HtrA4 is required for human trophoblast stem cell differentiation into syncytiotrophoblast

INTRODUCTION

The syncytiotrophoblast (STB) of the human placenta facilitates vital maternal-fetal communication and is maintained by fusion (syncytialization) of cytotrophoblasts. Serine protease HtrA4 (high temperature requirement factor A4) is highly expressed only in the human placenta and was previously reported to be important for BeWo fusion. This study investigated whether HtrA4 is critical for differentiation of human trophoblast stem cells (TSCs) into STB.

METHODS

Primary TSCs were isolated from first trimester placentas (n = 5) and validated by immunofluorescence (IF) for CD49f, CK7 and vimentin. TSCs were then differentiated into STB and the success of syncytialization was confirmed by RT-PCR, IF and ELISA of known markers. TSCs were next stably transfected with a HtrA4-targetting CRISPR/Cas9 plasmid, and cells with severe HtrA4 knockdown (HtrA4-KD) were analyzed to investigate the impact on STB differentiation.

RESULTS

Primary TSCs were confirmed to be of high purity by staining positively for CD49f and CK7 but negatively for vimentin. These TSCs readily syncytialized when stimulated for STB differentiation, significantly increasing β-hCG and syncytin-1, substantially decreasing E-cadherin, and markedly losing cell borders. While TSCs produced very low levels of HtrA4, upon stimulation for STB differentiation the cells drastically upregulated HtrA4 expression; secretion of HtrA4 protein also increased sharply, correlating positively and significantly with that of β-hCG. The HtrA4-KD TSCs, however, failed to show this surge of HtrA4 production upon stimulation, and ultimately remained primarily mononucleated with no significant STB differentiation.

DISCUSSION

This study demonstrates that HtrA4 plays a critical role in TSC differentiation into syncytiotrophoblast.

Targeted m6A demethylation of ITGA6 mRNA by a multisite dCasRx-m6A editor inhibits bladder cancer development

INTRODUCTION

N6-methyladenosine (m6A) modification contributes to the pathogenesis and development of various cancers, including bladder cancer (BCa). In particular, integrin α6 (ITGA6) promotes BCa progression by cooperatively regulating multisite m6A modification. However, the therapeutic effect of targeting ITGA6 multisite m6A modifications in BCa remains unknown.

OBJECTIVES

We aim to develop a multisite dCasRx- m6A editor for assessing the effects of the multisite dCasRx-m6A editor targeted m6A demethylation of ITGA6 mRNA in BC growth and progression.

METHODS

The multisite dCasRx- m6A editor was generated by cloning. m6A-methylated RNA immunoprecipitation (meRIP), luciferase reporter, a single-base T3 ligase-based qPCR-amplification, Polysome profiling and meRIP-seq experiments were performed to determine the targeting specificity of the multisite dCasRx-m6A editor. We performed cell phenotype analysis and used in vivo mouse xenograft models to assess the effects of the multisite dCasRx-m6A editor in BC growth and progression.

RESULTS

We designed a targeted ITGA6 multi-locus guide (g)RNA and established a bidirectional deactivated RfxCas13d (dCasRx)-based m6A-editing platform, comprising a nucleus-localized dCasRx fused with the catalytic domains of methyltransferase-like 3 (METTL3-CD) or α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5-CD), to simultaneously manipulate the methylation of ITGA6 mRNA at four m6A sites. The results confirmed the dCasRx-m6A editor modified m6A at multiple sites in ITGA6 mRNA, with low off-target effects. Moreover, targeted m6A demethylation of ITGA6 mRNA by the multisite dCasRx-m6A editor significantly reduced BCa cell proliferation and migration in vitro and in vivo. Furthermore, the dCasRx-ALKBH5-CD and ITGA6 multi-site gRNA delivered to 5-week-old BALB/cJNju-Foxn1nu/Nju nude mice via adeno-associated viral vectors significantly inhibited BCa cell growth.

CONCLUSION

Our study proposes a novel therapeutic tool for the treatment of BC by applying the multisite dCasRx-m6A editor while highlighting its potential efficacy for treating other diseases associated with abnormal m6A modifications.

Biophysical phenotype mixtures reveal advantages for tumor muscle invasion in vivo

Bladder, colon, gastric, prostate, and uterine cancers originate in organs surrounded by laminin-coated smooth muscle. In human prostate cancer, tumors that are organ confined, without extracapsular extension through muscle, have an overall cancer survival rate of up to 97% compared with 32% for metastatic disease. Our previous work modeling extracapsular extension reported the blocking of tumor invasion by mutation of a laminin-binding integrin called α6β1. Expression of the α6AA mutant resulted in a biophysical switch from cell-ECM (extracellular matrix) to cell-cell adhesion with drug sensitivity properties and an inability to invade muscle. Here we used different admixtures of α6AA and α6WT cells to test the cell heterogeneity requirements for muscle invasion. Time-lapse video microscopy revealed that tumor mixtures self-assembled into invasive networks in vitro, whereas α6AA cells assembled only as cohesive clusters. Invasion of α6AA cells into and through live muscle occurred using a 1:1 mixture of α6AA and α6WT cells. Electric cell-substrate impedance sensing measurements revealed that compared with α6AA cells, invasion-competent α6WT cells were 2.5-fold faster at closing a cell-ECM or cell-cell wound, respectively. Cell-ECM rebuilding kinetics show that an increased response occurred in mixtures since the response was eightfold greater compared with populations containing only one cell type. A synthetic cell adhesion cyclic peptide called MTI-101 completely blocked electric cell-substrate impedance sensing cell-ECM wound recovery that persisted in vitro up to 20 h after the wound. Treatment of tumor-bearing animals with 10 mg/kg MTI-101 weekly resulted in a fourfold decrease of muscle invasion by tumor and a decrease of the depth of invasion into muscle comparable to the α6AA cells. Taken together, these data suggest that mixed biophysical phenotypes of tumor cells within a population can provide functional advantages for tumor invasion into and through muscle that can be potentially inhibited by a synthetic cell adhesion molecule.

Integrin alpha 6 is upregulated and drives hepatocellular carcinoma progression through integrin α6β4 complex

Integrin α6 (ITGA6) forms integrin receptors with either integrin β1 (ITGB1) or integrin β4 (ITGB4). How it functions to regulate hepatocellular carcinoma (HCC) progression is not well-elucidated. We found that ITGA6 RNA and protein expression levels are significantly elevated in human HCC tissues in comparison with paired adjacent nontumor tissues by RNA sequencing, RT-qPCR, Western blotting and immunofluorescence staining. Stable knockdown of ITGA6 with different ITGA6 shRNA expression lentivectors significantly inhibited proliferation, migration and anchorage-independent growth of HCC cell lines in vitro, and xenograft tumor growth in vivo. The inhibition of anchorage-dependent and -independent growth of HCC cell lines was also confirmed with anti-ITGA6 antibody. ITGA6 knockdown was shown to induce cell-cycle arrest at G0/G1 phase. Immunoprecipitation assay revealed apparent interaction of ITGA6 with ITGB4, but not ITGB1. Expression studies showed that ITGA6 positively regulates the expression of ITGB4 with no or negative regulation of ITGB1 expression. Finally, while high levels of ITGA6 and ITGB4 together were associated with significantly worse survival of HCC patients in TCGA data set, the association was not significant for high levels of ITGA6 and ITGB1. In conclusion, ITGA6 is upregulated in HCC tumors and has a malignant promoting role in HCC cells through integrin α6β4 complex. Thus, integrin α6β4 may be a therapeutic target for treating patients with HCC.

Protein Ligand Nanopattern Size Selects for Cellular Adhesion via Hemidesmosomes over Focal Adhesions

Hemidesmosomes (HDs) are multiprotein complexes that firmly anchor epidermal cells to the basement membrane of skin through the interconnection of the cytoplasmic intermediate filaments with extracellular laminin 332 (Ln332). Considerably less attention has been paid to HDs compared to focal complexes/focal adhesions (FC/FAs) in mechanistic single-cell structures due to the lack of suitable in vitro model systems. Here nanopatterns of Ln332 (100-1000 nm) are created to direct and study the formation of HD in adherent HaCaT cells. It is observed that HaCaT cells at Ln 332 nanopatterns adhere via hemidesmosomes, in stark contrast to cells at homogeneous Ln332 surfaces that adhere via FC/FAs. Clustering of α6 integrin is observed at nanopatterned Ln332 of 300 nm patches and larger. Cells at 500 nm diameter patterns show strong colocalization of α6 integrin with ColXVII or pan-cytokeratin compared to 300 nm/1000 nm indicating a threshold for HD initiation >100 nm but a pattern size selection for maturation of HDs. It is demonstrated that the pattern of Ln332 can determine the cellular selection of adhesion types with a size-dependent initiation and maturation of HDs. The protein nanopatterning approach that is presented provides a new in vitro route to study the role of HDs in cell signaling and function.

Identification of Surface Antigens That Define Human Pluripotent Stem Cell-Derived PRRX1+Limb-Bud-like Mesenchymal Cells

Stem cell-based therapies and experimental methods rely on efficient induction of human pluripotent stem cells (hPSCs). During limb development, the lateral plate mesoderm (LPM) produces limb-bud mesenchymal (LBM) cells that differentiate into osteochondroprogenitor cells and form cartilage tissues in the appendicular skeleton. Previously, we generated PRRX1-tdTomato reporter hPSCs to establish the protocol for inducing the hPSC-derived PRRX1⁺ LBM-like cells. However, surface antigens that assess the induction efficiency of hPSC-derived PRRX1⁺ LBM-like cells from LPM have not been identified. Here, we used PRRX1-tdTomato reporter hPSCs and found that high pluripotent cell density suppressed the expression of PRRX1 mRNA and tdTomato after LBM-like induction. RNA sequencing and flow cytometry suggested that PRRX1-tdTomato⁺ LBM-like cells are defined as CD44^high CD140B^high CD49f⁻. Importantly, other hPSC lines, including four human induced pluripotent stem cell lines (414C2, 1383D2, HPS1042, HPS1043) and two human embryonic stem cell lines (SEES4, SEES7), showed the same results. Thus, an appropriate cell density of hPSCs before differentiation is a prerequisite for inducing the CD44^high CD140B^high CD49f⁻ PRRX1⁺ LBM-like cells.

In vitro propagation of XXY human Klinefelter spermatogonial stem cells: A step towards new fertility opportunities

Klinefelter Syndrome (KS) is characterized by a masculine phenotype, supernumerary sex chromosomes (47, XXY), and impaired fertility due to loss of spermatogonial stem cells (SSCs). Early testicular cryopreservation could be an option for future fertility treatments in these patients, including SSCs transplantation or in vitro spermatogenesis. It is critically essential to adapt current in vitro SSCs propagation systems as a fertility option for KS patients. KS human testicular samples (13,15- and 17-year-old non-mosaic KS boys) were donated by patients enrolled in an experimental testicular tissue banking program. Testicular cells were isolated from cryopreserved tissue and propagated in long-term culture for 110 days. Cell-specific gene expression confirmed the presence of all four main cell types found in testes: Spermatogonia, Sertoli, Leydig, and Peritubular cells. A population of ZBTB16⁺ undifferentiated spermatogonia was identified throughout the culture using digital PCR. Flow cytometric analysis also detected an HLA^-/CD9⁺/CD49f⁺ population, indicating maintenance of a stem cell subpopulation among the spermatogonial cells. FISH staining for chromosomes X and Y showed most cells containing an XXY karyotype with a smaller number containing either XY or XX. Both XY and XX populations were able to be enriched by magnetic sorting for CD9 as a spermatogonia marker. Molecular karyotyping demonstrated genomic stability of the cultured cells, over time. Finally, single-cell RNAseq analysis confirmed transcription of ID4, TCN2, and NANOS 3 within a population of putative SSCs population. This is the first study showing successful isolation and long-term in vitro propagation of human KS testicular cells. These findings could inform the development of therapeutic fertility options for KS patients, either through in vitro spermatogenesis or transplantation of SSC, in vivo.

Increased Expression of Integrin Alpha 6 in Nucleus Pulposus Cells in Response to High Oxygen Tension Protects against Intervertebral Disc Degeneration

The destruction of the low oxygen microenvironment in nucleus pulposus (NP) cells played a critical role in the pathogenesis of intervertebral disc degeneration (IVDD). The purpose of this study was to determine the potential role of integrin alpha 6 (ITG α6) in NP cells in response to high oxygen tension (HOT) in IVDD. Immunofluorescence staining and western blot analysis showed that the levels of ITG α6 expression were increased in the NP tissue from IVDD patients and the IVDD rat model with mild degeneration, which were reduced as the degree of degeneration increases in severity. In NP cells, the treatment of HOT resulted in upregulation of ITG α6 expression, which could be alleviated by blocking the PI3K/AKT signaling pathway. Further studies found that ITG α6 could protect NP cells against HOT-induced apoptosis and oxidative stress and protect NP cells from HOT-inhibited ECM protein synthesis. Upregulation of ITG α6 expression by HOT contributed to maintaining NP tissue homeostasis through the interaction with hypoxia-inducible factor-1α (HIF-1α). Furthermore, silencing of ITG α6 in vivo could obviously accelerate puncture-induced IVDD. Taken together, these results revealed that the increase of ITG α6 expression by HOT in NP cells might be a protective factor in IVD degeneration as well as restore NP cell function.

Anoikis resistance in mammary epithelial cells is mediated by semaphorin 7a

Semaphorin-7a (SEMA7A), best known as a neuroimmune molecule, plays a diverse role in many cellular processes and pathologies. Here, we show that SEMA7A promotes anoikis resistance in cultured mammary epithelial cells through integrins and activation of pro-survival kinase AKT, which led us to investigate a role for SEMA7A during postpartum mammary gland involution-a normal developmental process where cells die by anoikis. Our results reveal that SEMA7A is expressed on live mammary epithelial cells during involution, that SEMA7A expression is primarily observed in α6-integrin expressing cells, and that luminal progenitor cells, specifically, are decreased in mammary glands of SEMA7A-/- mice during involution. We further identify a SEMA7A-α6/β1-integrin dependent mechanism of mammosphere formation and chemoresistance in mammary epithelial cells and suggest that this mechanism is relevant for recurrence in breast cancer patients.

Circular RNA circFAT1(e2) Promotes Colorectal Cancer Tumorigenesis via the miR-30e-5p/ITGA6 Axis

circRNAs (circular RNAs) are a family of noncoding RNAs and have diverse physiological and pathological functions. However, the functions and mechanisms of circRNAs in the development and progression of colorectal cancer (CRC) remain largely unknown. Here, we aimed to explore the functions and roles of circFAT1(e2) in CRC. qRT-PCR revealed that circFAT1(e2) in CRC tumor tissues was upregulated compared with that in adjacent normal tissues and was also upregulated in CRC cell lines. Small interfering RNAs (siRNAs) against circFAT1(e2) were used to decrease the expression of circFAT1(e2) in HCT116 and RKO cells in vitro. The roles of circFAT1(e2) in CRC cell metastasis and proliferation were then determined by transwell and CCK-8 assays. The results showed that circFAT1(e2) silencing markedly suppressed CRC growth. Moreover, we identified circFAT1(e2) as a promoter of CRC metastasis. Knockdown of circFAT1(e2) evidently reduced HCT116 and RKO cell migration and invasion. Furthermore, the regulatory relationship between circFAT1(e2) and its target miRNAs was verified by a luciferase reporter assay. We demonstrated that circFAT1(e2) could sponge miR-30e-5p, which regulated the expression level of integrin α6 (ITGA6), the downstream target gene of miR-30e-5p. Rescue assays demonstrated that knockdown of miR-30e-5p enhanced CRC proliferation and migration via ITGA6. Taken together, our results reveal the novel oncogenic roles of circFAT1(e2) in CRC through the miR-30e-5p/ITGA6 axis.

Steroid hormones and human choriogonadotropin influence the distribution of alpha6-integrin and desmoplakin 1 in gland-like endometrial epithelial spheroids

In human glandular endometrial epithelial cells, desmosomal and adherens junction proteins have been shown to extend from a subapically restricted lateral position to the entire lateral membrane during the implantation window of the menstrual cycle. Similarly, a menstrual cycle stage-dependent redistribution of the extracellular matrix adhesion protein α6-integrin has been reported. These changes are believed to be important for endometrial receptiveness and successful embryo implantation. To prove the hypothesis that steroid hormones and human choriogonadotropin can induce the redistribution of these adhesion molecules, we used the human endometrial cell line Ishikawa in a 3D culture system. Gland-like spheroids were grown in reconstituted basement membrane (Matrigel™). The lumen-bearing spheroids were treated for 2 or 4 days with ovarian steroids or human choriogonadotropin and then assessed by immunofluorescence microscopy. In addition, human endometrial biopsies were obtained from patients, who were in therapy for assisted reproductive technology, and were examined in parallel. Lateral redistribution of the desmosomal plaque protein desmoplakin 1 was observed in the spheroids treated either with progesterone, medroxyprogesterone acetate or human choriogonadotropin. Furthermore, the extracellular matrix adhesion protein α6-integrin showed an increased lateral membrane localization upon gestagen stimulation in the 3D culture system. The results of this study demonstrate that the 3D endometrial Ishikawa cell culture might be suited as an experimental model system to prove the effect of hormonal changes like those occurring during the window of implantation.

Pharmacological HIF-1 stabilization promotes intestinal epithelial healing through regulation of α-integrin expression and function

Intestinal epithelia are critical for maintaining gastrointestinal homeostasis. Epithelial barrier injury, causing inflammation and vascular damage, results in inflammatory hypoxia, and thus, healing occurs in an oxygen-restricted environment. The transcription factor hypoxia-inducible factor (HIF)-1 regulates genes important for cell survival and repair, including the cell adhesion protein β1-integrin. Integrins function as αβ-dimers, and α-integrin-matrix binding is critical for cell migration. We hypothesized that HIF-1 stabilization accelerates epithelial migration through integrin-dependent pathways. We aimed to examine functional and posttranslational activity of α-integrins during HIF-1-mediated intestinal epithelial healing. Wound healing was assessed in T84 monolayers over 24 h with/without prolyl-hydroxylase inhibitor (PHDi) (GB-004), which stabilizes HIF-1. Gene and protein expression were measured by RT-PCR and immunoblot, and α-integrin localization was assessed by immunofluorescence. α-integrin function was assessed by antibody-mediated blockade, and integrin α6 regulation was determined by HIF-1α chromatin immunoprecipitation. Models of mucosal wounding and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were used to examine integrin expression and localization in vivo. PHDi treatment accelerated wound closure and migration within 12 h, associated with increased integrin α2 and α6 protein, but not α3. Functional blockade of integrins α2 and α6 inhibited PHDi-mediated accelerated wound closure. HIF-1 bound directly to the integrin α6 promoter. PHDi treatment accelerated mucosal healing, which was associated with increased α6 immunohistochemical staining in wound-associated epithelium and wound-adjacent tissue. PHDi treatment increased α6 protein levels in colonocytes of TNBS mice and induced α6 staining in regenerating crypts and reepithelialized inflammatory lesions. Together, these data demonstrate a role for HIF-1 in regulating both integrin α2 and α6 responses during intestinal epithelial healing.NEW & NOTEWORTHY HIF-1 plays an important role in epithelial restitution, selectively inducing integrins α6 and α2 to promote migration and proliferation, respectively. HIF-stabilizing prolyl-hydroxylase inhibitors accelerate intestinal mucosal healing by inducing epithelial integrin expression.

Granzyme B inhibition reduces disease severity in autoimmune blistering diseases

Pemphigoid diseases refer to a group of severe autoimmune skin blistering diseases characterized by subepidermal blistering and loss of dermal-epidermal adhesion induced by autoantibody and immune cell infiltrate at the dermal-epidermal junction and upper dermis. Here, we explore the role of the immune cell-secreted serine protease, granzyme B, in pemphigoid disease pathogenesis using three independent murine models. In all models, granzyme B knockout or topical pharmacological inhibition significantly reduces total blistering area compared to controls. In vivo and in vitro studies show that granzyme B contributes to blistering by degrading key anchoring proteins in the dermal-epidermal junction that are necessary for dermal-epidermal adhesion. Further, granzyme B mediates IL-8/macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity. Clinically, granzyme B is elevated and abundant in human pemphigoid disease blister fluids and lesional skin. Collectively, granzyme B is a potential therapeutic target in pemphigoid diseases.

ITGA6+ Human Testicular Cell Populations Acquire a Mesenchymal Rather than Germ Cell Transcriptional Signature during Long-Term Culture

Autologous spermatogonial stem cell transplantation is an experimental technique aimed at restoring fertility in infertile men. Although effective in animal models, in vitro propagation of human spermatogonia prior to transplantation has proven to be difficult. A major limiting factor is endogenous somatic testicular cell overgrowth during long-term culture. This makes the culture both inefficient and necessitates highly specific cell sorting strategies in order to enrich cultured germ cell fractions prior to transplantation. Here, we employed RNA-Seq to determine cell type composition in sorted integrin alpha-6 (ITGA6+) primary human testicular cells (n = 4 donors) cultured for up to two months, using differential gene expression and cell deconvolution analyses. Our data and analyses reveal that long-term cultured ITGA6+ testicular cells are composed mainly of cells expressing markers of peritubular myoid cells, (progenitor) Leydig cells, fibroblasts and mesenchymal stromal cells and only a limited percentage of spermatogonial cells as compared to their uncultured counterparts. These findings provide valuable insights into the cell type composition of cultured human ITGA6+ testicular cells during in vitro propagation and may serve as a basis for optimizing future cell sorting strategies as well as optimizing the current human testicular cell culture system for clinical use.

Flow-induced Reorganization of Laminin-integrin Networks Within the Endothelial Basement Membrane Uncovered by Proteomics

The vessel wall is continuously exposed to hemodynamic forces generated by blood flow. Endothelial mechanosensors perceive and translate mechanical signals via cellular signaling pathways into biological processes that control endothelial development, phenotype and function. To assess the hemodynamic effects on the endothelium on a system-wide level, we applied a quantitative mass spectrometry approach combined with cell surface chemical footprinting. SILAC-labeled endothelial cells were subjected to flow-induced shear stress for 0, 24 or 48 h, followed by chemical labeling of surface proteins using a non-membrane permeable biotin label, and analysis of the whole proteome and the cell surface proteome by LC-MS/MS analysis. These studies revealed that of the >5000 quantified proteins 104 were altered, which were highly enriched for extracellular matrix proteins and proteins involved in cell-matrix adhesion. Cell surface proteomics indicated that LAMA4 was proteolytically processed upon flow-exposure, which corresponded to the decreased LAMA4 mass observed on immunoblot. Immunofluorescence microscopy studies highlighted that the endothelial basement membrane was drastically remodeled upon flow exposure. We observed a network-like pattern of LAMA4 and LAMA5, which corresponded to the localization of laminin-adhesion molecules ITGA6 and ITGB4. Furthermore, the adaptation to flow-exposure did not affect the inflammatory response to tumor necrosis factor α, indicating that inflammation and flow trigger fundamentally distinct endothelial signaling pathways with limited reciprocity and synergy. Taken together, this study uncovers the blood flow-induced remodeling of the basement membrane and stresses the importance of the subendothelial basement membrane in vascular homeostasis.

CD49f Is a Novel Marker of Functional and Reactive Human iPSC-Derived Astrocytes

New methods for investigating human astrocytes are urgently needed, given their critical role in the central nervous system. Here we show that CD49f is a novel marker for human astrocytes, expressed in fetal and adult brains from healthy and diseased individuals. CD49f can be used to purify fetal astrocytes and human induced pluripotent stem cell (hiPSC)-derived astrocytes. We provide single-cell and bulk transcriptome analyses of CD49f⁺ hiPSC-astrocytes and demonstrate that they perform key astrocytic functions in vitro, including trophic support of neurons, glutamate uptake, and phagocytosis. Notably, CD49f⁺ hiPSC-astrocytes respond to inflammatory stimuli, acquiring an A1-like reactive state, in which they display impaired phagocytosis and glutamate uptake and fail to support neuronal maturation. Most importantly, we show that conditioned medium from human reactive A1-like astrocytes is toxic to human and rodent neurons. CD49f⁺ hiPSC-astrocytes are thus a valuable resource for investigating human astrocyte function and dysfunction in health and disease.

UNC5C‑knockdown enhances the growth and metastasis of breast cancer cells by potentiating the integrin α6/β4 signaling pathway

Unc‑5 Netrin Receptor C (UNC5C) is a netrin‑1 dependence receptor that mediates the induction of apoptosis in the absence of netrin‑1. The present study found that UNC5C is heterogeneously expressed in breast cancer cell lines. By knocking down UNC5C in SK‑BR‑3 and ZR‑75‑30 cells and overexpressing UNC5c in MDA‑MB‑231 cells, it was demonstrated that UNC5C exerts an inhibitory effect on the growth and metastasis of breast cancer cells. The mechanism involved a UNC5C‑knockdown‑induced enhancement of matrix metalloproteinase (MMP)3, MMP7, MMP9 and MMP10 expression via activation of the PI3K/AKT, ERK and p38 MAPK signaling pathways. Notably, UNC5C directly interacted with integrin α6, which is involved in the growth and metastasis of breast cancer cells. Additionally, UNC5C‑knockdown enhanced the phosphorylation of FAK and SRC, which are key kinases in the netrin‑1/Unc5C and netrin‑1/integrin α6/β4 signaling pathways. This suggests that netrin‑1 functions as an integrator for both the netrin‑1/Unc5C and netrin‑1/integrin α6/β4 signaling pathways. UNC5C‑knockdown potentiated netrin‑1/integrin α6/β4 signaling. Given that UNC5C‑knockdown inhibited integrin‑liked protein kinase phosphorylation at Thr‑173, at least in SK‑BR‑3 cells, this may be an inhibitory phosphorylation site rather than activating phosphorylation site for relaying integrin signaling.

Urothelial organoids originating from Cd49fhigh mouse stem cells display Notch-dependent differentiation capacity

Understanding urothelial stem cell biology and differentiation has been limited by the lack of methods for their unlimited propagation. Here, we establish mouse urothelial organoids that can be maintained uninterruptedly for >1 year. Organoid growth is dependent on EGF and Wnt activators. High CD49f/ITGA6 expression features a subpopulation of organoid-forming cells expressing basal markers. Upon differentiation, multilayered organoids undergo reduced proliferation, decreased cell layer number, urothelial program activation, and acquisition of barrier function. Pharmacological modulation of PPARγ and EGFR promotes differentiation. RNA sequencing highlighted genesets enriched in proliferative organoids (i.e. ribosome) and transcriptional networks involved in differentiation, including expression of Wnt ligands and Notch components. Single-cell RNA sequencing (scRNA-Seq) analysis of the organoids revealed five clusters with distinct gene expression profiles. Together, with the use of γ-secretase inhibitors and scRNA-Seq, confirms that Notch signaling is required for differentiation. Urothelial organoids provide a powerful tool to study cell regeneration and differentiation.

N6-methyladenosine modification of ITGA6 mRNA promotes the development and progression of bladder cancer

Background

Accumulating evidence has revealed the critical roles of N⁶-methyladenosine (m⁶A) modification of mRNA in various cancers. However, the biological function and regulation of m⁶A in bladder cancer (BC) are not yet fully understood.

Methods

We performed cell phenotype analysis and established in vivo mouse xenograft models to assess the effects of m⁶A-modified ITGA6 on BC growth and progression. Methylated RNA immunoprecipitation (MeRIP), RNA immunoprecipitation and luciferase reporter and mutagenesis assays were used to define the mechanism of m⁶A-modified ITGA6. Immunohistochemical analysis was performed to assess the correlation between METTL3 and ITGA6 expression in bladder cancer patients.

Findings

We show that the m⁶A writer METTL3 and eraser ALKBH5 altered cell adhesion by regulating ITGA6 expression in bladder cancer cells. Moreover, upregulation of ITGA6 is correlated with the increase in METTL3 expression in human BC tissues, and higher expression of ITGA6 in patients indicates a lower survival rate. Mechanistically, m⁶A is highly enriched within the ITGA6 transcripts, and increased m⁶A methylations of the ITGA6 mRNA 3’UTR promotes the translation of ITGA6 mRNA via binding of the m⁶A readers YTHDF1 and YTHDF3. Inhibition of ITGA6 results in decreased growth and progression of bladder cancer cells in vitro and in vivo. Furthermore, overexpression of ITGA6 in METTL3-depleted cells partially restores the BC adhesion, migration and invasion phenotypes.

Interpretation

Our results demonstrate an oncogenic role of m⁶A-modified ITGA6 and show its regulatory mechanisms in BC development and progression, thus identifying a potential therapeutic target for BC.

Fund

This work was supported by National Natural Science Foundation of China (81772699, 81472999).

The laminin binding α3 and α6 integrins cooperate to promote epithelial cell adhesion and growth

Integrins, the major receptors for cell-extracellular matrix (ECM) interactions, regulate multiple cell biological processes including adhesion, migration, proliferation and growth factor-dependent signaling. The principal laminin (LM) binding integrins α3β1, α6β1 and α6β4 are usually co-expressed in cells and bind to multiple laminins with different affinities making it difficult to define their specific function. In this study, we generated kidney epithelial collecting duct (CD) cells that lack both the α3 and α6 integrin subunits. This deletion impaired cell adhesion and migration to LM-332 and LM-511 more than deleting α3 or α6 alone. Cell adhesion mediated by both α3β1 and α6 integrins was PI3K independent, but required K63-linked polyubiquitination of Akt by the ubiquitin-modifying enzyme TRAF6. Moreover, we provide evidence that glial-derived neurotrophic factor (GDNF) and fibroblast growth factor 10 (FGF10)- mediated cell signaling, spreading and proliferation were severely compromised in double integrin α3/α6- but not single α3- or α6-null CD cells. Interestingly, these growth factor-dependent cell functions required both PI3K- and TRAF6-dependent Akt activation. These data suggest that expression of the integrin α3 or α6 subunit is sufficient to mediate GDNF- and FGF10-dependent spreading, proliferation and signaling on LM-511. Thus, our study shows that α3 and α6 containing integrins promote distinct functions and signaling by CD cells on laminin substrata.

Xeno-free expansion of adult keratinocytes for clinical application: the use of human-derived feeder cells and serum

Cultured epithelial autograft (CEA) was the birth of skin tissue engineering and encompassed methodologies for the isolation and expansion of autologous basal keratinocytes for burn treatment that are still practiced at some specialised units around the world. One of the limitations of CEA, however, is the reliance on animal-derived material during the manufacturing process and despite all efforts to date, no xeno-free alternative with proven efficacy has been reported. Here, we investigate whether human-derived fibroblast feeder cells and human serum can sufficiently and effectively provide a suitable microenvironment for adult keratinocyte isolation and expansion. Human dermal fibroblasts and epidermal keratinocytes were isolated from discarded skin during abdominoplasty and breast reduction procedures and cultured in xeno-free conditions. We report that these xeno-free adult keratinocytes form similar numbers of colony-forming units as those cultured using the Green's methods; however, xeno-free keratinocytes express lower levels of α6 integrin (CD49f; a progenitor and stem cell marker). We identified IL-8 as a potential growth factor secreted by adult human fibroblasts that may enhance keratinocyte colony formation in human serum. Finally, we propose a step-by-step xeno-free isolation and cultivation methodology for adult keratinocytes that can be tested further in serial cultivation for clinical application.

Integrin α6 and EGFR signaling converge at mechanosensitive calpain 2

Cells sense and respond to mechanical cues from the extracellular matrix (ECM) via integrins. ECM stiffness is known to enhance integrin clustering and response to epidermal growth factor (EGF), but we lack information on when or if these mechanosensitive growth factor receptors and integrins converge intracellularly. Towards closing this knowledge gap, we combined a biomaterial platform with transcriptomics, molecular biology, and functional assays to link integrin-mediated mechanosensing and epidermal growth factor receptor (EGFR) signaling. We found that high integrin α6 expression controlled breast cancer cell adhesion and motility on soft, laminin-coated substrates, and this mimicked the response of cells to EGF stimulation. The mechanisms that drove both mechanosensitive cell adhesion and motility converged on calpain 2, an intracellular protease important for talin cleavage and focal adhesion turnover. EGF stimulation enhanced adhesion and motility on soft substrates, but required integrin α6 and calpain 2 signaling. In sum, we identified a new role for integrin α6 mechanosensing in breast cancer, wherein cell adhesion to laminin on soft substrates mimicked EGF stimulation. We identified calpain 2, downstream of both integrin α6 engagement and EGFR phosphorylation, as a common intracellular signaling node, and implicate integrin α6 and calpain 2 as potential targets to inhibit the migration of cancer cells in stiff tumor environments.

Human long-term deregulated circadian rhythm alters regenerative properties of skin and hair precursor cells

In mammals, desynchronized circadian rhythm leads to various biological symptoms. In skin and hair, human epidermal stem cell function in vitro is regulated by circadian oscillations, and thus contributes to tissue aging when deregulated. In mice, circadian arrhythmia of hair follicle stem cells contributes to age-related hair follicle cycling defects. Despite the well-described impact of circadian oscillations through a feedback loop involving the clock pathway on hair and skin stem cell function in vitro, little is known about the change in characteristics or regenerative properties of hHF (human hair follicle keratinocytes), hEpi (human interfollicular epidermal keratinocytes), and hHFDP (hair follicle dermal papilla stem cells) after long-term alteration of circadian rhythm in vivo. The present study was designed to asses hHF, hEpi, and hHFDP precursors and stem cell properties in response to clock pathway alteration due to long-term deregulated circadian rhythm in vivo. A clinical study protocol was designed to include two groups of women: diurnal workers (control) and shift workers (deregulated). After informed consent, two 3-mm fresh punch biopsies were taken from the occipital region of each donor (10 donors/group). Cell culture characterization, measurement of colony area, culture medium analysis, and RT-qPCR analysis were carried out. Long-term circadian rhythm deregulation affected clock pathway protein expression and correlated with alterations in hHF, hEpi, and hHFDP properties. This study provides, for the first time in humans, evidence that in vivo deregulation of the clock pathway affects regenerative properties of human skin and hair precursor cells.

Enteric Species F Human Adenoviruses use Laminin-Binding Integrins as Co-Receptors for Infection of Ht-29 Cells

The enteric species F human adenovirus types 40 and 41 (HAdV-40 and -41) are the third most common cause of infantile gastroenteritis in the world. Knowledge about HAdV-40 and -41 cellular infection is assumed to be fundamentally different from that of other HAdVs since HAdV-40 and -41 penton bases lack the αV-integrin-interacting RGD motif. This motif is used by other HAdVs mainly for internalization and endosomal escape. We hypothesised that the penton bases of HAdV-40 and -41 interact with integrins independently of the RGD motif. HAdV-41 transduction of a library of rodent cells expressing specific human integrin subunits pointed to the use of laminin-binding α2-, α3- and α6-containing integrins as well as other integrins as candidate co-receptors. Specific laminins prevented internalisation and infection, and recombinant, soluble HAdV-41 penton base proteins prevented infection of human intestinal HT-29 cells. Surface plasmon resonance analysis demonstrated that HAdV-40 and -41 penton base proteins bind to α6-containing integrins with an affinity similar to that of previously characterised penton base:integrin interactions. With these results, we propose that laminin-binding integrins are co-receptors for HAdV-40 and -41.

α6 Integrin (α6high)/Transferrin Receptor (CD71)low Keratinocyte Stem Cells Are More Potent for Generating Reconstructed Skin Epidermis Than Rapid Adherent Cells

The epidermis basal layer is composed of two keratinocyte populations: Keratinocyte Stem cells (KSC) and Transitory Amplifying (TA) cells that arise from KSC division. Unfortunately, no specific marker exists to differ between KSC and TA cells. Here, we aimed at comparing two different methods that pretended to isolate these two populations: (i) the rapid adhesion method on coated substrate and (ii) the flow cytometry method, which is based on the difference in cell surface expressions of the α6 integrin and transferrin receptor (CD71). Then, we compared different parameters that are known to discriminate KSC and TA populations. Interestingly, we showed that both methods allow enrichment in stem cells. However, cell sorting by flow cytometry (α6^high/CD71^low) phenotype leads to a better enrichment of KSC since the colony forming efficiency is five times increased versus total cell suspension, whereas it is only 1.4 times for the adhesion method. Moreover, α6^high/CD71^low cells give rise to a thicker pluristratified epithelium with lower seeding density and display a low Ki67 positive cells number, showing that they have reached the balance between proliferation and differentiation. We clearly demonstrated that cells isolated by a rapid adherent method are not the same population as KSC isolated by flow cytometry following α6^high/CD71^low phenotype.

Beneficial Effects of the Genus Aloe on Wound Healing, Cell Proliferation, and Differentiation of Epidermal Keratinocytes

Aloe has been used as a folk medicine because it has several important therapeutic properties. These include wound and burn healing, and Aloe is now used in a variety of commercially available topical medications for wound healing and skin care. However, its effects on epidermal keratinocytes remain largely unclear. Our data indicated that both Aloe vera gel (AVG) and Cape aloe extract (CAE) significantly improved wound healing in human primary epidermal keratinocytes (HPEKs) and a human skin equivalent model. In addition, flow cytometry analysis revealed that cell surface expressions of β1-, α6-, β4-integrin, and E-cadherin increased in HPEKs treated with AVG and CAE. These increases may contribute to cell migration and wound healing. Treatment with Aloe also resulted in significant changes in cell-cycle progression and in increases in cell number. Aloe increased gene expression of differentiation markers in HPEKs, suggesting roles for AVG and CAE in the improvement of keratinocyte function. Furthermore, human skin epidermal equivalents developed from HPEKs with medium containing Aloe were thicker than control equivalents, indicating the effectiveness of Aloe on enhancing epidermal development. Based on these results, both AVG and CAE have benefits in wound healing and in treatment of rough skin.

Integrin α6/Akt/Erk signaling is essential for human breast cancer resistance to radiotherapy

Integrin α6 (ITGA6), a transmembrane glycoprotein adhesion receptor protein, is widely upregulated in many types of tumors and promotes migration and invasion in cancer cells. However, the role that the ITGA6-associated signaling network plays in radiosensitivity in breast cancer has not been described. The expression of ITGA6 was examined in human breast cancer and normal breast cell lines using western blot analysis. We also explored the role of ITGA6 in the regulation of radiation sensitivity in breast cancer using the colony formation assays, cell cycle analyses, apoptosis assays and immunofluorescence analyses. The results showed that the protein and mRNA expression levels of ITGA6 was higher in breast cancer cells than in normal cells. ITGA6 protectived responses to radiotherapy in breast cancer cells by altering cell apoptosis, DNA damage repair and cell-cycle regulation. Furthermore, ITGA6 enhanced radiation resistance via PI3K/Akt and MEK/Erk signaling. In addition, overexpressing ITGA6 promoted radiation resistance in cells, and this effect was neutralized by the PI3K inhibitor LY294002 and MEK inhibitor U0126. Taken together, these findings indicate that ITGA6 might be involved in a mechanism that underlies radiation resistance and that ITGA6 could be a potential target for therapies aimed at overcoming radiation resistance in breast cancer.

Exclusive expression of the Rab11 effector SH3TC2 in Schwann cells links integrin-α6 and myelin maintenance to Charcot-Marie-Tooth disease type 4C

Charcot-Marie-Tooth disease type 4C (CMT4C) is one of the commonest autosomal recessive inherited peripheral neuropathies and is associated with mutations in the Rab11 effector, SH3TC2. Disruption of the SH3TC2-Rab11 interaction is the molecular abnormality underlying this disease. However, why SH3TC2 mutations cause an isolated demyelinating neuropathy remains unanswered. Here we show that SH3TC2 is an exclusive Schwann cell protein expressed late in myelination and is downregulated following denervation suggesting a functional role in myelin sheath maintenance. We support our data with an evolutionary cell biological analysis showing that the SH3TC2 gene, and its paralogue SH3TC1, are derived from an ancestral homologue, the duplication of which occurred in the common ancestor of jawed vertebrates, coincident with the appearance of Schwann cells and peripheral axon myelination. Furthermore, we report that SH3TC2 associates with integrin-α6, suggesting that aberrant Rab11-dependent endocytic trafficking of this critical laminin receptor in myelinated Schwann cells is connected to the demyelination seen in affected nerves. Our study therefore highlights the inherent evolutionary link between SH3TC2 and peripheral nerve myelination, pointing also towards a molecular mechanism underlying the specific demyelinating neuropathy that characterizes CMT4C.

Characterization of cervical cancer stem cell-like cells: phenotyping, stemness, and human papilloma virus co-receptor expression

Cancer stem cells (CSC) exhibit high tumorigenic capacity in several tumor models. We have now determined an extended phenotype for cervical cancer stem cells. Our results showed increased CK-17, p63+, AII+, CD49f+ expression in these cells, together with higher Aldehyde dehydrogenase (ALDHbright)activity in Cervical CSC (CCSC) enriched in cervospheres. An increase in stem cell markers, represented by OCT-4, Nanog, and β-catenin proteins, was also observed, indicating that under our culture conditions, CCSC are enriched in cervospheres, as compared to monolayer cultures. In addition, we were able to show that an increased ALDHbright activity correlated with higher tumorigenic activity. Flow cytometry and immunflorescence assays demonstrated that CCSC in cervosphere cultures contain a sub-population of cells that contain Annexin II, a Human papillomavirus (HPV) co-receptor. Taken together, under our conditions there is an increase in the number of CCSC in cervosphere cultures which exhibit the following phenotype: CK-17, p63+, AII+, CD49f+ and high ALDH activity, which in turn correlates with higher tumorigenicity. The presence of Annexin II and CD49f in CCSC opens the possibility that normal cervical stem cells could be the initial target of infection by high risk HPV.

Comparison of colony formation of human spermatogonial stem cells (SSCs) with and without collagen

OBJECTIVE

To investigate the effects of collagen and growth factors on in vitro proliferation of human spermatogonial stem cells obtained from patients with non-obstructive azoospermia.

METHODS

The experimental cross-sectional study was conducted from February 2013 to April 2015 after obtaining approval from the ethics committee of Ahvaz Jundishapur University of Medical Sciences, Iran. Testicular sperm extractions of non-obstructive azoospermic patients were obtained from the Clinical Urology and Embryology, In Vitro Fertilization Department of Imam Khomeini Hospital. Spermatogonial stem cells and Sertoli cells, obtained from human testis biopsies by a two-step enzymatic digestion method, were purified using fluorescence- activated cell-sorting and daturastramonium-lectin, and were cultured separately. To investigate a more direct influential factor on colony formation, one control and two experimental groups were formed. Group 1 acted as the control in which spermatogonial stem cells were co-cultured with Sertoli cells alone. In group 2 they were co-cultured with Sertoli cells and growth factors such as leukaemia inhibitory factor, epidermal growth factor and glial cell-derived neurotrophic factor, and in group 3 with Sertoli cells along with growth factors in the presence of collagen-coated dishes. Number and diameter of the colonies were evaluated after 7 weeks.

RESULTS

Specimens obtained related to 21 patients. Number and diameter of the colonies in group 3 (18±2.6 and 276.6±45.5) were significantly more than both groups 1 (3.5±1 and D1:81.6±12) and group 2(11±2.2 and 165.2±32.5) (p<0.05 each). Also, the number and diameter of colony in group 2 were significantly better than the control group (p<0.05).Expression profile of the VASA, promyelocytic leukaemia zinc-finger (PLZF), Octamer-binding transcription factor 4 (OCT4) and integrin a6 (INTGa6) were detected in all groups. Based on cytochemical findings, OCT4 was expressed in the colonies of all three groups.

CONCLUSIONS

According to positive effects of collagen and growth factors on the colonisation of spermatogonial stem cells, it seems that using the cells may lead to better colonisation of this type of stem cells.

CD49f promotes proliferation of male dairy goat germline stem cells

OBJECTIVES

CD49f enhances multipotency and maintains stemness in embryonic stem cells (ESCs), however, whether it would be effective in mGSCs has remained unclear. Moreover, better standards for mGSC enrichment and purification are necessary. The present study was conducted to determine roles of CD49f in mGSC enrichment and regulation.

MATERIALS AND METHODS

CD49f expression patterns were investigated in dairy goats. CD49f positive cells were purified and enriched using magnetic-activated cell sorting (MACS), and characteristics of the cultured cells were assayed using alkaline phosphatase (AP) analysis, quantitative real-time PCR (QRT-PCR) and immunofluorescence analysis. Furthermore, the exogenous CD49f gene was transfected into mGSCs and its effects were analysed.

RESULTS

CD49f was found to be conserved in both mRNA and amino acid sequences and that it was an efficient marker for dairy goat mGSC identification, enrichment and purification. CD49f positive cells expressed higher levels of mGSC-specific markers, and proliferated faster than CD49f negative cells. Overexpression CD49f promoted proliferation of dairy goat mGSCs, and Oct4 expression was upregulated; histone H3-lysine 9 dimethylation (H3K9me2) was reduced.

CONCLUSIONS

Taken together, our data suggest that CD49f plays novel and dynamic roles in regulating maintenance of pluripotency in mGSCs via Oct4 crosstalk and histone methylation dynamics,which may provide new solutions for mGSCs stability in vitro.

Sulfated polysaccharide isolated from the sea cucumber Stichopus japonicas promotes the SDF-1α/CXCR4 axis-induced NSC migration via the PI3K/Akt/FOXO3a, ERK/MAPK, and NF-κB signaling pathways

The present study describes a positive regulatory loop between SJP and the SDF-1α/CXCR4 axis in NSC migration. The treatment of NSCs with SJP and SDF-1α increases the cell migration capacity and promotes cell migration from the neurospheres. These effects are accompanied by the up-regulation of Nestin, N-cadherin, TLR4, TNF-α, Cyclin D1, EGFR, Alpha 6 integrin, MMP-2, MMP-9, and iNOS, including SDF-1α and CXCR4 themselves. However, these effects are blocked by AMD3100, LY294002, U0126, and PDTC. SJP enhances the SDF-1α/CXCR4 axis-induced MMP-2 and MMP-9 secretion and NO release. Results demonstrate that interaction of SJP with the SDF-1α/CXCR4 axis regulates NSC migration via the PI3K/Akt/FOXO3a, ERK-MAPK, and NF-κB signaling pathways.

Genetic and Immunohistochemical Expression of Integrins ITGAV, ITGA6, and ITGA3 As Prognostic Factor for Colorectal Cancer: Models for Global and Disease-Free Survival

Objective

To evaluate the relationship between the expression profiles of 84 extracellular matrix (ECM) genes and the prognosis of patients with colorectal cancer (CRC).

Methods

This retrospective study included 114 patients with stage I–IV CRC who underwent primary tumour resection. Quantitative real-time PCR and immunohistochemistry assays were conducted using primary tumour samples. Kaplan-Meier survival curves were also generated to identify differences in global survival (GS) and disease-free survival (DFS) for the hypo- or hyperexpression status of each marker. The log-rank test was used to verify whether the differences were significant. Stepwise Cox regression models were also used to identify the risk factors associated with GS and DFS in a multivariate mode, and then were used to score the risk of death associated with each marker, either independently or in association.

Results

In the univariate analyses, significant differences in GS in relation to the expression profiles of ITGAV (p = 0.001), ITGA3 (p = 0.002), ITGA6 (p = 0.001), SPARC (p = 0.036), MMP9 (p = 0.034), and MMP16 (p = 0.038) were observed. For DFS, significant differences were observed in associated with ITGAV (p = 0.004) and ITGA3 (p = 0.001). However, only the ITGAV and ITGA6 gene markers for GS (hazard ratio (HR) = 3.209, 95% confidence interval (CI) = 1.412–7.293, p = 0.005 and HR = 3.105, 95% CI = 1.367–7.055, p = 0.007, respectively), and ITGA3 for DFS (HR = 3.806, 95% CI = 1.573–9.209, p = 0.003), remained in the final Cox regression models. A scoring system was developed to evaluate the risk of patient death based on the number of markers for the components of the final GS model. Scores of 0, 1, or 2 were associated with the following mean survival rates [CI]: 47.162 [44.613–49.711], 39.717 [35.471–43.964], 30.197 [24.030–36.327], respectively.

Conclusions

Multivariate mathematical models demonstrated an association between hyperexpression of the ITGAV and ITGA6 integrins and GS, and also between the ITGA3 integrin and DFS, in patients with colorectal tumours. A risk scoring system based on detected hyperexpression of 0, 1, or 2 markers (e.g., ITGAV and/or ITGA6) was also found to accurately correlate with the GS curves generated for the present cohort.

Differential Expression Levels of Integrin α6 Enable the Selective Identification and Isolation of Atrial and Ventricular Cardiomyocytes

Rationale

Central questions such as cardiomyocyte subtype emergence during cardiogenesis or the availability of cardiomyocyte subtypes for cell replacement therapy require selective identification and purification of atrial and ventricular cardiomyocytes. However, current methodologies do not allow for a transgene-free selective isolation of atrial or ventricular cardiomyocytes due to the lack of subtype specific cell surface markers.

Methods and Results

In order to develop cell surface marker-based isolation procedures for cardiomyocyte subtypes, we performed an antibody-based screening on embryonic mouse hearts. Our data indicate that atrial and ventricular cardiomyocytes are characterized by differential expression of integrin α6 (ITGA6) throughout development and in the adult heart. We discovered that the expression level of this surface marker correlates with the intracellular subtype-specific expression of MLC-2a and MLC-2v on the single cell level and thereby enables the discrimination of cardiomyocyte subtypes by flow cytometry. Based on the differential expression of ITGA6 in atria and ventricles during cardiogenesis, we developed purification protocols for atrial and ventricular cardiomyocytes from mouse hearts. Atrial and ventricular identities of sorted cells were confirmed by expression profiling and patch clamp analysis.

Conclusion

Here, we introduce a non-genetic, antibody-based approach to specifically isolate highly pure and viable atrial and ventricular cardiomyocytes from mouse hearts of various developmental stages. This will facilitate in-depth characterization of the individual cellular subsets and support translational research applications.

Ovine Hair Follicle Stem Cells Derived from Single Vibrissae Reconstitute Haired Skin

Hair follicle stem cells (HFSCs) possess fascinating self-renewal capacity and multipotency, which play important roles in mammalian hair growth and skin wound repair. Although HFSCs from other mammalian species have been obtained, the characteristics of ovine HFSCs, as well as the methods to isolate them have not been well addressed. Here, we report an efficient strategy to obtain multipotent ovine HFSCs. Through microdissection and organ culture, we obtained keratinocytes that grew from the bulge area of vibrissa hair follicles, and even abundant keratinocytes were harvested from a single hair follicle. These bulge-derived keratinocytes are highly positive for Krt15, Krt14, Tp63, Krt19 and Itga6; in addition to their strong proliferation abilities in vitro, these keratinocytes formed new epidermis, hair follicles and sebaceous glands in skin reconstitution experiments, showing that these are HFSCs from the bulge outer root sheath. Taken together, we developed an efficient in vitro system to enrich ovine HFSCs, providing enough HFSCs for the investigations about the ovine hair cycle, aiming to promote wool production in the future.

mPGES-1 in prostate cancer controls stemness and amplifies epidermal growth factor receptor-driven oncogenicity

There is evidence that an inflammatory microenvironment is associated with the development and progression of prostate cancer (PCa), although the determinants of intrinsic inflammation in PCa cells are not completely understood. Here we investigated whether expression of intrinsic microsomal PGE synthase-1 (mPGES-1) enhanced aggressiveness of PCa cells and might be critical for epidermal growth factor receptor (EGFR)-mediated tumour progression. In PCa, overexpression of EGFR promotes metastatic invasion and correlates with a high Gleason score, while prostaglandin E2 (PGE2) has been reported to modulate oncogenic EGFR-driven oncogenicity. Immunohistochemical studies revealed that mPGES-1 in human prostate tissues is correlated with EGFR expression in advanced tumours. In DU145 and PC-3 cell lines expressing mPGES-1 (mPGES-1(SC) cells), we demonstrate that silencing or 'knock down' of mPGES-1 (mPGES-1(KD)) or pharmacological inhibition by MF63 strongly attenuates overall oncogenic drive. Indeed, mPGES-1(SC) cells express stem-cell-like features (high CD44, β1-integrin, Nanog and Oct4 and low CD24 and α6-integrin) as well as mesenchymal transition markers (high vimentin, high fibronectin, low E-cadherin). They also show increased capacity to survive irrespective of anchorage condition, and overexpress EGFR compared to mPGES-1(KD) cells. mPGES-1 expression correlates with increased in vivo tumour growth and metastasis. Although EGFR inhibition reduces mPGES-1(SC) and mPGES-1(KD) cell xenograft tumour growth, we show that mPGES-1/PGE2 signalling sensitizes tumour cells to EGFR inhibitors. We propose mPGES-1 as a possible new marker of tumour aggressiveness in PCa.

CD49f-positive testicular cells in Saanen dairy goat were identified as spermatogonia-like cells by miRNA profiling analysis

miRNAs, a type of small RNA, play critical roles in mammalian spermatogenesis. Spermatogonia are the foundation of spermatogenesis and are valuable for the study of spermatogenesis. However, the expression profiling of the miRNAs in spermatogonia of dairy goats remains unclear. CD49f has been one of the surface markers used for spermatogonia enrichment by magnetic activated cell sorting (MACS). Therefore, we used a CD49f microbead antibody to purify CD49f-positive and -negative cells of dairy goat testicular cells by MACS and then analysed the miRNA expression in these cells in depth using Illumina sequencing technology. The results of miRNA expression profiling in purified CD49f-positive and -negative testicular cells showed that 933 miRNAs were upregulated in CD49f-positive cells and 916 miRNAs were upregulated in CD49f-negative cells with a twofold increase, respectively; several miRNAs and marker genes specific for spermatogonial stem cells (SSCs) in testis had a higher expression level in CD49f-positive testicular cells, including miR-221, miR-23a, miR-29b, miR-24, miR-29a, miR-199b, miR-199a, miR-27a, and miR-21 and CD90, Gfra1, and Plzf. The bioinformatics analysis of differently expressed miRNAs indicated that the target genes of these miRNAs in CD49f-positive cells were involved in cell-cycle biological processes and the cell-cycle KEGG pathway. In conclusion, our comparative miRNAome data provide useful miRNA profiling data of dairy goat spermatogonia cells and suggest that CD49f could be used to enrich dairy goat spermatogonia-like cells, including SSCs.

Differential gene expression profiling of functionally and developmentally distinct human prostate epithelial populations

BACKGROUND

Human fetal prostate buds appear in the 10th gestational week as solid cords, which branch and form lumens in response to androgen 1. Previous in vivo analysis of prostate epithelia isolated from benign prostatectomy specimens indicated that Epcam⁺ CD44⁻ CD49f(Hi) basal cells possess efficient tubule initiation capability relative to other subpopulations 2. Stromal interactions and branching morphogenesis displayed by adult tubule-initiating cells (TIC) are reminiscent of fetal prostate development. In the current study, we evaluated in vivo tubule initiation by human fetal prostate cells and determined expression profiles of fetal and adult epithelial subpopulations in an effort to identify pathways used by TIC.

METHODS

Immunostaining and FACS analysis based on Epcam, CD44, and CD49f expression demonstrated the majority (99.9%) of fetal prostate epithelial cells (FC) were Epcam⁺ CD44⁻ with variable levels of CD49f expression. Fetal populations isolated via cell sorting were implanted into immunocompromised mice. Total RNA isolation from Epcam⁺ CD44⁻ CD49f(Hi) FC, adult Epcam⁺ CD44⁻ CD49f(Hi) TIC, Epcam⁺ CD44⁺ CD49f(Hi) basal cells (BC), and Epcam⁺ CD44⁻ CD49f(Lo) luminal cells (LC) was performed, followed by microarray analysis of 19 samples using the Affymetrix Gene Chip Human U133 Plus 2.0 Array. Data was analyzed using Partek Genomics Suite Version 6.4. Genes selected showed >2-fold difference in expression and P < 5.00E-2. Results were validated with RT-PCR.

RESULTS

Grafts retrieved from Epcam⁺ CD44⁻ fetal cell implants displayed tubule formation with differentiation into basal and luminal compartments, while only stromal outgrowths were recovered from Epcam- fetal cell implants. Hierarchical clustering revealed four distinct groups determined by antigenic profile (TIC, BC, LC) and developmental stage (FC). TIC and BC displayed basal gene expression profiles, while LC expressed secretory genes. FC had a unique profile with the most similarities to adult TIC. Functional, network, and canonical pathway identification using Ingenuity Pathway Analysis Version 7.6 compiled genes with the highest differential expression (TIC relative to BC or LC). Many of these genes were found to be significantly associated with prostate tumorigenesis.

CONCLUSIONS

Our results demonstrate clustering gene expression profiles of FC and adult TIC. Pathways associated with TIC are known to be deregulated in cancer, suggesting a cell-of-origin role for TIC versus re-emergence of pathways common to these cells in tumorigenesis.

Hair-growth-promoting effect of conditioned medium of high integrin α6 and low CD 71 (α6bri/CD71dim) positive keratinocyte cells

Keratinocyte stem/progenitor cells (KSCs) reside in the bulge region of the hair follicles and may be involved in hair growth. Hair follicle dermal papilla cells (HFDPCs) and outer root sheath (ORS) cells were treated with conditioned medium (CM) of KSCs. Moreover, the effects of KSC-CM on hair growth were examined ex vivo and in vivo. A human growth factor chip array and RT-PCR were employed to identify enriched proteins in KSC-CM as compared with CM from keratinocytes. KSC-CM significantly increased the proliferation of HFDPCs and ORS cells, and increased the S-phase of the cell cycle in HFDPCs. KSC-CM led to the phosphorylation of ATK and ERK1/2 in both cell types. After subcutaneous injection of KSC-CM in C3H/HeN mice, a significant increase in hair growth and increased proliferation of hair matrix keratinocytes ex vivo was observed. We identified six proteins enriched in KSC-CM (amphiregulin, insulin-like growth factor binding protein-2, insulin-like growth factor binding protein-5, granulocyte macrophage-colony stimulating factor, Platelet-derived growth factor-AA, and vascular endothelial growth factor). A growth-factor cocktail that contains these six recombinant growth factors significantly increased the proliferation of HFDPCs and ORS cells and enhanced the hair growth of mouse models. These results collectively indicate that KSC-CM has the potential to increase hair growth via the proliferative capacity of HFDPCs and ORS cells.

[Expression and clinical significance of Tspan 1 and Integrin α6 in human pancreatic ductal adenocarcinoma]

OBJECTIVE

To explore the clinicopathological significance and relationship of Tspan 1 and Integrin α6 expression in pancreatic ductal adenocarcinoma (PDAC) tissue and pancreatic cancer cell lines.

METHODS

Immunohistochemistry was used to detect the expression of Tspan 1 and Integrin α6 in 95 paraffin-embedded PDAC specimens and 55 adjacent non-cancerous pancreatic tissues which were collected from May 2004 to January 2013.Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detected the protein and mRNA expression in 16 paired fresh PDAC specimens of the pancreas and adjacent non-cancerous pancreatic tissues and 6 different pancreatic cancer cell lines.χ(2) test, Spearman-rank correlation analysis, Kaplan-Meier method and multivariate Cox regression analysis were used to analyze the data.

RESULTS

Tspan 1 and Integrin α6 were significantly over-expressed in PDAC than in adjacent non-cancerous pancreatic tissues (χ(2) = 7.429, P < 0.05; χ(2) = 15.1, P < 0.01). Lymph node metastasis, TNM stage and post-operation recurrence were positively correlated with the expression of Tspan 1 (χ(2) = 6.688, P < 0.01; χ(2) = 13.055, P < 0.01; χ(2) = 6.116, P < 0.05) . TNM stage was positively correlated with the expression of Integrin α6 (χ(2) = 8.896, P < 0.05) . Tspan 1 was correlated with Integrin α6 (r = 0.223, P < 0.05) . The expressions of Tspan 1 and Integrin α6 were negatively correlated with survival time (χ(2) = 5.263, P < 0.05;χ(2) = 10.124, P < 0.01) . Multivariate analysis revealed that Tspan 1 and Integrin α6 expressions were independent prognostic factors in PDAC patients (χ(2) = 6.152, P < 0.05; χ(2) = 9.479, P < 0.01). Western blot (t = 2.278, P < 0.05; t = 3.153, P < 0.05) and qRT-PCR (t = 2.439, P < 0.05; t = 3.258, P < 0.05) showed that Tspan 1 and Integrin α6 expressions were higher in PDAC tissues than in adjacent non-cancerous pancreatic. Tspan 1 and Integrin α6 were expressed in all six pancreatic cancer cell lines.In SW1990 which derived from metastasis PDAC, Tspan 1 and Integrin α6 expressions were higher than the cell lines from primary tumor.

CONCLUSION

Tspan 1 and Integrin α6 expression can up-regulate the invasion and metastasis of PDAC and may be used to predict the prognosis of PDAC.

Microfluidic Isolation of CD34-Positive Skin Cells Enables Regeneration of Hair and Sebaceous Glands In Vivo

Skin stem cells resident in the bulge area of hair follicles and at the basal layer of the epidermis are multipotent and able to self-renew when transplanted into full-thickness defects in nude mice. Based on cell surface markers such as CD34 and the α6-integrin, skin stem cells can be extracted from tissue-derived cell suspensions for engraftment using the gold standard cell separation technique of fluorescence-activated cell sorting (FACS). This paper describes an alternative separation method using microfluidic devices coated with degradable antibody-functionalized hydrogels. The microfluidic method allows direct injection of tissue digestate (no preprocessing tagging of cells is needed), is fast (45 minutes from injected sample to purified cells), and scalable. This method is used in this study to isolate CD34-positive (CD34+) cells from murine skin tissue digestate, and the functional capability of these cells is demonstrated by transplantation into nude mice using protocols developed by other groups for FACS-sorted cells. Specifically, the transplantation of microfluidic isolated CD34+ cells along with dermal and epidermal cells was observed to generate significant levels of hair follicles and sebaceous glands consistent with those observed previously with FACS-sorted cells.

Behavioral heterogeneity of adult mouse lung epithelial progenitor cells

The existence and identity of multipotent stem cells in the adult lung is currently highly debated. At present, it remains unclear whether candidate stem/progenitor cells are located in the airways, alveoli, or throughout the epithelial lining of the lung. Here, we introduce a method of airway microdissection, which enabled us to study the progenitor behavior of pulmonary epithelial cells in region-specific contexts. The progenitor characteristics of epithelial cells isolated from the trachea, proximal and distal airways, and lung parenchyme were evaluated in vitro and in vivo. We identified a population of airway-derived basal-like epithelial cells with the potential to self-renew and differentiate into airway and alveolar lineages in culture and in vivo after subcutaneous transplantation. The multipotent candidate progenitors originated from a minor fraction of the airway epithelial cell population characterized by high expression of α6 integrin. Results of the current study provide new insights into the regenerative potential of region-specific integrin α6-positive pulmonary epithelial cells.

Isolation of a hemidesmosome-rich fraction from a human squamous cell carcinoma cell line

Hemidesmosomes are cell-to-matrix adhesion complexes anchoring keratinocytes to basement membranes. For the first time, we present a method to prepare a fraction from human cultured cells that are highly enriched in hemidesmosomal proteins. Using DJM-1 cells derived from human squamous cell carcinoma, accumulation of hemidesmosomes was observed when these cells were cultured for more than 10 days in a commercial serum-free medium without supplemental calcium. Electron microscopy demonstrated that numerous electron-dense adhesion structures were present along the basal cell membranes of DJM-1 cells cultured under the aforementioned conditions. After removing cellular materials using an ammonia solution, hemidesmosomal proteins and deposited extracellular matrix were collected and separated by electrophoresis. There were eight major polypeptides, which were determined to be plectin, BP230, BP180, integrin α6 and β4 subunits, and laminin-332 by immunoblotting and mass spectrometry. Therefore, we designated this preparation as a hemidesmosome-rich fraction. This fraction contained laminin-332 exclusively in its unprocessed form, which may account for the promotion of laminin deposition, and minimal amounts of Lutheran blood group protein, a nonhemidesmosomal transmembrane protein. This hemidesmosome-rich fraction would be useful not only for biological research on hemidesmosomes but also for developing a serum test for patients with blistering skin diseases.

Validation of stem cell markers in clinical prostate cancer: α6-integrin is predictive for non-aggressive disease

BACKGROUND

Stem cells are postulated to mediate prostate cancer progression, and represent a small fraction of the entire tumor. Various proteins (α2-integrin, α6-integrin, CD117, CD133, EZH2, OCT3/4) are associated with a prostate cancer stem cell phenotype in cell lines and xenografts. Our objective was to investigate expression of stem cell markers in clinical prostate cancer in relation to outcome.

METHODS

We validated immunohistochemical expression of stem cell markers in 481 prostate cancer patients and correlated expression with clinicopathologic parameters.

RESULTS

Sporadic expression of α2-integrin was present in a fraction of tumor cells (<5%) in 94.7% of tumors and associated with PSA > 10 ng/ml (P = 0.04). α6-Integrin expression (<5%) occurred in 28.4% patients, while ≥5% α6-integrin expression was associated with PSA≤10 ng/ml (P = 0.01), Gleason score <7 (P < 0.01) and pT2-disease (P = 0.02). α6-integrin was predictive for biochemical recurrence (P < 0.01), local recurrence (P = 0.03) and disease specific death (P = 0.03). EZH2 expression was generally low with 2.6% of tumors showing ≥1% positive cells. EZH2 was associated with Gleason score ≥7 (P = 0.01) and biochemical recurrence (P = 0.01). We did not identify expression of CD117, CD133, and OCT3/4 in prostate cancer samples.

CONCLUSIONS

Expression of α2-integrin and EZH2 in a small fraction of prostate cancer cells is supportive for their role as stem cell marker. Although α6-integrin was not a unique stem cell marker, it was predictive for prostate cancer biochemical and local recurrence, and disease specific death. The validity of CD117, CD133, and OCT3/4 as prostate cancer stem cell marker is questionable since these proteins were not expressed in clinical prostate cancer.

Dioscorin pre-treatment protects A549 human airway epithelial cells from hydrogen peroxide-induced oxidative stress

Hydrogen peroxide (H(2)O(2)) is a highly reactive oxygen species involved in lung and bronchial epithelium injury. Increased H(2)O(2) levels have been reported in expired breath condensates of patients with inflammatory airway diseases such as chronic obstructive pulmonary disease. Protecting airway epithelial cells from oxidative stress is an important task in the prevention and management of airway diseases. Previous studies demonstrate that yam (Dioscorea batatas Decne) has antioxidant and anti-trypsin activities. This study evaluated the validity of dioscorin in vitro. The results showed that dioscorin attenuated the alteration of H(2)O(2) on G2/M cell cycle arrest. This might be associated with the activation of IκB and subsequent inactivation of NF-κB. Furthermore, dioscorin suppressed IL-8 secretion and reduced changes of adhesion molecule expressions in H(2)O(2)-injured A549 cells. These results help in understanding the potential of traditional Chinese herbal medicine as treatment for airway inflammatory diseases.

Type VII collagen regulates expression of OATP1B3, promotes front-to-rear polarity and increases structural organisation in 3D spheroid cultures of RDEB tumour keratinocytes

Type VII collagen is the main component of anchoring fibrils, structures that are integral to basement membrane homeostasis in skin. Mutations in the gene encoding type VII collagen COL7A1 cause recessive dystrophic epidermolysis bullosa (RDEB) an inherited skin blistering condition complicated by frequent aggressive cutaneous squamous cell carcinoma (cSCC). OATP1B3, which is encoded by the gene SLCO1B3, is a member of the OATP (organic anion transporting polypeptide) superfamily responsible for transporting a wide range of endogenous and xenobiotic compounds. OATP1B3 expression is limited to the liver in healthy tissues, but is frequently detected in multiple cancer types and is reported to be associated with differing clinical outcome. The mechanism and functional significance of tumour-specific expression of OATP1B3 has yet to be determined. Here, we identify SLCO1B3 expression in tumour keratinocytes isolated from RDEB and UV-induced cSCC and demonstrate that SLCO1B3 expression and promoter activity are modulated by type VII collagen. We show that reduction of SLCO1B3 expression upon expression of full-length type VII collagen in RDEB cSCC coincides with acquisition of front-to-rear polarity and increased organisation of 3D spheroid cultures. In addition, we show that type VII collagen positively regulates the abundance of markers implicated in cellular polarity, namely ELMO2, PAR3, E-cadherin, B-catenin, ITGA6 and Ln332.

Disease-on-a-chip: mimicry of tumor growth in mammary ducts

We present a disease-on-a-chip model in which cancer grows within phenotypically normal breast luminal epithelium on semicircular acrylic support mimicking portions of mammary ducts. The cells from tumor nodules developing within these hemichannels are morphologically distinct from their counterparts cultured on flat surfaces. Moreover, tumor nodules cocultured with the luminal epithelium in hemichannels display a different anticancer drug sensitivity compared to nodules cocultured with the luminal epithelium on a flat surface and to monocultures of tumor nodules. The mimicry of tumor development within the epithelial environment of mammary ducts provides a framework for the design and test of anticancer therapies.

[Change of expression of integrins on multipotent mesenchymal stromal cells isolated from human adipose tissue during long cultivation]

An expression ofintegrins on multipotent mesenchymal stromal cells (MMSCs), isolated from human subcutaneous adipose tissue during long cultivation was studied. Results of the comparative analysis of MMSCs on the 2nd and 17th passages of cultivation revealed considerable distinctions in expression of α1, α4 and α6 integrins on these cells. Strong decrease for 87.2 and 11.2%, quantities of the cells which have been positively stained by AT against CD49a (α1 integrin) and CD49d (α4 integrin), respectively was observed. The share of the cells which have been positively stained by AT against CD49f (α6 integrin) and CD49b (α2 integrin) on the contrary was increased during long cultivation by 9.9 and 2.3%, respectively. The high expression of β1 integrin (98%) on MMSCs, wasn't changed significantly in the course of long cultivation. As a result of induction of MMSCs to a differentiation in the osteogenic direction it was revealed that cells on the 17th passage of cultivation concede by efficiency of formation of cells of bone tissue and extracellular matrix in vitro to cells which induced on the 2nd passage. Thus, long cultivation of MMSCs which is required for building of cellular population after isolation, influences on a cytoskeleton and adhesive abilities of cells that it is necessary to consider when using them for cellular technologies, including for modeling of this or that tissue in three-dimensional scaffolds.

Label retention identifies a multipotent mesenchymal stem cell-like population in the postnatal thymus

Thymic microenvironments are essential for the proper development and selection of T cells critical for a functional and self-tolerant adaptive immune response. While significant turnover occurs, it is unclear whether populations of adult stem cells contribute to the maintenance of postnatal thymic epithelial microenvironments. Here, the slow cycling characteristic of stem cells and their property of label-retention were used to identify a K5-expressing thymic stromal cell population capable of generating clonal cell lines that retain the capacity to differentiate into a number of mesenchymal lineages including adipocytes, chondrocytes and osteoblasts suggesting a mesenchymal stem cell-like phenotype. Using cell surface analysis both culture expanded LRCs and clonal thymic mesenchymal cell lines were found to express Sca1, PDGFRα, PDGFRβ,CD29, CD44, CD49F, and CD90 similar to MSCs. Sorted GFP-expressing stroma, that give rise to TMSC lines, contribute to thymic architecture when reaggregated with fetal stroma and transplanted under the kidney capsule of nude mice. Together these results show that the postnatal thymus contains a population of mesenchymal stem cells that can be maintained in culture and suggests they may contribute to the maintenance of functional thymic microenvironments.