Temporal and spatial profiling of ALKBH5 activity through NAIL-MS and compartmentalized RNA isolation

Area of Science:

• Molecular Biology
• Epigenetics
• RNA Biology

Background:

• N6-methyladenosine (m6A) is a crucial RNA modification regulating gene expression.
• ALKBH5 is identified as a major m6A demethylase, but its in vivo function remains unclear.
• Understanding m6A dynamics is vital for comprehending gene regulation.

Purpose of the Study:

• To investigate the in vivo role of ALKBH5 in human mRNA m6A demethylation.
• To analyze the impact of ALKBH5 on m6A turnover dynamics using pulse-chase experiments.
• To explore potential compartment-specific functions of ALKBH5 in m6A regulation.

Main Methods:

• Nucleic acid isotope labelling coupled mass spectrometry (NAIL-MS) in a pulse-chase setup.
• Subcellular fractionation to isolate chromatin-associated, nucleoplasmic, and cytoplasmic RNA.
• Comparison of m6A levels and turnover in wild-type (WT) versus ALKBH5 knockout (KO) HEK 293T cells.

Main Results:

• Steady-state m6A levels and turnover dynamics were nearly identical between WT and ALKBH5 KO cells.
• m6A levels peaked in nuclear fractions and decreased upon cytoplasmic export, confirming dynamic regulation.
• ALKBH5 knockout did not affect the spatial and temporal profiles of m6A distribution and decay, even in nuclear fractions.

Conclusions:

• ALKBH5 does not appear to play a major role in global mRNA m6A turnover in HEK 293T cells under optimal conditions.
• m6A modification dynamics during transcript maturation and export are independent of ALKBH5.
• Further studies are needed to elucidate the precise in vivo functions of m6A erasers.