Caspases in Life and Death: Their Role in Head Formation

The document discusses the multifunctional role of caspases, a family of protease enzymes, in craniofacial development and the development of various structures in the head. Initially associated with apoptosis (cell death) and inflammation, caspases are now known to also have non-lethal functions such as cell proliferation, differentiation, migration, and regulation of the cell cycle. Abnormalities in craniofacial development can result from inappropriate expression or activation of caspases. The study found that caspase-3-deficient mice showed inconsistent phenotypes, suggesting that other proteins or caspases may compensate depending on the genetic background. Caspase-2 was found to have a protective function in neural development, while caspase-8-deficient mice displayed neural tube malformations. Caspase-3, -7, and -8 are involved in apoptosis in mandibular bone cells, crucial for bone formation and physiology. In terms of hair growth, caspase-9 regulates apoptosis in hair follicle stem cells, and its deficiency can accelerate wound repair and hair follicle regeneration. Hair growth in caspase-2-deficient mice was impaired. The document concludes that while there are similarities in mice lacking apoptosis-related factors, similar groups of molecules have not been identified for non-apoptotic events, suggesting more variable pathways for non-apoptotic processes in contrast to apoptotic pathways.