cJun modulates Ggamma-globin gene expression via an upstream cAMP response element

Area of Science:

• Molecular Biology
• Gene Regulation
• Hematopoiesis

Background:

• The Ggamma-globin gene cAMP response element (G-CRE) is crucial for drug-mediated fetal hemoglobin induction.
• This induction is linked to p38 MAPK-dependent phosphorylation of CREB1 and ATF-2, leading to G-CRE transactivation.

Purpose of the Study:

• To investigate the role of c-Jun in gamma-globin gene transactivation via the G-CRE.
• To determine if c-Jun can activate gamma-globin expression similarly to CREB1.

Main Methods:

• Chromatin immunoprecipitation assays to assess in vivo binding of c-Jun and CREB1 to the G-CRE.
• Electrophoretic mobility shift assays and promoter pull-down assays to confirm in vitro binding and co-localization.
• Luciferase reporter assays and mutation analysis to evaluate functional transactivation.
• Enforced expression studies in K562 cells and primary erythroid progenitors.

Main Results:

• Comparable in vivo binding of c-Jun and CREB1 to the G-CRE was observed.
• c-Jun and CREB1 bind to the G-CRE in vitro, with co-localization confirmed with ATF-2.
• Enforced c-Jun expression led to a concentration-dependent increase in luciferase activity, similar to CREB1.
• A mutation in the G-CRE abolished c-Jun transactivation.
• Enforced c-Jun expression enhanced endogenous gamma-globin gene expression in relevant cell types.

Conclusions:

• c-Jun activates the Ggamma-globin promoter through the G-CRE in a manner comparable to CREB1.
• These findings propose a model for gamma-globin gene activation involving DNA-protein interactions at the G-CRE.
• The study highlights c-Jun as a potential target for modulating fetal hemoglobin production.