Transforming growth factor-beta-activated kinase 1 is essential for differentiation and the prevention of apoptosis in epidermis

Transforming growth factor-beta-activated kinase 1 (TAK1) is a member of the mitogen-activated protein (MAP) kinase family and is an upstream signaling molecule of nuclear factor-kappaB (NF-kappaB). Given that NF-kappaB regulates keratinocyte differentiation and apoptosis, TAK1 may be essential for epidermal functions. To test this, we generated keratinocyte-specific TAK1-deficient mice from Map3k7(flox/flox) mice and K5-Cre mice. The keratinocyte-specific TAK1-deficient mice were macroscopically indistinguishable from their littermates until postnatal day 2 or 3, when the skin started to roughen and wrinkle. This phenotype progressed, and the mice died by postnatal day 7. Histological analysis showed thickening of the epidermis with foci of keratinocyte apoptosis and intra-epidermal micro-abscesses. Immunohistochemical analysis showed that the suprabasal keratinocytes of the TAK1-deficient epidermis expressed keratin 5 and keratin 14, which are normally confined to the basal layer. The expression of keratin 1, keratin 10, and loricrin, which are markers for the suprabasal and late phase differentiation of the epidermis, was absent from the TAK1-deficient epidermis. Furthermore, the TAK1-deficient epidermis expressed keratin 16 and had an increased number of Ki67-positive cells. These data indicate that TAK1 deficiency in keratinocytes results in abnormal differentiation, increased proliferation, and apoptosis in the epidermis. However, the keratinocytes from the TAK1-deficient epidermis induced keratin 1 in suspension culture, indicating that the TAK1-deficient keratinocytes retain the ability to differentiate. Moreover, the removal of TAK1 from cultured keratinocytes of Map3k7(flox/flox) mice resulted in apoptosis, indicating that TAK1 is essential for preventing apoptosis. In conclusion, TAK1 is essential in the regulation of keratinocyte growth, differentiation, and apoptosis.

Bone morphogenetic protein-2 modulates Wnt and frizzled expression and enhances the canonical pathway of Wnt signaling in normal keratinocytes

BACKGROUND

Bone morphogenetic protein-2 (BMP-2) and Wnt are involved in the normal development and tumorigenesis of several organs, and in the development of skin and skin appendages as a morphogen. However, the crosstalk between BMP-2 and the Wnt/beta-catenin signaling pathway is not clear.

OBJECTIVE

We examined BMP-2-dependent expression of Wnt and its receptor frizzled in normal human keratinocytes.

METHODS

The mRNA expression of the Wnt and frizzled families was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) or ribonuclease protection assay. beta-Catenin expression was measured using RT-PCR and Western blotting. T-cell factor/lymphoid enhancing factor activity was analyzed using the luciferase reporter assay.

RESULTS

We detected the expression of Wnt-2b/13, -4, -5a, -5b, -7a, -7b, and -10a, frizzled-1, -4, -5, -6, -8, -9, and -10, MFRP, and SFRP-1/SARP-2 in keratinocytes. BMP-2 increased Wnt-2b/13, -5b, and -7b, and frizzled-6, -8, and -10. Conversely, BMP-2 suppressed Wnt-10a and SFRP-1/SARP-2. Although Wnt-4 expression was not affected by BMP-2 in confluent conditioned keratinocytes, BMP-2 suppressed cell density-dependent Wnt-4 induction. The transcriptional activity of TCF/LEF, which is a target of the canonical Wnt pathway, was upregulated by BMP-2 in both time- and dose-dependent manners. However, BMP-2-dependent differentiation of keratinocytes suppressed TCF/LEF transcriptional activity.

CONCLUSION

These results suggest that BMP-2 modulates the expression of molecules involved in Wnt signaling, and activates the canonical Wnt pathway in normal human keratinocytes. Moreover, Wnt signaling may be influenced by the fate of keratinocytes, such as proliferation, migration, and differentiation.

SOCS1-negative feedback of STAT1 activation is a key pathway in the dsRNA-induced innate immune response of human keratinocytes

Toll-like receptor (TLR)3 is a receptor for virus-associated double-stranded RNA, and triggers antiviral immune responses during viral infection. Epidermal keratinocytes express TLR3 and provide an innate immune defense against viral infection. Since the intracellular regulatory mechanism is unknown, we hypothesized that the signal transducers and activators of transcription (STAT)-suppressors of cytokine signaling (SOCS) system regulates the innate immune response of keratinocytes. Treatment with polyinosinic-polycytidylic acid (poly(I:C)) resulted in the rapid translocation of IFN regulatory factor (IRF)-3 into the nucleus, followed by phosphorylation of STAT1 and STAT3. The activation of STATs by poly(I:C) probably occurs in an indirect fashion, through poly(I:C)-induced IFN. We infected cells with the dominant-negative forms of STAT1 (STAT1F), STAT3 (STAT3F), and SOCS1 using adenovirus vectors. Infection with STAT1F suppressed the induction of macrophage inflammatory protein (MIP)-1alpha by poly(I:C), whereas STAT3F had a minimal effect, which indicates that STAT1 mediates MIP-1alpha induction. SOCS1, which is a negative feedback regulator of STAT1 signaling, was induced by treatment with poly(I:C). SOCS1 infection inhibited the phosphorylation of STAT1 and significantly reduced poly(I:C)-induced MIP-1alpha production. Furthermore, STAT1-SOCS1 regulated poly(I:C)-induced TLR3 and IRF-7 expression. However, SOCS1 did not affect NF-kappaB signaling. Thus, the STAT1-SOCS1 pathway regulates the innate immune response via TLR3 signaling in epidermal keratinocytes.

A novel function of angiotensin II in skin wound healing. Induction of fibroblast and keratinocyte migration by angiotensin II via heparin-binding epidermal growth factor (EGF)-like growth factor-mediated EGF receptor transactivation

The role of angiotensin II (Ang II) in the control of systemic blood pressure and volume homeostasis is well known and has been extensively studied. Recently, Ang II was suggested to also have a function in skin wound healing. In the present study, the in vivo function of Ang II in skin wound healing was investigated using Ang II type 1 receptor (AT1R) knock-out mice. Wound healing in these mice was found to be markedly delayed. Keratinocytes and fibroblasts play important roles in wound healing, and thus the effect of Ang II on the migration of these cells was examined. Ang II stimulated keratinocyte and fibroblast migration in a dose-dependent manner. It has been reported that G protein-coupled receptor (GPCR) activation induces epidermal growth factor (EGF) receptor (EGFR) transactivation through the shedding of heparin-binding EGF-like growth factor (HB-EGF). As AT1R is a GPCR, it was hypothesized that Ang II-induced keratinocyte and fibroblast migration is mediated by EGFR transactivation. Ang II induced EGFR phosphorylation, which was inhibited by an AT1R antagonist, HB-EGF neutralizing antibody, and an HB-EGF antagonist in both keratinocytes and in fibroblasts. Moreover, Ang II-induced migration of keratinocytes and fibroblasts was also prevented by these inhibitors. Taken together, these findings clearly demonstrate, for the first time, that Ang II plays an important role in skin wound healing and that it functions by accelerating keratinocyte and fibroblast migration in a process mediated by HB-EGF shedding.

Microbubble-enhanced ultrasound for gene transfer into living skin equivalents

BACKGROUND

Gene transfer to skin is an attractive therapeutic approach because of the accessibility of the skin and the high rate of cure for many cutaneous diseases. However, safety concerns over viral vectors and the low efficiency of most non-viral gene transfer techniques have encumbered their clinical application for gene transfer. By contrast, efficient gene transfers into various cell types using microbubble-enhanced ultrasound has been reported.

OBJECTIVES

The purpose of this study was to investigate whether ultrasound with microbubble enhancement allowed effective transfer of foreign genes into living skin equivalents (LSEs).

METHODS

Microbubbles and plasmid DNA encoding green fluorescent protein (GFP) were added to the dermal-epidermal junctions of LSEs, which were then exposed to ultrasound. The LSEs were harvested at different time points to investigate transgene expression using confocal laser microscopy. Transfected LSEs were also transplanted onto nude mice, and the in vivo transgene expression was observed.

RESULTS

From days 2 to 7 after transfection, most GFP-positive cells continued to migrate upward from the basal layer, while other GFP-positive cells lagged behind or remained in the basal layer on days 5 and 7. Transfection resulted in 20-30% GFP-positive cells. Multiple transfections further increased the percentage of transfected cells and resulted in multi-layer transgene expression. Grafts from the transfected LSEs survived on nude mice and continued to express GFP up to 2 weeks post-transplantation.

CONCLUSION

Gene transfer into LSE using ultrasound with microbubble enhancement is an effective alternative to viral and non-viral methods.

dsRNA-mediated innate immunity of epidermal keratinocytes

MIP-1alpha, a CC chemokine, recruits monocytes, natural killer cells, lymphocytes, and neutrophils, and plays a critical role in viral infection. Since, the lesional epidermis of herpes zoster expressed MIP-1alpha, we hypothesized that keratinocytes produce MIP-1alpha in response to virus-associated dsRNA via TLR3. To investigate this, we examined cultured human keratinocytes for MIP-1alpha production induced by poly(I:C), a TLR3 ligand. Poly(I:C) treatment induced MIP-1alpha production, interestingly, poly(I:C)-induced IFN-alpha and -beta production preceded MIP-1alpha production. A neutralizing antibody for IFN-beta significantly inhibited the poly(I:C)-induced MIP-1alpha production indicating that MIP-1alpha production is via IFN-beta. IFN-alpha priming enhanced TLR3 expression and MIP-1alpha production in poly(I:C)-treated keratinocytes. This suggests that IFN-alpha enhanced the TLR3 expression and reinforced the response of keratinocytes to poly(I:C), which resulted in an increase in MIP-1alpha production. In conclusion, normal human keratinocytes produce MIP-1alpha in response to dsRNA via TLR3, and this production is regulated by IFN-alpha/beta.

Induction of Keratinocyte Migration via Transactivation of the Epidermal Growth Factor Receptor by the Antimicrobial Peptide LL-37

The closure of skin wounds is essential for resistance against microbial pathogens, and keratinocyte migration is an important step in skin wound healing. Cathelicidin hCAP18/LL-37 is an innate antimicrobial peptide that is expressed in the skin and acts to eliminate microbial pathogens. Because hCAP18/LL-37 is up-regulated at skin wound sites, we hypothesized that LL-37 induces keratinocyte migration. In this study, we found that 1 microg/ml LL-37 induced the maximum level of keratinocyte migration in the Boyden chamber assay. In addition, LL-37 phosphorylated the epidermal growth factor receptor (EGFR) after 10 min, which suggests that LL-37-induced keratinocyte migration occurs via EGFR transactivation. To test this assumption, we used inhibitors that block the sequential steps of EGFR transactivation, such as OSU8-1, CRM197, anti-EGFR no. 225 Ab, and AG1478. All of these inhibitors completely blocked LL-37-induced keratinocyte migration, which indicates that migration occurs via HB-EGF-mediated EGFR transactivation. Furthermore, CRM197, anti-EGFR no. 225, and AG1478 blocked the LL-37-induced phosphorylation of STAT3, and transfection with a dominant-negative mutant of STAT3 abolished LL-37-induced keratinocyte migration, indicating the involvement of the STAT3 pathway downstream of EGFR transactivation. Finally, we tested whether the suppressor of cytokine signaling (SOCS)/cytokine-inducible Src homology 2-containing protein (CIS) family of negative regulators of STAT3 regulates LL-37-induced keratinocyte migration. Transfection with SOCS1/Jak2 binding protein or SOCS3/CIS3 almost completely abolished LL-37-induced keratinocyte migration. In conclusion, LL-37 induces keratinocyte migration via heparin-binding-EGF-mediated transactivation of EGFR, and SOCS1/Jak 2 binding and SOCS3/CIS3 negatively regulate this migration. The results of this study suggest that LL-37 closes skin wounds by the induction of keratinocyte migration.

In vitro keratinocyte dissociation assay for evaluation of the pathogenicity of anti-desmoglein 3 IgG autoantibodies in pemphigus vulgaris

Patients with pemphigus vulgaris (PV) have circulating anti-desmoglein (Dsg) 3 immunoglobulin G (IgG) autoantibodies that induce blister formation. We developed an in vitro quantitative assay to evaluate the pathogenic strength of anti-Dsg3 IgG autoantibodies in blister formation. To obtain intercellular adhesion mediated dominantly by Dsg3, we used primary cultured normal human keratinocytes expressing low level of Dsg2 in the presence of exfoliative toxin A that specifically digests Dsg1. After incubation with various antibodies, monolayers released by dispase were subjected to mechanical stress by pipetting, and the number of cell fragments were counted. When anti-Dsg3 monoclonal antibodies (mAb) obtained from pemphigus model mice were tested, pathogenic AK23 mAb yielded significantly higher number of cell fragments than AK7 or AK20 non-pathogenic mAb. Dissociation scores, defined with AK23 mAb as the positive control, were significantly higher with active stage PV sera (n=10, 77.4+/-21.4) than controls (n=11, 16.0+/-9.6; p=0.003). When pair sera obtained from 6 PV patients in active stage and in remission were compared, the dissociation scores reflected well the disease activity as those in active stage were four to 17 times higher than those in remission. When sera from different patients showing similar ELISA scores but different clinical severity were tested (n=6), the dissociation scores with sera from severe disease activity were significantly higher than those with sera in remission. These findings indicate that this dissociation assay will provide a simple and objective biological method to measure the pathogenic strength of pemphigus autoantibodies.

New mechanisms of skin innate immunity: ASK1-mediated keratinocyte differentiation regulates the expression of β-defensins, LL37, and TLR2

Epidermal keratinocytes differentiate and form a multilayered epidermis, which is the primary barrier between the body and the outer environment. As the epidermis is constantly exposed to a variety of microbial pathogens, its function of resisting microbial pathogens is vital. This characteristic feature is formed during differentiation. Immunohistochemical analysis revealed that the upper epidermis of normal human skin expresses beta-defensins 1-3 and LL37. We hypothesized that epidermal keratinocytes develop an innate immune barrier based on human beta-defensins (hBD) and LL37 during differentiation. To prove this, we introduced an active form of the apoptosis signal-regulating kinase-1 (ASK1), an intracellular regulator of keratinocyte differentiation, into cultured normal human keratinocytes. Transfection of this active form, ASK1-DeltaN, significantly enhanced the expression of hBD1-3 and LL37. In addition, a p38 inhibitor abolished this induction, indicating that the ASK1-p38 cascade regulates the expression of hBD1-3 and LL37. Furthermore, the ASK1-p38 pathway also regulated the expression of Toll-like receptor (TLR)2 in keratinocytes. Contact between S. aureus and keratinocytes resulted in the phosphorylation of p38 and induced the expression of hBD2 and hBD3. Moreover, the p38 inhibitor reduced this induction. In conclusion, the ASK1-p38 cascade regulates the innate immunity of the skin by forming an immune barrier consisting of hBD, LL37, and TLR2 during epidermal differentiation.

Heparin-binding EGF-like growth factor accelerates keratinocyte migration and skin wound healing

Members of the epidermal growth factor (EGF) family are the most important growth factors involved in epithelialization during cutaneous wound healing. Heparin-binding EGF-like growth factor (HB-EGF), a member of the EGF family, is thought to play an important role in skin wound healing. To investigate the in vivo function of HB-EGF in skin wound healing, we generated keratinocyte-specific HB-EGF-deficient mice using Cre/loxP technology in combination with the keratin 5 promoter. Studies of wound healing revealed that wound closure was markedly impaired in keratinocyte-specific HB-EGF-deficient mice. HB-EGF mRNA was upregulated at the migrating epidermal edge, although cell growth was not altered. Of the members of the EGF family, HB-EGF mRNA expression was induced the most rapidly and dramatically as a result of scraping in vitro. Combined, these findings clearly demonstrate, for the first time, that HB-EGF is the predominant growth factor involved in epithelialization in skin wound healing in vivo and that it functions by accelerating keratinocyte migration, rather than proliferation.

SOCS3/CIS3 negative regulation of STAT3 in HGF-induced keratinocyte migration

Hepatocyte growth factor (HGF) is a potent mitogen for mature hepatocytes. Because HGF has strong effects on the motility of keratinocytes and is produced by fibroblasts, HGF is thought to regulate keratinocyte migration during wound healing. However, the intracellular signaling mechanism of HGF-induced keratinocyte migration is poorly understood. In this report, we clarify the roles of STAT3 and SOCS/CIS family in HGF-induced keratinocyte migration. HGF activated STAT3 and strongly induced keratinocyte migration. Transfection with the dominant-negative mutant of STAT3 almost completely abolished HGF-induced keratinocyte migration and STAT3 phosphorylation. Next, we studied the mechanisms that regulate STAT3 phosphorylation. HGF enhanced the expression of SOCS3/CIS3 by sixfold within 1h, but had minimum effect on SOCS1/JAB expression. Transfection with SOCS3/CIS3 almost completely abolished HGF-induced STAT3 phosphorylation and keratinocyte migration, indicating that SOCS3/CIS3 acts as a negative regulator of HGF-induced keratinocyte migration. In conclusion, SOCS3/CIS3 regulates HGF-induced keratinocyte migration by inhibiting STAT3 phosphorylation.

All-trans-retinoic acid induces interleukin-8 via the nuclear factor-kappaB and p38 mitogen-activated protein kinase pathways in normal human keratinocytes

Retinoic acid derivatives have been used successfully for the treatment of various dermatoses, such as psoriasis; however, topical application of these compounds often elicits skin irritation. We hypothesized that this irritation was as a result of the local production of interleukin-8 (IL-8). To test this hypothesis, we investigated whether all-trans-retinoic acid (ATRA) induced IL-8 production in normal human keratinocytes. Stimulation with 10(-7) M ATRA enhanced IL-8 mRNA expression and induced IL-8 production. We also studied the intracellular signaling mechanisms of ATRA-induced IL-8 production in keratinocytes. ATRA increased the expression of RelA (p65), RelB, nuclear factor (NF)-kappaB2 (p52), and NF-kappaB1 (p50), and elevated the DNA-binding activity of p65 and phosphorylation of inhibitor kappaB (IkappaB) alpha. Introduction of a dominant-negative mutant of IkappaBalpha completely abolished ATRA-induced IL-8 production, which indicates that this process is NF-kappaB-dependent. We also studied the role of the p38 mitogen-activated protein kinase (MAPK) pathway in this phenomenon. ATRA phosphorylated the p38 MAPK, and SB202180 inhibited ATRA-induced IL-8 production, which indicates that the p38 MAPK is also involved in ATRA-induced IL-8 production. In summary, ATRA induces IL-8 production in both NF-kappaB- and p38 MAPK-dependent manners in normal human keratinocytes.

TGF-β is not involved in early phase growth inhibition of keratinocytes by 1α,25(OH)2vitamin D3

BACKGROUND

It has been proposed that transforming growth factor-beta (TGF-beta) is involved in the growth inhibition of normal human epidermal keratinocytes (NHEK) by 1alpha,25-dihydoxyvitamin D(3) (1alpha,25(OH)(2)D(3)), although this is still controversial because of the difficulty in blocking TGF-beta activity completely.

OBJECTIVE

To determine whether TGF-beta is involved in early phase growth inhibition by 1alpha,25(OH)(2)D(3).

METHODS

TGF-beta mRNA was detected by ribonuclease protection assay (RPA), and biological active TGF-beta was determined by a luciferase reporter assay. To block intrinsic TGF-beta activity completely, we constructed an adenovirus vector expressing a truncated TGF-beta type II receptor with a dominant negative effect (AdexTbetaTR) that blocks TGF-beta signal transduction.

RESULTS

1alpha,25(OH)(2)D(3) slightly upregulated TGF-beta1 and TGF-beta2 after 24 h according to an RPA and a luciferase reporter assay, however growth inhibition by 1alpha,25(OH)(2)D(3) occurred at 6 h. The addition of 10(-6) M of 1alpha,25(OH)(2)D(3) to NHEK infected with AdexTbetaTR or AdexLacZ (control vector) reduced DNA synthesis to 59.3 and 62.2% at 6 h, respectively. There was no significant difference in cell number after a 3-day incubation with AdexTbetaTR or AdexLacZ-infected cells treated with 1alpha,25(OH)(2)D(3).

CONCLUSION

Since 1alpha,25(OH)(2)D(3) rapidly inhibits NHEK growth regardless of the prevention of TGF-beta signal transduction, TGF-beta is not involved in early phase growth inhibition by 1alpha,25(OH)(2)D(3).

Keratinocyte G2/M growth arrest by 1,25-dihydroxyvitamin D3 is caused by Cdc2 phosphorylation through Wee1 and Myt1 regulation

1,25-dihydroxyvitamin D3 (1,25[OH]2VD3) has an antiproliferative effect on keratinocyte growth, and its derivatives are used for the treatment of psoriasis. It was reported previously that 1,25[OH]2VD3 induced cell cycle arrest not only at the G0/G1 phase but also at the G2/M phase. However, the mechanism of 1,25[OH]2VD3-induced G2/M phase arrest in keratinocytes has not been fully understood. The addition of 10(-8) to 10(-6) M 1,25[OH]2VD3 to cultured normal human keratinocytes enhanced the expression of Myt1 mRNA preceding Wee1 mRNA; 10(-6) M 1,25[OH]2VD3 unregulated Myt1 mRNA from 6 h to 24 h and Wee1 mRNA from 12 to 48 h. Interestingly, the levels of phosphorylated Cdc2 were increased between 6 h and 48 h after 1,25[OH]2VD3 treatment, although the expression levels of Cdc2 mRNA and its protein production were reduced. 1,25[OH]2VD3 also decreased the expression of cyclin B1, which forms a complex with Cdc2. These data indicated that the increase of Myt1 and Wee1 induced the phosphorylation of Cdc2 leading to G2/M arrest. In conclusion, the induction of Cdc2 phosphorylation due to the increase of Wee1 and Myt1 as well as the reduction of Cdc2 and cyclin B1 are involved in 1,25[OH]2VD3-induced G2/M arrest of keratinocytes.

Nuclear translocation of phosphorylated STAT3 is essential for vascular endothelial growth factor-induced human dermal microvascular endothelial cell migration and tube formation

Vascular endothelial growth factor (VEGF) is a potent, multifunctional, endothelial-cell-specific growth factor. It stimulates proliferation and migration of endothelial cells. Characterization of intracellular signal transduction after VEGF and VEGF receptor (VEGFR) interaction has demonstrated the involvement of the mitogen-activated protein kinase pathway. However, several studies indicated that signal transducers and activators of transcription (STAT) is another important pathway downstream of VEGF/VEGFR interaction. Therefore, we studied the role of STAT3 in the migration and tube formation of the human dermal microvascular endothelial cells (HDMEC). HDMEC expressed phosphorylated forms of STAT1, STAT3, and STAT5, and a marked increase of phosphorylated STAT3 in the nuclear fraction after addition of VEGF was observed by Western blot and immunohistochemical staining. To verify the functional implication of STAT3 phosphorylation in HDMEC migration, we introduced a dominant-negative STAT3 using adenovirus vector system. Dominant-negative STAT3 abolished the VEGF-induced nuclear translocation of phosphorylated STAT3 and inhibited HDMEC migration completely. Dominant-negative STAT3 also suppressed VEGF-induced HDMEC tube formation on Matrigel and on collagen gel. These data demonstrate that STAT3 and its phosphorylation are involved in the downstream pathway of VEGF/VEGFR interaction and regulate VEGF-induced HDMEC migration and tube formation.

So-called biological dressing effects of cultured epidermal sheets are mediated by the production of EGF family, TGF-β and VEGF

BACKGROUND

Cultured epidermal sheet (CES) grafts accelerate wound healing as a result of so-called biological dressing effect, which is thought to be mediated by various growth factors. However, the profile of growth factor expression in CESs is unclear.

OBJECTIVE

To investigate whether CESs produce growth factors along with stratification we investigated the production of growth factors and their regulation in CESs.

METHODS

CESs conditioned medium was harvested and the concentration of TGF-alpha, TGF-beta1, TGF-beta2, and VEGF was measured using ELISA. The mRNA of EGF family, TGF-beta family and VEGF was detected by Northern blot or RNase protection assay.

RESULTS

The concentration of TGF-alpha was 100 pg/ml in the monolayer culture, but dramatically increased to 600 pg/ml 2 days after stratification. It decreased to baseline, and then gradually increased to 300 pg/ml in the presence of EGF and remained at that level until day 20. TGF-beta1 increased from 50 to 400 pg/ml after stratification, and remained at that level day 20. TGF-beta2 was undetectable in the monolayer culture, but dramatically increased to 200 pg/ml 2 days after stratification. Unlike TGF-beta1, TGF-beta2 gradually increased over time after stratification. VEGF increased with stratification from 500 to 1500 pg/ml. The addition of EGF upregulated EGF family, TGF-beta, and VEGF production in CESs, as confirmed by ELISA, Northern blot, and RNase protection assay.

CONCLUSION

These results indicate that so-called biological dressing effect of CESs is mediated by production of the EGF family, TGF-beta, and VEGF. Our results also demonstrate the ability of EGF to enhance growth factor production in CESs.

A Japanese case of segmental Darier's disease caused by mosaicism for the ATP2A2 mutation

Darier's disease is an autosomal dominant skin disorder that is characterized by multiple keratotic papules, focal loss of adhesion and abnormal keratinization. Mutations in the ATP2A2 gene encoding sarco/endoplasmic reticulum calcium pumping ATPase type 2 have been identified as the molecular basis of Darier's disease. Segmental Darier's disease is a rare type of Darier's disease in which there is characteristic localization of the keratotic papules in a linear pattern following Blaschko's lines. In this study we examined ATP2A2 mutations in a Japanese patient with segmental Darier's disease. The samples from affected skin, unaffected skin and peripheral leucocytes were subjected to polymerase chain reaction (PCR). Direct sequencing of the PCR products was performed. Sequence analysis revealed that the patient had 160A-->G substitution mutation which predicts I54V. This novel mutation was present in the affected skin, but not in the unaffected skin or peripheral leucocytes. This is the first report of segmental Darier's disease caused by mosaicism for an ATP2A2 mutation in Japan.

Phospholipase Cdelta1 is required for skin stem cell lineage commitment

Phosphoinositide-specific phospholipase C (PLC) is a key enzyme in phosphoinositide turnover and is involved in a variety of physiological functions. Here we report that PLCdelta(1)-deficient mice undergo progressive hair loss in the first postnatal hair cycle. Epidermal hyperplasia was observed, and many hairs in the skin of PLCdelta(1)-deficient mice failed to penetrate the epidermis and became zigzagged owing to occlusion of the hair canal. Two major downstream signals of PLC, calcium elevation and protein kinase C activation, were impaired in the keratinocytes and skin of PLCdelta(1)-deficient mice. In addition, many cysts that had remarkable similarities to interfollicular epidermis, as well as hyperplasia of sebaceous glands, were observed. Furthermore, PLCdelta(1)-deficient mice developed spontaneous skin tumors that had characteristics of both interfollicular epidermis and sebaceous glands. From these results, we conclude that PLCdelta(1) is required for skin stem cell lineage commitment.

Keratinocyte growth inhibition by high-dose epidermal growth factor is mediated by transforming growth factor beta autoinduction: a negative feedback mechanism for keratinocyte growth

The epidermal growth factor receptor and its ligands initiate a major signaling pathway that regulates keratinocyte growth in an autocrine manner. It is well known that high doses of epidermal growth factor receptor ligands inhibit keratinocyte growth. Recently, signal transducers and activators of transcription 1-dependent p21Waf1/Cip1 induction were reported to be involved in high-dose epidermal growth factor-dependent cell growth arrest in the A431 squamous cell carcinoma cell line; however, transfection of dominant-negative signal transducers and activators of transcription 1 adenovirus vector did not block epidermal growth factor-induced growth inhibition in normal human keratinocytes. As transforming growth factor beta is a potent inhibitor of keratinocyte proliferation, we hypothesized that transforming growth factor beta contributes to epidermal growth factor-mediated keratinocyte growth inhibition. Epidermal growth factor concentrations of 10 ng per ml enhanced transforming growth factor beta1 mRNA expression from 3 to 6 h poststimulation. Enzyme-linked immunosorbent assay analysis detected 150 pg per ml of transforming growth factor beta1 in the culture medium of keratinocytes incubated with 10 and 100 ng per ml epidermal growth factor, whereas 0.1 and 1.0 ng per ml epidermal growth factor slightly enhance transforming growth factor beta1 production. Epidermal growth factor (100 ng per ml) upregulated luciferase activity of p3TP-lux, which contains three tandem transforming growth factor beta-Smad signaling responsive elements, 6-fold compared with unstimulated cells. The epidermal growth factor-dependent induction of p3TP-lux luciferase activity was disrupted by transfection of the dominant negative form of transforming growth factor beta type I receptor adenovirus vector (AxdnALK5), which suggests that epidermal growth factor-induced transforming growth factor beta acts in an autocrine manner in keratinocytes. Moreover, transfection of AxdnALK5 completely blocked the growth inhibition induced by 100 ng per ml of epidermal growth factor in normal keratinocytes. These data demonstrate that an autocrine transforming growth factor beta1-ALK5 pathway is a negative feedback mechanism for epidermal growth factor-induced normal human keratinocyte growth.

Identification of the human IAI.3B promoter element and its use in the construction of a replication-selective adenovirus for ovarian cancer therapy

Little is known concerning promoters or gene therapy specific for ovarian cancer. To explore the potential use of IAI.3B isolated from ovarian cancer cells in gene therapy for ovarian cancer, we identified the promoter region of the IAI.3B gene and created a replication-selective adenovirus, AdE3-IAI.3B, driven by the promoter. Transient transfection experiments showed that the DNA segment located between -1816 and -1 bp resulted in preferential expression in ovarian cancer cells with negligible expression in squamous cell carcinoma and normal cells. The promoter activity of IAI.3B was almost the same as that of cytomegalovirus and an order of magnitude higher than those of midkine and cyclooxygenase-2 in ovarian cancer cells. AdE3-IAI.3B replicated as efficiently as the wild-type adenovirus and caused extensive cell killing in a panel of ovarian cancer cells in vitro. In contrast, squamous cell carcinoma and normal cells were not able to support AdE3-IAI.3B replication. In animal studies, AdE3-IAI.3B administered to flank and i.p. xenografts of ovarian cancer cells led to a significant therapeutic effect. These results demonstrate the usefulness of the IAI.3B promoter for generation of ovarian cancer-specific adenoviral vectors and provide a potential for the development of ovarian cancer-specific oncolytic viral therapies.

Suppressor of cytokine signaling 1/JAB and suppressor of cytokine signaling 3/cytokine-inducible SH2 containing protein 3 negatively regulate the signal transducers and activators of transcription signaling pathway in normal human epidermal keratinocytes

The suppressor of cytokine signaling/cytokine-inducible SH2 containing proteins are cytokine inducible and are negative regulators of the signal transducers and activators of the transcription signaling pathway. We investigated the mechanism regulating signal transducers and activators of transcription and the suppressor of cytokine signaling/cytokine-inducible SH2 containing protein family in keratinocytes, one of the major target cells for cytokines. Suppressor of cytokine signaling 1 mRNA was upregulated 3 h post-interferon gamma, and a 8.1-fold increase in the suppressor of cytokine signaling 1 mRNA occurred 48 h post-interferon gamma. The suppressor of cytokine signaling 3 mRNA was also upregulated from 1 h post-interferon gamma, and a 6.7-fold increase in the suppressor of cytokine signaling 3/cytokine-inducible SH2 containing protein 3 mRNA occurred between 6 and 12 h post-interferon gamma. Interleukin-6 exposure for 1 h enhanced the expression of the suppressor of cytokine signaling 3/cytokine-inducible SH2 containing protein 3 mRNA, but the suppressor of cytokine signaling 1/JAB mRNA was not induced by interleukin-6. Interleukin-4 upregulated the suppressor of cytokine signaling 1/JAB and cytokine-inducible SH2 containing protein 1 mRNA, with 3.4-fold and 5.1-fold increases in mRNA observed at 1 h post-interleukin-4, respectively. In contrast, epidermal growth factor, which phosphorylates signal transducers and activators of transcription 3, did not influence the level of the suppressor of cytokine signaling/cytokine-inducible SH2 containing protein family mRNA expression. Transfection of an adenovirus vector expressing the suppressor of cytokine signaling 1/JAB completely inhibited interferon gamma-dependent signal transducers and activators of transcription 1 phosphorylation and interleukin-4-dependent signal transducers and activators of transcription 6 phosphorylation. Transfection of adenovirus vector expressing the suppressor of cytokine signaling 1/JAB did not inhibit interleukin-6-dependent signal transducers and activators of transcription 3 phosphorylation-several reports show that the suppressor of cytokine signaling 1/JAB is a potent inhibitor of signal transducers and activators of transcription 3 signaling in the myeloid leukemia M1 cell. Transfection of the adenovirus vector expressing suppressor of cytokine signaling 3/cytokine-inducible SH2 containing protein 3 completely inhibited interleukin-6-dependent signal transducers and activators of transcription 3 phosphorylation and partially inhibited interferon gamma-dependent signal transducers and activators of transcription 1 phosphorylation. Transfection of the adenovirus vector expressing suppressor of cytokine signaling 3/cytokine-inducible SH2 containing protein 3, however, did not inhibit interleukin-4-dependent signal transducers and activators of transcription 6 phosphorylation. Transfection of the adenovirus vector expressing cytokine-inducible SH2 containing protein 1 had no effect on signal transducers and activators of transcription 1, 3, and 6 signaling in normal keratinocytes. Therefore, the relationship between signal transducers and activators of transcription and suppressor of cytokine signaling is unique in the keratinocytes, and the suppressor of cytokine signaling regulates cytokine signals in these cells.

Essential roles of perforin in antigen-specific cytotoxicity mediated by human CD4+ T lymphocytes: analysis using the combination of hereditary perforin-deficient effector cells and Fas-deficient target cells

Although the cytotoxic mechanisms of murine CTLs have been investigated extensively using various mutant and knockout mice, those of human CTLs, especially CD4+ CTLs, are still obscure. To clarify the roles of perforin in Ag-specific cytotoxicity mediated by human CD4+ CTLs, alloantigen-specific and HSV-specific human CD4+ T lymphocyte bulk lines and clones were established from a patient with hereditary perforin deficiency and her healthy father, and their cytotoxic activities were investigated. Alloantigen-specific CD4+ T lymphocytes expressing perforin exerted cytotoxicity against Fas-negative as well as Fas-positive allogeneic B lymphoblastoid cell lines established from members of a family with hereditary Fas deficiency. Perforin-deficient, but not perforin-expressing, CD4+ T lymphocytes failed to show strong cytotoxicity against HSV-infected autologous B lymphoblastoid cells. Perforin-deficient CD4+ T lymphocytes could exert relatively low level cytotoxicity against allogeneic IFN-gamma-treated keratinocytes. Although cytotoxicity mediated by perforin-expressing CD4+ CTLs was almost completely inhibited by concanamycin A, a potent inhibitor of the perforin-mediated cytotoxic pathway, cytotoxicity against IFN-gamma-treated keratinocytes mediated by perforin-deficient CD4+ T lymphocytes was inhibited only partially by concanamycin A, but was inhibited significantly by antagonistic anti-Fas Ab and anti-Fas ligand Ab. The combination of perforin-deficient effector T lymphocytes and Fas-negative target cells used in the present study provides a novel experimental system for studying the detailed mechanisms of human CTL-mediated cytotoxicity. The present data demonstrate that perforin-negative CD4+ CTLs can exert cytotoxicity against Fas-sensitive target cells; however, perforin plays essential roles in Ag-specific cytotoxicity mediated by human CD4+ as well as CD8+ CTLs.

Severe palmo-plantar hyperkeratosis in Koebner epidermolysis bullosa simplex

A 22-year-old Japanese woman with Koebner epidermolysis bullosa simplex presented with severe palmo-plantar hyperkeratosis. Skin biopsy specimens from the palm revealed hyperkeratosis and acanthosis with blistering in the basal cell layer. An electron microscopic study showed cytolysis of basal cells and clumping of tonofilaments forming thick bundles and perinuclear electron-dense bodies. Hand contractures were released and covered with full thickness autografts or split thickness autografts. The donor site was successfully treated with cultured epidermal autografts.