Stem cells repurpose proliferation to contain a breach in their niche barrier
- Howard Hughes Medical Institute, The Rockefeller University, United States
- Howard Hughes Medical Institute, Janelia Research Campus, United States
Figures
Figure 1 with 3 supplements
Adherens junctions in the niche but not its stem cells are affected by E-cadherin depletion.
Images are from whole-mount immunofluorescence microscopy; DAPI (blue) marks chromatin. Antibodies are color-coded. (A) E-cadherin and P-cadherin expression (magnified views at right), summarized in …
Figure 1—figure supplement 1
Cdh3-Null HFs have proper architecture and undergo hair cycling normally.
Scale bars, 30 μm. (A) FACS strategy to purify WT 2nd telogen HF stem cells (HFSCs) for ELISA. Live cells were first gated with exclusion markers Sca1 (epidermis), CD45 (immune cells), CD140a …
Figure 1—figure supplement 2
E-cadherin is critical to maintain the integrity of the stem cell niche.
Scale bars, 30 μm. (A) Whole-mount immunofluorescence of adherens junction proteins P-cadherin (PCAD), p120-catenin (p120), β-catenin (β-CAT) and α-catenin (α-CAT). White boxed regions are presented …
Figure 1—figure supplement 3
Desmosomes are intact in E-cadherin-deficient bulge.
Scale bars = 30 μm unless indicated otherwise. (A) Electron microscopy of Cdh1-cKO and WT bulge. (B) Whole-mount immunofluorescence of desmosomal proteins. DSG3, desmoglein 3; DP1/2, desmoplakin …
Figure 2 with 1 supplement
Telogen stem cells proliferate when E-cadherin is depleted from the bulge.
Scale bars, 30 μm unless indicated otherwise. (A) (Left) Whole-mount immunofluorescence of HFs from mice pulsed with nucleotide analogue EdU for 24 hr prior to analysis. Proliferation dynamics are …
Figure 2—figure supplement 1
Dissecting the causes of telogen HF stem cell proliferation upon loss of E-cadherin.
Scale bars, 30 μm. (A) Progeny of the proliferative Cdh1-null HF stem cells maintain expression of the HF stem cell transcription factors TCF4 and LHX2. (B) Whole-mount immunofluorescence of Cdh1-nul…
Figure 3
When the stem cell niche is breached, bacteria infiltrate but are not required for the stem cell response.
(A) Gram staining of sagittal skin sections reveals near absence of bacteria in control HFs but presence of Gram-positive (deep violet; arrows) and Gram-negative (pink; arrowheads) bacteria in Cdh1 …
Figure 4 with 1 supplement
A barrier breach within the stem cell niche results in immune cell recruitment.
Scale bars, 30 μm. (A) Immunofluorescence (left) and flow cytometry quantifications (right; details below) of immune cells (CD45+) in Sox9CreER; Cdh1fl/fl cKO and control skins. (B) Sagittal skin …
Figure 4—figure supplement 1
A barrier breach within the stem cell niche results in immune cell recruitment.
Scale bars, 30 μm. (A) CD45+ immune cells were still recruited to Cdh1 cKO bulge despite the reduced bacterial load by antibiotics treatment. (B) ECAD loss of function specifically in HF stem cells …
Figure 5 with 1 supplement
HF stem cells up-regulate chemokines to recruit immune cells.
Stem cells or inner bulge niche cells were isolated from Sox9CreER cKO or matched littermate heterozygous control animals, that were either treated with low-dose Tamoxifen (Tamlow, to target only …
Figure 5—figure supplement 1
HF stem cells from Cdh1-null bulge display a gene expression profile distinct from WT HF stem cells that are naturally proliferating in anagen.
(A) FACS strategy to purify inner bulge cells from Sox9CreER-activated HFs based on YFP+; Sca1-;CD34-; b1-; CD200Lo. (B) FACS strategy to purify WT bulge HF stem cells in anagen sub-stages II and/or …
Figure 6 with 2 supplements
Stem cell proliferation and bulge hyperthickening arise from immune cell stimulation.
Scale bars, 30 μm unless indicated otherwise. (A) Dexamethasone suppressed infiltration of immune cells to the bulge when administered after ECAD loss of function but prior to the immune response,. …
Figure 6—figure supplement 1
Analysis of BMP signaling in HF stem cells and inner bulge niche cells with breached barrier function.
Scale bars, 30 μm. (A) Fgf18 and Bmp6 transcripts remain high in the Cdh1-null inner bulge niche cells. Krt6a encodes K6, a marker of the inner bulge. ns, non-significant. Left are fold-changes …
Figure 6—figure supplement 2
E-cadherin expression in the HF stem cell bulge niche is essential to maintain tissue barrier function.
(A) Relative expression of NOTCH target genes in various HF stem cell and inner bulge populations. *p < 0.05 (absolute fold-change ≥1.5) relative to control HFSCs. (B) Relative expression of HF …
Figure 7
Stem cell transcriptomic changes occur in direct response to a barrier breach.
(A, B) Comparisons of transcriptomes of HF stem cells (HFSCs) from Cdh1 cKO vs.Ctrl bulges ±Dex. Venn Diagram (A) showed 392 overlapping genes that were significantly up-regulated (p < 0.05, …
Figure 8
Model Summarizing How Stem Cells Respond to a Breach in Their Niche Barrier and Launch a Patch Process by Repurposing Stem Cell Proliferation.
During telogen, inner bulge niche cells express BMP6 and FGF18, which maintain stem cell quiescence. When the sole cadherin (ECAD) of the inner bulge is removed, the niche cannot make adherens …
Additional files
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Transparent reporting form
- https://doi.org/10.7554/eLife.41661.019
