dedifferentiations

Dedifferentiation is a biological process in which mature, specialized cells lose their differentiated features and revert to a less specialized, progenitor-like state. This cellular plasticity can enable tissue repair and regeneration, and it is distinct from differentiation, in which progenitor cells become specialized, and from transdifferentiation, the direct switch from one mature lineage to another.

In plants, dedifferentiation is common and essential. Mature cells can re-enter the cell cycle and form callus tissue, a mass of proliferating cells that can differentiate into various tissues. This process underlies wound healing, shoot and root formation, and the success of plant tissue culture. Plant hormones, notably auxins and cytokinins, modulate dedifferentiation and subsequent redifferentiation.

In animals, dedifferentiation is more context-dependent and is prominently involved in certain regenerative phenomena. It contributes to limb and heart regeneration in some amphibians and fish, where differentiated cells revert to progenitors that rebuild tissues and form a blastema. In mammals, evidence for dedifferentiation exists but is limited and debated; many regenerative processes rely on proliferation of resident progenitor cells or mature cells with limited plasticity, rather than widespread dedifferentiation.

Mechanistically, dedifferentiation involves changes in gene expression, epigenetic remodeling, and signaling pathways such as Wnt, Notch, FGF, and TGF-β. Mature-cell markers are downregulated while progenitor- or stem-cell genes are upregulated, accompanied by chromatin reconfiguration and, in some cases, partial re-entry into the cell cycle.

Implications and challenges include the potential to enhance tissue repair and regenerative medicine, balanced against risks of uncontrolled growth or tumorigenesis. Understanding how to induce controlled dedifferentiation while preventing adverse outcomes remains an active area of research.