Hypothalamic tanycytes in median eminence (ME) are emerging as a crucial cell population that regulates endocrine output, energy balance and the diffusion of blood-born molecules. Tanycytes have recently been considered as potential somatic stem cells in the adult mammalian brain. While somatic stem cells in general are characterized by their self-renewal, regenerative and tumorigenic potential, it remains largely unknown how ME tanycytes maintain themselves and to what extent the disturbance of such homeostasis contributes to diseases such as cancer.
Recently, a study led by Dr. WU Qingfeng from Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, revealed the regenerative and tumorigenic potential of adult Rax+ tanycytes in the context of ME stem cell niche.
In this study, single-cell RNA sequencing (scRNA-seq), cell lineage tracing, and single-molecule fluorescent in situ hybridization (smFISH) were used. And the researchers found that Rax+ tanycytes in ME of mice are largely quiescent but quickly enter the cell cycle upon neural injury for self-renewal and regeneration. Mechanistically, genetic ablation of Igf1r signaling in tanycytes impairs tissue repair under injury conditions. Further investigation showed that Braf oncogenic activation is sufficient to transform Rax+ tanycytes into actively dividing tumor cells that eventually develop into a papillary craniopharyngioma-like tumor. These findings uncover the regenerative and tumorigenic potential of tanycytes.
This study identified Rax+ tanycytes as slow-cycling cells wherein quiescence may preserve their inherent longevity and further revealed the previously underappreciated role of adult tanycytes in tissue repair and tumorigenesis. The craniopharyngioma mouse model that the researchers established may unlock an avenue for regenerative medicine and cancer therapy in the central nervous system.
A graphical model showing the regenerative and tumorigenic potential of Rax+ tanycytes in ME. (Image by IGDB)
Contact:
Dr. WU Qingfeng
Institute of Genetics and Development Biology, Chinese Academy of Sciences
