Simultaneous Isolation of High-Quality RNA and DNA From Postmortem Human Central Nervous System Tissues for Omics Studies

Sequential extraction of RNA, DNA and protein from cultured cells of the same group

BACKGROUND

Efficient extraction of nucleic acids and proteins (ENAP) from cells is a prerequisite for precise annotation of gene function, and has become laboratory routine for revealing the mysteries of life. However, cell samples are often from different culture dishes, resulting in inevitable experimental errors and sometimes poor repeatability.

AIM

To explore a method to improve the efficiency of ENAP, minimizing errors in ENAP processes, enhancing the reliability and repeatability of subsequent experimental results.

METHODS

A protocol for the sequential isolation of RNA, DNA, and proteins from the same cultured HepG2 cells using RNAzol reagent is presented here. The first step involves culturing HepG2 cells to the exponential phase, followed by the sequential isolation of RNA, DNA, and proteins from the same cultured cells in the second step. The yield of nucleic acids and proteins is detected in the third step, and their purity and integrity are verified in the last step.

RESULTS

The procedure takes as few as 3-4 d from the start to quality verification and is highly efficient. In contrast to the existing kits and reagents, which are primarily based on independent isolation, this RNAzol reagent-based method is characterized by the sequential isolation of RNA, DNA, and proteins from the same cells, and therefore saves time, and has low cost and high efficiency.

CONCLUSION

The RNA, DNA, and proteins isolated using this method can be used for reverse transcription-polymerase chain reaction, polymerase chain reaction, and western blotting, respectively.

Integrative Analyses of scRNA-seq, Bulk mRNA-seq, and DNA Methylation Profiling in Depressed Suicide Brain Tissues

BACKGROUND

Suicidal behaviors have become a serious public health concern globally due to the economic and human cost of suicidal behavior to individuals, families, communities, and society. However, the underlying etiology and biological mechanism of suicidal behavior remains poorly understood.

METHODS

We collected different single omic data, including single-cell RNA sequencing (scRNA-seq), bulk mRNA-seq, DNA methylation microarrays from the cortex of Major Depressive Disorder (MDD) in suicide subjects' studies, as well as fluoxetine-treated rats brains. We matched subject IDs that overlapped between the transcriptome dataset and the methylation dataset. The differential expression genes and differentially methylated regions were calculated with a 2-group comparison analysis. Cross-omics analysis was performed to calculate the correlation between the methylated and transcript levels of differentially methylated CpG sites and mapped transcripts. Additionally, we performed a deconvolution analysis for bulk mRNA-seq and DNA methylation profiling with scRNA-seq as the reference profiles.

RESULTS

Difference in cell type proportions among 7 cell types. Meanwhile, our analysis of single-cell sequence from the antidepressant-treated rats found that drug-specific differential expression genes were enriched into biological pathways, including ion channels and glutamatergic receptors.

CONCLUSIONS

This study identified some important dysregulated genes influenced by DNA methylation in 2 brain regions of depression and suicide patients. Interestingly, we found that oligodendrocyte precursor cells (OPCs) have the most contributors for cell-type proportions related to differential expression genes and methylated sites in suicidal behavior.