β-Arrestin1-mediated decrease in endoplasmic reticulum stress impairs intestinal stem cell proliferation following...

Area of Science:

• Gastroenterology
• Radiation Oncology
• Stem Cell Biology

Background:

• Gastrointestinal toxicity is a major limitation in abdominal and pelvic radiotherapy, with no effective treatments currently available.
• Radiation-induced intestinal injury is primarily caused by the depletion and loss of proliferative ability in intestinal leucine-rich-repeat-containing GPCR 5 (Lgr5)-positive stem cells.

Purpose of the Study:

• To investigate the role of beta-arrestin1 (βarr1) in radiation-induced intestinal injury.
• To explore the potential of targeting βarr1 as a therapeutic strategy for mitigating radiation enteritis.

Main Methods:

• Utilized a radiation model in mice to assess intestinal injury and stem cell response.
• Examined the expression of βarr1 in radiation enteritis and its effects in βarr1 knockout/knockdown mice.
• Investigated the interaction between βarr1 and the endoplasmic reticulum stress pathway, specifically the PERK/eIF2α signaling cascade, using in vitro and in vivo methods.
• Employed small interfering RNA (siRNA) to knockdown βarr1 expression and evaluated its impact on Lgr5+ stem cell proliferation.

Main Results:

• βarr1 expression was significantly elevated in radiation-induced enteritis.
• Mice lacking βarr1 (KO or knockdown) demonstrated enhanced intestinal Lgr5+ stem cell proliferation, crypt regeneration, and improved survival following radiation.
• The protective effects of βarr1 deficiency were dependent on the PERK/eIF2α pathway; inhibition compromised these benefits.
• βarr1 knockdown via siRNA directly targeted PERK, leading to increased intestinal Lgr5+ stem cell proliferation post-radiation.

Conclusions:

• βarr1 plays a critical role in mediating radiation-induced intestinal injury by impairing Lgr5+ stem cell proliferation.
• Targeting βarr1 presents a promising therapeutic approach to protect against radiation enteritis and improve patient outcomes.
• The mechanism involves βarr1-mediated regulation of endoplasmic reticulum stress and its impact on intestinal stem cell function.