Mesenchymal–Epithelial Interactions During Hair Follicle Morphogenesis and Cycling

This study reports that hair regeneration in live mice involves spatially regulated stem cell divisions and requires mesenchymal interactions, observed in real-time using a novel non-invasive imaging method.

This study found that dermal Shh signaling regulates specific dermal papilla signatures essential for maintaining hair follicle development, suggesting that the Shh-Noggin signaling loop is crucial for hair morphogenesis.

In this mouse study, researchers found that dermal Wnt signaling/β-catenin activity is essential for fibroblast proliferation and initiating hair follicle formation by interacting with epidermal Wnt ligands.

FGF18 helps keep hair in its resting phase, affecting hair growth cycles.

This review discusses the role of stem cell progeny as integral components of stem cell niches, offering feedback that may influence different stem cell systems' microenvironments, but it presents no new research findings.

This study identified TGF-β2 as a crucial signal in hair follicle stem cell regeneration, highlighting its role in counteracting BMP signaling to promote tissue regeneration.

This study found that adult mouse dermis can be reprogrammed by epidermal cues to resemble neonatal dermis, with changes in fibroblast proliferation and extracellular matrix composition.

This study found that intradermal adipocyte lineage cells in mice are necessary and sufficient to activate follicular stem cells, highlighting their role in regulating skin stem cell activity.

This study found that Wnt signaling in the hair follicle is crucial for coordinating the behavior of epithelial and melanocyte stem cells, which drives hair regeneration and melanocyte differentiation in mice.

This study found that in a population of hair follicles, regenerative cycling stages are regulated by both intrinsic and extrinsic signals, with WNT/BMP signaling mediating interactions among follicles for adaptability.

This review discusses the identification and characteristics of melanocyte stem cells, emphasizing their role in hair pigmentation, greying, and skin repigmentation, but reports no new research findings.

COL17A1 is crucial for preventing hair graying and loss by supporting hair and pigment stem cells.

Nephronectin helps attach muscle cells to hair follicles.

This study found that Acvr1b signaling is crucial for both hair follicle development and cycling in mice, with the genetic disruption leading to hair loss and a thickened epidermis.

In this study, the researchers reported that Notch/CSL signaling is crucial for hair follicle differentiation, with Wnt5a signaling and FoxN1 acting as mediators in mice.

This study found that in mice, inactivating beta-catenin in the dermal papilla reduces hair follicle progenitor proliferation and disrupts the hair cycle.

This study demonstrates that Sox2-positive dermal papilla cells specify particular hair follicle types by showing heterogeneity in gene expression and pathway activation in these cells.

This review discusses the reuse of molecular mechanisms involved in embryonic skin development for maintaining adult epidermal homeostasis and reports no new results.

This review summarizes fundamental concepts and recent advancements in hair follicle biology, including insights from mouse models into broader molecular and cellular processes relevant to regeneration and development.

This review discusses the role of activin signaling in hair follicle formation, hair growth cycling, and skin healing, but presents no new clinical findings.

This study found that activating β-catenin signaling in embryonic epidermis promoted hair follicle characteristics at the expense of normal epidermal differentiation, leading to early pigmentation and innervation.

This study identified that Eda-A1 unexpectedly induces placode inhibitors dkk4 and lrp4, indicating the importance of tightly regulated signaling for proper ectodermal organ development.

This research discusses how epithelial stem cells in the skin maintain normal homeostasis, contribute to wound repair, and highlights the importance of these processes, as defects can lead to skin diseases including cancers, but provides no new experimental results.

NFATc1 controls hair stem cell activity, affecting hair growth and could be a target for hair loss treatments.

Hair follicles can regrow in wounded adult mouse skin using a process like embryo development.

This study found that the Wnt inhibitor Dkk4 may play a role in regulating hair follicle development through a feedback loop with canonical Wnt signaling pathways.

This article reviews the similarities in early development processes of hair follicles, teeth, and mammary glands and reports no new experimental findings.

This study found that loss of Apc due to K14-cre-mediated gene recombination in mice led to aberrant growth in ectodermally derived squamous epithelia, implicating its critical role in specifying epithelial cell fates during embryonic development.

This study found that active BMP signaling prevents epithelial stem cell activation and expansion in hair follicles, while its inhibition leads to HF stem/progenitor cell overproduction and matricomas.

This review summarizes the major events and regulators of the hair cycle in mammals but reports no new experimental results; it emphasizes the complex regulation of stem cell activation and differentiation during hair growth.

This study found that the absence of the vitamin D receptor disrupts hair follicle structure during the first catagen in mice, linked to increased expression of the hairless gene.

This study developed molecular signatures for dermal papilla cells and their niche, uncovering novel signaling regulators and genes linked to hair disorders, which may inform future hair development research.

This study found that stabilized beta-catenin is crucial for activating stem cell transition from quiescence to proliferation in hair follicles by influencing gene expression within the stem cell niche.

This study describes a system for generating hair follicles from dissociated cells in mice, suggesting that successful development requires a foundational epithelial platform.

This article reviews follicular melanogenesis, detailing how melanin synthesis and its regulation in hair follicles depend on a complex interplay of cellular and molecular mechanisms, but reports no new clinical findings.

This study found that continuous β-catenin signaling in adult mouse epidermis can reprogram hair follicles to form benign tumors, which regress after the signaling is discontinued.

This study found that modulating BMP activity in transgenic mice affects the development and characteristics of several ectodermal organs, such as skin, hair, and claws, highlighting a stage-dependent influence on organogenesis.

This study found that BMP receptor IA is crucial for hair progenitor cell differentiation in mice, and its sequential inhibition and activation are necessary to generate a functioning hair shaft.

The K15 promoter effectively targets stem cells in the hair follicle bulge.

This study in mice found that overexpressing Sonic Hedgehog in basal cells caused skin anomalies and a lack of certain hair fibers, underscoring its key role in hair follicle development.

This study found that follistatin and activin interactions are important for hair follicle development and cycling in mice, suggesting that they may regulate processes involving BMP-2 and its antagonist.

This review summarizes recent advances in understanding the molecular mechanisms of hair follicle formation and discusses potential future clinical applications for treating hair loss and skin tumors, but it reports no new clinical results.

This review classifies mutant mice with hair abnormalities into six categories, providing an annotated table that serves as a reference for understanding the molecular controls of hair growth.

This study found that the BMP antagonist noggin induces hair growth in postnatal skin by neutralizing BMP4's inhibitory activity, potentially mediated by changes in Shh expression.

This study found that Tcf3 and Lef1 differently regulate cell differentiation in multipotent skin stem cells, with Tcf3 promoting follicle-like features and Lef1, when modified, promoting sebocyte differentiation.

This study demonstrated that multipotent stem cells in adult mice whisker follicles migrate to produce whisker growth, and that this process requires precise control of stem cell trafficking.

Inhibiting Bmp signaling disrupts hair growth and differentiation.

This study demonstrated that anagen can be induced in Stat3-disrupted mice, suggesting that both Stat3-dependent and independent pathways, possibly involving PKC, mediate hair cycle progression with required PI3K activation.

This study reports that activating Notch signaling in the hair follicle cortex of transgenic mice caused abnormal differentiation of the medulla and cuticle, highlighting potential cell-cell interactions.

This study found that LEF1/TCF3 is necessary but not sufficient for TOPGAL activation in hair follicle development, indicating complex regulation in the skin.

This study found that the loss of a functional hr gene in mice leads to premature and abnormal hair follicle regression, disrupting normal hair cycling and architecture.

This study found that ectopic expression of the lymphoid-enhancer factor can induce K17 protein in the skin, suggesting a link between skin development and wound repair processes in mice.

TGF-β receptors are crucial for hair follicle development.

This chapter reviews laboratory models used for studying alopecia therapies but provides no new experimental findings.

This article describes the potential role of various growth factors and molecules in regulating mammalian hair follicle development but does not present new experimental results.

This study found that dermal papilla cells may play a critical role in hair follicle development and cycling by promoting epidermal proliferation and potentially mediating systemic factors that influence follicle behavior.

This paper provides evidence supporting the formation of new hair follicles in adult humans, building on findings previously demonstrated in rabbits.