MBD3L2 promotes Tet2 enzymatic activity for mediating 5-methylcytosine oxidation

Area of Science:

• Epigenetics and Molecular Biology
• Cancer Biology

Background:

• Ten-eleven translocation (Tet) proteins regulate DNA methylation dynamics, crucial for cellular function.
• Inactivating mutations in Tet2 are common in human cancers, underscoring its role in preventing cellular transformation.
• Factors controlling Tet protein enzymatic activity are largely unknown.

Purpose of the Study:

• To identify factors that modulate the enzymatic activity of Tet proteins, specifically Tet2.
• To investigate the role of methyl-CpG-binding domain protein 3 (MBD3) and MBD3-like 2 (MBD3L2) in Tet2 regulation.
• To understand the impact of MBD3/MBD3L2-mediated Tet2 modulation on gene expression in cancer development.

Main Methods:

• Assessing the effect of MBD3 and MBD3L2 on the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) by Tet proteins.
• Evaluating the binding affinity between Tet2 and methylated DNA targets in the presence of MBD3 and MBD3L2.
• Analyzing DNA methylation levels at genomic regions co-occupied by MBD3L2 and Tet2.

Main Results:

• MBD3 and MBD3L2 specifically modulate Tet2 enzymatic activity, but not Tet1 or Tet3.
• MBD3L2 enhances Tet2 activity more effectively than MBD3 by increasing binding affinity to methylated DNA.
• Significant decreases in 5mC levels were observed in regions co-occupied by MBD3L2 and Tet2, particularly at promoters of cancer-related and metabolic genes.

Conclusions:

• MBD3 and MBD3L2 are key regulators of Tet2 enzymatic activity.
• Tet2 dysregulation, influenced by MBD3/MBD3L2, plays a role in cancer development through modulation of target gene promoters.
• These findings offer insights into epigenetic mechanisms underlying human malignancies.