The innate immune sensor Toll-like receptor 2 controls the senescence-associated secretory phenotype

Area of Science:

• Cellular Biology
• Immunology
• Oncology

Background:

• Cellular senescence is a stress response involving cell cycle arrest and a proinflammatory senescence-associated secretory phenotype (SASP).
• The precise mechanisms triggering senescence, particularly the senescence-associated secretory phenotype (SASP), remain largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying oncogene-induced senescence (OIS).
• To identify key mediators of the senescence response and the senescence-associated secretory phenotype (SASP) in OIS.

Main Methods:

• Investigated the role of Toll-like receptor 2 (TLR2) and TLR10 in in vitro and murine models of OIS.
• Analyzed the regulation of tumor suppressors (p53-p21^CIP1, p16^INK4a, p15^INK4b) and senescence-associated secretory phenotype (SASP) components.
• Examined the involvement of the cGAS-STING pathway in priming senescence signaling.

Main Results:

• Toll-like receptor 2 (TLR2) and TLR10 were identified as critical mediators of OIS.
• TLR2 promotes cell cycle arrest by regulating key tumor suppressors and induces the senescence-associated secretory phenotype (SASP) via serum amyloids (A-SAAs) acting as damage-associated molecular patterns (DAMPs).
• The cGAS-STING pathway was found to prime TLR2 and A-SAA expression in OIS.

Conclusions:

• Innate immune sensing of senescence-associated damage-associated molecular patterns (DAMPs) by TLR2 is crucial for controlling the senescence-associated secretory phenotype (SASP).
• TLR2 signaling reinforces the cell cycle arrest program during oncogene-induced senescence (OIS).
• This study reveals a novel link between innate immunity and cellular senescence.