The Complex of p-Tyr42 RhoA and p-p65/RelA in Response to LPS Regulates the Expression of Phosphoglycerate Kinase 1

Area of Science:

• Molecular Biology
• Cancer Research
• Cell Signaling

Background:

• Inflammation is a key driver of tumorigenesis, with Nuclear Factor-kappa B (NF-κB) signaling playing a central role.
• RhoA GTPases are critical regulators of NF-κB activation pathways.
• Specific phosphorylation of RhoA at Tyrosine 42 is essential for NF-κB activation via IKKβ/NEMO.

Purpose of the Study:

• To elucidate the molecular mechanisms by which phosphorylated RhoA (p-Tyrosine 42) and NF-κB contribute to tumor development.
• To investigate the interaction between p-Tyrosine 42 RhoA, NF-κB, and downstream targets in tumorigenesis.

Main Methods:

• Co-immunoprecipitation assays to detect protein-protein interactions.
• LPS stimulation to activate NF-κB signaling.
• Subcellular localization studies (nuclear translocation).
• Chromatin immunoprecipitation to assess promoter binding.
• RNA interference (siRNA) to study gene function.

Main Results:

• p-Tyrosine 42 RhoA co-immunoprecipitated with phosphorylated p65/RelA (p-Ser 536) subunit of NF-κB.
• Both p-Tyrosine 42 RhoA and p-p65/RelA translocated to the nucleus and bound to the phosphoglycerate kinase 1 (PGK1) promoter, regulating its expression.
• p-p65/RelA and p-Tyr42 RhoA formed a complex with p300 histone acetyltransferase.
• PGK1 interacted with β-catenin, PKM1, and PKM2.
• siRNA-mediated knockdown of PGK1 reduced β-catenin and phosphorylated pyruvate dehydrogenase A1 (p-PDHA1) levels.
• PGK1 was found to phosphorylate β-catenin at Thr551 and Ser552 residues.

Conclusions:

• p-Tyrosine 42 RhoA, through NF-κB activation, promotes tumorigenesis by upregulating PGK1 expression.
• PGK1 plays a significant role in tumorigenesis, potentially through its interactions with β-catenin and its phosphorylation activity.
• These findings highlight a novel signaling axis involving RhoA, NF-κB, and PGK1 in cancer development.