keratinocyte
keratino.site · being built
| What it is | The main cell of the epidermis, the outer layer of the skin. |
|---|---|
| Comes from | Epidermal stem cell |
| About | Human keratinocytes form three kinds of clone: holoclones with the greatest capacity to multiply, paraclones that stop within 15 generations, and meroclones between them; older donors give fewer holoclones. |
| Source | Barrandon Y, Green H. Three clonal types of keratinocyte with different capacities for multiplication. Proc Natl Acad Sci U S A. 1987;84(8):2302-6. PMID: 2436229 |
| Status | being built; its twin, knowledge and helper come with keratino.site |
Where it lives
| The epidermis: basal cells on the basement membrane, spinous and granular cells above, the stratum corneum on top; the cellular epidermis is about 57 um thick on the forearm and the stratum corneum about 18 um | human · PMID 14690333 |
| About 450 to 490 nucleated epidermal cells under every 10,000 um2 of skin surface | human · PMID 641379 |
What it does
| Divides in the basal layer with a cell cycle of 311 h, then moves up and differentiates; the epidermis renews itself continuously | human · PMID 6725985 |
| Three clonal types: holoclones with the greatest capacity to multiply, meroclones, and paraclones that end in terminal differentiation | human · PMID 2436229 |
What goes wrong
| In psoriasis the normal-appearing epidermis already proliferates faster: a labeling index of 4.2 percent, about 50 percent above normal | human · PMID 6725985 |
| The stratum corneum thickens with pigmentation and thins with years of smoking | human · PMID 14690333 |
Pictures 4
(A) Immunostaining of pPG(S665) and DP in control skin 1 (pemphigus-negative). White dotted lines represent basement membrane of epidermis. DP costaining was used as desmosome marker. Scale bars: 10 µm; 20 µm. (human (control epidermis, pemphigus-negative); Figure 1, panel A, control arm (pemphigus-negative human skin; cols 22-567 of figure).)
Vielmuth, Sigmund, Egu et al 2026, JCI Insight · CC BY 4.0
Representative immunofluorescence images of YBX1 (left panel, green), pYBX1 (right panel, green), and DAPI (blue) in young (upper panel) and old (lower panel) human skin samples. Scale bar, 50 um. (human; Figure 1, panel A (IF micrograph section; quantification panels B-E excluded; rows 0-808 of full figure).)
Japranata, Liu, Boncimino et al 2026, Cells · CC BY 4.0
(A) TEM of the junction between the corneocyte and granular keratinocyte layers. The interphase is bordered by corneodesmosomes (CDs). Each tonofibril (TF) forms a complex lattice of keratin bundles connecting different keratinocytes (Ker) through desmosomes (D). These bundles form a mantle around the DR perimeter. (B) Higher magnification of a TD between a corneocyte and a keratinocyte. TFs extend from the desmosome into the cytoplasm. (C) TD and serially connected desmosomes between keratinocytes (Hitachi TEM system). Difference in structure between the inter-keratinocyte D and the TD is noticeable; the TD lacking a cytoplasmic plaque on the corneocyte side (abdominal skin). (Cuban crocodile (abdominal skin epidermis, granular and corneocyte keratinocyte layers); FIGURE 3, full figure (panels A-C, all TEM).)
Melkersson, Hodik, Staxang et al 2026, Frontiers in Cell and Developmental Biology · CC BY 4.0
Keratin expression in first outgrowing and adherent keratinocytes. Brightfield image (A) of the bubble-like keratinocytes in the area of the ORS, with an IF image (B) of the same region stained for K14 (green). Brightfield image (C) showing the first outgrowing keratinocytes in the ORS area, with corresponding IF images for K5 (D) and K15 (E). Cells positive only for K5 are marked with orange arrows, and double- positive K5 and K15 cells are marked with white arrows Brightfield image (F) of a HF at a later culture stage, showing thickening of the ORS in distal and proximal regions, with proliferating keratinocytes visible near the follicle. Immunofluorescence staining for K5 and K15 in the same HF region (G). In the magnified section (H), magenta arrows mark K5/K15 double-positive keratinocytes, red arrows indicate cells positive for K15 only. Scale bar: 500 um (F, G), 250 um (A-E), 100 um (H). (human (plucked hair follicle, outgrowing and adherent keratinocytes); Figure 7.)
Klingenstein, Boenke, Wustner et al 2025, PeerJ · CC BY 4.0
Papers 4
- Japranata VV, Liu M, Boncimino F, Di Cicco E, Palumbo S, Todorova K, et al. Age-Associated YBX1 Phosphorylation Regulates the Keratinocyte Senescence-Associated Secretory Phenotype Through Translational Control. Cells. 2026;15:1586. PMID: 42738881.
- Melkersson KG, Hodik M, Staxäng K, Hakizimana P, Li H, Rask-Andersen H. A transitional desmosome/tonofibril network may relay mechanical strain to epidermal nerve terminals with high fidelity and sensitivity in the Cuban crocodile (Crocodylus rhombifer): an ultrastructural study. Front Cell Dev Biol. 2026;14:1739378. PMID: 41727316.
- Vielmuth F, Sigmund AM, Egu DT, Hiermaier M, Steinert LS, Moztarzadeh S, et al. Plakoglobin phosphorylation at serine 665 is capable of stabilizing cadherin-mediated adhesion in keratinocytes. JCI Insight. 2026;11:e190359. PMID: 41657310.
- Klingenstein S, Boenke J, Wüstner LS, Liebau S, Klingenstein M. Detailed morphological characterization and improvement of keratinocyte outgrowth from plucked human hair follicle. PeerJ. 2025;13:e20214. PMID: 41189574.