Glucose-dependent transcriptional regulation by an evolutionarily conserved glucose-sensing module

Area of Science:

• Molecular Biology
• Gene Regulation
• Biochemistry

Background:

• Carbohydrate response element binding protein (ChREBP) is a transcription factor regulating glucose-responsive genes.
• ChREBP activation by glucose is crucial for metabolic homeostasis.
• Existing mechanisms for ChREBP activation are not fully understood.

Purpose of the Study:

• To elucidate the novel mechanism of glucose-mediated ChREBP activation.
• To identify the specific domains responsible for glucose sensing in ChREBP.
• To investigate the conservation and regulatory role of this mechanism.

Main Methods:

• Structure-function analysis using GAL4-ChREBP fusion constructs in a glucose-sensitive system.
• Comparative analysis of conserved domains (GSM, LID, GRACE) across species (mammalian MondoA, Drosophila homolog).
• Assays to assess transactivation activity, subcellular localization, and DNA binding.

Main Results:

• A glucose-sensing module (GSM) was identified, mediating glucose responsiveness in ChREBP.
• GSM comprises a low-glucose inhibitory domain (LID) and a glucose-response activation conserved element (GRACE).
• A novel mechanism involving intramolecular inhibition of GRACE by LID under low glucose, reversed by glucose, was revealed, independent of localization or DNA binding.

Conclusions:

• A conserved, evolutionarily ancient mechanism for glucose-mediated ChREBP activation has been identified.
• This mechanism relies on intramolecular regulation within ChREBP, distinct from changes in localization or DNA binding.
• This regulatory pathway plays a vital role in glucose-responsive gene expression.