Related Experiment Video
Updated: Jul 1, 2025
Isolation and Culture of Primary Mouse Keratinocytes from Neonatal and Adult Mouse Skin
Published on: July 14, 2017
Calcitriol modulates epidermal tight junction barrier function in human keratinocytes
Juan Valentin Trujillo-Paez1, Ge Peng2, Hai Le Thanh Nguyen2
1Atopy (Allergy) Research Center, Juntendo University Graduate School of Medicine, Tokyo, Japan.
Background:
The aberrant expression of tight junction (TJ) proteins play an important role in several diseases with impaired skin barriers, including atopic dermatitis, psoriasis, and chronic wounds. The evidence provided thus far suggests an important role of calcitriol in skin homeostasis. However, it is not known whether calcitriol improves the impaired skin barrier.
Objective:
To investigate the effect of calcitriol on TJ barrier function in human primary keratinocytes.
Methods:
Normal human primary keratinocytes were stimulated with calcitriol, and the expression of TJ-related proteins was measured by real-time PCR and Western blotting. Immunofluorescence was used to examine the intercellular distribution of TJ-related proteins. TJ barrier function was assessed by the transepithelial electrical resistance (TER) assay.
Results:
We demonstrated that calcitriol increased the expression levels of TJ-related proteins, including claudin-4, claudin-7, occludin, and zonula occludens (ZO)- 1. Calcitriol enhanced the distribution of TJ-related proteins at cellcell borders and induced the phosphorylation of pathways involved in the regulation of TJ barrier function, such as atypical protein kinase C (aPKC), Ras-related C3 botulinum toxin substrate 1 (Rac1), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt), as evidenced by the effects of specific inhibitors on the above pathways. Indeed, we confirmed that calcitriol enhanced TER in keratinocyte monolayers.
Conclusion:
These findings showed that calcitriol could modify the expression of keratinocyte TJ proteins, contributing to the maintenance of homeostatic barrier function.
Insights
Calcitriol enhances skin barrier function by increasing tight junction proteins in keratinocytes. This vitamin D metabolite supports skin homeostasis and may help treat barrier-impaired diseases.
Area of Science:
- Dermatology
- Cell Biology
- Molecular Biology
Background:
- Aberrant expression of tight junction (TJ) proteins is linked to skin barrier diseases like atopic dermatitis and psoriasis.
- Calcitriol is known to play a role in skin homeostasis, but its effect on skin barrier function is unclear.
Purpose of the Study:
- To investigate the impact of calcitriol on TJ barrier function in human primary keratinocytes.
Main Methods:
- Human primary keratinocytes were treated with calcitriol.
- TJ protein expression was analyzed using real-time PCR and Western blotting.
- Immunofluorescence and transepithelial electrical resistance (TER) assays assessed TJ distribution and barrier function.
Main Results:
- Calcitriol significantly increased the expression of TJ proteins (claudin-4, claudin-7, occludin, ZO-1).
- It improved TJ protein distribution at cell borders and activated key signaling pathways (aPKC, Rac1, PI3K, Akt).
- Calcitriol treatment enhanced TER in keratinocyte monolayers, indicating improved barrier function.
Conclusions:
- Calcitriol modulates the expression of keratinocyte TJ proteins.
- This action contributes to maintaining normal skin barrier function.
Related Concept Videos
01:29Tight Junctions
00:51Synthesis and Functions of Calcitonin
The exact mechanisms by which calcitonin operates in calcium homeostasis remain elusive, but its significance is evident in several vital...
01:23Role of Skin in Vitamin D Synthesis
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin...
01:12Renewal of Skin Epidermal Stem Cells
01:19Clinical Applications of Epidermal Stem Cells
01:24Cells of the Epidermis
The cells in all these layers except the stratum basale are called keratinocytes, a type of cell that manufactures and stores the protein keratin. The keratinocytes in the stratum corneum are dead and regularly slough away, being replaced by cells from...