Growth and regeneration of one tissue within an organ compels accommodative changes in the surrounding tissues. However, the molecular nature and operating logic governing these concurrent changes remain poorly defined. The dermal adipose layer expands concomitantly with hair follicle downgrowth, providing a paradigm for studying coordinated changes of surrounding lineages with a regenerating tissue. Here, we discover that hair follicle transitamplifying cells (HF-TACs) play an essential role in orchestrating dermal adipogenesis through secreting Sonic Hedgehog (SHH). Depletion of Shh from HF-TACs abrogates both dermal adipogenesis and hair follicle growth. Using cell type-specific deletion of Smo, a gene required in SHH-receiving cells, we found that SHH does not act on hair follicles, adipocytes, endothelial cells, and hematopoietic cells for adipogenesis. Instead, SHH acts directly on adipocyte precursors, promoting their proliferation and their expression of a key adipogenic gene, peroxisome proliferator-activated receptor γ (Pparg), to induce dermal adipogenesis. Our study therefore uncovers a critical role for TACs in orchestrating the generation of both their own progeny and a neighboring lineage to achieve concomitant tissue production across lineages.

Merkel cells are innervated mechanosensory cells responsible for light-touch sensations. In murine dorsal skin, Merkel cells are located in touch domes and found in the epidermis around primary hairs. While it has been shown that Merkel cells are skin epithelial cells, the progenitor cell population that gives rise to these cells is unknown. Here, we show that during embryogenesis, SOX9-positive (+) cells inside hair follicles, which were previously known to give rise to hair follicle stem cells (HFSCs) and cells of the hair follicle lineage, can also give rise to Merkel Cells. Interestingly, while SOX9 is critical for HFSC specification, it is dispensable for Merkel cell formation. Conversely, FGFR2 is required for Merkel cell formation but is dispensable for HFSCs. Together, our studies uncover SOX9(+) cells as precursors of Merkel cells and show the requirement for FGFR2-mediated epithelial signalling in Merkel cell specification.

Ethanol exposure during pregnancy is an established cause of birth defects, including neurodevelopmental defects. Most adult neurons are produced during the second trimester-equivalent period. The fetal neural stem cells (NSCs) that generate these neurons are an important but poorly understood target for teratogenesis. A cohort of miRNAs, including miR-153, may serve as mediators of teratogenesis. We previously showed that ethanol decreased, while nicotine increased miR-153 expression in NSCs. To understand the role of miR-153 in the etiology of teratology, we first screened fetal cortical NSCs cultured ex vivo, by microarray and quantitative RT-PCR analyses, to identify cell-signaling mRNAs and gene networks as important miR-153 targets. Moreover, miR-153 over-expression prevented neuronal differentiation without altering neuroepithelial cell survival or proliferation. Analysis of 3′UTRs and in utero over-expression of pre-miR-153 in fetal mouse brain identified Nfia (nuclear factor-1A) and its paralog, Nfib, as direct targets of miR-153. In utero ethanol exposure resulted in a predicted expansion of Nfia and Nfib expression in the fetal telencephalon. In turn, miR-153 over-expression prevented, and partly reversed, the effects of ethanol exposure on miR-153 target transcripts. Varenicline, a partial nicotinic acetylcholine receptor agonist that, like nicotine, induces miR-153 expression, also prevented and reversed the effects of ethanol exposure. These data collectively provide evidence for a role for miR-153 in preventing premature NSC differentiation. Moreover, they provide the first evidence in a preclinical model that direct or pharmacological manipulation of miRNAs have the potential to prevent or even reverse effects of a teratogen like ethanol on fetal development.

Rhox6 is one of the Reproductive Homeobox genes on the X chromosome (Rhox) that is expressed in the placenta and the post-migratory primordial germ cells (PGCs) in the nascent gonad. Despite its novel expression pattern, the significance of Rhox6 expression in the differentiation of these cell types remains unknown. To investigate the role that Rhox6 plays in PGCs, cDNA encoding Rhox6 and short-hairpin (sh) RNA directed against Rhox6 transcripts were introduced by unique expression vectors into a genetically engineered mouse embryonic stem cell (ESC) line. This ESC line expresses enhanced green fluorescent protein (EGFP) under the Oct3/4 promoter, thereby allowing us to monitor the presence of undifferentiated ESCs and PGCs in culture in real time. This ESC line was used to isolate clones that stably expressed Rhox6 cDNA, shRNA against Rhox6 transcripts, or controls. Quantitative RT-PCR results validated that overexpression had been achieved, as well as knockdown of Rhox6 transcripts in these ESC clones. However, these clones exhibited a normal appearance of undifferentiated ESCs and expressed EGFP. Next, these ESC clones were induced to differentiate into PGCs by generating embryoid bodies (EBs) in culture medium without leukemia inhibitory factor. Detection of EGFP expression by fluorescence microscopy and germ cell markers by RT-PCR validated the differentiation of PGCs in EBs. The Rhox6 transgene had little, if any, effect on EGFP expression in EBs, whereas Rhox6 knockdown significantly decreased EGFP expression in EBs. Thus, it is suggested with these results that Rhox6 is necessary for determination of the germ cell lineage.

No abstract

Approved therapies for Fabry disease (FD) include migalastat, an oral pharmacological chaperone, and agalsidase beta and agalsidase alfa, 2 forms of enzyme replacement therapy. Broad tissue distribution may be beneficial for clinical efficacy in FD, which has severe manifestations in multiple organs. Here, migalastat and agalsidase beta biodistribution were assessed in mice and modeled using physiologically based pharmacokinetic (PBPK) analysis, and migalastat biodistribution was subsequently extrapolated to humans. In mice, migalastat concentration was highest in kidneys and the small intestine, 2 FD-relevant organs. Agalsidase beta was predominantly sequestered in the liver and spleen (organs unaffected in FD). PBPK modeling predicted that migalastat 123 mg every other day resulted in concentrations exceeding the in vitro halfmaximal effective concentration in kidneys, small intestine, skin, heart, and liver in human subjects. However, extrapolation of mouse agalsidase beta concentrations to humans was unsuccessful. In conclusion, migalastat may distribute to tissues that are inaccessible to intravenous agalsidase beta in mice, and extrapolation of mouse migalastat concentrations to humans showed adequate tissue penetration, particularly in FD-relevant organs.

The originally published version of this Article contained an error in Figure 2. In panel e, the blue bar was incorrectly labelled ‘KRT8(+)/TOMATO(-)’. Furthermore, during the process of preparing a correction, the publication date of the Article was inadvertently changed to June 20th 2018. Both of these errors have been corrected in the PDF and HTML versions of the Article.

Frontal Fibrosing Alopecia (FFA) is a lymphocytic cicatricial alopecia that predominantly occurs in post-menopausal women. It is characterized by a band-like loss of hair and follicular ostia of the frontal temporal scalp, and commonly involves bilateral eyebrow loss. Over the last 15 years the incidence of FFA has shown a noticeable, albeit unexplained rise. Current accepted treatment is based on expert opinion and includes steroids, hormone blockers, and hydroxychloroquine. To delineate the transcriptional landscape of FFA, we performed RNAseq on scalp biopsies of 18 FFA patients compared with controls. We found three major pathways associated with FFA: 1) downregulation of steroid/cholesterol/fatty acid pathways (NSDHL and FADS); 2) upregulation of fibrosis and hypertrophic scarring pathways (COL1A1, COL1A1, TIMP1 and MMPs); and 3) upregulation of mast cell genes. Histology of FFA lesions showed increased presence of mast cells. Similar downregulation of cholesterol synthesis pathways was found in non-lesional FFA scalp, suggesting that molecular changes can be detected even before obvious hair loss. FFA lesional scalp also showed upregulation of T cell activation and antigen presentation genes such JAK3, TAP2, and ICOS, which were not observed in other forms of cicatricial alopecia. To our surprise, we found that cicatricial alopecias share a core set dysregulated gene expression pathways consisting of downregulation of steroid and cholesterol metabolism and upregulation of fibrotic and mast cell signatures. Additionally, FFA displays immune response pathway dysregulation, suggesting that a set of drugs may be useful in targeting these pathways in all cicatricial alopecia patients, potentially combined with immunomodulatory drugs, as indicated by the unique pathways in FFA. These findings provide a molecular framework in which to further investigate the pathomechanisms of FFA in the broader context of cicatricial alopecias.