Cultures Of Human Epidermal Keratinocytes Research Articles

Re-Epithelialization of Neuropathic Diabetic Foot Wounds with the Use of Cryopreserved Allografts of Human Epidermal Keratinocyte Cultures (Epifast).

The application of tissue-engineering technology to wound healing has become an option for the treatment of diabetic foot ulcers (DFU). A comparative, prospective study was conducted to assess the efficacy of a cryopreserved allograft of human epidermal keratinocytes (Epifast) to enhance wound healing in granulating DFU. Eighty patients were assigned to receive Epifast (n = 40) or Standard Care (SC) treatment (n = 40). The Epifast group displayed a shorter duration of the epithelialization phase (3.5 ± 4 vs. 6.4 ± 3.6 weeks, p < 0.05) and upon the entire wound healing process than the SC group (10 ± 5.7 vs. 14.5 ± 8.9 weeks, p < 0.05), reaching wound closure at 16 and 30 weeks, respectively. The Kaplan-Meier analysis revealed that Epifast group patients were 50% more likely than the SC to heal wounds faster (Cox-hazards ratio of 0.5, 95% CI = 0.3-0.8, p < 0.0001; Likelihood Ratio of 7.8. p < 0.05). Patients in the control group displayed a slower healing as the Saint Elian (SEWSS) severity grade increased (group differences of 0.6, 3.8, and 4.3 weeks for grades I, II, and III, respectively). DFW treated with Epifast displayed a shorter time to complete re-epithelialization than wounds treated with standard care.

Epidermal cell cultures from white and green sturgeon (Acipenser transmontanus and medirostris): Expression of TGM1-like transglutaminases and CYP4501A.

Using a system optimized for propagating human keratinocytes, culture of skin samples from white and green sturgeons generated epithelial cells capable of making cross-linked protein envelopes. Two distinct forms of TGM1-like mRNA were molecularly cloned from the cells of white sturgeon and detected in green sturgeon cells, accounting for their cellular envelope forming ability. The protein translated from each displayed a cluster of cysteine residues resembling the membrane anchorage region expressed in epidermal cells of teleosts and tetrapods. One of the two mRNA forms (called A) was present at considerably higher levels than the other (called B) in both species. Continuous lines of white sturgeon epidermal cells were established and characterized. Size measurements indicated that a substantial fraction of the cells became enlarged, appearing similar to squames in human epidermal keratinocyte cultures. The cultures also expressed CYP1A, a cytochrome P450 enzyme inducible by activation of aryl hydrocarbon receptor 2 in fish. The cells gradually improved in growth rate over a dozen passages while retaining envelope forming ability, TGM1 expression and CYP1A inducibility. These cell lines are thus potential models for studying evolution of fish epidermis leading to terrestrial adaptation and for testing sturgeon sensitivity to environmental stresses such as pollution.

Mangostanin, a Xanthone Derived from Garcinia mangostana Fruit, Exerts Protective and Reparative Effects on Oxidative Damage in Human Keratinocytes.

The fruit of Garcinia mangostana (mangosteen) is known in ancient traditional Asian medicine for its antioxidant, anti-inflammatory, immunomodulatory and anticancer activities. These effects are mainly due to the action of polyphenols known as xanthones, which are contained in the pericarp of the fruit. In recent years, there has been a growing interest from pharmaceutical companies in formulating new topicals based on mangosteen full extracts to prevent skin aging. However, the molecules responsible for these effects and the mechanisms involved have not been investigated so far. Here, the arils and shells of Garcinia mangostana were extracted with chloroform and methanol, and the extracts were further purified to yield 12 xanthone derivatives. Their effects were evaluated using in vitro cultures of human epidermal keratinocytes. After confirming the absence of cytotoxicity, we evaluated the antioxidant potential of these compounds, identifying mangostanin as capable of both protecting and restoring oxidative damage induced by H2O2. We showed how mangostanin, by reducing the generation of intracellular reactive oxygen species (ROS), prevents the activation of AKT (protein kinase B), ERK (extracellular signal-regulated kinase), p53, and other cellular pathways underlying cell damage and apoptosis activation. In conclusion, our study is the first to demonstrate that mangostanin is effective in protecting the skin from the action of free radicals, thus preventing skin aging, confirming a potential toward its development in the nutraceutical and cosmeceutical fields.

A combination of Vitreoscilla filiformis extract and Vichy volcanic mineralizing water strengthens the skin defenses and skin barrier.

Probiotics are live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host. Semiactive, non-replicating bacteria or extracts used in dermocosmetics have interesting properties for skin quality. Vitreoscilla filiformis is cultured by a fermentation process to obtain an extract. It is considered as a probiotic fraction and topical application of this extract has shown activity to strengthen the skin physical barrier function and maintain good homeostasis of skin defenses. Vichy volcanic mineralizing water (VVMW) is a pure, highly mineralized water that has been shown to strengthen the skin against exposome aggressions. This manuscript reviews properties of probiotic fractions used in skin care, especially studies on an extract of V. filiformis grown in a medium containing VVMW (VfeV) and evaluated in combination with VVMW. Skin barrier function: In normal human epidermal keratinocyte cultures, the combination of 10% VVMW and 0.002% VfeV significantly increased transglutaminase, filaggrin, involucrin, claudin-1, and zonula occludens-1 in comparison with the controls. Antimicrobial peptide defenses: The combination of 16.7% VVMW and 0.1% VfeV increased the expression of β-defensin-4A and S100A7. Skin immune defense functions: In lipopolysaccharide-stimulated peripheral blood mononuclear cells, the combination of 16.7% VVMW and 0.1% VfeV down-regulated IL-8, TNF-α, IL-12/IL-23p40, and increased IL10 and IL-10/IL-12 ratio compared to the control. Additionally, the combination of 79% VVMW plus 5% VfeV protected Langerhans cells in skin explants exposed to ultraviolet radiation. In conclusion, the combination of VfeV plus VVMW has properties to strengthen the skin barrier by stimulating skin differentiation and tight junctions, biochemical defenses by stimulating antimicrobial peptides, and cellular immune defenses by increasing the IL-10/IL-12 ratio and by protecting Langerhans cells challenged by ultraviolet radiation.

Enhancing electrospun scaffolds of PVP with polypyrrole/iodine for tissue engineering of skin regeneration by coating via a plasma process

Electrospun scaffolds of biopolymers have been used in skin tissue engineering to develop and create artificial skin tissue for replacement dermal substitutes. Moreover, electrospun scaffolds are used to improve wound dressing for assisting the wound healing process. We focus on the polypyrrole/iodine coating viability and observe the cultures of human epidermal keratinocytes (HaCaT) responding to improve scaffolds for skin tissue engineering. For this purpose, polyvinylpyrrolidone polymer was used as a polymer matrix. The FE-SEM analysis showed the morphologies obtained (fibers and spheres) by the different solvents used in polyvinylpyrrolidone solutions due to the polarity of the solvents. The polyvinylpyrrolidone fibers have an average diameter of 135.6 nm ± 1.4 nm, and polyvinylpyrrolidone spheres have diameters of 1.01–1.6 µm. Elemental analysis showed the incorporation of polypyrrole/iodine on polyvinylpyrrolidone scaffolds. An XRD study displayed the amorphous structure of polyvinylpyrrolidone fibers and spheres. Using FTIR, it was possible to identify the functional groups representative of polyvinylpyrrolidone, and the presence of the coating of polypyrrole was demonstrated. Polypyrrole/iodine proved to be a scaffolding with an optimal coating for the cellular growth of HaCaT cells, increasing viability, adhesion, and cell healing.

Does blue light restore human epidermal barrier function via activation of Opsin during cutaneous wound healing?

Visible light has beneficial effects on cutaneous wound healing, but the role of potential photoreceptors in human skin is unknown. In addition, inconsistency in the parameters of blue and red light-based therapies for skin conditions makes interpretation difficult. Red light can activate cytochrome c oxidase and has been proposed as a wound healing therapy. UV-blue light can activate Opsin 1-SW, Opsin 2, Opsin 3, Opsin 4, and Opsin 5 receptors, triggering biological responses, but their role in human skin physiology is unclear. Localization of Opsins was analyzed in situ in human skin derived from face and abdomen by immunohistochemistry. An ex vivo human skin wound healing model was established and expression of Opsins confirmed by immunohistochemistry. The rate of wound closure was quantitated after irradiation with blue and red light and mRNA was extracted from the regenerating epithelial tongue by laser micro-dissection to detect changes in Opsin 3 (OPN3) expression. Retention of the expression of Opsins in primary cultures of human epidermal keratinocytes and dermal fibroblasts was confirmed by qRT-PCR and immunocytochemistry. Modulation of metabolic activity by visible light was studied. Furthermore, migration in a scratch-wound assay, DNA synthesis and differentiation of epidermal keratinocytes was established following irradiation with blue light. A role for OPN3 in keratinocytes was investigated by gene silencing. Opsin receptors (OPN1-SW, 3 and 5) were similarly localized in the epidermis of human facial and abdominal skin in situ. Corresponding expression was confirmed in the regenerating epithelial tongue of ex vivo wounds after 2 days in culture, and irradiation with blue light stimulated wound closure, with a corresponding increase in OPN3 expression. Expression of Opsins was retained in primary cultures of epidermal keratinocytes and dermal fibroblasts. Both blue and red light stimulated the metabolic activity of cultured keratinocytes. Low levels of blue light reduced DNA synthesis and stimulated differentiation of keratinocytes. While low levels of blue light did not alter keratinocyte migration in a scratch wound assay, higher levels inhibited migration. Gene silencing of OPN3 in keratinocytes was effective (87% reduction). The rate of DNA synthesis in OPN3 knockdown keratinocytes did not change following irradiation with blue light, however, the level of differentiation was decreased. Opsins are expressed in the epidermis and dermis of human skin and in the newly regenerating epidermis following wounding. An increase in OPN3 expression in the epithelial tongue may be a potential mechanism for the stimulation of wound closure by blue light. Since keratinocytes and fibroblasts retain their expression of Opsins in culture, they provide a good model to investigate the mechanism of blue light in wound healing responses. Knockdown of OPN3 led to a reduction in early differentiation of keratinocytes following irradiation with blue light, suggesting OPN3 is required for restoration of the barrier function. Understanding the function and relationship of different photoreceptors and their response to specific light parameters will lead to the development of reliable light-based therapies for cutaneous wound healing. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Transcription and microRNA Profiling of Cultured Human Tympanic Membrane Epidermal Keratinocytes.

The human tympanic membrane (TM) has a thin outer epidermal layer which plays an important role in TM homeostasis and ear health. The specialised cells of the TM epidermis have a different physiology compared to normal skin epidermal keratinocytes, displaying a dynamic and constitutive migration that maintains a clear TM surface and assists in regeneration. Here, we characterise and compare molecular phenotypes in keratinocyte cultures from TM and normal skin. TM keratinocytes were isolated by enzymatic digestion and cultured in vitro. We compared global mRNA and microRNA expression of the cultured cells with that of human epidermal keratinocyte cultures. Genes with either relatively higher or lower expression were analysed further using the biostatistical tools g:Profiler and Ingenuity Pathway Analysis. Approximately 500 genes were found differentially expressed. Gene ontology enrichment and Ingenuity analyses identified cellular migration and closely related biological processes to be the most significant functions of the genes highly expressed in the TM keratinocytes. The genes of low expression showed a marked difference in homeobox (HOX) genes of clusters A and C, giving the TM keratinocytes a strikingly low HOX gene expression profile. An in vitro scratch wound assay showed a more individualised cell movement in cells from the tympanic membrane than normal epidermal keratinocytes. We identified 10 microRNAs with differential expression, several of which can also be linked to regulation of cell migration and expression of HOX genes. Our data provides clues to understanding the specific physiological properties of TM keratinocytes, including candidate genes for constitutive migration, and may thus help focus further research.

An evaluation of the choice of feeder cell growth arrest for the production of cultured epidermis

Growth arrested 3T3 cells have been used as feeder cells in human epidermal keratinocyte cultures to produce cultured epidermal autografts for the treatment of burns. The feeder cells were ideally growth-arrested by gamma-irradiation. Alternatively, growth arrest by mitomycin C treatment is a cost effective option. We compared the functional efficacy of these two approaches in keratinocyte cultures by colony forming efficiency, the net growth area of colonies, BrdU labeling and histological features of cultured epidermal sheets. The growth area estimation involved a semi-automated digital technique using the Adobe Photoshop and comprised of isolation and enumeration of red pixels in Rhodamine B-stained keratinocyte colonies. A further refinement of the technique led to the identification of critical steps to increasing the degree of accuracy and enabling its application as an extension of colony formation assay. The results on feeder cell functionality revealed that the gamma irradiated feeders influenced significantly higher colony forming efficiency and larger growth area than the mitomycin C treated feeders. The BrdU labeling study indicated significant stimulation of the overall keratinocyte proliferation by the gamma irradiated feeders. The cultured epidermal sheets produced by gamma feeders were relatively thicker than those produced by mitomycin C feeders. We discussed the clinical utility of mitomycin C feeders from the viewpoint of cost-effective burn care in developing countries.

Melanin Uptake Reduces Cell Proliferation of Human Epidermal Keratinocytes

Melanin, synthesized by melanocyte, is transferred to neighboring keratinocyte and finally accumulates in perinuclear site. Except functioning as an internal sunscreen to protect from UV damage, the potential effect of melanin on modulating the bioactivity of keratinocyte has not yet been fully investigated. In this study, we added melanin directly to the culture of human epidermal keratinocytes and the uptake of melanin was found to be dose- and time-dependent as determined by spectrophotometric method. The uptaken melanin accumulated perinuclearly in keratinocytes that is similar to the pattern observed in human solar lentigo tissue by microscopic examination. Pretreatment of keratinocytes with either niacinamide or trypsin inhibitor reduced the uptake of melanin dose-dependently, indicating a PAR-2-dependent pathway involved. Melanin uptake by keratinocytes inhibited cell proliferation as demonstrated both by the decrease of cell number and nuclear Ki-67 expression. Inhibited Ki-67 expression in melanin-containing keratinocyte was also found in human lentigo tissue. The cell cycle arrested at G1 phase in melanin-uptaken keratinocytes was confirmed by flow cytometric method. The protein expressions of cyclin-dependent kinase 1 (CDK1), CDK2, cyclin E, cyclin A and cyclin B were significantly reduced by melanin treatment. Microarray analysis, RT/real-time PCR and western blot demonstrated the inhibited expression of DKK1, a protein known to reduce skin pigmentation, in melanin-uptaken keratinocytes. Together, the direct incubation of keratinocyte with melanin might serve as a useful model to study the potential mechanisms involved in melanin uptake and pigmentation process.

Nifedipine Prevents Sodium Caprate-Induced Barrier Dysfunction in Human Epidermal Keratinocyte Cultures

Tight junctions (TJs) of the epidermis play an important role in maintaining the epidermal barrier. TJ breakdown is associated with skin problems, such as wrinkles and transepidermal water loss (TEWL). Clinical studies have reported that topical nifedipine is effective in reducing the depth of wrinkles and improving TEWL. However, it remains unknown whether nifedipine influences the TJ function in the epidermis. In the present study, we investigated the effect of nifedipine on epidermal barrier dysfunction in normal human epidermal keratinocytes (NHEKs) treated with sodium caprate (C10), a TJ inhibitor. Nifedipine reversed the C10-decreased transepithelial electrical resistance values as a measure of disruption of the epidermal barrier. Immunocytochemical observations revealed that nifedipine improved the C10-induced irregular arrangement of claudin-1, a key protein in TJs. Taken together, these findings suggest that nifedipine prevents epidermal barrier dysfunction, at least in part, by reconstituting the irregular claudin-1 localization at TJs in C10-treated NHEKs.

P38δ Regulates p53 to Control p21Cip1 Expression in Human Epidermal Keratinocytes

PKCδ suppresses keratinocyte proliferation via a mechanism that involves increased expression of p21(Cip1). However, the signaling mechanism that mediates this regulation is not well understood. Our present studies suggest that PKCδ activates p38δ leading to increased p21(Cip1) promoter activity and p21(Cip1) mRNA/protein expression. We further show that exogenously expressed p38δ increases p21(Cip1) mRNA and protein and that p38δ knockdown or expression of dominant-negative p38 attenuates this increase. Moreover, p53 is an intermediary in this regulation, as p38δ expression increases p53 mRNA, protein, and promoter activity, and p53 knockdown attenuates the activation. We demonstrate a direct interaction of p38δ with PKCδ and MEK3 and show that exogenous agents that suppress keratinocyte proliferation activate this pathway. We confirm the importance of this regulation using a stratified epidermal equivalent model, which mimics in vivo-like keratinocyte differentiation. In this model, PKCδ or p38δ knockdown results in reduced p53 and p21(Cip1) levels and enhanced cell proliferation. We propose that PKCδ activates a MEKK1/MEK3/p38δ MAPK cascade to increase p53 levels and p53 drives p21(Cip1) gene expression.

An ErbB receptor mediated AP-1 regulatory network is modulated by STAT3 and c-MYC during calcium dependent keratinocyte differentiation

A calcium gradient in skin epidermis is known to regulate epidermal differentiation. In cultures of human epidermal keratinocytes (NHEK), induction of calcium-dependent differentiation is associated with phosphorylation of ErbB receptors, including the epidermal growth factor receptor (EGFR). The activation of EGFR triggers the induction of activator protein 1 (AP-1) proteins necessary for keratinocyte terminal differentiation. Interestingly, an in vitro long-term calcium treatment revealed the activation of different ErbB receptors with different timings, which is consistent with the differential localization of each receptor in the skin layers in vivo. In the current study, the regulatory relationship between ErbB receptor activation and induction of AP-1 proteins in calcium-dependent keratinocyte differentiation was analysed. For this purpose, we used a mathematical method to predict molecular regulations from time-course proteomic data of 30 target components. The predicted network showed that the ErbB receptor might regulate AP-1 protein expression via two pathways: positive regulation by c-MYC and negative regulation by signal transducer and activator of transcription 3 (STAT3) pathways. Experimental validation analysis revealed that ErbB receptor inhibition resulted in defective induction of AP-1 proteins and suppressed terminal differentiation of keratinocytes. Inhibition of STAT3, however, affected expression of a partial set of AP-1 proteins and resulted in premature differentiation. Studies using RNAi to diminish expression of each ErbB receptor and the AP-1 proteins strongly suggested that STAT3 established a balance that maintains the appropriate set of AP-1 proteins and participates in a complex network for regulating keratinocyte differentiation.

Sulforaphane Induction of p21Cip1 Cyclin-dependent Kinase Inhibitor Expression Requires p53 and Sp1 Transcription Factors and Is p53-dependent

Sulforaphane (SFN) is an important cancer preventive agent derived from cruciferous vegetables. We show that SFN treatment suppresses normal human keratinocyte proliferation via a mechanism that involves increased expression of p21(Cip1). SFN treatment produces a concentration-dependent increase in p21(Cip1) promoter activity via a mechanism that involves stabilization of the p53 protein leading to increased p53 binding to the p21(Cip1) promoter p53 response elements. The proximal p21(Cip1) promoter GC-rich Sp1 factor binding elements are also required, as the SFN-dependent increase is lost when these sites are mutated. SFN treatment increases Sp1 binding to these elements, and the response is enhanced in the presence of exogenous Sp1 and reduced in the presence of ΔN-Sp3. CpG island methylation alters p21(Cip1) promoter activity some systems; however, expression in SFN-treated keratinocytes does not involve changes in proximal promoter methylation. The promoter is minimally methylated, and the methylation level is not altered by SFN treatment. This study indicates that SFN increases p21(Cip1) promoter transcription via a mechanism that involves SFN-dependent stabilization of p53 and increased p53 and Sp1 binding to their respective response elements in the p21(Cip1) promoter. These results are in marked contrast to the mechanisms observed in skin cancer cell lines and suggest that SFN may protect normal keratinocytes from damage while causing cancer cells to undergo apoptosis.

An ErbB receptor–mediated AP‐1 regulatory network is modulated by STAT3 and c‐MYC during calcium‐dependent keratinocyte differentiation

A calcium gradient in skin epidermis is known to regulate epidermal differentiation. In cultures of human epidermal keratinocytes (NHEK), induction of calcium-dependent differentiation is associated with phosphorylation of ErbB receptors, including the epidermal growth factor receptor (EGFR). The activation of EGFR triggers the induction of activator protein 1 (AP-1) proteins necessary for keratinocyte terminal differentiation. Interestingly, an in vitro long-term calcium treatment revealed the activation of different ErbB receptors with different timings, which is consistent with the differential localization of each receptor in the skin layers in vivo. In the current study, the regulatory relationship between ErbB receptor activation and induction of AP-1 proteins in calcium-dependent keratinocyte differentiation was analysed. For this purpose, we used a mathematical method to predict molecular regulations from time-course proteomic data of 30 target components. The predicted network showed that the ErbB receptor might regulate AP-1 protein expression via two pathways: positive regulation by c-MYC and negative regulation by signal transducer and activator of transcription 3 (STAT3) pathways. Experimental validation analysis revealed that ErbB receptor inhibition resulted in defective induction of AP-1 proteins and suppressed terminal differentiation of keratinocytes. Inhibition of STAT3, however, affected expression of a partial set of AP-1 proteins and resulted in premature differentiation. Studies using RNAi to diminish expression of each ErbB receptor and the AP-1 proteins strongly suggested that STAT3 established a balance that maintains the appropriate set of AP-1 proteins and participates in a complex network for regulating keratinocyte differentiation.

Effect of growth factors on morphogenesis of human keratinocytes in vitro

The effect of some growth factors on morphogenetic processes in the primary culture of human epidermal keratinocytes was studied in the model of formation of tubule-like structures in collagen gel. Culturing of keratinocytes in the presence of IGF and bFGF did not induce growth of tubule-like structures, whereas EGF, KGF, and HGF promoted the growth of three-dimensional epidermal outgrowths whose shape and size varied depending on the growth factor used.

Fibromodulin gene is expressed in human epidermal keratinocytes in culture and in human epidermis in vivo

Fibromodulin is a small leucine-rich proteoglycan that has a central role in the maintenance of collagen fibrils structure, and in regulation of TGF-β biological activity. Although, it is mainly found in cartilage and tendon, little is known regarding the expression of the fibromodulin gene in other cell types. By RT-PCR, real time PCR and immunohistochemistry, we describe the expression of the fibromodulin gene and the presence of the protein in human epidermal keratinocytes (HEK), both in culture and in normal human epidermis. Our results show, for the first time, that fibromodulin gene is constantly expressed in HEK during culture time. Immunostaining showed that fibromodulin is located intracytoplasmically in basal and stratified keratinocytes of the growing colonies, confluent cultures, and epidermis in vivo. The expression and intracellular localization of fibromodulin in HEK is a new finding and opens new possible biological roles for the SLRP family.

In vitro cytotoxicology model of oligo-chitosan and n, o-carboxymethyl chitosan using primary normal human epidermal keratinocyte cultures.

Chitosan (beta-1, 4-D-glucosamine) is a deacetylated form of chitin with excellent biological properties in wound management. The natural properties of chitosan have the physical and chemical limitations to be widely used in biomedical fields. The improvement of the physical and chemical properties of chitosan with some additional chemicals will alter its biocompatibility. Therefore, the biological attribute of the modified chitosan must be evaluated. In this study, the cytotoxicity of oligo-chitosan (OC) and N, O- carboxymethyl-chitosan (NO-CMC) derivatives (O-C 1%, O-C 5%, NO-CMC 1% and NO-CMC 5%) was evaluated using primary normal human epidermal keratinocyte (pNHEK) cultures as an in vitro toxicology model at standardized cell passages (fourth passages). 3-[4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl tetrazolium bromide (MTT) was used as a cell viability assay. The O-C 1% is one of the most compatible chitosan derivatives because it steadily sustained >70% of viable cells until 72 hr post-treatment. This was followed by O-C 5%, NO-CMC 5% and NO-CMC 1%. Therefore, oligo-chitosan had the ideal properties of a biocompatible material compared to N, O- carboxymethyl-chitosan in this study.

Expression of keratin 19 in a culture of human epidermal keratinocytes

Expression of keratin 19 in a culture of human epidermal keratinocytes

The putative human stem cell marker,Rex-1 (Zfp42): Structural classification and expression in normal human epithelial and carcinoma cell cultures

Human Rex-1 (hRex-1) (also referred to as zinc-finger protein-42, Zfp42) encodes a zinc finger protein expression of which is believed to be characteristic of pluripotent stem cells. We have applied bioinformatics to classify the relationship of human, rat, and mouse REX1 proteins in the C2H2 family of zinc finger proteins and demonstrate that REX1 is a member of the YY1 sub-family of transcription factors, which includes the Drosophila pleiohomeotic (Pho) protein. We have generated a molecular model of the human REX1 zinc finger domains based on the crystal structure of the YY1 transcription factor. To date, expression of hRex-1 and its extensively studied mouse homolog mRex-1, has been reported only in embryonic and adult stem cells and in differentiated spermatocytes. In this study, reverse transcription-PCR and Western analysis were employed to assay for hRex-1 expression in cultured normal human epithelial cells and human carcinoma cell lines. Expression of hRex-1 mRNA was detected in normal human epidermal keratinocytes, normal prostate epithelial cells (PrEC), bronchial, and small airway lung epithelial cells. Other stem cell markers, such as Oct 4, DAB2, and cMyc were also detected in normal human epidermal keratinocyte cultures. Expression of hRex-1 was also detected in some human tumor cell lines including MDA-MB-468 mammary carcinoma, SCC-15 head and neck squamous cell carcinoma, and N-TERA2 human teratocarcinoma cells. Western analyses confirmed expression of the human REX1 (ZFP42) protein in MDA-MB-468 cells and normal human keratinocytes. This research has identified model human cell culture systems, in addition to embryonic stem (ES) cells, in which Rex-1 is expressed, and this should enable the characterization of REX1 functions in normal adult epithelial cells and tumorigenic stem cells.

Expression of Cholesterol Sulfotransferase (SULT2B1b) in Human Skin and Primary Cultures of Human Epidermal Keratinocytes

Cholesterol sulfate is a highly amphipathic molecule that is present in a relatively high concentration in the epidermis of human skin, particularly in the granular layer. The physiologic significance of this finding, however, is not well-understood. Therefore, we examined expression of the gene encoding for the enzyme that sulfonates cholesterol (SULT2B1b). Of the three enzymes known to sulfonate steroids/sterols, only the SULT2B1b isozyme was detected in cultures of normal human epidermal keratinocytes (NHEK) in response to Ca(2+)-induced terminal differentiation as well as by normal human epidermal tissue. Immunocytochemical analysis of normal skin as well as specific skin disorders was carried out. In normal skin, the expression of SULT2B1b was localized to the granular layer of the epidermis similar to that of filaggrin, an acknowledged late marker of differentiation and in contrast to that of involucrin, an early marker of terminal differentiation, which was expressed throughout the suprabasal region. The confinement of SULT2B1b to the granular layer coincides with this being the area with the highest cholesterol sulfate content suggesting that the physiologic action of cholesterol sulfate is likely carried out in this region of the living epidermis. Additionally, 88% of cholesterol sulfate in NHEK was membrane-associated further suggesting a cellular location for cholesterol sulfate action.