Table 1. Vitamin D and VDR influence the expression and function of cell junction proteins.
| VDR and proteins | In vitro | In vivo | Conclusion | References |
|---|---|---|---|---|
| ZO-1, E-cadherin, b-catenin |
|
Rat |
Rat treated with 1,25(OH)2D3 is able to abrogate podocytes injury, detected as desmin expression and loss of nephrin and ZO-1. |
24 |
| SW480 |
|
1,25(OH)2D3 induced the expression of adhesion proteins and promoted the translocation of nuclear beta-catenin and ZO-1 to the plasma membrane. |
22 |
|
| Occludin |
Corneal epithelium |
Mouse, Rabbit, Human |
Vitamin D enhances corneal epithelial barrier function. Cells showed increased TER, decreased IP and increased occludin levels when cultured with 25(OH)D3 and 1,25(OH)2D3. |
25 |
| SW480-ADH |
|
ROCK and MSK inhibition abrogates the induction of 1,25(OH)2D3 24-hydroxylase (CYP24), E-cadherin and vinculin and the repression of cyclin D1 by 1,25(OH)2D3. |
68 |
|
| Caco-2 |
VDR-/-, Mice, DSS-colitis model |
1,25(OH)2D3 enhanced TJs by increasing junction protein expression and TER and preserved the structural integrity of TJs in the presence of DSS. VDR knockdown reduced the junction proteins and TER. 1,25(OH)2D3 can also stimulate epithelial cell migration in vitro. |
27 |
|
| claudins |
|
|
1,25(OH)2D3 induces RANKL, SPP1 (osteopontin) and BGP (osteocalcin) to govern bone mineral remodeling; TRPV6, CaBP(9k) and claudin 2 to promote intestinal calcium absorption; and TRPV5, klotho and Npt2c to regulate renal calcium and phosphate reabsorption. |
69 |
| SW480-ADH |
|
1,25(OH)2D3 activates the JMJD3 gene promoter and increases JMJD3 RNA in human cancer cells. JMJD3 knockdown or expression of an inactive mutant JMJD3 fragment decreased the induction by 1,25(OH)2D3 of several target genes and of an epithelial adhesive phenotype. It downregulated the E-cadherin, Claudin-1 and Claudin-7. |
70 |
|
| |
calbindin-D9k-/- mutant mice |
1,25(OH)2D3 downregulates cadherin-17 and upregulates claudin2 and claudin12 in the intestine, suggesting that 1,25(OH)2D3 can route calcium through the paracellular path by regulating the epithelial cell junction proteins. |
33 |
|
| Caco-2 cells |
VDR-/- mice |
Claudin2 and/or claudin12-based TJs form paracellular Ca(2+) channels in intestinal epithelia claudins-2 and -12 are up-regulated by 1alpha,1,25(OH)2D3 through the vitamin D receptor. This study highlights a vitamin D-dependent mechanism in calcium homeostasis. |
26 |
|
| VDR and mucosal barrier | Caco-2 cells | DSS-colitis model | 1,25(OH)2D3 play a protective role in mucosal barrier homeostasis by maintaining the integrity of junction complexes and in healing capacity of the colon epithelium. | 42 |