postmitotische

Postmitotische, often translated as postmitotic in English, describes cells that have exited the cell cycle and no longer undergo mitosis. In this state, cells are typically permanently withdrawn from division after differentiation, spending their lifespan in a non-proliferative, metabolically active condition. Postmitotic status is usually distinguished from temporary quiescence (G0) by its permanence, reflecting terminal differentiation rather than a reversible pause in the cell cycle.

Classic examples are neurons in the vertebrate central nervous system and mature cardiac muscle cells; many skeletal muscle fibers are also formed from postmitotic precursor cells that fuse into multinucleated, non-dividing myofibers. In contrast, tissues with high regenerative capacity maintain proliferative potential longer or rely on stem or progenitor cells to replenish lost cells. Some postmitotic cells can be induced to re-enter the cell cycle only under experimental or pathological conditions, but such re-entry often leads to abnormal outcomes or cell death.

Molecularly, the postmitotic state is enforced by cell cycle inhibitors (for example p16INK4a, p21CIP1, p27KIP1) and by the retinoblastoma (Rb) pathway which suppresses E2F target genes essential for S phase entry. Epigenetic remodeling and sustained suppression of mitogenic signaling help maintain permanence. The postmitotic condition supports long-term cell survival and function, but also underlies limited tissue regeneration, prompting research into reprogramming or replacement strategies for damaged postmitotic tissues.