day7 GEO下载多样本数据的聚类注释

2024-07-01 11:47:30 浏览数 (1)

R基础知识补充:

字符串处理函数 - str_split_i() - str_sub() - str_remove() - str_detect() - str_replace() 文件处理函数 - dir(pattern = ".R$") - file.create(" ") - file.exists(" ") - file.remove(" ") - f = paste0("douhua",1:10,".txt"); file.create(f) - lappy函数 自定义函数 my_install = function(pkg){ if (!require(pkg,character.only = T))install.packages(pkg,update = F,ask = F) }

my_install("tidyr") my_install("dplyr") my_install("stringr") ps = c("tidyr","dplyr","stringr") lapply(ps, my_install) #利用好lappy写简洁函数;有点>for循环的意思？

ifelse 函数 ：根据逻辑值是T还是F产生不同的值

数据获取 文件名修改

数据来自GEO的GSE231920,有3个treat，3个control样本

  • 全部下载并解压
代码语言：R复制
untar("GSE231920_RAW.tar",exdir = "GSE231920_RAW") #解包
  • 改名 利用lapply套自定义函数实现了批量操作
    • 为每个样本创建单独的文件夹
    • 把每个样本的三个文件复制进去
    • 所有文件改名，去掉前缀
代码语言：R复制
library(stringr)

fs = paste0("GSE231920_RAW/",dir("GSE231920_RAW/"));fs #所有文件的路径
samples = dir("GSE231920_RAW/") %>% str_split_i(pattern = "_",i = 2) %>% unique();samples  #str_split_i()进行拆分，并选择想要的第2个部分(i=2)，即sample
##############################
#01自定义函数批量创建文件目录 #s即sample
lapply(samples, function(s){ 
  sdir = paste0("02_data/",s)
  if(!file.exists(sdir))dir.create(sdir,recursive = T)
})
#02自定义函数批量移动文件 #匹配到相同的sample名称就copy
lapply(fs, function(s){
  for(i in 1:length(samples)){
    if(str_detect(s,samples[[i]])){ file.copy(s,paste0("02_data/",samples[[i]])) }
  }
})
#03去掉文件的前缀 #修改文件名时，路径时要从工作目录之下开始写的
on = paste0("01_data/",dir("01_data/",recursive = T));on 
nn = str_remove(on,"GSM\d _sample\d_");nn
file.rename(on,nn)
##############################

批量读取和抽样保存

  • 批量读取 接下来就是批量读取文件，前面我们知道利用Read10X()函数读取三个固定文件的目录名称，利用for循环每读取一个samplepda，就创建一个对象SeuratObjectsce，并存储在列表中scelist:
代码语言：R复制
f = dir("01_data/")
scelist = list() #创建空的列表，下面的for循环每执行一次，scelist里面就会多一个元素。
for(i in 1:length(f)){
    pda <- Read10X(paste0("01_data/",f[[i]]))
    scelist[[i]] <- CreateSeuratObject(counts = pda, 
                                       project = f[[i]],
                                       min.cells = 3,
                                       min.features = 200)
    print(dim(scelist[[i]]))
}
  • 合并 然后我们再把列表中的每个sce合并，合并后每个样本的表达矩阵是一个独立的的layer，JoinLayers是合并为一个表达矩阵：
代码语言：R复制
sce.all = merge(scelist[[1]],scelist[-1]) #合并多个对象
sce.all = JoinLayers(sce.all)
  • 抽样保存
代码语言：R复制
set.seed(335)
sce.all = subset(sce.all,downsample=700)
save(sce.all,file = rdaf)

质控 降维 注释

  • 质控
代码语言：R复制
#除了线粒体基因，核糖体和红细胞基因也是常见的过滤指标
sce.all[["percent.mt"]] <- PercentageFeatureSet(sce.all, pattern = "^MT-")
sce.all[["percent.rp"]] <- PercentageFeatureSet(sce.all, pattern = "^RP[SL]")
sce.all[["percent.hb"]] <- PercentageFeatureSet(sce.all, pattern = "^HB[^(P)]")

VlnPlot(sce.all, 
        features = c("nFeature_RNA",
                     "nCount_RNA", 
                     "percent.mt",
                     "percent.rp",
                     "percent.hb"),
        ncol = 3,pt.size = 0.5, group.by = "orig.ident")
#根据小提琴图指定指标去掉离群值
sce.all = subset(sce.all,percent.mt < 20&
                   nCount_RNA < 40000 &
                   nFeature_RNA < 6000)
table(sce.all@meta.data$orig.ident)
  • 降维聚类，多样本使用harmony，它需要的计算资源少且准确程度高，是最受欢迎的方法
代码语言：R复制
f = "obj.Rdata"
library(harmony)
if(!file.exists(f)){
  sce.all = sce.all %>% 
    NormalizeData() %>%  
    FindVariableFeatures() %>%  
    ScaleData(features = rownames(.)) %>%  
    RunPCA(pc.genes = VariableFeatures(.))  %>%
    RunHarmony("orig.ident") %>%
    FindNeighbors(dims = 1:15, reduction = "harmony") %>% 
    FindClusters(resolution = 0.5) %>% 
    RunUMAP(dims = 1:15,reduction = "harmony") %>% 
    RunTSNE(dims = 1:15,reduction = "harmony")
  save(sce.all,file = f)
}
load(f)
ElbowPlot(sce.all)

p1 =  DimPlot(sce.all, reduction = "umap",label = T,pt.size = 0.5)  NoLegend();p1
DimPlot(sce.all, reduction = "umap",pt.size = 0.5,group.by = "orig.ident") #按照样本来分配颜色。可以看看去除样本间批次效应的效果如何
  • 注释
代码语言：R复制
library(celldex)
library(SingleR)

f = "../day5-6/ref_BlueprintEncode.RData"

if(!file.exists(f)){
  ref <- celldex::BlueprintEncodeData()
  save(ref,file = f)
}
ref <- get(load(f))
library(BiocParallel)
scRNA = sce.all
test = scRNA@assays$RNA$data
pred.scRNA <- SingleR(test = test, 
                      ref = ref,
                      labels = ref$label.main, 
                      clusters = scRNA@active.ident)
pred.scRNA$pruned.labels
new.cluster.ids <- pred.scRNA$pruned.labels
names(new.cluster.ids) <- levels(scRNA)
scRNA <- RenameIdents(scRNA,new.cluster.ids)
save(scRNA,file = "scRNA.Rdata")

p2 <- DimPlot(scRNA, reduction = "umap",label = T,pt.size = 0.5)   NoLegend()
p1 p2

分组可视化和组间细胞比例比较

  • 添加分组信息 library(tinyarray) edat = geo_download("GSE231920") pd = edat$pd 可以自行提取GSE的分组信息
代码语言：R复制
scRNA$seurat_annotations = Idents(scRNA) #加入细胞类型列
#利用ifelse函数判断是处理组还是对照组
scRNA$group = ifelse(scRNA$orig.ident %in% c("sample1","sample2","sample3"), "treat","control")
DimPlot(scRNA, reduction = "umap", group.by = "group")
  • 计算每个亚群的细胞数量占全部细胞的比例
代码语言：R复制
cell_counts <- table(Idents(scRNA))
cell.all <- cbind(cell_counts = cell_counts, 
                  cell_Freq = round(prop.table(cell_counts)*100,2))
#各组中每种细胞的数量和比例
cell.num.group <- table(Idents(scRNA), scRNA$group) 
cell.freq.group <- round(prop.table(cell.num.group, margin = 2) *100,2)
cell.all = cbind(cell.all,cell.num.group,cell.freq.group)
cell.all = cell.all[,c(1,3,4,2,5,6)]
colnames(cell.all) = paste(rep(c("all","control","treat"),times = 2),
                           rep(c("count","freq"),each = 3),sep = "_")
cell.all

差异分析

  • 组间差异基因 以NK细胞为例，FindMarkers()找差异基因dfmarkers
代码语言：R复制
sub.obj = subset(scRNA,idents = "NK cells")
dfmarkers <- FindMarkers(scRNA, ident.1 = "treat", group.by = "group",min.pct = 0.25, logfc.threshold = 0.25,verbose = F)
head(dfmarkers)
  • 保守 marker基因，FindConservedMarkers()找NK细胞与其他亚群细胞的相比的差异保守基因sub.markers
代码语言：R复制
if(!require("multtest"))BiocManager::install('multtest')
if(!require("metap"))install.packages('metap')

sub.markers <- FindConservedMarkers(scRNA, ident.1 = "NK cells", grouping.var = "group", min.pct = 0.25, logfc.threshold = 0.25,verbose = F)
head(sub.markers)
  • 组间比较气泡图,把感兴趣的基因进行
代码语言：R复制
markers.to.plot = c("CD3D", "CREM", "HSPH1", "SELL", "GIMAP5", "CACYBP", "GNLY", "NKG7", "CCL5",
                    "CD8A", "MS4A1", "CD79A", "MIR155HG", "NME1", "FCGR3A", "VMO1", "CCL2", "S100A9", "HLA-DQA1",
                    "GPR183", "PPBP", "GNG11", "HBA2", "HBB", "TSPAN13", "IL3RA", "PRSS57")

DotPlot(scRNA, features = markers.to.plot, cols = c("blue", "red"), 
        dot.scale = 8, split.by = "group")  
  RotatedAxis()
  • 回溯细胞图和小提琴图
代码语言：R复制
#FeaturePlot
FeaturePlot(scRNA, features = c("CD3D", "GNLY", "IFI6"), split.by = "group", max.cutoff = 3, cols = c("grey","red"), reduction = "umap")

#小提琴图
plots <- VlnPlot(scRNA, features = c("LYZ", "ISG15", "MS4A1"), split.by = "group", group.by = "seurat_annotations",
                 pt.size = 0, combine = FALSE)

library(patchwork)
wrap_plots(plots = plots, ncol = 1)

伪bulk转录组分析

把单细胞数据整合为常规转录组数据的方式

代码语言：R复制
#每个组需要多个样本才能做，如两组各有3个
bulk <- AggregateExpression(scRNA, return.seurat = T, slot = "counts", assays = "RNA", group.by = c("seurat_annotations","orig.ident", "group"))
colnames(bulk)#整合成了多个“样本”
sub <- subset(bulk, seurat_annotations == "CD8  T-cells")
colnames(sub)

Idents(sub) <- "group"
de_markers <- FindMarkers(sub, ident.1 = "treat", ident.2 = "control", slot = "counts", test.use = "DESeq2",
                          verbose = F)
de_markers$gene <- rownames(de_markers)

k1 = de_markers$avg_log2FC< -1 & de_markers$p_val <0.01
k2 = de_markers$avg_log2FC> 1 & de_markers$p_val <0.01
de_markers$change <- ifelse(k1,"down",ifelse(k2,"up","not"))

de_markers火山图可视化

代码语言：R复制
library(ggplot2)
ggplot(de_markers, aes(avg_log2FC, -log10(p_val),color = change))   
  geom_point(size = 2, alpha = 0.5)   
  geom_vline(xintercept = c(1,-1),linetype = 4) 
  geom_hline(yintercept = -log10(0.01),linetype = 4) 
  scale_color_manual(values = c("#2874C5", "grey", "#f87669")) 
  theme_bw()  
  ylab("-log10(unadjusted p-value)")
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