title: The Tcl1 oncogene defines secondary hair germ cells differentiation at catagen-telogen transition and affects stem-cell marker CD34 expression.
abstract: Overexpression of the TCL1 gene family plays a role in the onset of T-cell leukemias in mice and in humans. The Tcl1 gene is tightly regulated during early embryogenesis in which it participates in embryonic stem (ES)-cells proliferation and during lymphoid differentiation. Here, we provide evidences that Tcl1 is also important in mouse hair follicle (HF) and skin homeostasis. We found that Tcl1(-/-) adult mice exhibit hair loss, leading to alopecia with extensive skin lesions. By analysing Tcl1 expression in the wild-type (wt) skin through different stages of hair differentiation, we observe high levels in the secondary hair germ (HG) cells and hair bulges, during early anagen and catagen-telogen transition phases. The loss of Tcl1 does not result in apparent skin morphological defects during embryonic development and at birth, but its absence causes a reduction of proliferation in anagen HFs. Importantly, we show the that absence of Tcl1 induces a significant loss of the stem-cell marker CD34 (but not alpha6-integrin) expression in the bulge cells, which is necessary to maintain stem-cell characteristics. Therefore, our findings indicate that Tcl1 gene(s) might have important roles in hair formation, by its involvement in cycling and self-renewal of transient amplifying (TA) and stem-cell (SC) populations.
authors.affiliation: Molecular Oncology Laboratory, Istituto Dermopatico dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ragone
authors.forename: A
authors.initials: A
authors.lastname: Bresin
authors.forename: F
authors.initials: F
authors.lastname: Piermarini
authors.forename: C
authors.initials: C
authors.lastname: Lazzeri
authors.forename: M C
authors.initials: MC
authors.lastname: Picchio
authors.forename: D
authors.initials: D
authors.lastname: Remotti
authors.forename: S-M
authors.initials: SM
authors.lastname: Kang
authors.forename: M D
authors.initials: MD
authors.lastname: Cooper
authors.forename: C M
authors.initials: CM
authors.lastname: Croce
authors.forename: M G
authors.initials: MG
authors.lastname: Narducci
authors.forename: G
authors.initials: G
authors.lastname: Russo
mesh_terms: D000505:Alopecia / Q000209:etiology; D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D002454:Cell Differentiation; D018859:Hair Follicle / Q000196:embryology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D012867:Skin / Q000473:pathology; D013234:Stem Cells / Q000502:physiology*
chemical_list: D018952:Antigens, CD34; D011518:Proto-Oncogene Proteins; C490393:Tcl1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt