cAMP promotes acute lysosome biogenesis through TFEB nuclear import-export dynamics

Area of Science:

• Cellular Biology
• Molecular Signaling
• Metabolism

Background:

• Cyclic adenosine monophosphate (cAMP) signaling influences lipid and glucose metabolism.
• Lysosome-dependent degradation is crucial for cellular catabolism.
• The regulation of lysosomal dynamics by cAMP signaling is not well understood.

Purpose of the Study:

• To investigate the impact of cAMP signaling on lysosomal dynamics.
• To elucidate the role of Transcription factor EB (TFEB) in cAMP-mediated lysosomal regulation.

Main Methods:

• Stimulation of intracellular cAMP levels using forskolin and IBMX.
• Tracking TFEB-GFP nuclear import and export dynamics.
• Analysis of TFEB target lysosome gene expression.
• Inhibition of cAMP-dependent protein kinase A (PKA) with H89.
• Phosphoproteomic profiling to identify phosphorylation sites.

Main Results:

• Elevated cAMP induced rapid TFEB nuclear import and transient upregulation of TFEB target genes.
• TFEB returned to the cytoplasm within 8 hours, accompanied by gene downregulation.
• PKA inhibition led to sustained TFEB nuclear accumulation, indicating PKA promotes TFEB export.
• Phosphoproteomic analysis revealed increased phosphorylation of a PKA motif during TFEB export.

Conclusions:

• cAMP-PKA signaling plays a novel role in modulating lysosomal gene expression.
• TFEB nuclear-cytoplasmic shuttling is a key mechanism for temporal tuning of lysosomal activity.
• This signaling pathway provides insights into the coordination of catabolism and lysosomal function.