NIH Research Festival
Histone 3 lysine 4 (H3K4) methyltransferases MLL3 and MLL4 (MLL3/4) are required for enhancer activation during cell differentiation, though the mechanism is incompletely understood. We have attempted to address this issue by generating two mouse lines: one expressing H3.3K4M, a lysine-4-tomethionine (K4M) mutation of histone H3.3 that inhibits H3K4 methylation, and the other carrying conditional double knockout of MLL3/4 enzymatic SET domain. Expression of H3.3K4M in lineagespecific precursor cells depletes H3K4 methylation and impairs adipogenesis and adipose tissue development. Mechanistically, H3.3K4M prevents enhancer activation in adipogenesis by destabilizing MLL3/4 proteins but not other Set1-like H3K4 methyltransferases MLL1, MLL2, SET1A, and SET1B. Notably, deletion of the enzymatic SET domain of MLL3/4 in lineage-specific precursor cells mimics H3.3K4M expression and prevents adipose tissue development. Interestingly, destabilization of MLL3/4 by H3.3K4M in adipocytes does not affect adipose tissue maintenance and function. Together, our findings indicate that expression of H3.3K4M, or deletion of the enzymatic SET domain, destabilizes enhancer H3K4 methyltransferases MLL3/4 and impairs adipose tissue development.
Scientific Focus Area: Molecular Biology and Biochemistry
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