNase/pwfits/chr", .x))) {
    dir.create(paste0("output/DNase/pwfits/chr", .x))
  }
})

iwalk(fits, ~ saveRDS(.x, paste0("output/DNase/pwfits/", .y, "/pwfits.rds")))

Step 2: Finding candidate classes

# This finds the dimension of the data directly from the pairwise fits
D <- as.numeric(strsplit(tail(names(fits[[1]]),1), "_")[[1]][2])

# calculates the sample sizes from the pairwise fits
n <- map_dbl(fits, ~ length(.x[[1]]$cluster))

if(!dir.exists("output/DNase/reduced_classes")) {
  dir.create("output/DNase/reduced_classes")
}
walk(chr, ~ {
  if (!dir.exists(paste0("output/DNase/reduced_classes/chr", .x))) {
    dir.create(paste0("output/DNase/reduced_classes/chr", .x))
  }
})

# Get the list of candidate latent classes
reduced_classes <-
  imap(fits, ~ get_reduced_classes(
    .x,
    D,
    paste0("output/DNase/reduced_classes/", .y, "/lgf.txt"),
    split_in_two = FALSE
  ))
Writing LGF file...done!
Finding latent classes...done!
Writing LGF file...done!
Finding latent classes...done!
# write the output to a text file
iwalk(reduced_classes, ~ {
  readr::write_tsv(
    data.frame(.x),
    file = paste0("output/DNase/reduced_classes/", .y, "/red_class.txt"),
    col_names = FALSE
  )
})

Step 3: Computing prior hyperparameters

if(!dir.exists("output/DNase/mcmc")) {
    dir.create("output/DNase/mcmc")
}
walk(chr, ~ {
  if (!dir.exists(paste0("output/DNase/mcmc/chr", .x))) {
    dir.create(paste0("output/DNase/mcmc/chr", .x))
  }
})

# Compute the prior weights
prior_weights <-
  pmap(list(fits, reduced_classes, names(fits)), function(.x, .y, .z)
    get_prior_weights(
      .y,
      .x,
      parallel = FALSE,
      delta = 0:10
    )) %>%
  # just keep all classes since the analysis is small
  map(~ tail(.x, 1)[[1]])
iwalk(prior_weights, ~ saveRDS(.x, paste0("output/DNase/mcmc/", .y, "/prior_weights.rds")))

# obtain the hyperparameters
hyp <-
  pmap(list(my_dat, fits, reduced_classes, prior_weights), function(.w, .x, .y, .z)
    get_hyperparameters(
      as.data.frame(dplyr::select(.w, 4:last_col())),
      .x,
      as.data.frame(.y),
      as.vector(.z)
    )) %>%
  set_names(names(fits))

iwalk(hyp, ~ saveRDS(.x, file = paste0("output/DNase/mcmc/", .y, "/hyperparameters.rds")))

Step 4: Running the MCMC

results <-
  pmap(list(my_dat, hyp, reduced_classes), function(.x, .y, .z) run_mcmc(
    dplyr::select(.x, 4:last_col()),
    hyp =  .y,
    nstep = 2000,
    retained_classes = .z
  )) %>%
  set_names(names(fits))
Julia version 1.8.0-rc3 at location /Applications/Julia-1.8.app/Contents/Resources/julia/bin will be used.
Loading setup script for JuliaCall...
Finish loading setup script for JuliaCall.
chains <- map(results, extract_chains)

iwalk(chains, ~ saveRDS(.x, file = paste0("output/DNase/mcmc/", .y, "/chain.rds")))

Downstream analyses

Merge classes from chromosome-specific analyses

Since each chromosome was analyzed separately, we merge the 2 sets of results. We opt to maintain 12 parent groups after merging clusters from both chromosomes, in order to be consistent with the analysis in the CLIMB paper.

burnin <- 1:500
merged <-
  suppressMessages(merge_classes(
    n_groups = 12,
    # number of classes used in the CLIMB article's analysis
    chain = chains,
    burnin = burnin,
    multichain = TRUE
  ))

Visualize clustering of loci across cell populations

col_distmat <- compute_distances_between_conditions(chains, burnin, multichain = TRUE)
row_distmat <- suppressMessages(compute_distances_between_clusters(chains, burnin, multichain = TRUE))
colnames(col_distmat) <- names(my_dat[[1]])[-(1:3)]

hc_row <- hclust(as.dist(row_distmat), method = "complete")
hc_col <- hclust(as.dist(col_distmat), method = "complete")

# Get a row reordering for plotting
row_reordering <-
    get_row_reordering(
        row_clustering = hc_row,
        chain = chains,
        burnin = burnin,
        dat = purrr::map(my_dat, ~ dplyr::select(.x, 4:last_col())),
        multichain = TRUE
    )

molten <- bind_rows(my_dat) %>%
    dplyr::mutate(row = row_reordering) %>%
    dplyr::select(4:last_col()) %>%
    tidyr::pivot_longer(!last_col(), names_to = "cell") %>%
    # Relevel factors, for column sorting on the plot
    mutate(cell = forcats::fct_relevel(cell, ~ hc_col$labels[hc_col$order]))


p1 <- ggplot(data = molten,
             aes(x = cell,
                 y = row,
                 fill = value)) +
  geom_raster() +
  theme_minimal() +
  theme(
    axis.text.x = element_blank(),
  ) +
  labs(fill = "Z-score", x = "", y = "") +
  ggtitle("Bi-clustering heatmap") +
  scale_fill_distiller(palette = "Greens", direction = 1) +
  coord_flip()
print(p1)

Version Author Date
f1a7b55 Hillary Koch 2022-08-13

Estimated class means and first 2 principal components

#-------------------------------------------------------------------------------
# Read in colormap for plotting, to match cell type by function 
#-------------------------------------------------------------------------------
pal <- read_delim(file = "data/color_mapper.txt", col_names = FALSE, delim = " ") %>%
    set_names(c("cell_pop", "hex"))
Rows: 38 Columns: 2
── Column specification ────────────────────────────────────────────────────────
Delimiter: " "
chr (2): X1, X2

ℹ Use `spec()` to retrieve the full column specification for this data.
ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
# mean trends ---------------------------------------------------
# each row of merged_mu should correspond to a different factor
# each column is a cell population
mu <- merged$merged_mu %>%
  set_colnames(cell_pops_to_keep) %>%
  as_tibble() %>%
  mutate(group = 1:n(), .before = 1) %>%
  pivot_longer(cols = 2:last_col(),
               names_to = "cell_pop",
               values_to = "mu_est")

# covariance trends ---------------------------------------------------
sigmas <- merged$merged_sigma %>%
    apply(MARGIN = 3, function(X) {
      X %>%
        set_colnames(cell_pops_to_keep) %>%
        as_tibble(X, .name_repair = "minimal")
    })

sigma_df <- sigmas %>%
    imap_dfr(
        ~ mutate(
            .x,
            group = .y,
            cell_pop1 = cell_pops_to_keep,
            .before = 1
        ) %>%
            pivot_longer(
                cols = 3:last_col(),
                names_to = "cell_pop2",
                values_to = "covariance"
            )
    )

#-------------------------------------------------------------------------------
# Use row and column clustering for row reordering
#-------------------------------------------------------------------------------
cl <- list(row_clustering = hc_row, col_clustering = hc_col)
pcs <- map(sigmas, ~ prcomp(.x, center = TRUE))

out_plots <- list()
clusts_to_plot <- seq_along(pcs)

for(ccc in clusts_to_plot) {
    pc_df <- as_tibble(pcs[[ccc]]$rotation) %>%
        mutate(cell_pop = cell_pops_to_keep, .before = 1) %>%
        pivot_longer(cols = !cell_pop, names_to = "PC", values_to = "score") %>%
        mutate(PC = factor(PC, levels = paste0("PC", seq_along(cell_pops_to_keep)))) %>%
        group_split(PC) %>%
        map2_dfr((pcs[[ccc]]$sdev ^2) / sum(pcs[[ccc]]$sdev^2), ~ mutate(.x, percent_var = round(.y * 100, digits = 2))) %>%
        left_join(
            filter(mu, group == ccc) %>%
                mutate(group = NULL), by = "cell_pop") %>%
        left_join(pal, by = "cell_pop") %>%
        mutate(
            cell_pop = factor(cell_pop, levels = cl$col_clustering$labels[cl$col_clustering$order])
        ) %>%
        arrange(cell_pop) %>%
        mutate(hex = factor(hex, levels = unique(.$hex)))
    
   
    mu_plot <- ggplot(filter(pc_df, PC %in% "PC1"), aes(x = cell_pop, y  = mu_est)) +
        geom_bar(aes(fill = hex), stat = "identity", color = "black", show.legend = FALSE) +
        scale_fill_manual(values = levels(pc_df$hex)) +
        labs(x = "", y = "Estimated\ncluster mean") +
        theme_minimal()
    if(ccc == 12) {
        mu_plot <- mu_plot + theme(axis.text.x = element_text(angle = 45, hjust = 1, vjust = 1),
                                   legend.position = "none")
    } else {
        mu_plot <- mu_plot + theme(axis.text.x = element_blank(), legend.position = "none")
    }
        
        
    pc_df2 <- filter(pc_df, PC %in% paste0("PC", 1:2)) %>%
        unite(col = PC_var, PC, percent_var, sep = " (") %>%
        mutate(PC_var = paste0(PC_var, "%)"))
    
    pc_plot <- ggplot(pc_df2, aes(x = cell_pop, y = score)) +
        geom_bar(aes(fill = hex), stat = "identity", color = "black", show.legend = FALSE) +
        scale_fill_manual(values = levels(pc_df$hex)) +
        labs(x = "") +
        facet_wrap(~ PC_var, nrow = 1, ncol = 2) +
        theme_minimal()
    if(ccc == 12) {
        pc_plot <- pc_plot + theme(axis.text.x = element_text(angle = 45, hjust = 1, vjust = 1),
                                   legend.position = "none")
    } else {
        pc_plot <- pc_plot + theme(axis.text.x = element_blank(), legend.position = "none")
    }
    
    out_plots[[ccc]] <- cowplot::plot_grid(mu_plot, pc_plot, nrow = 1, ncol = 2, rel_widths = c(1,2))
}

cowplot::plot_grid(plotlist = out_plots, nrow = length(out_plots), ncol = 1, rel_heights = c(rep(1,11), 2))

Version Author Date
f1a7b55 Hillary Koch 2022-08-13

Session Information

print(sessionInfo())
R version 4.2.1 (2022-06-23)
Platform: aarch64-apple-darwin20 (64-bit)
Running under: macOS Monterey 12.5

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] cowplot_1.1.1     ggplot2_3.3.6     tidyr_1.2.0       CLIMB_1.0.0      
 [5] R.utils_2.12.0    R.oo_1.25.0       R.methodsS3_1.8.2 magrittr_2.0.3   
 [9] stringr_1.4.0     readr_2.1.2       purrr_0.3.4       dplyr_1.0.9      
[13] readxl_1.4.0     

loaded via a namespace (and not attached):
 [1] sass_0.4.2           bit64_4.0.5          LaplacesDemon_16.1.6
 [4] vroom_1.5.7          jsonlite_1.8.0       foreach_1.5.2       
 [7] bslib_0.4.0          brio_1.1.3           assertthat_0.2.1    
[10] highr_0.9            cellranger_1.1.0     yaml_2.3.5          
[13] pillar_1.8.0         glue_1.6.2           digest_0.6.29       
[16] RColorBrewer_1.1-3   promises_1.2.0.1     colorspace_2.0-3    
[19] htmltools_0.5.3      httpuv_1.6.5         plyr_1.8.7          
[22] JuliaCall_0.17.4     pkgconfig_2.0.3      mvtnorm_1.1-3       
[25] scales_1.2.0         whisker_0.4          later_1.3.0         
[28] tzdb_0.3.0           git2r_0.30.1         tibble_3.1.8        
[31] generics_0.1.3       farver_2.1.1         ellipsis_0.3.2      
[34] cachem_1.0.6         withr_2.5.0          cli_3.3.0           
[37] crayon_1.5.1         evaluate_0.15        fs_1.5.2            
[40] fansi_1.0.3          doParallel_1.0.17    forcats_0.5.1       
[43] tools_4.2.1          hms_1.1.1            lifecycle_1.0.1     
[46] munsell_0.5.0        compiler_4.2.1       jquerylib_0.1.4     
[49] rlang_1.0.4          grid_4.2.1           iterators_1.0.14    
[52] rstudioapi_0.13      labeling_0.4.2       rmarkdown_2.14      
[55] testthat_3.1.4       gtable_0.3.0         codetools_0.2-18    
[58] abind_1.4-5          DBI_1.1.3            rematch_1.0.1       
[61] R6_2.5.1             knitr_1.39           fastmap_1.1.0       
[64] bit_4.0.4            utf8_1.2.2           workflowr_1.7.0     
[67] rprojroot_2.0.3      stringi_1.7.8        parallel_4.2.1      
[70] Rcpp_1.0.9           vctrs_0.4.1          tidyselect_1.1.2    
[73] xfun_0.31