Hair follicle (HF) regeneration can be achieved in the center of large full-thickness wounds on mouse backs (wound-induced HF neogenesis model, WIHN). Investigations with this model have allowed for the identification of some of the factors limiting the extent of fibrosis, which creates a permissive environment for the reposition of HF. For WIHN, specific subpopulations of cells rather than cell types are permissive to this process. Detailed information on the cellular composition in WIHN is not available. Here, we provide a description of changes in cell numbers of fibroblasts, HF dermal papilla, endothelial cells, keratinocytes (interfollicular epidermis, HF-infundibulum, HF-isthmus, HF-bulge (basal and suprabasal), HF-hair germ) and immune cells (macrophages, monocytes, dendritic cells, T cells (CD4+, CD8+, CD4+/CD8+, regulatory T cells) and neutrophils) based on flow cytometric analysis. We compared unwounded skin with large wounds (1.5 × 1.5 cm) at different time points after wounding. We found that non-immune dermal cells have the largest share in the skin at all time points studied, and that the number of epidermal cells started increasing nine days after wounding, which precede isthmus cells and bulge cells, mirroring the development of hair follicles. Monocytes and neutrophils represent most myeloid cells in wounds and remain in wounds even beyond the inflammatory phase of wound healing. Macrophages can be identified as inflammatory and alternative cells and are also found in wounds even in the late remodeling phase of wound healing. Lastly, we provide information about T cells in large wounds. Most T cells in the wounds were CD8+ at all time points and expressed γδTCR, which was previously thought to be expressed mainly on CD4+. We also report the existence of double positive CD4/CD8. Our study provides a guide in terms of time points suitable for the further study of cell subpopulations aiming to dissect the cellular heterogeneity in WIHN. Our results might set the base for the comparison of WIHN between control mice and animals manipulated to influence HF neogenesis and the full understanding of the responsible actors allowing for HF regeneration.

Single-cell RNA sequencing (scRNA-seq) has revealed that adult white adipose tissue (WAT) harbors functionally diverse subpopulations of mesenchymal stromal cells that differentially impact tissue plasticity. To date, the molecular basis of this cellular heterogeneity has not been fully defined. Here, we describe a multilayered omics approach to dissect adipose progenitor cell heterogeneity in three dimensions: progenitor subpopulation, sex, and anatomical localization. We applied state-of-the-art mass spectrometry methods to quantify 4,870 proteins in eight different stromal cell populations from perigonadal and inguinal WAT of male and female mice and acquired transcript expression levels of 15,477 genes using RNA-seq. Our data unveil molecular signatures defining sex differences in preadipocyte differentiation and identify regulatory pathways that functionally distinguish adipose progenitor subpopulations. This multilayered omics analysis, freely accessible at http://preadprofiler.net/, provides unprecedented insights into adipose stromal cell heterogeneity and highlights the benefit of complementary proteomics to support findings from scRNA-seq studies.
Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.

Adipose precursor cells (APCs) exhibit regional variation in response to obesity, for unclear reasons. Here, we reveal that HIFα-induced PDGFRβ signaling within murine white adipose tissue (WAT) PDGFRβ+ cells drives inhibitory serine 112 (S112) phosphorylation of PPARγ, the master regulator of adipogenesis. Levels of PPARγ S112 phosphorylation in WAT PDGFRβ+ cells are depot dependent, with levels of PPARγ phosphorylation in PDGFRβ+ cells inversely correlating with their capacity for adipogenesis upon high-fat-diet feeding. HIFα suppression in PDGFRβ+ progenitors promotes subcutaneous and intra-abdominal adipogenesis, healthy WAT remodeling, and improved metabolic health in obesity. These metabolic benefits are mimicked by treatment of obese mice with the PDGFR antagonist Imatinib, which promotes adipocyte hyperplasia and glucose tolerance in a progenitor cell PPARγ-dependent manner. Our studies unveil a mechanism underlying depot-specific responses of APCs to high-fat feeding and highlight the potential for APCs to be targeted pharmacologically to improve metabolic health in obesity.
Copyright © 2020 Elsevier Inc. All rights reserved.