Dynamic interaction between TAL1 oncoprotein and LSD1 regulates TAL1 function in hematopoiesis and leukemogenesis

Area of Science:

• Molecular Biology
• Epigenetics
• Hematopoiesis

Background:

• TAL1/SCL is a key oncogene in hematopoiesis, and its dysregulation is linked to T-cell leukemogenesis.
• The precise regulation of TAL1 interactions with co-activators and corepressors remains incompletely understood.

Purpose of the Study:

• To investigate the role of protein kinase A (PKA)-mediated phosphorylation in regulating TAL1 interactions.
• To elucidate the impact of these interactions on epigenetic modifications and gene expression in hematopoiesis and leukemia.

Main Methods:

• Investigated the effect of PKA phosphorylation on TAL1 interaction with lysine-specific demethylase 1 (LSD1).
• Analyzed histone H3 lysine 4 (H3K4) methylation levels at target gene promoters.
• Utilized knockdown of TAL1 and LSD1, and treatment with PKA activator (forskolin) and inhibitor (H89) in Jurkat cells.
• Examined the recruitment of LSD1 and hSET1 during erythroid differentiation.

Main Results:

• PKA-mediated phosphorylation of serine 172 in TAL1 destabilizes the TAL1-LSD1 interaction.
• This destabilization leads to H3K4 hypermethylation and activation of TAL1 target genes.
• Knockdown of TAL1 or LSD1, or modulation of PKA activity, altered target gene expression and H3K4 methylation levels.
• During erythroid differentiation, LSD1 recruitment decreases while hSET1 recruitment increases at TAL1 targets, correlating with increased H3K4 methylation.

Conclusions:

• PKA phosphorylation acts as a crucial regulator of TAL1-LSD1 interaction, impacting epigenetic modifications.
• This interplay influences hematopoietic transcription and differentiation, offering insights into leukemogenesis.
• The findings reveal a novel mechanism linking PKA signaling to TAL1-mediated epigenetic control in blood development and disease.