1. Computational and Systems Biology
  2. Developmental Biology and Stem Cells
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A multi-scale model for hair follicles reveals heterogeneous domains driving rapid spatiotemporal hair growth patterning

  1. Qixuan Wang
  2. Ji Won Oh
  3. Hye-Lim Lee
  4. Anukriti Dhar
  5. Tao Peng
  6. Raul Ramos
  7. Christian Fernando Guerrero-Juarez
  8. Xiaojie Wang
  9. Ran Zhao
  10. Xiaoling Cao
  11. Jonathan Le
  12. Melisa A Fuentes
  13. Shelby C Jocoy
  14. Antoni R Rossi
  15. Brian Vu
  16. Kim Pham
  17. Xiaoyang Wang
  18. Nanda Maya Mali
  19. Jung Min Park
  20. June-Hyug Choi
  21. Hyunsu Lee
  22. Julien M D Legrand
  23. Eve Kandyba
  24. Jung Chul Kim
  25. Moonkyu Kim
  26. John Foley
  27. Zhengquan Yu
  28. Krzysztof Kobielak
  29. Bogi Andersen
  30. Kiarash Khosrotehrani
  31. Qing Nie  Is a corresponding author
  32. Maksim V Plikus  Is a corresponding author
  1. University of California, United States
  2. Kyungpook National University, Korea
  3. Biomedical Research Institute, Kyungpook National University Hospital
  4. Kyungpook National University Hospital
  5. College of Biological Sciences, China Agricultural University, China
  6. The First Affiliated Hospital, Sun Yat-sen University, China
  7. Keimyung University, Korea
  8. The University of Queensland, Australia
  9. University of Southern California, United States
  10. Medical Sciences Program, Indiana University School of Medicine, United States
  11. CeNT, University of Warsaw, Poland
Research Article
Cite as: eLife 2017;6:e22772 doi: 10.7554/eLife.22772
7 figures, 2 data sets and 3 additional files


Model recapitulates hair cycling and its associated activator and inhibitor signaling dynamics.

(A) Schematic depiction of HF growth dynamics during telogen and anagen. Telogen and anagen HFs are shown on the left and in the center, respectively. In both hair cycle phases, Region I (purple) represents bulge and Region II (orange) represents DP with HG during telogen phase, and DP with matrix during anagen phase. On the right, schematic drawing of diffusive activator (Act. L. in green) and inhibitor (Inh. L. in red) interactions with their corresponding receptors (Act. R and Inh. R, not depicted) that form ligand-bond-receptors (Act. LR and Inh. LR) and their coupling with physical growth of the HF (blue) is shown. (B) Typical noise-free dynamics of the activator (green) and inhibitor (red) and cyclic HF growth (blue) are shown. X-axis is time in simulated days. Y-axis for activator and inhibitor shows simulated signaling levels, and for HF growth – simulated length of the HF. Grey area demarcates one modeled hair growth cycle. (C) The duration of ~anagen and ~telogen phases as the function of inhibitor signaling strengths. X-axis shows modeled inhibitor levels with ‘0’ being an arbitrary baseline levels. Y-axis shows time in simulated days. Upon stronger inhibitory signaling (high Inh. L level) ~anagen shortens (yellow) and ~telogen lengthens (purple). The entire cycle (blue) becomes longer either with stronger or weaker inhibitory signaling. When inhibitory signaling becomes either very strong or very weak, the excitability of the system breaks down and HFs equilibrate in one state (grey regions). Also see Appendix 2—tables 1, 2 and 4. (D–E’’) A total of 236 putative activator genes (green) and 122 putative inhibitor genes (red) available from a whole skin microarray dataset were identified to recapitulate temporal dynamics of the simulated activator (D) and inhibitor (E), respectively. Multiple WNT pathway members are in the putative activator gene set (D’, D’’), while BMP pathway members are among the putative inhibitor genes (E’, E’’). See gene list in Dataset 1. For all genes log-transformed, zero-mean expression profile values were calculated using colorimetric ratio-scale algorithm as reported in (Lin et al., 2009).

Spatiotemporal patterning of early hair cycles.

(A–D) Analysis of the whole mount dorsal skin samples from P0 (n = 3) (A) and P1 WT mice (n = 3) (A’) reveals subtle head-to-tail and lateral-to-medial hair cycle asynchronies. Asynchronies were inferred from examining the size of pigmented HFs. Larger HFs result from earlier anagen onset. (B) Heatmaps of skin samples from A and A’ built based on black pixel density (reflecting pigmented anagen HFs). (C) Quantification of anagen HFs at different phases confirms head-to-tail pattern asynchrony. Morphological definition of anagen phases used for this analysis is provided at the bottom on the panel. (D) Analysis of the whole mount dorsal skin samples from P0 220bpMsx2-hsplacZ mice, where lacZ reporter activates in anagen HFs starting from phase IIIb, confirms head-to-tail asynchrony. (E, F) Modeling rapid hair growth pattern evolution in the context of two heterogeneous domains. (E) Schematic depiction of the modeling conditions with central Dorsal domain flanked by two lateral Ventral sub-domains with coupling between Dorsal and Ventral HFs. (F) Compared to Dorsal domain HFs, Ventral domain HFs were assigned with higher levels of total available activator and inhibitor receptors, allowing shorter ~anagen and ~telogen duration. Furthermore, hair cycle asynchrony was introduced into Dorsal domain to model the initial head-to-tail asynchrony. In simulations, interactions between HFs across domain boundaries result in bilateral symmetry during the second cycle (simulated time t68-78.5). Also, initial asynchrony breaks down in the cycle 3 (t130), and partial bilateral symmetry maintains into the late cycles (see Appendix 2—video 4). Scale bars: A, A’, D – 5 mm. Images on A, A’ and D are composites.

Dorsal-ventral HF interactions produce bilateral symmetry.

(A) Time-lapse bioluminescence in dorsal and ventral skin of the representative Flash mouse between days P5-P48. Bioluminescent signal is color-coded according to the colorimetric scale on the right. (B) Combined temporal dynamics (from 6 Flash mice) of the bioluminescent signal-based anagen measurements over four hair cycles (days P5-P119). Dorsal skin dynamics are in brown and ventral skin dynamics are in blue. Prominent temporal advancement of ventral over dorsal anagen initiation can be seen during second, third and fourth cycles (light blue areas). This advancement is accompanied by dominant ventral-to-dorsal anagen wave spreading. (C, C’) Mapping of Flash-based anagen reveals ventral-to-dorsal hair growth wave propagation and bilateral pattern symmetry. New anagen areas for each time point are color-coded. Second anagen initiation is shown on panel C, and third anagen initiation on panel C’. Also see Appendix 1—figure 6. (D–G) Hair growth distribution patterns on P17 (D), P21 (E), P39 (F) and P55 (G). Three mice were analyzed at each time point. Inverted whole mount skin samples from representative mice are shown. Schematic pattern maps are provided with color-coded anagen (green), catagen (yellow) and telogen (red) regions. Also see Appendix 1—figures 712. (H, I) HF cycling dynamics in chin skin grafts remain faster compared to dorsal skin grafts. After transplantation, first anagen initiated similarly in both chin and dorsal skin grafts, however, second anagen initiated significantly faster in chin grafts. Representative chin and dorsal skin grafts are shown on (H). Combined temporal dynamics of skin grafts in anagen and telogen are shown on (I). Dorsal graft dynamics are in brown and chin graft dynamics are in blue. Temporal advancement of chin over dorsal second anagen initiation is highlighted with light blue color. Also see Appendix 1—figure 13.

BMP and WNT signaling differences underlie regionally specific telogen phase duration.

(A–B’’) PCA analysis reveals largely non-overlapping transcriptomic trajectories across six hair cycle stages in chin (B), ventral (B’) and dorsal domains (B’’). Combined, deconstructed PCA plots are shown with all data points marked as grey dots and domain-specific data points outlined and color-coded. Color-coding is based on the hair cycle timeline from Appendix 1—figure 14A; transcriptomic trajectories are drawn with dark lines. (C) Deconstructed PCA plot for refractory (early second) telogen is shown with domain-specific data points highlighted and color-coded based on the schematic drawing on A. (D–F) Analysis of refractory telogen data identified 1407 differentially expressed genes across the three domains (D), with each domain showing enrichment for distinct gene ontologies (E). Multiple putative hair cycle activator and inhibitor genes show domain-specific differential expression (F). Putative activators are in green and putative inhibitors are in red. For each gene, relative fold changes for ventral over chin and dorsal over chin expression levels are indicated. Genes that show cyclic expression patterns are highlighted with blue. See additional expression data analysis on Appendix 1—figures 1419 and in Dataset 2. Asterisk marks non-canonical WNT ligand. (G, H) Analysis of Axin2-lacZ skin during second telogen reveals faster activation of WNT signaling in chin and ventral HFs over dorsal HFs. At P36 majority of HFs in chin and ventral skin have WNT-active DPs. In dorsal skin, the number of HFs with WNT-active DPs is low at P36, but increases by P42. (I) Analysis of P42 BRE-gal skin shows that many more dorsal HFs have BMP-active bulges as compared to chin and ventral HFs. Also see Appendix 1—figure 22. (J) Overexpression of Wnt7a results in disruption of ventral-to-dorsal hair growth wave dominance and spontaneous anagen appears in the dorsal domain at P60. (K) Overexpression of Bmp4 results in stalled ventral-to-dorsal hair growth wave spreading and patchy, asymmetric hair growth at P57. Scale bars: G-I – 200 um, J-K – 500 um.

Ear skin shows hyper-refractory properties with telogen arrested HFs.

(A–C) Morphogenesis and physiological cycling of ear HFs. (A) Analysis of ear tissue histology shows that developing HFs first appear on day P4, and progress toward mature anagen by P7. They enter catagen around P15 and first telogen by P17 (based on three mice for each time point). (B, C) Whole mount ear skin analyses show that ear HFs fail to enter second coordinated anagen and, instead, remain in an extended telogen. Seldom, isolated anagen HFs can be found (see P95 sample on B). Data are based on three mice for each time point. (D) HFs along medial side of the ear re-enter anagen after plucking (also see Appendix 1—figure 25). Experiment is based on five mice for each time point analyzed. Representative ear skin image and accompanying heatmap is shown. Heatmap criteria are shown at the bottom. (E) Unlike in dorsal skin (see Appendix 1—figure 27A), ear HFs poorly respond to topical SAG treatment. Anagen induction is limited to the medial edge of the ear. (F) Unlike in dorsal skin (see Appendix 1—figure 27B), ear HFs fail to re-enter anagen in response to topical cyclosporin A treatment. Experiments on E and F are based on three mice for each time point analyzed. Representative ear skin images and accompanying heatmaps are shown. Scale bars: A – 100 um.

WNT and BMP signalings modulate ear HF hyper-refractory state.

(A–C) Transcriptomes of first telogen ear skin, first telogen dorsal skin and ear cartilage/muscle complex are distinct, as revealed by PCA analysis (A). They contain 1334 differentially expressed genes (B), spanning distinct gene ontologies (C). (D, E) These tissues show differential expression of multiple ligands and antagonists for several major signaling pathways, prominently WNT and BMP. Putative activators are in green and putative inhibitors are in red. For each gene, relative fold changes for ear skin over dorsal skin and cartilage/muscle complex over dorsal skin expression levels are indicated. Select genes are highlighted. (F, F’) BRE-gal reporter reveals high BMP activity in telogen ear HFs and in the adjacent cartilage/muscle complex (n = 8). (G, G’) Axin2-lacZ reporter reveals near absence of WNT activity in ear HFs and cartilage/muscle complex. Seldom, sites of dermal reporter activity can be found (n = 8). (H–H’’) Compared to wild type mice (n = 4) (H), ears of Krt14-Noggin (n = 4) (H’) and Krt14-Wnt7a mice (n = 4) (H’’) show prominent increases in spontaneous anagen frequency. Cumulative heatmaps from four individual ear samples are shown. Also see Appendix 1—figure 28. Scale bars: F, G – 500 um; F’, G’ – 100 um.

Hair growth waves distort at the non-propagating boundaries.

(A, B) Introduction of a non-propagating barrier (A) or an aperture (B) into the model produces simulations with distorted anagen spreading wave front (green). (C, E) Distortions in the geometry of hair growth waves are commonly seen in the head region at the boundaries with the hyper-refractory ears and eyelids, the physical breaks in the skin. Seldom, similar distorted patterns can be seen around limb skin (D). Hair growth patterns on C-E are accompanied by color-coded schematic drawings. Colors are defined at the bottom. Hair growth distortion patterns shown were documented in ten mice each.


Data availability

The following data sets were generated
  1. 1
The following previously published data sets were used
  1. 1
    Expression profiling of mouse dorsal skin during hair follicle cycling
    1. Lin KK
    2. Kumar V
    3. Geyfman M
    4. Chudova D
    5. Ihler AT
    6. Smyth P
    7. Paus R
    8. Takahashi JS
    9. Andersen B
    Publicly available at the NCBI Gene Expression Omnibus (accession no: GSE11186).

Additional files

Supplementary file 1

Dataset 1: Putative activator genes (tabs #1, #2) and putative inhibitor genes (tabs #3, #4) available from a whole skin microarray dataset.

Supplementary file 2

Dataset 2: Putative activator and inhibitor genes displaying domain-specific expression patterns at all hair cycle time points on whole skin RNA-seq profiling.

Genes are grouped into individual tabs based on (i) their activator or inhibitor expression profile and (ii) their specificity to one or several skin domains.

Supplementary file 3

Dataset 3: Differentially expressed genes specific to refractory telogen dorsal skin, telogen ear skin and cartilage/muscle complex.


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