Contents

0.1 Introduction

mist (Methylation Inference for Single-cell along Trajectory) is an R package for differential methylation (DM) analysis of single-cell DNA methylation (scDNAm) data. The package employs a Bayesian approach to model methylation changes along pseudotime and estimates developmental-stage-specific biological variations. It supports both single-group and two-group analyses, enabling users to identify genomic features exhibiting temporal changes in methylation levels or different methylation patterns between groups.

This vignette demonstrates how to use mist for: 1. Single-group analysis. 2. Two-group analysis.

0.2 Installation

To install the latest version of mist, run the following commands:

if (!requireNamespace("BiocManager", quietly = TRUE)) {
    install.packages("BiocManager")
}

# Install mist from GitHub
BiocManager::install("https://github.com/dxd429/mist")

From Bioconductor:

if (!requireNamespace("BiocManager", quietly = TRUE)) {
    install.packages("BiocManager")
}
BiocManager::install("mist")

To view the package vignette in HTML format, run the following lines in R:

library(mist)
vignette("mist")

0.3 Example Workflow for Single-Group Analysis

In this section, we will estimate parameters and perform differential methylation analysis using single-group data.

1 Step 1: Load Example Data

Here we load the example data from GSE121708.

library(mist)
library(SingleCellExperiment)
# Load sample scDNAm data
Dat_sce <- readRDS(system.file("extdata", "group1_sampleData_sce.rds", package = "mist"))

2 Step 2: Estimate Parameters Using estiParam

# Estimate parameters for single-group
Dat_sce <- estiParam(
    Dat_sce = Dat_sce,
    Dat_name = "Methy_level_group1",
    ptime_name = "pseudotime"
)

# Check the output
head(rowData(Dat_sce)$mist_pars)
##                      Beta_0      Beta_1      Beta_2      Beta_3      Beta_4
## ENSMUSG00000000001 1.248307 -0.32076637  0.23208752  0.25004153  0.06893146
## ENSMUSG00000000003 1.592233  1.66580639  2.26253608 -1.85226041 -2.33987443
## ENSMUSG00000000028 1.284370 -0.00608650  0.10429107  0.04707951 -0.01972436
## ENSMUSG00000000037 1.024039 -3.87345822 10.31656683 -3.41003908 -3.05071729
## ENSMUSG00000000049 1.027007 -0.04912175  0.05783529  0.07452194  0.05228232
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  5.459454 12.469965 3.764669 1.785071
## ENSMUSG00000000003 26.183231  6.219113 5.565072 8.797245
## ENSMUSG00000000028  7.949602  8.220084 3.258056 2.220716
## ENSMUSG00000000037  8.918608 12.812793 7.212077 2.128206
## ENSMUSG00000000049  6.066276  8.849229 2.980045 1.157891

3 Step 3: Perform Differential Methylation Analysis Using dmSingle

# Perform differential methylation analysis for the single-group
Dat_sce <- dmSingle(Dat_sce)

# View the top genomic features with drastic methylation changes
head(rowData(Dat_sce)$mist_int)
## ENSMUSG00000000037 ENSMUSG00000000003 ENSMUSG00000000001 ENSMUSG00000000049 
##        0.055556615        0.030537733        0.010302694        0.006123931 
## ENSMUSG00000000028 
##        0.005325092

4 Step 4: Perform Differential Methylation Analysis Using plotGene

# Produce scatterplot with fitted curve of a specific gene
library(ggplot2)
plotGene(Dat_sce = Dat_sce,
         Dat_name = "Methy_level_group1",
         ptime_name = "pseudotime", 
         gene_name = "ENSMUSG00000000037")

4.1 Example Workflow for Two-Group Analysis

In this section, we will estimate parameters and perform DM analysis using data from two phenotypic groups.

5 Step 1: Load Two-Group Data

# Load two-group scDNAm data
Dat_sce_g1 <- readRDS(system.file("extdata", "group1_sampleData_sce.rds", package = "mist"))
Dat_sce_g2 <- readRDS(system.file("extdata", "group2_sampleData_sce.rds", package = "mist"))

6 Step 2: Estimate Parameters Using estiParam

# Estimate parameters for both groups
Dat_sce_g1 <- estiParam(
     Dat_sce = Dat_sce_g1,
     Dat_name = "Methy_level_group1",
     ptime_name = "pseudotime"
 )

Dat_sce_g2 <- estiParam(
     Dat_sce = Dat_sce_g2,
     Dat_name = "Methy_level_group2",
     ptime_name = "pseudotime"
 ) 

# Check the output
head(rowData(Dat_sce_g1)$mist_pars, n = 3)
##                      Beta_0      Beta_1     Beta_2      Beta_3      Beta_4
## ENSMUSG00000000001 1.242068 -0.44050624 0.22410813  0.34686864  0.14668732
## ENSMUSG00000000003 1.639647  1.77956229 2.43843580 -1.94648773 -2.60354521
## ENSMUSG00000000028 1.289386 -0.02279722 0.08811998  0.05518299  0.02541573
##                     Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001  5.091809 14.518908 3.203293 1.822668
## ENSMUSG00000000003 26.263682  3.356110 5.939064 8.954333
## ENSMUSG00000000028  7.688547  7.493357 3.101238 2.328775
head(rowData(Dat_sce_g2)$mist_pars, n = 3)
##                        Beta_0     Beta_1    Beta_2     Beta_3     Beta_4
## ENSMUSG00000000001  1.9239899 -0.3251663  3.252234  -1.911634 -1.1376255
## ENSMUSG00000000003 -0.8531602 -1.6923463  5.911375  -4.964182  0.8175813
## ENSMUSG00000000028  2.2902083 -6.4640277 29.189754 -37.807580 15.2146883
##                    Sigma2_1  Sigma2_2 Sigma2_3 Sigma2_4
## ENSMUSG00000000001 5.539727  6.164198 2.831261 1.463195
## ENSMUSG00000000003 6.425620 10.997343 5.212602 3.113019
## ENSMUSG00000000028 9.814264  5.467274 3.754816 3.607554

7 Step 3: Perform Differential Methylation Analysis for Two-Group Comparison Using dmTwoGroups

# Perform DM analysis to compare the two groups
dm_results <- dmTwoGroups(
     Dat_sce_g1 = Dat_sce_g1,
     Dat_sce_g2 = Dat_sce_g2
 )

# View the top genomic features with different temporal patterns between groups
head(dm_results)
## ENSMUSG00000000037 ENSMUSG00000000003 ENSMUSG00000000001 ENSMUSG00000000028 
##        0.063565921        0.029265786        0.021157990        0.019653982 
## ENSMUSG00000000049 
##        0.009947614

7.1 Conclusion

mist provides a comprehensive suite of tools for analyzing scDNAm data along pseudotime, whether you are working with a single group or comparing two phenotypic groups. With the combination of Bayesian modeling and differential methylation analysis, mist is a powerful tool for identifying significant genomic features in scDNAm data.

Session info

## R version 4.5.1 Patched (2025-09-10 r88807)
## Platform: aarch64-apple-darwin20
## Running under: macOS Ventura 13.7.7
## 
## Matrix products: default
## BLAS:   /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRblas.0.dylib 
## LAPACK: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.1
## 
## locale:
## [1] C/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
## 
## time zone: America/New_York
## tzcode source: internal
## 
## attached base packages:
## [1] stats4    stats     graphics  grDevices utils     datasets  methods  
## [8] base     
## 
## other attached packages:
##  [1] ggplot2_4.0.0               SingleCellExperiment_1.32.0
##  [3] SummarizedExperiment_1.40.0 Biobase_2.70.0             
##  [5] GenomicRanges_1.62.0        Seqinfo_1.0.0              
##  [7] IRanges_2.44.0              S4Vectors_0.48.0           
##  [9] BiocGenerics_0.56.0         generics_0.1.4             
## [11] MatrixGenerics_1.22.0       matrixStats_1.5.0          
## [13] mist_1.2.0                  BiocStyle_2.38.0           
## 
## loaded via a namespace (and not attached):
##  [1] tidyselect_1.2.1         dplyr_1.1.4              farver_2.1.2            
##  [4] Biostrings_2.78.0        S7_0.2.0                 bitops_1.0-9            
##  [7] fastmap_1.2.0            RCurl_1.98-1.17          GenomicAlignments_1.46.0
## [10] XML_3.99-0.19            digest_0.6.37            lifecycle_1.0.4         
## [13] survival_3.8-3           magrittr_2.0.4           compiler_4.5.1          
## [16] rlang_1.1.6              sass_0.4.10              tools_4.5.1             
## [19] yaml_2.3.10              rtracklayer_1.70.0       knitr_1.50              
## [22] labeling_0.4.3           S4Arrays_1.10.0          curl_7.0.0              
## [25] DelayedArray_0.36.0      RColorBrewer_1.1-3       abind_1.4-8             
## [28] BiocParallel_1.44.0      withr_3.0.2              grid_4.5.1              
## [31] scales_1.4.0             MASS_7.3-65              mcmc_0.9-8              
## [34] tinytex_0.57             dichromat_2.0-0.1        cli_3.6.5               
## [37] mvtnorm_1.3-3            rmarkdown_2.30           crayon_1.5.3            
## [40] httr_1.4.7               rjson_0.2.23             cachem_1.1.0            
## [43] splines_4.5.1            parallel_4.5.1           BiocManager_1.30.26     
## [46] XVector_0.50.0           restfulr_0.0.16          vctrs_0.6.5             
## [49] Matrix_1.7-4             jsonlite_2.0.0           SparseM_1.84-2          
## [52] carData_3.0-5            bookdown_0.45            car_3.1-3               
## [55] MCMCpack_1.7-1           Formula_1.2-5            magick_2.9.0            
## [58] jquerylib_0.1.4          glue_1.8.0               codetools_0.2-20        
## [61] gtable_0.3.6             BiocIO_1.20.0            tibble_3.3.0            
## [64] pillar_1.11.1            htmltools_0.5.8.1        quantreg_6.1            
## [67] R6_2.6.1                 evaluate_1.0.5           lattice_0.22-7          
## [70] Rsamtools_2.26.0         cigarillo_1.0.0          bslib_0.9.0             
## [73] MatrixModels_0.5-4       Rcpp_1.1.0               coda_0.19-4.1           
## [76] SparseArray_1.10.0       xfun_0.53                pkgconfig_2.0.3