Characterization of Kdap, A Protein Secreted by Keratinocytes

Repurposing Metformin for periodontal disease management as a form of oral-systemic preventive medicine

BACKGROUND

Despite the improvements in treatment over the last decades, periodontal disease (PD) affects millions of people around the world and the only treatment available is based on controlling microbial load. Diabetes is known to increase the risk of PD establishment and progression, and recently, glucose metabolism modulation by pharmaceutical or dietarian means has been emphasised as a significant modulator of non-communicable disease development.

METHODS

The impact of pharmaceutically controlling glucose metabolism in non-diabetic animals and humans (REBEC, UTN code: U1111-1276-1942) was investigated by repurposing Metformin, as a mean to manage periodontal disease and its associated systemic risk factors.

RESULTS

We found that glucose metabolism control via use of Metformin aimed at PD management resulted in significant prevention of bone loss during induced periodontal disease and age-related bone loss in vivo. Metformin also influenced the bacterial species present in the oral environment and impacted the metabolic epithelial and stromal responses to bacterial dysbiosis at a single cell level. Systemically, Metformin controlled blood glucose levels and age-related weight gain when used long-term. Translationally, our pilot randomized control trial indicated that systemic Metformin was safe to use in non-diabetic patients and affected the periodontal tissues. During the medication window, patients showed stable levels of systemic blood glucose, lower circulating hsCRP and lower insulin levels after periodontal treatment when compared to placebo. Finally, patients treated with Metformin had improved periodontal parameters when compared to placebo treated patients.

CONCLUSION

This is the first study to demonstrate that systemic interventions using Metformin in non-diabetic individuals aimed at PD prevention have oral-systemic effects constituting a possible novel form of preventive medicine for oral-systemic disease management.

Topical heparin as an effective and safe treatment for patients with capecitabine-induced hand-foot syndrome: results of a phase IIA trial supported by proteomic profiling of skin biopsies

Background:

Hand-foot syndrome (HFS) is a common adverse reaction associated with capecitabine chemotherapy that significantly affects the quality of life of patients. This study evaluates the safety and effectiveness of a topical heparin (TH) treatment on the clinical manifestations and anatomopathological alterations of capecitabine-induced HFS. In addition, we performed proteome profiling of skin biopsies obtained from patients with HFS at baseline and after heparin treatment.

Methods:

Patients with grade ⩽ 2 HFS associated with capecitabine were included in this study. The primary end point was the effectiveness of TH in reducing HFS of any grade. Clinical improvement was evaluated by clinicians, and an improvement was perceived by patients who performed a weekly visual analog scale questionnaire. Secondary end points included a comparative histological analysis and protein expression in skin biopsies at baseline and after 3 weeks of HT treatment. Proteomic profiling was carried out using quantitative isobaric labelling and subsequently validated by a T-array.

Results:

Twenty-one patients were included in the study. The median TH treatment time was 7.6 weeks (range = 3.6–41.6 weeks), and the median response time was 3.01 weeks (95% CI = 2.15–3.97). At the end of treatment, 19 of 21 patients (90.48%) responded to treatment with a decrease in one or more grades of HFS. None of the patients experienced adverse effects related to TH usage, nor did they suspend chemotherapy treatment. The main findings observed in skin biopsies after treatment were a decrease in hyperkeratosis and lymphocytic infiltrates. The proteomic analysis showed altered expression of 34 proteins that were mainly related to wound healing, cell growth, and the immune response.

Conclusion:

Based on our results, topical heparin is an effective and safe treatment for clinical manifestations of HFS, probably due to the restauration of skin homeostasis after heparin treatment, as supported by our proteomics-derived data.

Trial registration:

EudraCT 2009-018171-13

The WNK1 kinase regulates the stability of transcription factors during wound healing of human corneal epithelial cells

Due to its superficial anatomical localization, the cornea is continuously subjected to injuries. Damages to the corneal epithelium trigger important changes in the composition of the extracellular matrix to which the basal human corneal epithelial cells (hCECs) attach. These changes are perceived by membrane-bound integrins and ultimately lead to re-epithelialization of the injured epithelium through intracellular signalin. Among the many downstream targets of the integrin-activated signaling pathways, WNK1 is the kinase whose activity is the most strongly increased during corneal wound healing. We previously demonstrated that pharmacological inhibition of WNK1 prevents proper closure of wounded human tissue-engineered cornea in vitro. In the present study, we investigated the molecular mechanisms by which WNK1 contributes to corneal wound healing. By exploiting transcription factors microarrays, electrophoretic mobility-shift assay, and gene profiling analyses, we demonstrated that the DNA binding properties and expression of numerous transcription factors (TFs), including the well-known, ubiquitous TFs specific protein 1 (Sp1) and activator protein 1 (AP1), were reduced in hCECs upon WNK1 inhibition by WNK463. This process appears to be mediated at least in part by alteration in both the ubiquitination and glycosylation status of these TFs. These changes in TFs activity and expression impacted the transcription of several genes, including that encoding the α5 integrin subunit, a well-known target of both Sp1 and AP1. Gene profiling revealed that only a moderate number of genes in hCECs had their level of expression significantly altered in response to WNK463 exposition. Interestingly, analysis of the microarray data for these deregulated genes using the ingenuity pathway analysis software predicted that hCECs would stop migrating and proliferating but differentiate more when they are grown in the presence of the WNK1 inhibitor. These results demonstrate that WNK1 plays a critical function by orienting hCECs into the appropriate biological response during the process of corneal wound healing.

A Pilot Screen of a Novel Peptide Hormone Library Identified Candidate GPR83 Ligands

The identification of novel peptide hormones by functional screening is challenging because posttranslational processing is frequently required to generate biologically active hormones from inactive precursors. We developed an approach for functional screening of novel potential hormones by expressing them in endocrine host cells competent for posttranslational processing. Candidate preprohormones were selected by bioinformatics analysis, and stable endocrine host cell lines were engineered to express the preprohormones. The production of mature hormones was demonstrated by including the preprohormones insulin and glucagon, which require the regulated secretory pathway for production of the active forms. As proof of concept, we screened a set of G-protein-coupled receptors (GPCRs) and identified protein FAM237A as a specific activator of GPR83, a GPCR implicated in central nervous system and regulatory T-cell function. We identified the active form of FAM237A as a C-terminally cleaved, amidated 9 kDa secreted protein. The related protein FAM237B, which is 64% homologous to FAM237A, demonstrated similar posttranslational modification and activation of GPR83, albeit with reduced potency. These results demonstrate that our approach is capable of identifying and characterizing novel hormones that require processing for activity.

Human papillomavirus elevated genetic biomarker signature by statistical algorithm

Head and neck squamous cell carcinoma (HNSCC) is the one of the most frequently found cancers in the world. The aim of the study was to find the genes responsible and enriched pathways associated with HNSCC using bioinformatics and survival analysis methods. A total of 646 patients with HNSCC based on clinical information were considered for the study. HNSCC samples were grouped according to the parameters (RFS, DFS, PFS, or OS). The probe ID of these 11 genes was retrieved by Affymetrix using the NetAffx Query algorithm. The protein-protein interaction (PPI) network and Kaplan-Meier curve were used to find associations among the genes' expression data. We found that among these 11 genes, nine genes, CCNA1, MMP3, FLRT3, GJB6, ZFR2, PITX2, SYCP2, MEI1, and UGT8 were significant (p < .05). A survival plot was drawn between the p value and gene expression. This study helped us find the nine significant genes which play vital roles in HNSCC along with their key pathways and their interaction with other genes in the PPI network. Finally, we found the biomarker index for relapse time and risk factors for HNSCC in cancer patients.

Identification of Novel Candidate Biomarkers for Oral Squamous Cell Carcinoma Based on Whole Gene Expression Profiling

This study aimed to determine the whole gene expression profiles and to ascertain potential biomarkers for 22 oral squamous cell carcinoma (OSCC) among Thai patients using the Illumina Human HT-12, V4.0 Expression BeadChip array. Result indicated 2,724 differential expressed genes composed of 1,560 up-regulated and 1,164 down-regulated genes (unpaired t-test, p-value <0.05; fold change ≥2.0 and ≤2.0). The top 9 up-regulated genes were validated in 39 OSCC cases using TaqMan real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assay. Among these, the up-regulation of peptidase inhibitor 3 (PI3) and keratin 17 (KRT17) genes was harbored in all 39 OSCC patients (100%). Likewise, statistical analysis indicated that gene expression in 8 selective genes including keratin 16 (KRT16), keratin 14 (KRT14), keratinocyte differentiation-associated protein (KRTDAP), keratin 6B (KRT6B), PI3, S100 calcium binding protein A7 (S100A7), stratifin (SFN) and keratin 5 (KRT5) was significantly associated with well differentiated OSCC (p-value <0.05). Moreover, high level of KRT17 protein was significantly associated with well differentiated OSCC compared to moderately OSCC (p-value = 0.041). Notably, using nested-PCR analysis indicated all OSCC cases in this study were HPV-free. Especially, KRTDAP, PI3, SFN mRNA expression were first reported among patients with OSCC. Conclusion, the whole transcript expression study and TaqMan real-time qRT-PCR assay were relevant regarding the increase in gene expression in OSCC. In addition, the up-regulation of PI3 and KRT17 might constitute potential candidate molecular biomarkers to diagnose patients with OSCC.

Homeostatic Function of Dermokine in the Skin Barrier and Inflammation

Dermokine is a chiefly skin-specific secreted glycoprotein localized in the upper epidermis, and its family consists of three splice variants in mice and five in humans. To investigate the pathophysiological impact of dermokine, we generated mice deficient for two (βγ) or all dermokine isoforms (αβγ). Both variants, especially dermokine αβγ-deficient mice exhibited scale and wrinkle formation resembling ichthyosis accompanied by transepidermal water imbalance at the neonatal stage. Several dermokine αβγ-deficient mice died by postnatal day 21 when reared under low humidity. Moreover, the cornified envelope was vulnerable, and skin barrier lipid ceramides were reduced in the epidermis of dermokine αβγ-deficient mice. cDNA microarray and quantitative reverse transcriptase-PCR assays of the epidermis revealed the upregulation of small proline-rich protein and late cornified envelope family members, as well as antimicrobial peptides in the dermokine αβγ-deficient mice. These barrier gene signatures were similar to that seen in psoriasis, whereas recent studies demonstrated that congenital ichthyosis has gene profiles resembling psoriasis. In line with these findings, adult dermokine αβγ-deficient mice exhibited aggravated phenotypes in psoriasis-like dermatitis models but not in allergic dermatitis models. Dermokine may play a regulatory role in inflammatory dyskeratotic diseases, such as congenital ichthyosis and psoriasis, in the crosstalk between barrier dysfunction and inflammation.

Single-Cell Transcriptomics Reveals Spatial and Temporal Turnover of Keratinocyte Differentiation Regulators

Keratinocyte differentiation requires intricately coordinated spatiotemporal expression changes that specify epidermis structure and function. This article utilizes single-cell RNA-seq data from 22,338 human foreskin keratinocytes to reconstruct the transcriptional regulation of skin development and homeostasis genes, organizing them by differentiation stage and also into transcription factor (TF)–associated modules. We identify groups of TFs characterized by coordinate expression changes during progression from the undifferentiated basal to the differentiated state and show that these TFs also have concordant differential predicted binding enrichment in the super-enhancers previously reported to turn over between the two states. The identified TFs form a core subset of the regulators controlling gene modules essential for basal and differentiated keratinocyte functions, supporting their nomination as master coordinators of keratinocyte differentiation. Experimental depletion of the TFs ZBED2 and ETV4, both predicted to promote the basal state, induces differentiation. Furthermore, our single-cell RNA expression analysis reveals preferential expression of antioxidant genes in the basal state, suggesting keratinocytes actively suppress reactive oxygen species to maintain the undifferentiated state. Overall, our work demonstrates diverse computational methods to advance our understanding of dynamic gene regulation in development.

A study on periostin involvement in the pathophysiology of canine atopic skin

Atopic dermatitis (AD) is a chronic, pruritic, and allergic skin disease in humans and animals, particularly dogs. Canine AD (cAD) has received attention as a spontaneous atopic animal model because domesticated dogs inhabit a human environment, and cAD shares several clinicopathological features with human AD (hAD). In hAD, periostin (PO) is suggested to play a critical role in the enhancement and chronicity of allergic skin inflammation; however, PO involvement in the pathogenesis of cAD is unknown. Here we aimed to clarify PO involvement in the pathophysiology of cAD and focused on the inducing factor and function of PO in canine atopic skin. Using double-labeled in situ hybridization (ISH), interleukin (IL)-13 mRNA-positive cells were detected near the keratinocytes and dermal fibroblasts expressing PO mRNA in atopic skin. Using an in vitro assay, IL-13 induced PO gene expression in both canine dermal fibroblasts and keratinocytes. PO enhanced in vitro growth of canine keratinocytes. Moreover, among PO-induced genes in cultured canine keratinocytes detected using a microarray, we identified IL-25 as a possible mediator in canine atopic skin. In addition, real time polymerase chain reaction (PCR) analysis revealed upregulation of IL-25 gene expression in PO-stimulated keratinocytes. These data suggest that IL-13 possibly derived from T helper 2 (Th2) cells stimulates PO production in both keratinocytes and fibroblasts, and then PO may play a critical role in the pathophysiology of cAD, particularly in the enhancement and chronicity of skin lesions via IL-25.

MCPIP1 RNase Is Aberrantly Distributed in Psoriatic Epidermis and Rapidly Induced by IL-17A

ZC3H12A, which encodes the RNase monocyte chemotactic protein-induced protein 1 (MCPIP1), is up-regulated in psoriatic skin and reduced to normal levels after clinical treatments with anti-IL-17A/IL-17R neutralizing antibodies. In IL-17A-stimulated keratinocytes, MCPIP1 is rapidly increased at the transcript and protein levels. Also, IL-17A was found to be the main inducer of ZC3H12A expression in keratinocytes treated with supernatants derived from a Streptococcus pyogenes-activated psoriatic ex vivo model based on the co-culture of psoriatic cutaneous lymphocyte-associated antigen (CLA(+)) T cells and lesional epidermal cells. Moreover, MCPIP1 was aberrantly distributed in the suprabasal layers of psoriatic epidermis. In psoriatic samples, IL-17A-stimulated epidermal cell suspensions showed an increased MCPIP1 expression, especially in the mid-differentiated cellular compartment. The knockdown of ZC3H12A showed that this RNase participates in the regulation of the mRNAs present in suprabasal differentiated keratinocytes. Furthermore, JAK/STAT3 inhibition prevented the IL-17A-dependent induction of MCPIP1. In the mouse model of imiquimod-induced psoriasis, Zc3h12a expression was abrogated in Il17ra(-/-) mice. These results support the notion that IL-17A-mediated induction of MCPIP1 is involved in the regulation of local altered gene expression in suprabasal epidermal layers in psoriasis.

Storage Temperature Alters the Expression of Differentiation-Related Genes in Cultured Oral Keratinocytes

Purpose

Storage of cultured human oral keratinocytes (HOK) allows for transportation of cultured transplants to eye clinics worldwide. In a previous study, one-week storage of cultured HOK was found to be superior with regard to viability and morphology at 12°C compared to 4°C and 37°C. To understand more of how storage temperature affects cell phenotype, gene expression of HOK before and after storage at 4°C, 12°C, and 37°C was assessed.

Materials and Methods

Cultured HOK were stored in HEPES- and sodium bicarbonate-buffered Minimum Essential Medium at 4°C, 12°C, and 37°C for one week. Total RNA was isolated and the gene expression profile was determined using DNA microarrays and analyzed with Partek Genomics Suite software and Ingenuity Pathway Analysis. Differentially expressed genes (fold change > 1.5 and P < 0.05) were identified by one-way ANOVA. Key genes were validated using qPCR.

Results

Gene expression of cultures stored at 4°C and 12°C clustered close to the unstored control cultures. Cultures stored at 37°C displayed substantial change in gene expression compared to the other groups. In comparison with 12°C, 2,981 genes were differentially expressed at 37°C. In contrast, only 67 genes were differentially expressed between the unstored control and the cells stored at 12°C. The 12°C and 37°C culture groups differed most significantly with regard to the expression of differentiation markers. The Hedgehog signaling pathway was significantly downregulated at 37°C compared to 12°C.

Conclusion

HOK cultures stored at 37°C showed considerably larger changes in gene expression compared to unstored cells than cultured HOK stored at 4°C and 12°C. The changes observed at 37°C consisted of differentiation of the cells towards a squamous epithelium-specific phenotype. Storing cultured ocular surface transplants at 37°C is therefore not recommended. This is particularly interesting as 37°C is the standard incubation temperature used for cell culture.

Gene Expression Characterization of HPV Positive Head and Neck Cancer to Predict Response to Chemoradiation

Human papillomavirus (HPV) has been shown to have a causal role in the development of head and neck squamous cell carcinoma. While HPV-positive head and neck cancer is associated with a better response to treatment in the majority of patients, there is a subset who does not respond favorably to current therapy. Identification of these patients could prevent unnecessary morbidity and indicate the need for alternative therapeutic options. Tissue samples were obtained from 19 patients with HPV-positive head and neck squamous carcinoma treated with chemoradiation therapy. HPV status was confirmed by polymerase chain reaction analysis through detection of HPV16 E7 in both DNA and RNA. RNA was isolated from tissue samples and subjected to microarray gene expression analysis. In addition to identification of potential genetic biomarkers (including LCE3D, KRTDAP, HMOX1, KRT19, MDK, TSPAN1), differentially expressed genes associated with genomic stability, cell cycle, and DNA damage were detected between responders and non-responders. These results were further validated with publicly available gene expression studies. This pilot study suggests prospective biomarkers that predict response to therapy. The importance of genes involved with genomic stability is highlighted in both development and progression of head and neck squamous cell carcinoma but also recurrence. Potential development of an assay may prove beneficial to clinicians, assisting them to provide alternative care sooner thus lowering morbidity.

A predictive transcriptomic signature of oropharyngeal cancer according to HPV16 status exclusively

OBJECTIVE

Human-papillomaviruses (HPV) type 16 is a causative agent in an increasing subset of oropharyngeal squamous cell carcinomas (OPSCCs). These tumors have distinct oncogenic mechanisms and a more favorable prognosis than tobacco-induced OPSCCs. Although these differences emphasize the need for a specific therapeutic approach, HPV status is still not used to guide treatment. A better characterization of the molecular profile related to HPV16-induced OPSCC might help to develop personalized treatments.

PATIENTS AND METHODS

Using a human whole-genome DNA-microarray, we have examined the gene expression profiles in 15 HPV-negative and 15 transcriptionally-active HPV-positive OPSCCs. The study was conducted in two steps. Firstly, a learning/training-set consisting of 8 HPV16-positive and 8 HPV16-negative OPSCCs was analyzed to identify a specific signature. Potentially confounding factors (stage, sex and tobacco) were equally distributed in both groups. Subsequently the robustness of this signature was confirmed by blind case-by-case classification of a validation-set composed of the 14 remaining tumors.

RESULTS

We have identified a signature composed of 224 genes, which discriminates HPV16-induced OPSCC from their HPV-negative counterparts. After the blind classification of the 14 tumours, the viral status was revealed: 13 out of 14 tumors were correctly classified according to tumor etiology, 1/14 was not determined and none were misclassified. Several of the differentially expressed genes were involved in cell-cycle regulation, DNA replication and repair, transcription regulation, immune response and apoptosis.

CONCLUSION

Our study contributes to a better understanding of pathogenic mechanisms involved in the development of HPV-positive OPSCCs and in the identification of potential therapeutic targets.

Changes in gene expression in human meibomian gland dysfunction

PURPOSE

Meibomian gland dysfunction (MGD) may be the leading cause of dry eye syndrome throughout the world. However, the precise mechanism(s) underlying the pathogenesis of this disease is unclear. This study was conducted to identify meibomian gland genes that may promote the development and/or progression of human MGD.

METHODS

Lid tissues were obtained from male and female MGD patients and age-matched controls after eyelid surgeries (e.g., to correct entropion or ectropion). Meibomian glands were isolated and processed for RNA extraction and the analysis of gene expression.

RESULTS

The results show that MGD is associated with significant alterations in the expression of almost 400 genes in the human meibomian gland. The levels of 197 transcripts, including those encoding various small proline-rich proteins and S100 calcium-binding proteins, are significantly increased, whereas the expression of 194 genes, such as claudin 3 and cell adhesion molecule 1, is significantly decreased. These changes, which cannot be accounted for by sex differences, are accompanied by alterations in many gene ontologies (e.g., keratinization, cell cycle, and DNA repair). The findings also show that the human meibomian gland contains several highly expressed genes that are distinct from those in an adjacent tissue (i.e., conjunctival epithelium).

CONCLUSIONS

The results demonstrate that MGD is accompanied by multiple changes in gene expression in the meibomian gland. The nature of these alterations, including the upregulation of genes encoding small proline-rich proteins and S100 calcium-binding proteins, suggest that keratinization plays an important role in the pathogenesis of MGD.

Transcriptome profiles of carcinoma-in-situ and invasive non-small cell lung cancer as revealed by SAGE

Background

Non-small cell lung cancer (NSCLC) presents as a progressive disease spanning precancerous, preinvasive, locally invasive, and metastatic lesions. Identification of biological pathways reflective of these progressive stages, and aberrantly expressed genes associated with these pathways, would conceivably enhance therapeutic approaches to this devastating disease.

Methodology/Principal Findings

Through the construction and analysis of SAGE libraries, we have determined transcriptome profiles for preinvasive carcinoma-in-situ (CIS) and invasive squamous cell carcinoma (SCC) of the lung, and compared these with expression profiles generated from both bronchial epithelium, and precancerous metaplastic and dysplastic lesions using Ingenuity Pathway Analysis. Expression of genes associated with epidermal development, and loss of expression of genes associated with mucociliary biology, are predominant features of CIS, largely shared with precancerous lesions. Additionally, expression of genes associated with xenobiotic metabolism/detoxification is a notable feature of CIS, and is largely maintained in invasive cancer. Genes related to tissue fibrosis and acute phase immune response are characteristic of the invasive SCC phenotype. Moreover, the data presented here suggests that tissue remodeling/fibrosis is initiated at the early stages of CIS. Additionally, this study indicates that alteration in copy-number status represents a plausible mechanism for differential gene expression in CIS and invasive SCC.

Conclusions/Significance

This study is the first report of large-scale expression profiling of CIS of the lung. Unbiased expression profiling of these preinvasive and invasive lesions provides a platform for further investigations into the molecular genetic events relevant to early stages of squamous NSCLC development. Additionally, up-regulated genes detected at extreme differences between CIS and invasive cancer may have potential to serve as biomarkers for early detection.

Expression of canine Kdap in normal, hyperplastic and neoplastic epidermis

Keratinocyte differentiation-associated protein, Kdap, is a recently identified small secretory protein that may act as a soluble regulator for the cornification and/or desquamation of keratinocytes. To clarify the role of Kdap in the terminal differentiation of keratinocytes, detailed in situ localisation of Kdap was studied using canine skin with normal, hyperplastic and neoplastic epidermis. In normal canine trunk skin, Kdap was expressed by granular keratinocytes, with polarity to the apical side of the cells, suggesting that canine Kdap is present in lamellar granules, as in humans. Expression of Kdap was widespread in the spinous layers in hyperplastic epidermis, but was undetectable in squamous cell carcinomas. These findings suggest that Kdap is closely related to the delay of terminal differentiation and/or release of cells in hyperplastic epidermis.

Keratinization of outer root sheath cells is prevented by contact with inner root sheath of rat hair follicles

The purpose of the present study was to elucidate why keratinocytes of the outer root sheath (ORS) do not keratinize in situ. Two possibilities were considered--inhibition of keratinization is caused by contact of ORS with inner root sheath (IRS) or insufficient supply of keratinization promoting factors from the surrounding tissues to the ORS. In order to distinguish between these possibilities mid-segments of hair follicles were liberated from the dermis by dissection followed by collagenase digestion. ORS cells were then either allowed to migrate from the mid-segments or were kept on the agarose layer which prevented cell spreading and preserved three dimensional structure of hair root. Cultures were stimulated with calcium or EGF, and studied morphologically at the light and transmission electron microscope level. The level of mRNA for differentiation cell markers was also studied by RealTime PCR. ORS cells growing in a medium with low Ca2+ content formed monolayers, which after elevation of Ca2+ produced multilayers with cells containing keratohyalin-like granules. Ca2+ or EGF treatment upregulated expression of involucrin, filaggrin and keratinocyte differentiation associated protein (Kdap). Culture of mid-segments of hair follicles in low calcium culture medium kept on agarose increased expression of filaggrin and Kdap, but downregulated expression of involucrin. Stimulation by Ca2+ further increased expression of filaggrin and Kdap, but had no effect on the level of involucrin expression. EGF stimulated expression of filaggrin only. It is concluded that IRS exerted an inhibitory effect on the expression of involucrin, an essential component of the cornified envelope, thus preventing keratinization of ORS cells in situ. On the other hand, improved access of nutrients or promoting factors of keratinization to the mid-segment of hair follicles augmented expression of filaggrin and Kdap, proteins engaged in the differentiation of keratinocytes but not involved in its terminal phase.

Transcriptional profiling of developing mouse epidermis reveals novel patterns of coordinated gene expression

The mammalian epidermis is the first line of defense against external environmental challenges including dehydration. The epidermis undergoes a highly intricate developmental program in utero, transforming from a simple to a complex stratified epithelium. During this process of stratification and differentiation, epidermal keratinocytes express a defined set of structural proteins, mainly keratins, whose expression is controlled by largely unknown mechanisms. In order to identify novel factors contributing to epidermal morphogenesis, we performed a global transcriptional analysis of the developing mouse epidermis after separating it from the underlying dermis (E12.5-E15.5). Unexpectedly, the recently identified genes encoding secreted peptides dermokine (Dmkn), keratinocyte differentiation-associated protein (krtdap), and suprabasin (Sbsn) as well as a largely uncharacterized embryonic keratin (Krt77), were among the most highly differentially expressed genes. The three genes encoding the secreted proteins form a cluster in an approximately 40-Kb locus on human chromosome 19 and the syntenic region on mouse chromosome 7 known as the stratified epithelium secreted peptides complex (SSC). Using whole mount in situ hybridization, we show that these genes show a coordinated spatio-temporal expression pattern during epidermal morphogenesis. The expression of these genes initiates in the nasal epithelium and correlates with the initiation of other epidermal differentiation markers such as K1 and loricrin (Byrne et al. [1994] Development 120:2369-2383), as well as the initiation of barrier formation. Our observations reveal a coordinated mode of expression of the SSC genes as well as the correlation of their initiation in the nasal epithelium with the initiation of barrier formation at this site.

Dynamic changes in the cervical epithelial tight junction complex and differentiation occur during cervical ripening and parturition

Cervical epithelia have numerous functions that include proliferation, differentiation, maintenance of fluid balance, protection from environmental hazards, and paracellular transport of solutes via tight junctions (TJs). Epithelial functions must be tightly regulated during pregnancy and parturition as the cervix undergoes extensive growth and remodeling. This study evaluated TJ proteins, as well as markers of epithelial cell differentiation in normal and cervical ripening defective mice to gain insights into how the permeability barrier is regulated during pregnancy and parturition. Although numerous TJ proteins are expressed in the nonpregnant cervix, claudins 1 and 2 are temporally regulated in pregnancy. Claudin 1 mRNA expression is increased, whereas claudin 2 expression declines. The cellular localization of claudin 1 shifts at the end of pregnancy (gestation d 18.75) to the plasma membrane in a lattice pattern, consistent with TJs in the apical cells. The timing of claudin 1-enriched TJs coincides with initiation of terminal differentiation of cervical squamous epithelia as evidenced by the increased expression of genes by differentiated epithelia late on gestation d 18. The cervical ripening defective steroid 5alpha-reductase type 1 deficient mouse, which has an elevated local progesterone concentration, also has aberrant claudin 1 and 2 expressions, fails to form claudin 1-enriched TJs, and lacks normal expression of genes involved in epithelial terminal differentiation. These data suggest that changes in permeability barrier properties during cervical ripening are, in part, negatively regulated by progesterone, and that dynamic changes in barrier properties of the cervix occur during pregnancy and parturition.

Identification and cornification-related gene expression of canine keratinocyte differentiation-associated protein, Kdap

The outermost layer of skin, the epidermis, is cornified epithelial tissue composed of keratinocytes. To maintain the structure and function of the epidermis, the regulation of proliferation, differentiation, and cornification of keratinocytes is crucial, and various soluble factors secreted by keratinocytes are involved in these regulations. Previously, work has shown that keratinocytes secreted the protein Kdap (keratinocyte differentiation-associated protein) associated with the formation of cornified cell envelopes, a specialized protective barrier structure on the periphery of terminally differentiating keratinocytes. In the present report, the canine counterpart of human Kdap is identified and an attempt has been made to define its physiological role in canine keratinization. Canine Kdap (cKdap) showed structural features commonly observed in other counterparts and is secreted from transfected cells. The expression profile of cKdap mRNA, which was restrictively expressed in cornified epithelial tissues besides skin has also been determined. These findings indicate that there is a strong association between cKdap expression and cornification, which supports previous observations that Kdap is involved in the synthesis and/or degradation of cornified cell envelopes in humans and mice.