GENETIC AND PHARMACOLOGIC MANIPULATION OF VACUOLAR ATPASE; EFFECTS ON ZYMOGEN ACTIVATION IN PANCREATIC ACINI

Area of Science:

• Gastroenterology
• Cell Biology
• Biochemistry

Background:

• Premature activation of digestive enzymes (zymogens) in pancreatic acinar cells initiates acute pancreatitis (AP).
• This process is linked to the vacuolar ATPase (vATPase), an ATP-dependent proton pump.
• Previous studies used non-specific vATPase inhibitors, necessitating further investigation with novel agents.

Purpose of the Study:

• To investigate the role of vATPase in AP using specific inhibitors and genetic manipulation.
• To confirm the role of vATPase in cerulein (CER)-stimulated zymogen activation.
• To evaluate the efficacy of novel vATPase inhibitors, lobatomide-B and salicylihalamide-A.

Main Methods:

• Utilized novel vATPase inhibitors: lobatomide-B and salicylihalamide-A.
• Employed a genetic approach using small interfering RNA (siRNA) targeting the vATPase E-subunit (V1E).
• Assessed CER-stimulated zymogen (trypsinogen, chymotrypsinogen) activation and amylase secretion in isolated acinar cells.

Main Results:

• Lobatomide-B and salicylihalamide-A significantly inhibited CER-stimulated zymogen activation without affecting amylase secretion.
• Lobatomide-B demonstrated high potency, reducing activation to baseline levels at 0.1µM.
• V1E siRNA significantly reduced V1E expression and chymotrypsinogen activation, but not amylase secretion.

Conclusions:

• These findings confirm the critical role of vATPase in zymogen activation during the early stages of AP.
• Novel, specific vATPase inhibitors (lobatomide-B, salicylihalamide-A) effectively reduce pancreatitis-associated zymogen activation.
• This study validates new therapeutic targets for managing acute pancreatitis.