The mRNA-Binding Protein HuR Is a Kinetically-Privileged Electrophile Sensor

Area of Science:

• Cellular stress response
• Oxidative stress signaling
• mRNA regulation

Background:

• HuR and AUF1 are critical mammalian stress sensors.
• Electrophilic lipids like prostaglandin A2 and redox signals influence these proteins.
• 4-hydroxynonenal (HNE) is a key redox-linked lipid-derived electrophile.

Purpose of the Study:

• To investigate the sensing capabilities of HuR and AUF1 towards HNE.
• To elucidate the specific mechanisms and cellular consequences of HNE sensing by HuR.
• To understand HuR's role in regulating the Nrf2-driven antioxidant response.

Main Methods:

• Utilized the T-REX electrophile delivery platform for precise HNE application.
• Employed HEK293T cells for in vitro studies.
• Conducted mutagenesis studies targeting specific cysteine residues in HuR (C13).
• Performed cell depletion experiments for HuR and assessed cell viability and antioxidant response.

Main Results:

• HuR, not AUF1, is a kinetically privileged sensor of HNE in HEK293T cells.
• HNE sensing by HuR is mediated through a specific cysteine residue, C13.
• HuR depletion leads to significant changes in cell viability and Nrf2-transcription-factor-driven antioxidant response.
• Mutagenesis of C13 alone did not fully explain HuR's stress responsivity.

Conclusions:

• HuR is a specific sensor for the electrophilic lipid HNE, functioning via C13.
• HuR plays a crucial role in modulating cell viability and antioxidant responses to HNE.
• The regulation of the Nrf2/antioxidant response by HuR is complex and context-dependent, extending beyond simple C13-mediated sensing.