Hepatic Polarization Accelerated by Mechanical Compaction Involves HNF4α Activation

Area of Science:

• Cell Biology
• Hepatology
• Biophysics

Background:

• Limited data exists on how mechanical forces influence liver cell organization and function.
• Previous studies suggest mechanical compaction aids hepatocyte polarization, but the underlying cellular mechanisms remain largely unknown.
• Hepatocyte nuclear factor 4 alpha (HNF4α) is a critical regulator of liver development and function.

Purpose of the Study:

• To investigate the role of Hepatocyte nuclear factor 4 alpha (HNF4α) in mechanical compaction-induced hepatocyte polarization.
• To elucidate the cellular mechanisms linking mechanical forces to hepatic polarization.

Main Methods:

• Mechanical compaction simulated using transient centrifugation on cell aggregates (HEK-293T and primary hepatocytes).
• Quantification of HNF4α promoter activity, mRNA, and protein expression under varying compaction forces (0g vs. 500g).
• Assessment of biliary canalicular formation, albumin, and urea production.
• Inhibition of F-actin and E-cadherin pathways using Latrunculin B and SHE78-7, respectively, to study mechanical signal transduction.

Main Results:

• Mechanical compaction directly activated HNF4α promoter expression in both non-hepatic and primary hepatic cells.
• HNF4α expression (mRNA and protein) increased significantly with higher compaction force.
• Activated HNF4α correlated with enhanced biliary canalicular formation and increased albumin and urea production.
• Inhibiting mechanical transduction pathways partially reduced HNF4α expression and liver function marker production.

Conclusions:

• Hepatocyte nuclear factor 4 alpha (HNF4α) plays an active role in hepatic polarization driven by environmental mechanical compaction.
• Mechanical forces regulate hepatic polarization through HNF4α activation, impacting liver-specific functions.
• Understanding this mechanotransduction pathway offers insights into liver morphogenesis and disease.