The TIP60 Complex Is a Conserved Coactivator of HIF1A

Area of Science:

• Molecular Biology
• Gene Regulation
• Cellular Response to Hypoxia

Background:

• Hypoxia-inducible factors (HIFs) are key regulators of cellular responses to low oxygen conditions.
• Their precise molecular mechanisms in controlling gene expression are not fully understood.
• HIFs play significant roles in normal physiology and various diseases.

Purpose of the Study:

• To investigate the role of the TIP60 complex as a transcriptional cofactor for HIF1.
• To elucidate the molecular mechanisms by which HIF1 controls gene expression.
• To identify cofactors involved in HIF1-mediated gene activation.

Main Methods:

• Utilized Drosophila and human cell lines, including colorectal cancer cells.
• Investigated the interaction between HIF1A and TIP60.
• Assessed HIF1-dependent gene expression and chromatin modifications.
• Performed global analysis of HIF1A-dependent gene activity.

Main Results:

• A conserved role for the TIP60 complex as a HIF1 transcriptional cofactor was identified in Drosophila and human cells.
• TIP60 is essential for HIF1-dependent gene expression in fly cells, embryos, and colorectal cancer cells.
• TIP60 facilitates HIF1A-dependent chromatin modification and RNA polymerase II activation, but not initial gene association.
• Most HIF1A targets require TIP60, CDK8-Mediator, or both for maximal expression under hypoxia.

Conclusions:

• The TIP60 complex is a crucial cofactor for HIF1 transcriptional activity.
• HIF1A utilizes functionally diverse cofactors, including TIP60 and CDK8-Mediator, to regulate distinct gene subsets.
• This finding advances the understanding of HIF-mediated transcriptional regulation in hypoxia.