Isolation, sequence and expression of the gene encoding human keratin 13

Complement Regulatory Protein CD46 Manifests a Unique Role in Promoting the Migration of Bladder Cancer Cells

CD46 is a membrane-bound complement regulatory protein (mCRP) possessing a regulatory role with the complement system. CD46 protects the host cells from damage by complement. Expression of CD46 is also highly maintained in many cancers, including bladder cancers, and thus functions as a receptor for many cancer therapeutic viruses. In this study we report a unique role of CD46 as a progression factor of cancer cells in bladder cancers. Resulting data from a DNA microarray using CD46-altered HT1376 bladder cancers demonstrated a pool of target genes, including complement C3 α chain (C3α), matrix Gla protein (MGP), AFAP-AS1, follicular dendritic cell secreted protein (FDCSP), MAM domain containing 2 (MAMDC2), gamma-aminobutyric acid A receptor pi (GABRP), transforming growth factor, beta-induced (TGFBI), a family of cytochrome P450 (CYP24A1), sialic acid binding Ig-like lectin 6 (SIGLEC6), metallothionein 1E (MT1E), and several members of cytokeratins. Subsequent studies using quantitative RT-PCR and Western blot analyses confirmed CD46-mediated regulation of C3α, MGP, and keratin 13 (KRT13). MGP and KRT13 are known to be involved in cell migration and cancer cell metastasis. A cell migration assay demonstrated that CD46 enhanced migratory potential of bladder cancer cells. Taken all together, this report demonstrated that CD46 is generally overexpressed in bladder cancers and plays a unique role in the promotion of cancer cell migration. Further detailed studies are needed to be performed to clarify the action mechanism of CD46 and its application to cancer therapeutics.

Cytokeratin 13 (CK13) expression in cancer: a tissue microarray study on 10,439 tumors

Cytokeratin 13 (CK13) is a type I acidic low molecular weight cytokeratin, which is mainly expressed in urothelium and in the squamous epithelium of various sites of origin. Loss of CK13 has been implicated in the development and progression of squamous epithelial neoplasms. To comprehensively determine CK13 expression in normal and neoplastic tissues, a tissue microarray containing 10,439 samples from 131 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. CK13 immunostaining was detectable in 42 (32.1%) of the 131 tumor categories including 24 (18.3%) tumor types with at least one strongly positive case. The highest rate of positive staining was found in various urothelial neoplasms (52.1-92.3%) including Brenner tumor of the ovary (86.8%) and in squamous cell carcinomas from various sites of origin (39.1-77.6%), Warthin tumors of parotid glands (66.7%), adenosquamous carcinomas of the cervix (33.3%), thymomas (16.0%), and endometroid carcinomas of the ovary (15.3%). Twenty other epithelial or germ cell neoplasms showed - a usually weak - CK13 positivity in less than 15% of the cases. In bladder cancer, reduced CK13 expression was linked to high grade and advanced stage (p < 0.0001 each). In squamous cell carcinoma of the cervix, reduced CK13 immunostaining was related to high grade (p = 0.0295) and shortened recurrence-free (p = 0.0094) and overall survival (p = 0.0274). In a combined analysis of 1,151 squamous cell carcinomas from 11 different sites of origin, reduced CK13 staining was linked to high grade (p = 0.0050). Our data provide a comprehensive overview on CK13 expression in normal and neoplastic human tissues. CK13 expression predominates in urothelial neoplasms and in squamous cell carcinomas of different organs, and a loss of CK13 expression is associated with aggressive disease in these tumors.

Morphological and Molecular Functional Evidence of the Pharyngeal Sac in the Digestive Tract of Silver Pomfret, Pampus argenteus

The pharyngeal sac is a comparatively rare organ in the digestive tract among teleost fishes. However, our understanding of this remarkable organ in the silver pomfret (Pampus argenteus) is limited. In the present study, we examined the various morphological and histological characteristics of the pharyngeal sac using histochemical techniques and electron microscopy. The pharyngeal sac showed unique characteristics such as well-developed muscular walls, weakly keratinized epithelium, numerous goblet cells, and needle-like processes on the papillae. The porous cavity of the papillae contained numerous adipocytes and was tightly enveloped by type I collagen fibers. These structures might provide mechanical protection and excellent biomechanical properties for grinding and shredding prey. A comparison of gene expression levels between the pharyngeal sac and esophagus using RNA-seq showed that phenotype-associated genes (epithelial genes and muscle genes) were upregulated, whereas genes related to nutrient digestion and absorption were downregulated in the pharyngeal sac. These results support the role of the pharyngeal sac in shredding and predigesting food. Overall, these findings provide a clearer understanding of the pharyngeal sac morphology and explain the morphological adaptations of the digestive tract for feeding on gelatinous prey. To our knowledge, this is the first report on pharyngeal sac gene expression in P. argenteus.

Brain metastatic outgrowth and osimertinib resistance are potentiated by RhoA in EGFR-mutant lung cancer

The brain is a major sanctuary site for metastatic cancer cells that evade systemic therapies. Through pre-clinical pharmacological, biological, and molecular studies, we characterize the functional link between drug resistance and central nervous system (CNS) relapse in Epidermal Growth Factor Receptor- (EGFR-) mutant non-small cell lung cancer, which can progress in the brain when treated with the CNS-penetrant EGFR inhibitor osimertinib. Despite widespread osimertinib distribution in vivo, the brain microvascular tumor microenvironment (TME) is associated with the persistence of malignant cell sub-populations, which are poised to proliferate in the brain as osimertinib-resistant lesions over time. Cellular and molecular features of this poised state are regulated through a Ras homolog family member A (RhoA) and Serum Responsive Factor (SRF) gene expression program. RhoA potentiates the outgrowth of disseminated tumor cells on osimertinib treatment, preferentially in response to extracellular laminin and in the brain. Thus, we identify pre-existing and adaptive features of metastatic and drug-resistant cancer cells, which are enhanced by RhoA/SRF signaling and the brain TME during the evolution of osimertinib-resistant disease.

Screening of primary open-angle glaucoma diagnostic markers based on immune-related genes and immune infiltration

Purpose

Primary open-angle glaucoma (POAG) continues to be a poorly understood disease. Although there were multiple researches on the identification of POAG biomarkers, few studies systematically revealed the immune-related cells and immune infiltration of POAG. Bioinformatics analyses of optic nerve (ON) and trabecular meshwork (TM) gene expression data were performed to further elucidate the immune-related genes of POAG and identify candidate target genes for treatment.

Methods

We performed a gene analysis of publicly available microarray data, namely, the GSE27276-GPL2507, GSE2378-GPL8300, GSE9944-GPL8300, and GSE9944-GPL571 datasets from the Gene Expression Omnibus database. The obtained datasets were used as input for parallel pathway analyses. Based on random forest and support vector machine (SVM) analysis to screen the key genes, significantly changed pathways were clustered into functional categories, and the results were further investigated. CIBERSORT was used to evaluate the infiltration of immune cells in POAG tissues. A network visualizing the differences between the data in the POAG and normal groups was created. GO and KEGG enrichment analyses were performed using the Metascape database. We divided the differentially expressed mRNAs into upregulated and downregulated groups and predicted the drug targets of the differentially expressed genes through the Connectivity Map (CMap) database.

Results

A total of 49 differentially expressed genes, including 19 downregulated genes and 30 upregulated genes, were detected. Five genes ((Keratin 14) KRT14, (Hemoglobin subunit beta) HBB, (Acyl-CoA Oxidase 2) ACOX2, (Hephaestin) HEPH and Keratin 13 (KRT13)) were significantly changed. The results showed that the expression profiles of drug disturbances, including those for avrainvillamide-analysis-3, cytochalasin-D, NPI-2358, oxymethylone and vinorelbine, were negatively correlated with the expression profiles of disease disturbances. This finding indicated that these drugs may reduce or even reverse the POAG disease state.

Conclusion

This study provides an overview of the processes involved in the molecular pathogenesis of POAG in the ON and TM. The findings provide a new understanding of the molecular mechanism of POAG from the perspective of immunology.

KRT13 promotes stemness and drives metastasis in breast cancer through a plakoglobin/c-Myc signaling pathway

Background

Keratins (KRTs) are intermediate filament proteins that interact with multiple regulatory proteins to initiate signaling cascades. Keratin 13 (KRT13) plays an important role in breast cancer progression and metastasis. The objective of this study is to elucidate the mechanism by which KRT13 promotes breast cancer growth and metastasis.

Methods

The function and mechanisms of KRT13 in breast cancer progression and metastasis were assessed by overexpression and knockdown followed by examination of altered behaviors in breast cancer cells and in xenograft tumor formation in mouse mammary fat pad. Human breast cancer specimens were examined by immunohistochemistry and multiplexed quantum dot labeling analysis to correlate KRT13 expression to breast cancer progression and metastasis.

Results

KRT13-overexpressing MCF7 cells displayed increased proliferation, invasion, migration and in vivo tumor growth and metastasis to bone and lung. Conversely, KRT13 knockdown inhibited the aggressive behaviors of HCC1954 cells. At the molecular level, KRT13 directly interacted with plakoglobin (PG, γ-catenin) to form complexes with desmoplakin (DSP). This complex interfered with PG expression and nuclear translocation and abrogated PG-mediated suppression of c-Myc expression, while the KRT13/PG/c-Myc signaling pathway increased epithelial to mesenchymal transition and stem cell-like phenotype. KRT13 expression in 58 human breast cancer tissues was up-regulated especially at the invasive front and in metastatic specimens (12/18) (p < 0.05). KRT13 up-regulation in primary breast cancer was associated with decreased overall patient survival.

Conclusions

This study reveals that KRT13 promotes breast cancer cell growth and metastasis via a plakoglobin/c-Myc pathway. Our findings reveal a potential novel pathway for therapeutic targeting of breast cancer progression and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-022-01502-6.

The Effect of Gender-Affirming Medical Care on the Vaginal and Neovaginal Microbiomes of Transgender and Gender-Diverse People

Transgender and gender diverse individuals may seek gender-affirming medical care, such as hormone therapy or surgery, to produce primary and/or secondary sex characteristics that are more congruent with their gender. Gender-affirming medical care for transmasculine individuals can include testosterone therapy, which suppresses circulating estrogen and can lead to changes in the vaginal epithelium that are reminiscent of the post-menopausal period in cisgender females. Among transfeminine individuals, gender-affirming medical care can include vaginoplasty, which is the surgical creation of a vulva and neovaginal canal, commonly using penile and scrotal skin. The effect of gender-affirming medical care on the vagina of transmasculine individuals and on the neovagina of transfeminine individuals is poorly characterized. This review summarizes what is known of the epithelium and local microbiota of the testosterone-exposed vagina and the neovagina. We focus on potential pathogens and determinants of gynecological health and identify key knowledge gaps for future research.

Cellular Imprinting Proteomics Assay: A Novel Method for Detection of Neural and Ocular Disorders Applied to Congenital Zika Virus Syndrome

Congenital Zika syndrome was first described due to increased incidence of congenital abnormalities associated with Zika virus (ZIKV) infection. Since the eye develops as part of the embryo central nervous system (CNS) structure, it becomes a specialized compartment able to display symptoms of neurodegenerative diseases and has been proposed as a noninvasive approach to the early diagnosis of neurological diseases. Ocular lesions result from defects that occurred during embryogenesis and can become apparent in newborns exposed to ZIKV. Furthermore, the absence of microcephaly cannot exclude the occurrence of ocular lesions and other CNS manifestations. Considering the need for surveillance of newborns and infants with possible congenital exposure, we developed a method termed cellular imprinting proteomic assay (CImPA) to evaluate the ocular surface proteome specific to infants exposed to ZIKV during gestation compared to nonexposure. CImPA combines surface cells and fluid capture using membrane disks and a large-scale quantitative proteomics approach, which allowed the first-time report of molecular alterations such as neutrophil degranulation, cell death signaling, ocular and neurological pathways, which are associated with ZIKV infection with and without the development of congenital Zika syndrome, CZS. Particularly, infants exposed to ZIKV during gestation and without early clinical symptoms could be detected using the CImPA method. Lastly, this methodology has broad applicability as it could be translated in the study of several neurological diseases to identify novel diagnostic biomarkers. Data are available via ProteomeXchange with identifier PXD014038.

Development, characterization and virus susceptibility of a continuous cell line from the caudal fin of marbled eel (Anguilla marmorata)

A continuous cell line consisting mostly of epithelioid cells was established from the caudal fin of marbled eels (Anguilla marmorata) and designated as marbled eel caudal fin (MECF)-1. The cells multiplied well in Leibovitz's L-15 medium containing 2% to 15% foetal bovine serum at temperatures of 20°C to 35°C and were subcultured for >90 passages during a 5-year period from 2012 to 2017. Transcripts of ictacalcin, keratin 13, cd146, nestin, ncam1 and myod1 were demonstrated in the cells using reverse transcription polymerase chain reaction. The results indicated that MECF-1 was composed of epidermal and mesenchyme stem and progenitor cells including myoblasts. MECF-1 was susceptible to Japanese eel herpesvirus HVA980811, marbled eel polyoma-like virus (MEPyV), aquabirnavirus MEIPNV1310 and aquareovirus CSV. By contrast, MECF-1 was noted refractory to megalocytiviruses RSIV-Ku and GSIV-K1 infection. Moreover, the cells were resistant to betanodavirus infection. In conclusion, MECF-1 derived from marbled eel is suitable for studies on anguillid viruses and interaction with host cells.

Keratin 13 gene is epigenetically suppressed during transforming growth factor-β1-induced epithelial-mesenchymal transition in a human keratinocyte cell line

Epithelial-mesenchymal transition (EMT) is a biological event in which epithelial cells lose their polarity and cell-cell adhesions and concomitantly acquire mesenchymal traits, and is thought to play an important role in pathological processes such as wound healing and cancer progression. In this study, we evaluated transforming growth factor (TGF)-β1-treated human keratinocyte HaCaT cells as an in vitro model of EMT. HaCaT cells were changed into an elongated fibroblast-like morphology, which is indicative of EMT in response to TGF-β1. Phalloidin staining demonstrated the formation of actin stress fibers in TGF-β1-treated cells. Quantitative RT-PCR analysis revealed that TGF-β1 increased the mRNA levels of EMT transcription factors (SNAI2, TWIST1, and ZEB1) and mesenchymal markers (CDH2, VIM, and FN1), while it decreased the transcripts of epithelial phenotypic genes (CLDN1, OCLN, KRT5, KRT15, KRT13, and TGM1). Furthermore, we found that KRT13 was drastically suppressed through the reduction of RNA polymerase II occupancy of its promoter, which was accompanied by a decrease in active histone marks (H3K4me3 and H3K27ac) and an increase in a repressive mark (H3K27me3) during EMT. These findings indicate that the TGF-β1-induced EMT program regulates a subset of epithelial and mesenchymal marker genes, and that KRT13 is transcriptionally suppressed through the modulation of the chromatin state at the KRT13 promoter in HaCaT cells.

Comparative study of cytokeratin and langerin expression in keratinized cystic lesions of the oral and maxillofacial regions

Dermoid cysts (DMCs) and epidermoid cysts (EDMCs) usually arise in soft tissues, whereas orthokeratinized odontogenic cysts (OOCs) and keratocystic odontogenic tumors (KCOTs) develop in the jaw. In this study, we performed immunohistochemical analysis of cytokeratins (CKs) to examine differences in the lining epithelium of DMCs, EDMCs, OOCs, and KCOTs. In addition, we carried out immunohistochemical examination of langerin to clarify the biological characteristics of the orthokeratinized lining epithelium of DMCs, EDMCs, and OOCs. Seven DMCs, 30 EDMCs, 11 OOCs, and 28 KCOTs were examined immunohistochemically using antibodies against CK10, 13, 14, 16, 17, 19, and langerin. Immunoreactivities for CKs and langerin in oral DMCs and EDMCs were similar to those of lesions affecting the skin. Positive reactivity for CK13 and 17 was evident in OOCs, but not in DMCs/EDMCs. CK10 was significantly positive in all layers except for the basal layer in OOCs, but was negative in KCOTs. CK17 was positive in all layers in KCOTs, and in all layers except for the basal layer in both OOCs and dentigerous cysts. CK19 was negative in OOCs. Langerhans cells were found mainly in OOCs, but were hardly evident in KCOTs. These results suggest that DMCs/EDMCs, OOCs and KCOTs are independent diseases.

Keratin 13 Is Enriched in Prostate Tubule-Initiating Cells and May Identify Primary Prostate Tumors that Metastasize to the Bone

Background

Benign human prostate tubule-initiating cells (TIC) and aggressive prostate cancer display common traits, including tolerance of low androgen levels, resistance to apoptosis, and microenvironment interactions that drive epithelial budding and outgrowth. TIC can be distinguished from epithelial and stromal cells that comprise prostate tissue via cell sorting based upon Epcam, CD44, and CD49f antigenic profiles. Fetal prostate epithelial cells (FC) possess a similar antigenic profile to adult TIC and are capable of inducing tubule formation. To identify the TIC niche in human prostate tissue, differential keratin (KRT) expression was evaluated.

Results

Gene expression data generated from Affymetrix Gene Chip human U133 Plus 2.0 array of sorted adult and fetal epithelial cells revealed KRT13 to be significantly enriched in FC and TIC compared to basal cells (BC) and luminal cells (LC) (p<0.001). Enriched KRT13 expression was confirmed by RT-PCR and cytospin immunostaining. Immunohistochemical analysis of KRT13 expression revealed rare KRT13⁺ epithelia throughout prostatic ducts/acini in adult tissue specimens and differentiated tubules in 24-week recombinant grafts, In contrast, abundant KRT13 expression was observed in developing ducts/acini in fetal prostate and cord-like structures composing 8-week recombinant grafts. Immunostaining of a prostate tissue microarray revealed KRT13⁺ tumor foci in approximately 9% of cases, and this subset displayed significantly shorter time to recurrence (p = 0.031), metastases (p = 0.032), and decreased overall survival (p = 0.004). Diagnostic prostate needle biopsies (PNBX) from untreated patients with concurrent bone metastases (clinical stage M1) displayed KRT13⁺ tumor foci, as did bone metastatic foci.

Conclusions

The expression profile of KRT13 in benign fetal and adult prostate tissue and in recombinant grafts, as well as the frequency of KRT13 expression in primary and metastatic prostate cancer indicates that it may be a marker of a stem/progenitor-like cell state that is co-opted in aggressive tumor cells. KRT13 is enriched in benign stem-like cells that display androgen-resistance, apoptosis-resistance, and branching morphogenesis properties. Collectively our data demonstrate that KRT13 expression is associated with poor prognosis at multiple stages of disease progression and may represent an important biomarker of adverse outcome in patients with prostate cancer.

Epigenetic alterations of the keratin 13 gene in oral squamous cell carcinoma

Background

Epigenetic modifications play important roles in the regulation of gene expression determining cellular phenotype as well as various pathologies such as cancer. Although the loss of keratin 13 (KRT13) is reportedly linked to malignant transformation of oral epithelial cells, the molecular mechanisms through which KRT13 is repressed in oral squamous cell carcinoma (OSCC) remain unclear. The aim of this study is to identify the epigenetic alterations of the KRT13 gene in OSCCs.

Methods

We investigated KRT13 expression levels and chromatin modifications of the KRT13 promoter in the three OSCC cell lines (HSC4, HSC3, and SAS). The expression levels of KRT13 protein and mRNA were analyzed by western blotting and quantitative reverse-transcription polymerase chain reaction, respectively, and the localization of KRT13 protein was detected by immunofluorescence. DNA methylation and histone modifications in the KRT13 promoter were determined by bisulfite sequencing and chromatin immunoprecipitation (ChIP), respectively. For the pharmacological depletion of Polycomb repressive complex 2 (PRC2), cells were treated with 3-deazaneplanocin A (DZNep).

Results

KRT13 expression was transcriptionally silenced in the HSC3 and SAS cells and post-transcriptionally repressed in the HSC4 cells, while the KRT13 promoter was hypermethylated in all of the three OSCC cell lines. ChIP analysis revealed that PRC2-mediated trimethylation of Lys 27 on histone H3 (H3K27me3) was increased in the KRT13 promoter in the HSC3 and SAS cells. Finally, we demonstrated that the treatment of SAS cells with DZNep reactivated the transcription of KRT13 gene.

Conclusions

Our data provide mechanistic insights into the epigenetic silencing of KRT13 genes in OSCC cells and might be useful for the development of diagnostic markers and novel therapeutic approaches against OSCCs.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-988) contains supplementary material, which is available to authorized users.

Exploration of global gene expression changes during the estrous cycle in equine endometrium

The equine endometrium exhibits characteristic morphological and functional changes during the estrous cycle controlled by the interplay of progesterone and estradiol. A microarray analysis of endometrial tissue samples derived from five time points of the estrous cycle (Day [D] 0, D3, D8, D12, and D16) was performed to study the dynamics of equine endometrial gene expression. Statistical analysis revealed 4996 genes differentially expressed during the estrous cycle. Clustering of similar expression profiles was performed to find groups of coregulated genes. This revealed eight major profiles: highest mRNA concentrations on D0, from D0 to D3, on D3, from D3 to D8, on D8, from D8 to D12, from D12 to D16, and on D16. Bioinformatics analysis revealed distinct molecular functions and biological processes for the individual expression profiles characterizing the different phases of the estrous cycle (e.g., extracellular matrix and inflammatory response during the estrus phase, cell division and cell cycle during early luteal phase, and endoplasmic reticulum, protein transport, and lipid metabolism in the luteal phase). A comparison to dynamic gene expression changes in bovine endometrium identified common and species-specific gene regulations in cyclic endometrium. Analysis of expression changes during the estrous cycle for genes previously found to be differentially expressed on D12 of pregnancy provided new evidence for possible regulation of these genes. This study provides new insights regarding global changes of equine endometrial gene expression as molecular reflections of physiological changes in the cyclic equine endometrium with regard to the crucial role of this tissue for successful reproduction.

Sex differences in the response of the alveolar macrophage proteome to treatment with exogenous surfactant protein-A

Background

Male wild type (WT) C57BL/6 mice are less capable of clearing bacteria and surviving from bacterial pneumonia than females. However, if an oxidative stress (acute ozone exposure) occurs before infection, the advantage shifts to males who then survive at higher rates than females. We have previously demonstrated that survival in surfactant protein-A (SP-A) knockout (KO) mice compared to WT was significantly reduced. Because the alveolar macrophage (AM) is pivotal in host defense we hypothesized that SP-A and circulating sex hormones are responsible for these sex differences. We used 2D-DIGE to examine the relationship of sex and SP-A on the AM proteome. The role of SP-A was investigated by treating SP-A KO mice with exogenous SP-A for 6 and 18 hr and studying its effects on the AM proteome.

Results

We found: 1) less variance between KO males and females than between the WT counterparts by principal component analysis, indicating that SP-A plays a role in sex differences; 2) fewer changes in females when the total numbers of significantly changing protein spots or identified whole proteins in WT or 18 hr SP-A-treated males or females were compared to their respective KO groups; 3) more proteins with functions related to chaperones or protease balance and Nrf2-regulated proteins changed in response to SP-A in females than in males; and 4) the overall pattern of SP-A induced changes in actin-related proteins were similar in both sexes, although males had more significant changes.

Conclusions

Although there seems to be an interaction between sex and the effect of SP-A, it is unclear what the responsible mechanisms are. However, we found that several of the proteins that were expressed at significantly higher levels in females than in males in WT and/or in KO mice are known to interact with the estrogen receptor and may thus play a role in the SP-A/sex interaction. These include major vault protein, chaperonin subunit 2 (beta) (CCT2), and Rho GDP alpha dissociation inhibitor. We conclude that sex differences exist in the proteome of AM derived from male and female mice and that SP-A contributes to these sex differences.

Effects of multiple agents on epithelial differentiation of rabbit adipose-derived stem cells in 3D culture

Mesenchymal stem cells have been given particular attention in tissue regeneration research due to their multipotency and proliferative activity. In this study, we investigated the possibility of epithelial differentiation of rabbit adipose-derived stem cells (rASCs) in an in vitro 3D culture system. The experimental procedure was performed with different contributing factors including all-trans retinoic acid (ATRA), epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), and hydrocortisone in air-liquid interface culture, for modulating proliferation and providing a synergistic effect on epithelial differentiation of rASCs. After induction, immunofluorescence staining, western blot analysis, flow cytometry analysis, and quantitative real-time polymerase chain reaction assay have been performed to detect the expression of epithelial-specific markers and mesenchymal marker alpha-smooth muscle actin (α-SMA). The growth pattern and viability of cells were evaluated by transmission electron microscopy and Hoechst 33258 assay, respectively. After treated with optimized induction medium (including 2.5 μM ATRA, 20 ng/mL EGF, 10 ng/mL KGF, 10 ng/mL HGF, and 0.5 μg/mL hydrocortisone), rASCs were observed to display a stratified epithelial-like morphology, with the expression of cytokeratin 19 and cytokeratin 13 in 63.69%±2.63% and 22.17%±1.51%, respectively, and the relative expression level of cytokeratin 19 increased to 3.152 compared with 0.151 before induction. The expression of α-SMA decreased to 19.40%±1.45% after induction, but almost no expression of involucrin was detected. The results showed that the establishment of an epithelial-specific microenvironment may be a feasible way for epithelial differentiation of ASCs in vitro, and provided an alternative for research on epithelium regeneration.

A multiplex (m)RNA-profiling system for the forensic identification of body fluids and contact traces

In current forensic practice, information about the possible biological origin of forensic traces is mostly determined using protein-based presumptive testing. Recently, messenger RNA-profiling has emerged as an alternative strategy to examine the biological origin. Here we describe the development of a single multiplex mRNA-based system for the discrimination of the most common forensic body fluids as well as skin cells. A DNA/RNA co-isolation protocol was established that results in DNA yields equivalent to our standard in-house validated DNA extraction procedure which uses silica-based columns. An endpoint RT-PCR assay was developed that simultaneously amplifies 19 (m)RNA markers. This multiplex assay analyses three housekeeping, three blood, two saliva, two semen, two menstrual secretion, two vaginal mucosa, three general mucosa and two skin markers. The assay has good sensitivity as full RNA profiles for blood, semen and saliva were obtained when using ≥0.05 μL body fluid starting material whereas full DNA profiles were obtained with ≥0.1 μL. We investigated the specificity of the markers by analysing 15 different sets of each type of body fluid and skin with each set consisting of 8 individuals. Since skin markers have not been incorporated in multiplex endpoint PCR assays previously, we analysed these markers in more detail. Interestingly, both skin markers gave a positive result in samplings of the hands, feet, back and lips but negative in tongue samplings. Positive identification (regarding both DNA- and RNA-profiling) was obtained for specimens stored for many years, e.g. blood (28 years-old), semen (28 years-old), saliva (6 years-old), skin (10 years-old) and menstrual secretion (4 years-old). The described approach of combined DNA- and RNA-profiling of body fluids and contact traces assists in the interpretation of forensic stains by providing information about not only the donor(s) that contributed to the stain but also by indicating which cell types are present.

In vivo rescue of alveolar macrophages from SP-A knockout mice with exogenous SP-A nearly restores a wild type intracellular proteome; actin involvement

BACKGROUND

Mice lacking surfactant protein-A (SP-A-/-; knockout; KO) exhibit increased vulnerability to infection and injury. Although many bronchoalveolar lavage (BAL) protein differences between KO and wild-type (WT) are rapidly reversed in KO after infection, their clinical course is still compromised. We studied the impact of SP-A on the alveolar macrophage (AM) proteome under basal conditions. Male SP-A KO mice were SP-A-treated (5 micrograms/mouse) and sacrificed in 6 or 18 hr. The AM proteomes of KO, SP-A-treated KO, and WT mice were studied by 2D-DIGE coupled with MALDI-ToF/ToF and AM actin distribution was examined by phalloidon staining.

RESULTS

We observed: a) significant differences from KO in WT or exogenous SP-A-treated in 45 of 76 identified proteins (both increases and decreases). These included actin-related/cytoskeletal proteins (involved in motility, phagocytosis, endocytosis), proteins of intracellular signaling, cell differentiation/regulation, regulation of inflammation, protease/chaperone function, and proteins related to Nrf2-mediated oxidative stress response pathway; b) SP-A-induced changes causing the AM proteome of the KO to resemble that of WT; and c) that SP-A treatment altered cell size and F-actin distribution.

CONCLUSIONS

These differences are likely to enhance AM function. The observations show for the first time that acute in vivo SP-A treatment of KO mice, under basal or unstimulated conditions, affects the expression of multiple AM proteins, alters F-actin distribution, and can restore much of the WT phenotype. We postulate that the SP-A-mediated expression profile of the AM places it in a state of "readiness" to successfully conduct its innate immune functions and ensure lung health.

Farnesoid X receptor protects human and murine gastric epithelial cells against inflammation-induced damage

Bile acids from duodenogastric reflux promote inflammation and increase the risk for gastro-oesophageal cancers. FXR (farnesoid X receptor/NR1H4) is a transcription factor regulated by bile acids such as CDCA (chenodeoxycholic acid). FXR protects the liver and the intestinal tract against bile acid overload; however, a functional role for FXR in the stomach has not been described. We detected FXR expression in the normal human stomach and in GC (gastric cancer). FXR mRNA and protein were also present in the human GC cell lines MKN45 and SNU5, but not in the AGS cell line. Transfection of FXR into AGS cells protected against TNFα (tumour necrosis factor α)-induced cell damage. We identified K13 (keratin 13), an anti-apoptotic protein of desmosomes, as a novel CDCA-regulated FXR-target gene. FXR bound to a conserved regulatory element in the proximal human K13 promoter. Gastric expression of K13 mRNA was increased in an FXR-dependent manner by a chow diet enriched with 1% (w/w) CDCA and by indomethacin (35 mg/kg of body weight intraperitoneal) in C57BL/6 mice. FXR-deficient mice were more susceptible to indomethacin-induced gastric ulceration than their WT (wild-type) littermates. These results suggest that FXR increases the resistance of human and murine gastric epithelial cells to inflammation-mediated damage and may thus participate in the development of GC.

Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia

Historically, the term 'keratin' stood for all of the proteins extracted from skin modifications, such as horns, claws and hooves. Subsequently, it was realized that this keratin is actually a mixture of keratins, keratin filament-associated proteins and other proteins, such as enzymes. Keratins were then defined as certain filament-forming proteins with specific physicochemical properties and extracted from the cornified layer of the epidermis, whereas those filament-forming proteins that were extracted from the living layers of the epidermis were grouped as 'prekeratins' or 'cytokeratins'. Currently, the term 'keratin' covers all intermediate filament-forming proteins with specific physicochemical properties and produced in any vertebrate epithelia. Similarly, the nomenclature of epithelia as cornified, keratinized or non-keratinized is based historically on the notion that only the epidermis of skin modifications such as horns, claws and hooves is cornified, that the non-modified epidermis is a keratinized stratified epithelium, and that all other stratified and non-stratified epithelia are non-keratinized epithelia. At this point in time, the concepts of keratins and of keratinized or cornified epithelia need clarification and revision concerning the structure and function of keratin and keratin filaments in various epithelia of different species, as well as of keratin genes and their modifications, in view of recent research, such as the sequencing of keratin proteins and their genes, cell culture, transfection of epithelial cells, immunohistochemistry and immunoblotting. Recently, new functions of keratins and keratin filaments in cell signaling and intracellular vesicle transport have been discovered. It is currently understood that all stratified epithelia are keratinized and that some of these keratinized stratified epithelia cornify by forming a Stratum corneum. The processes of keratinization and cornification in skin modifications are different especially with respect to the keratins that are produced. Future research in keratins will provide a better understanding of the processes of keratinization and cornification of stratified epithelia, including those of skin modifications, of the adaptability of epithelia in general, of skin diseases, and of the changes in structure and function of epithelia in the course of evolution. This review focuses on keratins and keratin filaments in mammalian tissue but keratins in the tissues of some other vertebrates are also considered.

Differential estradiol and selective estrogen receptor modulator (SERM) regulation of Keratin 13 gene expression and its underlying mechanism in breast cancer cells

Expression of the Keratin 13 (KRT13) gene, which encodes a cytoskeletal protein thought to play important roles in breast cancer growth and metastasis, is differentially regulated by estradiol (E2) and the selective estrogen receptor modulators (SERMs) tamoxifen and raloxifene. While stimulation of KRT13 by tamoxifen is robust and prolonged, stimulation by E2 is more transient and raloxifene has virtually no effect. To investigate the mechanistic basis for the differential ligand regulation of KRT13, we have defined the regulatory regions of KRT13, compared gene expression by E2 and SERMs, and explored the magnitudes and time courses of estrogen receptor (ER) and cofactor recruitment patterns on these regions. Using a ChIP scanning approach and reporter transactivation assays, we identified a 2.5 kb upstream ER-binding regulatory region for KRT13. Directed composite mutations in this region revealed that three estrogen response elements and three Sp1 sites were involved in its ligand-dependent regulation. Differential recruitment of ERalpha and cofactors to the KRT13 regulatory sites paralleled the different time course and magnitude of regulation by these ligands: there was almost no ERalpha or cofactor recruitment with raloxifene, whereas there was strong, prolonged ER recruitment and histone acetylation with tamoxifen, and an early and more transient recruitment with E2. Taken together, our results suggest that the different ligand regulations of KRT13 are due to ligand-differential recruitment of ER and coactivators, and they provide insight into the mechanisms responsible for the different agonistic activities and differential gene regulation by estradiol and the SERMs tamoxifen and raloxifene.

Two new mutations in the keratin 4 gene causing oral white sponge nevus in Chinese family

OBJECTIVE

We investigated white sponge nevus (WSN) in a Chinese family, and tried to find new mutation and demonstrated that this mutation is the causative mutation for WSN in this family and this condition affects a functionally important segment of the keratin 4 protein.

MATERIALS AND METHODS

We studied the affected family with the 32-year-old female patient, her mother, her younger sister and her daughter. Pathologic examinations were performed. DNA was extracted from peripheral blood lymphocytes, K4 and K13 genes were amplified by polymerase chain reaction (PCR) and sequenced.

RESULTS

Direct sequencing of PCR products revealed two new mutations in the keratin 4 gene, the heterozygous missense mutation 1829G-->A in exon 2B, and 2324A-->G in non-coding region. No any mutation was found in the keratin 13 gene.

CONCLUSIONS

We found two new mutations in the keratin 4, which may be related with the development of WSN.

Activation of peroxisome proliferator-activated receptor-gamma reverses squamous metaplasia and induces transitional differentiation in normal human urothelial cells

We observed that in urothelium, both cornifying and noncornifying forms of squamous metaplasia are accompanied by changes in the localization of the nuclear hormone receptors, peroxisome proliferator activated receptor gamma (PPAR-gamma) and retinoid X receptor (RXR-alpha). To obtain objective evidence for a role for PPAR-gamma-mediated signaling in urothelial differentiation, we examined expression of the cytokeratin isotypes CK13, CK20, and CK14 as indicators of transitional, terminal transitional, and squamous differentiation, respectively, in cultures of normal human urothelial cells. In control culture conditions, normal human urothelial cells showed evidence of squamous differentiation (CK14+, CK13-, CK20-). Treatment with the high-affinity PPAR-gamma agonist, troglitazone (TZ), resulted in gain of CK13 and loss of CK14 protein expression. The effect of TZ was significantly augmented when the autocrine-stimulated epidermal growth factor receptor pathway was inhibited and this resulted in induction of CK20 expression. The RXR-specific inhibitors PA452, HX531, and HX603 inhibited the TZ-induced CK13 expression, supporting a role for RXR in the induction of CK13 expression. Thus, signaling through PPAR-gamma can mediate transitional differentiation of urothelial cells and this is modulated by growth regulatory programs.

Constitutional mutation of keratin 13 gene in familial white sponge nevus

OBJECTIVE

We sought to investigate a novel mutation in the keratin genes assumed to be responsible for a familial case of oral white sponge nevus.

PATIENTS AND METHODS

The affected family consisted of a 36-year-old woman, her 17-year-old daughter, and her 14-year-old son. Keratin 4 and 13 genes extracted from venous blood lymphocytes were amplified by using the polymerase chain reaction and directly sequenced.

RESULTS

Sequencing analysis of the 3 patients revealed the presence of a novel heterozygous T-to-C transition mutation in exon 1 of the keratin 13 gene, with no abnormalities detected in the keratin 4 gene.

CONCLUSION

We identified a novel heterozygous missense mutation at 332T>C in the keratin 13 gene believed to be related to the development of white sponge nevus.

Adducin expression in cutaneous and oral lesions: alpha- and beta-adducin transcripts down-regulate with keratinocyte differentiation in stratified epithelia

Adducin is a heterodimer of alpha- with beta- or gamma-subunits that regulates the assembly of the spectrin-based membrane skeleton in erythrocytes. Although adducin has been identified in various non-erythroid cells and tissues, it has been localized at intercellular junctions only in keratinocytes and epidermis. However, no data are available yet on the regulation of individual adducin genes in differentiating versus hyperproliferating keratinocytes. Due to the unavailability of mono-specific antibodies for individual adducins, this study has used RT-PCR and in situ hybridization to investigate the expression of alpha- and beta-adducins in cultured cells and in stratified epithelia including cutaneous and oral lesions. Using RT-PCR, the alpha-transcripts were consistently expressed in all cell lines tested, as well as in normal interfollicular epidermis, whereas the beta-transcripts were more variable and were strongly expressed in K562, A431, and primary keratinocytes. However, in normal skin, oral mucosa, and attached gingivae, the levels of alpha-transcripts closely paralleled those for the beta-subunit. In most normal tissues, adducin expression was observed primarily in the proliferating compartments including the basal layer and lower suprabasal layers. Expression of both genes was also up-regulated in skin diseases characterized by increased cell proliferation and keratinocyte activation, such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and psoriasis. It was observed that, in most cases, the expression of both alpha- and beta-adducin was accompanied by increased expression of the proliferation marker Ki-67 and keratins K6 and K16. Differentiating keratinocytes in normal epithelia as well as in tumours appear to suppress the expression of adducin transcripts. The data suggest that the expression of adducin genes may be linked to cell proliferation and starts to down-regulate at the onset of differentiation.

Requirement of STAT3 activation for differentiation of mucosal stratified squamous epithelium

STAT3, a member of the signal transducers and activators of transcription (STAT) family, has been shown to play a key role in promoting proliferation, differentiation, or cell cycle progression, depending on cell type. A number of signaling pathways are altered in laryngeal papillomas, benign tumors induced by human papillomavirus 6/11. Papillomas overexpress the epidermal growth factor receptor and display enhanced MAP kinase and PI-3-kinase activity. They also show reduced activation of Akt and reduced levels of tyrosine-phosphorylated STAT3, due to overexpression of the tumor suppressor, PTEN. As papillomas show abnormalities in terminal differentiation, we examined the potential role of STAT3 in regulating epithelial differentiation. Laryngeal epithelial cells were suspended in supplemented serum-free medium. Differentiation was measured by Western blot analysis of keratin 13. Normal laryngeal epithelial cells were transfected with a constitutively active STAT3 or a dominant negative STAT3. Cells were transferred to suspension culture 24 h after transfection. Increased expression of keratin 13 was accompanied by the activation of STAT3 when differentiation was induced, and expression of a constitutively active STAT3 (STAT3C) enhanced the expression of keratin 13. In contrast, expression of a dominant negative STAT3 (Y705F) inhibited the expression of keratin 13. We conclude that activation of STAT3 is required for the differentiation of normal human stratified squamous epithelium.

Stage-specific expression of the intermediate filament protein cytokeratin 13 in luminal epithelial cells of secretory phase human endometrium and peri-implantation stage rabbit endometrium

In preparation for blastocyst implantation, uterine luminal epithelial cells express new cell adhesion molecules on their apical plasma membrane. Since one mechanism epithelial cells employ to regulate membrane polarity is the establishment of specific membrane-cytoskeletal interactions, this study was undertaken to determine if new cytokeratin (CK) intermediate filament assemblies are expressed in endometrial epithelial cells during developmental stages related to blastocyst implantation. Type-specific CK antibodies were used for immunocytochemical and immunoblot analyses of 1) intermediate filament networks of the endometrial epithelium during embryo implantation in rabbits and 2) proliferative and secretory phases of the human menstrual cycle. CK18, a type I CK found in most simple epithelia, was expressed in all luminal and glandular epithelial cells of both the human and rabbit endometrium at all developmental stages analyzed; it was also strongly expressed in trophectoderm of the implanting rabbit blastocyst. In contrast, CK13, another type I cytokeratin, exhibited a regulated expression pattern in luminal, but not glandular, epithelial cells of secretory phase human and peri-implantation stage rabbit endometrium. Furthermore, in the rabbit implantation chambers, CK13 was predominantly localized at the cell apex of luminal epithelial cells, where it assembled into a dense filamentous network. These data suggest that the stage-specific expression of CK13 and a reorganization of the apical intermediate filament cytoskeleton of uterine luminal epithelial cells may play important functions in preparation for the implantation process.

A novel mutation in the keratin 13 gene causing oral white sponge nevus

White sponge nevus (WSN) is an autosomal-dominantly inherited form of mucosal leukokeratosis. Defects in keratins, proteins that form the stress-bearing cytoskeleton in epithelia, have been shown to cause several epithelial fragility disorders. Recently, mutations in the genes encoding mucosal-specific keratins K4 and K13 were shown to be the underlying cause of WSN. We have studied a large Scottish family with 19 persons affected by WSN in four generations. The K4 locus was excluded by genetic linkage analysis; however, genetic linkage consistent with a K13 defect was obtained. Subsequently, a heterozygous missense mutation 335A>G was detected in exon 1 of the KRT13 gene, predicting the amino acid change N112S in the 1A domain of the K13 polypeptide. The mutation was confirmed in affected family members and was excluded from 50 unaffected people by restriction enzyme analysis. These results confirm that mucosal keratin defects are the cause of WSN.

Keratin 15 expression in stratified epithelia: downregulation in activated keratinocytes

Keratin 15 (K15) is a type I keratin without a defined type II partner whose expression in epidermal diseases has not been investigated. In this study we have used LHK15, a monoclonal antibody raised against the last 17 amino acids of the K15 polypeptide, to show that K15 is expressed primarily in the basal keratinocytes of stratified tissues, including the fetal epidermis and fetal nail. Although K15 in normal hair follicles was virtually absent from hair bulbs, it was expressed by a subset of keratinocytes in the outer root sheath. By comparison, K14 expression was found throughout the outer root sheath of hair follicles; however, when both K14 alleles were naturally ablated, the expression of K15 was also observed throughout the outer root sheath of the follicles. Expression of K15 mRNA was assessed by in situ hybridization and corroborated the data from immunostaining. An increase in K15 mRNA and protein expression in hair follicles from the K14 ablated epidermis suggested an upregulation of the K15 gene in the absence of the K14 protein. In organotypical cultures where differentiating keratinocytes expressed markers of activated phenotype, i.e., K6 and K16, expression of K15 was undetectable. The expression of K15 mRNA and protein was also downregulated in two hyperproliferating situations, psoriasis and hypertrophic scars. Because keratinocytes in psoriasis and hypertrophic scars are activated, we conclude that K15 expression is not compatible with keratinocyte activation and the K15 gene is downregulated to maintain the activated phenotype.