KLF6 negatively regulates HIF-1α in extravillous trophoblasts under hypoxia

Area of Science:

• Cell Biology
• Molecular Biology
• Reproductive Biology

Background:

• Hypoxia-inducible factor 1-alpha (HIF-1α) is a master regulator of cellular response to low oxygen.
• KLF6 is a transcription factor involved in cell proliferation, differentiation, and apoptosis.
• KLF6 is upregulated in extravillous trophoblasts under hypoxia in a HIF-1α-dependent manner.

Purpose of the Study:

• To investigate whether KLF6 modulates HIF-1α expression in HTR8/SVneo cells.
• To understand the role of KLF6 in regulating HIF-1α levels under hypoxic conditions.
• To explore the implications of KLF6-HIF-1α interaction for trophoblast adaptation to hypoxia.

Main Methods:

• HTR8/SVneo cells were cultured under acute hypoxia (1% oxygen) or in 3D culture to generate oxygen gradients.
• Gene expression was analyzed using qRT-PCR and Western blot.
• Gene silencing (siRNA, shRNA) and overexpression (plasmids) were employed to manipulate KLF6 levels.
• The NF-κB pathway and HIF-1α degradation were modulated using specific inhibitors and mutants.

Main Results:

• KLF6 was found to negatively regulate HIF-1α expression in HTR8/SVneo cells under hypoxia.
• Silencing KLF6 led to a partially HIF-1α-dependent increase in MMP9 and VEGF expression.
• KLF6-dependent regulation of HIF-1α involved the NF-κB pathway and HIF-1α degradation.
• 3D culture confirmed KLF6's negative regulation of HIF-1α in a physiological hypoxic microenvironment.

Conclusions:

• KLF6 plays a role in the fine-tuning modulation of HIF-1α levels during hypoxia.
• By sustaining a homeostatic level of HIF-1α, KLF6 may contribute to extravillous trophoblast adaptation to hypoxic conditions.
• The interplay between KLF6 and HIF-1α is important for regulating trophoblast behavior in response to oxygen levels.