Transit-Amplifying Cell Frequency and Cell Cycle Kinetics Are Altered in Aged Epidermis

Altered expression of cell cycle regulators in adult T-cell leukemia/lymphoma patients

Abstract Background: Adult T-cell leukemia/lymphoma (ATLL) is caused by human T-cell lymphotropic virus type-1 (HTLV-1).  HTLV-1 oncogenes can induce malignancy through controlled gene expression of cell cycle checkpoints in the host cell. HTLV-I genes play a pivotal role in overriding cell cycle checkpoints and deregulate cellular division. In this study, we aimed to determine and comp...

Sic transit gloria: farewell to the epidermal transit amplifying cell?

For the past 30 years, the prevailing model of epidermal homeostasis has been that epidermal stem cells give rise to transit amplifying cells, which undergo a limited number of cell divisions before initiating terminal differentiation. Recent studies challenge the existence of a transit amplifying cell compartment and suggest a new paradigm for epidermal homeostasis.

Transit-Amplifying Cells Orchestrate Stem Cell Activity and Tissue Regeneration

Transit-amplifying cells (TACs) are an early intermediate in tissue regeneration. Here, using hair follicles (HFs) as a paradigm, we show that emerging TACs constitute a signaling center that orchestrates tissue growth. Whereas primed stem cells (SCs) generate TACs, quiescent SCs only proliferate after TACs form and begin expressing Sonic Hedgehog (SHH). TAC generation is independent of autocri...

Cell cycle kinetics in leukemia.

Strategies of epithelial repair: modulation of stem cell and transit amplifying cell proliferation.

Using double labeling techniques, we studied the replication of corneal epithelial stem cells that reside exclusively in the limbal zone, and their progeny transit amplifying cells. We show that corneal epithelial stem cells can be induced to enter DNA synthesis by wounding and by TPA. We demonstrate the existence of a hierarchy of TA cells; those of peripheral cornea undergo at least two round...