DOT1L Mediated Gene Repression in Extensively Self-Renewing Erythroblasts

Area of Science:

• * Developmental Biology
• * Molecular Biology
• * Epigenetics

Background:

• * DOT1L (Disruptor of Telomeric Silencing 1-Like) is crucial for embryonic hematopoiesis.
• * Its precise mechanisms, particularly the role of H3K79 methylation, remain unclear.
• * DOT1L's function in transcriptional regulation is implicated in both activation and repression.

Purpose of the Study:

• * To elucidate DOT1L-mediated gene regulation during early embryonic erythropoiesis.
• * To clarify the specific role of H3K79 methylation in DOT1L's functions.
• * To differentiate between methyltransferase-dependent and -independent activities of DOT1L.

Main Methods:

• * Generation of mouse models with DOT1L gene deletion (Dot1L-KO) and methyltransferase domain mutation (Dot1L-MM).
• * Culture of extensively self-renewing erythroblast (ESRE) cells from yolk sac.
• * Whole transcriptome analysis (RNA-sequencing) of wildtype and mutant ESRE cells.

Main Results:

• * Over 80% of differentially expressed genes (DEGs) were upregulated in DOT1L-mutant cells.
• * Approximately 45% of DEGs were unique to either Dot1L-KO or Dot1L-MM mutants, indicating dual regulatory functions.
• * Dot1L-KO primarily affected HPC proliferation genes, while Dot1L-MM impacted HPC development genes.

Conclusions:

• * DOT1L exhibits both methyltransferase-dependent and -independent gene regulatory functions.
• * DOT1L primarily functions to repress gene expression in hematopoietic progenitor cells.
• * This repressive function is, at least partially, independent of its methyltransferase activity.