Publications by authors named "Maryline Paris"

In mammals, desynchronized circadian rhythm leads to various biological symptoms. In skin and hair, human epidermal stem cell function in vitro is regulated by circadian oscillations, and thus contributes to tissue aging when deregulated. In mice, circadian arrhythmia of hair follicle stem cells contributes to age-related hair follicle cycling defects.

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Keratinocytes of the basal layer function are to maintain tissue homoeostasis and to fulfil skin repair in response to an external aggression. In wound-healing, during re-epithelialization phase, epithelial precursor cells gradually migrate from the edges of the wound. The epidermal reconstruction model called standard model allows the vertical skin regeneration process (proliferation/differentiation) to being investigated, and keratinocyte function in preserving skin homoeostasis to being assessed.

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Here, we asked whether we could identify pharmacological agents that enhance endogenous stem cell function to promote skin repair, focusing on skin-derived precursors (SKPs), a dermal precursor cell population. Libraries of compounds already used in humans were screened for their ability to enhance the self-renewal of human and rodent SKPs. We identified and validated five such compounds, and showed that two of them, alprostadil and trimebutine maleate, enhanced the repair of full thickness skin wounds in middle-aged mice.

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Recent reports of directed reprogramming have raised questions about the stability of cell lineages. Here, we have addressed this issue, focusing upon skin-derived precursors (SKPs), a dermally derived precursor cell. We show by lineage tracing that murine SKPs from dorsal skin originate from mesenchymal and not neural crest-derived cells.

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The decline of tissue regenerative potential of skin and hair is a hallmark of physiological ageing and may be associated with age-related changes in tissue-specific stem cells and/or their environment. Human hair follicles (hHF) contain keratinocytes having the property of stem cells such as clonogenic potential. Growth capacity of hHF keratinocytes shows that most of the colony-forming cells are classified as holoclones, meroclones or paraclones when analysed in a clonal assay (Cell, Volume 76, page 1063).

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Skin-derived precursors (SKPs) are multipotent dermal stem cells that reside within a hair follicle niche and that share properties with embryonic neural crest precursors. Here, we have asked whether SKPs and their endogenous dermal precursors originate from the neural crest or whether, like the dermis itself, they originate from multiple developmental origins. To do this, we used two different mouse Cre lines that allow us to perform lineage tracing: Wnt1-cre, which targets cells deriving from the neural crest, and Myf5-cre, which targets cells of a somite origin.

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Despite the remarkable regenerative capacity of mammalian skin, an adult dermal stem cell has not yet been identified. Here, we investigated whether skin-derived precursors (SKPs) might fulfill such a role. We show that SKPs derive from Sox2(+) hair follicle dermal cells and that these two cell populations are similar with regard to their transcriptome and functional properties.

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The cellular mechanisms that regulate the maintenance of adult tissue stem cells are still largely unknown. We show here that the p53 family member, TAp63, is essential for maintenance of epidermal and dermal precursors and that, in its absence, these precursors senesce and skin ages prematurely. Specifically, we have developed a TAp63 conditional knockout mouse and used it to ablate TAp63 in the germline (TAp63(-/-)) or in K14-expressing cells in the basal layer of the epidermis (TAp63(fl/fl);K14cre+).

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Mechanisms coordinating neural progenitor cell cycle exit and differentiation are incompletely understood. The cyclin-dependent kinase inhibitor p27(Kip1) is transcriptionally induced, switching specific neural progenitors from proliferation to differentiation. However, neuronal differentiation-specific transcription factors mediating p27(Kip1) transcription have not been identified.

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Combined BMP2 and cAMP signaling induces the catechola-minergic lineage in neural crest (NC) cultures by increasing expression of the proneural transcription factor Phox2a, in a cAMP response element (CRE)-binding protein (CREB)-mediated mechanism. To determine whether CREB acts directly on Phox2a transcription induced by BMP2+cAMP-elevating agent IBMX, transient transfections of hPhox2a-reporter constructs were performed in avian NC cultures and murine, catecholaminergic CAD cells. Although BMP2+IBMX increased endogenous Phox2a expression, the 7.

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Pluripotent neural crest (NC) cells differentiate to diverse lineages, including the neuronal, sympathoadrenal lineage. In primary NC cultures, bone morphogenetic protein 2 (BMP2) requires moderate activation of cAMP signaling for induction of the sympathoadrenal lineage. However, the mechanism by which cAMP signaling synergizes with BMP2 to induce the sympathodrenal lineage is unknown.

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In neural crest (NC) cultures cAMP signaling is an instructive signal in catecholaminergic, sympathoadrenal cell development. However, the extracellular signals activating the cAMP pathway during NC cell development have not been identified. We demonstrate that in avian NC cultures, evidenced by tyrosine hydroxylase expression and catecholamine biosynthesis, adenosine and not adrenergic signaling, together with BMP2, promotes sympathoadrenal cell development.

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We investigated the possible interplay between insulin and glucose signaling pathways in rat pancreatic beta-cell with a special focus on the role of glucose in IRS signaling in vivo. Three groups of rats were constituted by combining simultaneous infusion during 48 h either of glucose and/or insulin, or glucose+diazoxide: Hyperglycemic-Hyperinsulinemic (HGHI), euglycemic-Hyperinsulinemic (eGHI), Hyperglycemic-euinsulinemic (HGeI). Control rats were infused with 0,9%NaCl.

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Beta-cell neogenesis triggers the generation of new beta-cells from precursor cells. Neogenesis from duct epithelium is the most currently described and the best documented process of differentiation of precursor cells into beta-cells. It is contributes not only to beta-cell mass expansion during fetal and nonatal life but it is also involved in the maintenance of the beta-cell mass in adults.

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We investigated the specific and associated effects of insulin and glucose on beta-cell growth and function in adult rats. By combining simultaneous infusion either of glucose and/or insulin or glucose and diazoxide, three groups of rats were constituted: hyperglycemic-hyperinsulinemic rats (high glucose-high insulin), hyperglycemic-euinsulinemic rats (high glucose), and euglycemic-hyperinsulinemic rats (high insulin). All the infusions lasted 48 h.

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