RESUMO
Precise self-renewal of the germ cell lineage is fundamental to fertility and reproductive success. The early precursors for the germ lineage, primordial germ cells (PGCs), survive and proliferate in several embryonic locations during their migration to the embryonic gonad. By elucidating the active signaling pathways in migratory PGCs in vivo, we were able to create culture conditions that recapitulate this embryonic germ cell environment. In defined medium conditions without feeder cells, the growth factors FGF2, insulin, and Activin A, signaling through their cognate-signaling pathways, were sufficient for self-renewal of germline-competent PGCs. Forced expression of constitutively active MEK1, AKT, and SMAD3 proteins could replace their respective upstream growth factors. Unexpectedly, we found that BMP4 could replace Activin A in non-clonal growth conditions. These defined medium conditions identify the key molecular pathways required for PGC self-renewal and will facilitate efforts in biobanking of chicken genetic resources and genome editing.
Assuntos
Embrião de Galinha/citologia , Células Germinativas Embrionárias/citologia , Fatores de Crescimento de Fibroblastos/metabolismo , Insulina/metabolismo , Transdução de Sinais , Proteínas Smad/metabolismo , Ativinas/metabolismo , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Proliferação de Células , Células Cultivadas , Embrião de Galinha/metabolismo , Galinhas , Células Germinativas Embrionárias/metabolismo , Feminino , MasculinoRESUMO
Wnt signaling is required for both the development and homeostasis of the skin, yet its contribution to skin wound repair remains controversial. By employing Axin2(LacZ/+) reporter mice we evaluated the spatial and temporal distribution patterns of Wnt responsive cells, and found that the pattern of Wnt responsiveness varies with the hair cycle, and correlates with wound healing potential. Using Axin2(LacZ/LacZ) mice and an ear wound model, we demonstrate that amplified Wnt signaling leads to improved healing. Utilizing a biochemical approach that mimics the amplified Wnt response of Axin2(LacZ/LacZ) mice, we show that topical application of liposomal Wnt3a to a non-healing wound enhances endogenous Wnt signaling, and results in better skin wound healing. Given the importance of Wnt signaling in the maintenance and repair of skin, liposomal Wnt3a may have widespread application in clinical practice.
Assuntos
Orelha Externa/fisiopatologia , Pele/fisiopatologia , Via de Sinalização Wnt/fisiologia , Cicatrização/fisiologia , Animais , Proteína Axina/genética , Proteína Axina/metabolismo , Orelha Externa/lesões , Orelha Externa/metabolismo , Epiderme/metabolismo , Epiderme/fisiopatologia , Expressão Gênica , Folículo Piloso/metabolismo , Imuno-Histoquímica , Lipossomos , Camundongos , Camundongos Transgênicos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Pele/lesões , Pele/metabolismo , Fatores de Tempo , Via de Sinalização Wnt/genética , Proteína Wnt3A/genética , Proteína Wnt3A/metabolismo , Cicatrização/genética , beta-Galactosidase/genética , beta-Galactosidase/metabolismoRESUMO
Wnt signaling is activated by wounding and participates in every subsequent stage of the healing process from the control of inflammation and programmed cell death, to the mobilization of stem cell reservoirs within the wound site. In this review we summarize recent data elucidating the roles that the Wnt pathway plays in the injury repair process. These data provide a foundation for potential Wnt-based therapeutic strategies aimed at stimulating tissue regeneration.
Assuntos
Apoptose/fisiologia , Inflamação/fisiopatologia , Modelos Biológicos , Regeneração/fisiologia , Via de Sinalização Wnt/fisiologia , Cicatrização/fisiologia , Animais , Humanos , Especificidade da EspécieRESUMO
Mechanisms underlying the vascular differentiation of human bone marrow stromal cells (HBMSCs) and their contribution to neovascularisation are poorly understood. We report the essential role of cell density-induced signals in directing HBMSCs along endothelial or smooth muscle lineages. Plating HBMSCs at high density rapidly induced Notch signaling, which initiated HBMSC commitment to a vascular progenitor cell population expressing markers for both vascular lineages. Notch also induced VEGF-A, which inhibited vascular smooth muscle commitment while consolidating differentiation to endothelial cells with cobblestone morphology and characteristic endothelial markers and functions. These mechanisms can be exploited therapeutically to regulate HBMSCs during neovascularisation.