PDGFRα+ITGA11+ fibroblasts foster early-stage cancer lymphovascular invasion and lymphatic metastasis via ITGA11-SELE interplay

Cancer-associated fibroblasts (CAFs) exhibit considerable heterogeneity in advanced cancers; however, the functional annotation and mechanism of CAFs in early-stage cancers remain elusive. Utilizing single-cell RNA sequencing and spatial transcriptomic, we identify a previously unknown PDGFRα+ITGA11+ CAF subset in early-stage bladder cancer (BCa). Multicenter clinical analysis of a 910-case cohort confirms that PDGFRα+ITGA11+ CAFs are associated with lymphovascular invasion (LVI) and poor prognosis in early-stage BCa. These CAFs facilitate LVI and lymph node (LN) metastasis in early-stage BCa, as evidenced in a PDGFRα+ITGA11+ CAFs-specific deficient mouse model. Mechanistically, PDGFRα+ITGA11+ CAFs promote lymphangiogenesis via recognizing ITGA11 surface receptor SELE on lymphatic endothelial cells to activate SRC-p-VEGFR3-MAPK pathway. Further, CHI3L1 from PDGFRα+ITGA11+ CAFs aligns the surrounding matrix to assist cancer cell intravasation, fostering early-stage BCa LVI and LN metastasis. Collectively, our study reveals the crucial role of PDGFRα+ITGA11+ CAFs in shaping metastatic landscape, informing the treatment of early-stage BCa LVI.

ITGA7 loss drives the differentiation of adipose-derived mesenchymal stem cells to cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) represent a major cellular component of the tumor (pre-)metastatic niche and play an essential role in omental dissemination of ovarian cancer. The omentum is rich in adipose, and adipose-derived mesenchymal stem cells (ADSCs) have been identified as a source of CAFs. However, the molecular events driving the phenotype shift of ADSCs remain largely unexplored. In this research, we focus on integrins, transmembrane receptors that have been widely involved in cellular plasticity. We found that integrin α7 (ITGA7) was the only member of the integrin family that positively correlated with both overall survival and progression-free survival in ovarian cancer through GEPIA2. The immunohistochemistry signal of ITGA7 was apparent in the tumor stroma, and a lower omental ITGA7 level was associated with metastasis. Primary ADSCs were isolated from the omentum of patients with ovarian cancer and identified by cellular morphology, biomarkers, and multilineage differentiation. The conditional medium of ovarian cancer cells induced ITGA7 expression decrease and phenotypic changes in ADSCs. Downregulation of ITGA7 in primary omental ADSCs led to decrease in stemness properties and emerge of characteristic morphology and biomarkers of CAFs. Moreover, the conditioned medium of ADSCs with ITGA7 depletion exhibited enhanced abilities to improve the migration and invasion of ovarian cancer cells in vitro. Overall, these findings indicate that loss of ITGA7 may induce the differentiation of ADSCs to CAFs that contribute to a tumor-supportive niche.

Depletion of circPDSS1 inhibits ITGA11 production to confer cisplatin sensitivity through miR-515-5p in gastric cancer

Chemoresistance limits cisplatin (DDP)-mediated treatment for gastric cancer (GC). Circular RNA (circRNA) acts an important role in chemoresistance. However, the underlying mechanism of circPDSS1 regulating DDP sensitivity in GC remains unclear. The expression patterns of circPDSS1, miR-515-5p and integrin subunit alpha 11 (ITGA11) were analyzed by qRT-PCR. Protein expression was checked by Western blotting analysis. Cell viability was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation was evaluated by colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. The analysis of cell apoptosis, migration and invasion was performed by flow cytometry analysis and transwell assays. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to identify the associations among circPDSS1, miR-515-5p and ITGA11. In vivo assay was implemented using a xenograft mouse model assay. CircPDSS1 and ITGA11 expression were significantly upregulated, whereas miR-515-5p was downregulated in DDP-resistant GC tissues and cells in comparison with controls. CircPDSS1 depletion reduced DDP resistance, cell proliferation, migration and invasion but induced cell apoptosis in DDP-resistant GC cells. CircPDSS1 directly bound to miR-515-5p. CircPDSS1-mediated actions were dependent on the regulation of miR-515-5p. Besides, miR-515-5p was associated with ITGA11, and circPDSS1 regulated ITGA11 expression by binding to miR-515-5p. Overexpression of miR-515-5p improved DDP sensitivity owing to the downregulation of ITGA11. Further, circPDSS1 mediated DDP sensitivity by regulating miR-515-5p and ITGA11 in vivo. CircPDSS1 conferred DDP resistance through the miR-515-5p/ITGA11 axis in GC cells.

Prevalence of tumour-infiltrating CD103+ cells identifies therapeutic-sensitive prostate cancer with poor clinical outcome

BACKGROUND

The clinical significance and immune correlation of CD103+ cells in prostate cancer (PCa) remain explored.

METHODS

In total, 1080 patients with PCa underwent radical prostatectomy from three cohorts were enrolled for retrospective analysis. Tumour microarrays were constructed and fresh tumour samples were analysed by flow cytometry.

RESULTS

High CD103+ cell infiltration correlated with reduced biochemical recurrence (BCR)-free survival in PCa. Adjuvant hormone therapy (HT) prolonged the BCR-free survival for high-risk node-negative diseases with CD103+ cell abundance. CD103+ cell infiltration correlated with less cytotoxic expression and increased infiltration of CD8+ and CD4+ T cells, M1 macrophages and mast cells in PCa. Intratumoral CD8+ T cell was the predominant source of CD103, and the CD103+ subset of CD8+ T cells was featured with high IL-10, PD-1 and CTLA-4 expression. Tumour-infiltrating CD103+ CD8+ T cells exerted anti-tumour function when treated with HT ex vivo.

DISCUSSION

CD103+ cell infiltration predicted BCR-free survival and response to adjuvant HT in PCa. CD103+ cell infiltration correlated with an enriched but immune-evasive immune landscape. The study supported a model that CD103 expression conferred negative prognostic impact and immunosuppressive function to tumour-infiltrating CD8+ T cells, while the CD103+ CD8+ T cells exhibited a powerful anti-tumour immunity with response to HT.

Identification and characterization of murine glycoprotein 2-expressing intestinal dendritic cells

The intestinal lamina propria (LP) contains distinct subsets of classical dendritic cells (cDC), each playing key non-redundant roles in intestinal immune homeostasis. Here, we show that glycoprotein 2 (GP2), a GPI-anchored protein and receptor for bacterial type-I fimbriae, is selectively expressed by CD103+CD11b+ cDC in the murine small intestine (SI). GP2 expression was induced on CD103+CD11b+ cDC within the SI-LP and was regulated by IRF4, TGFβR1- and retinoic acid signalling. Mice selectively lacking Gp2 on CD103+CD11b+ cDC (huLang-Cre.gp2fl/fl mice) had normal numbers and proportions of innate and adaptive immune cells in the SI-LP suggesting that GP2 expression by CD103+CD11b+ cDC is not required for intestinal immune homoeostasis.

The multifunctional nature of CD103 (αEβ7 integrin) signaling in tissue-resident lymphocytes

Intestinal tissue-resident lymphocytes are critical for maintenance of the mucosal barrier and to prevent enteric infections. The activation of these lymphocytes must be tightly regulated to prevent aberrant inflammation and epithelial damage observed in autoimmune diseases, yet also ensure that antimicrobial host defense remains uncompromised. Tissue-resident lymphocytes express CD103, or αE integrin, which dimerizes with the β7 subunit to bind to E-cadherin expressed on epithelial cells. Although the role of CD103 in homing and retention of lymphocytes to and within peripheral tissues has been well characterized, the molecular signals activated following CD103 engagement remain understudied. Here, we highlight recent studies that elucidate the functional contribution of CD103 in various lymphocyte subpopulations, either as an independent signaling molecule or in the context of TCR co-stimulation. Finally, we will discuss the gaps in our understanding of CD103 biology and the therapeutic potential of targeting CD103 on tissue-resident lymphocytes.

Alpha Protein Kinase 2 Promotes Esophageal Cancer via Integrin Alpha 11

Background

As a common disease around the world, esophageal cancer (EC) primarily includes two subclasses: esophageal adenocarcinoma and esophageal squamous cell carcinoma. Mortality has been rising over the years; hence, exploring the mechanism of EC development has become critical. Among the alpha protein kinases, alpha protein kinase 2 (ALPK2) presumably has a connection with EC, but it has never been revealed before.

Methods

In this study, IHC analysis was used for ALPK2 expression quantification in ES tissues. TE-1 and Eca-109, which are both human EC cell lines, were used for in vitro analysis of cell proliferation, migration, apoptosis, and colony formation.

Results

ALPK2 was found to have an abundant expression within EC tissues (P < 0.001), as well as in the two selected human EC cell lines (P < 0.05). The data showed that ALPK2 depletion suppressed EC cell proliferation, migration, and colony formation, meanwhile stimulating apoptosis (P < 0.001). The in vivo experiments also displayed inhibitory effects caused by ALPK2 depletion on EC tumorigenesis (P < 0.001). It was further validated that ALPK2 depletion made the phosphorylation of Akt and mTOR, as well as CDK6 and PIK3CA levels downregulated (P < 0.001). Mechanistically, we identified integrin alpha 11 (ITGA11) as a downstream gene of ALPK2 regulating EC. More importantly, we found that ITGA11 elevation promoted cell proliferation and migration and rescued the suppression effects caused by ALPK2 depletion (P < 0.001).

Conclusions

ALPK2 promotes esophageal cancer via integrin its downstream gene alpha 11; ALPK2 can potentially act as a target for the treatment of EC.

Association between Decreased ITGA7 Levels and Increased Muscle α-Synuclein in an MPTP-Induced Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra (SN), reducing dopaminergic levels in the striatum and affecting motor control. Herein, we investigated the potential relationship between integrin α7 (ITGA7) and α-synuclein (α-syn) in the muscle of methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP)-induced mice and C2C12 cells. To characterize the pathology of PD, we examined the expression of tyrosine hydroxylase (TH) in the SN of the midbrain. Compared with the control group, MPTP-treated mice showed a significant decrease in TH expression in the SN, accompanied by a significant decrease in muscle ITGA7 expression. Compared with the control group, α-syn expression was increased in the MPTP group. Furthermore, the pattern of α-syn expression in the MPTP group was similar to the ITGA7 expression pattern in the control group (linear forms). To determine the relationship between ITGA7 and PD, we examined the expression of ITGA7 and α-syn after ITGA7 knockdown using siRNA in C2C12 cells. ITGA7 expression significantly decreased while α-syn expression significantly increased in siRNA-treated C2C12 cells. These results suggest that decreased ITGA7 muscle expression could increase α-syn expression. Moreover, α-syn accumulation, induced by decreased muscle ITGA7, might contribute to PD pathology.

CD103-CD23+ classical hair cell leukemia: A case report and review of the literature

INTRODUCTION

This case report is presented to improve our understanding of the atypical immunophenotype of hairy cell leukemia.

PATIENT CONCERNS

A 58-year-old woman presented to our department with fatigue for >10 days.

DIAGNOSIS

The patient was diagnosed with an increased proportion of abnormal lymphocytes in peripheral blood and bone marrow smear, positive for CD11c, CD19, CD20, CD22, CD25, CD123, CD200, and Kappa, partial expression of CD23, but no expression of CD103, positive for BRAF V600E mutation.

INTERVENTIONS AND OUTCOMES

Cladribine combined with rituximab achieved complete remission of minor residual disease negativity.

CONCLUSION

Hairy cell leukemia is rare, and the diagnosis and differential diagnosis should be made by combining the patient's medical history, clinical manifestations, immunophenotype, gene detection, and other means. Purine nucleoside analogs are the first-line treatments.

Class Ib MHC-Mediated Immune Interactions Play a Critical Role in Maintaining Mucosal Homeostasis in the Mammalian Large Intestine

Lymphocytes within the intestinal epithelial layer (IEL) in mammals have unique composition compared with their counterparts in the lamina propria. Little is known about the role of some of the key colonic IEL subsets, such as TCRαβ⁺CD8⁺ T cells, in inflammation. We have recently described liver-enriched innate-like TCRαβ⁺CD8αα regulatory T cells, partly controlled by the non-classical MHC molecule, Qa-1^b, that upon adoptive transfer protect from T cell-induced colitis. In this study, we found that TCRαβ⁺CD8αα T cells are reduced among the colonic IEL during inflammation, and that their activation with an agonistic peptide leads to significant Qa-1^b-dependent protection in an acute model of colitis. Cellular expression of Qa-1^b during inflammation and corresponding dependency in peptide-mediated protection suggest that Batf3-dependent CD103⁺CD11b^- type 1 conventional dendritic cells control the protective function of TCRαβ⁺CD8αα T cells in the colonic epithelium. In the colitis model, expression of the potential barrier-protective gene, Muc2, is enhanced upon administration of a Qa-1b agonistic peptide. Notably, in steady state, the mucin metabolizing Akkermansia muciniphila was found in significantly lower abundance amid a dramatic change in overall microbiome and metabolome, increased IL-6 in explant culture, and enhanced sensitivity to dextran sulfate sodium in Qa-1b deficiency. Finally, in patients with inflammatory bowel disease, we found upregulation of HLA-E, a Qa-1^b analog with inflammation and biologic non-response, in silico, suggesting the importance of this regulatory mechanism across species.

[Clinical and biological characteristics of non-IgM lymphoplasmacytic lymphoma]

OBJECTIVE

To observe the clinical and biological characteristics of Non-IgM-secreting lymphoplasmacytic lymphoma (LPL) and draw the differences between non-IgM LPL and Waldenström macroglobulinemia (WM).

METHODS

Records of 13 patients with non-IgM LPL were retrospectively analyzed between January 2000 and December 2013. The cytogenetic aberrations were detected by fluorescence in situ hybridisation (FISH).

RESULTS

In the cohort, 7 males and 6 females with a median age of 63 years (range 43 to 74), two patients were IgA secreting, 6 with IgG secreting and 5 patients without monoclonal globulin. The major complaint at diagnosis included anemia associated symptom (53.8%), mucocutaneous hemorrhage and superficial lymphadenopathy (15.4%). Eight patients had B symptom at diagnosis. All of the 13 patients had bone marrow involvement and anemia, and 10 patients had 2 or 3 lineage cytopenia. In 5 patients with available immunophenotypic data, all expressed CD19, CD20, CD22 and CD25, but missed the expression of CD10, CD103 and CD38. Two cases had CD5 or sIgM positive alone. Another 2 patients were CD23 or CD11c positive and 3 patients were FMC7 positive. Cytogenetic aberrations had been detected by FISH in 7 patients, but only two (28.6%) patients had aberrations with del(6q).

CONCLUSION

The clinical and biological characteristics had no significantly difference between non-IgM LPL and WM.

Macrophage IL-10 blocks CD8+ T cell-dependent responses to chemotherapy by suppressing IL-12 expression in intratumoral dendritic cells

Blockade of colony-stimulating factor-1 (CSF-1) limits macrophage infiltration and improves response of mammary carcinomas to chemotherapy. Herein we identify interleukin (IL)-10 expression by macrophages as the critical mediator of this phenotype. Infiltrating macrophages were the primary source of IL-10 within tumors, and therapeutic blockade of IL-10 receptor (IL-10R) was equivalent to CSF-1 neutralization in enhancing primary tumor response to paclitaxel and carboplatin. Improved response to chemotherapy was CD8(+) T cell-dependent, but IL-10 did not directly suppress CD8(+) T cells or alter macrophage polarization. Instead, IL-10R blockade increased intratumoral dendritic cell expression of IL-12, which was necessary for improved outcomes. In human breast cancer, expression of IL12A and cytotoxic effector molecules were predictive of pathological complete response rates to paclitaxel.

Diverse and potent chemokine production by lung CD11bhigh dendritic cells in homeostasis and in allergic lung inflammation

Lung CD11c(high) dendritic cells (DC) are comprised of two major phenotypically distinct populations, the CD11b(high) DC and the integrin alpha(E)beta(7)(+) DC (CD103(+) DC). To examine whether they are functionally distinguishable, global microarray studies and real-time PCR analysis were performed. Significant differences between the two major CD11c(high) DC types in chemokine mRNA expression were found. CD11b(high) DC is a major secretory cell type and highly expressed at least 16 chemokine mRNA in the homeostatic state, whereas CD103(+) DC highly expressed only 6. Intracellular chemokine staining of CD11c(high) lung cells including macrophages, and ELISA determination of sort-purified CD11c(high) cell culture supernatants, further showed that CD11b(high) DC produced the highest levels of 9 of 14 and 5 of 7 chemokines studied, respectively. Upon LPS stimulation in vitro and in vivo, CD11b(high) DC remained the highest producer of 7 of 10 of the most highly produced chemokines. Induction of airway hyperreactivity and lung inflammation increased lung CD11b(high) DC numbers markedly, and they produced comparable or higher amounts of 11 of 12 major chemokines when compared with macrophages. Although not a major producer, CD103(+) DC produced the highest amounts of the Th2-stimulating chemokines CCL17/thymus and activation-related chemokine and CCL22/monocyte-derived chemokine in both homeostasis and inflammation. Significantly, CCL22/monocyte-derived chemokine exhibited regulatory effects on CD4(+) T cell proliferation. Further functional analysis showed that both DC types induced comparable Th subset development. These studies showed that lung CD11b(high) DC is one of the most important leukocyte types in chemokine production and it is readily distinguishable from CD103(+) DC in this secretory function.

New insights into Drosophila larval haemocyte functions through genome-wide analysis

Drosophila blood cells or haemocytes comprise three cell lineages, plasmatocytes, crystal cells and lamellocytes, involved in immune functions such as phagocytosis, melanisation and encapsulation. Transcriptional profiling of activities of distinct haemocyte populations and from naive or infected larvae, was performed to find genes contributing to haemocyte functions. Of the 13 000 genes represented on the microarray, over 2500 exhibited significantly enriched transcription in haemocytes. Among these were genes encoding integrins, peptidoglycan recognition proteins (PGRPs), scavenger receptors, lectins, cell adhesion molecules and serine proteases. One relevant outcome of this analysis was the gain of new insights into the lamellocyte encapsulation process. We showed that lamellocytes require betaPS integrin for encapsulation and that they transcribe one prophenoloxidase gene enabling them to produce the enzyme necessary for melanisation of the capsule. A second compelling observation was that following infection, the gene encoding the cytokine Spatzle was uniquely upregulated in haemocytes and not the fat body. This shows that Drosophila haemocytes produce a signal molecule ready to be activated through cleavage after pathogen recognition, informing distant tissues of infection.

Comparative study of Oral versus Subcutaneous B:9-23 insulin peptide in Balb/c mice as an experimental model for Autoimmune Diabetes

Insulin peptide B:9-23 (amino acids 9 to 23 of the B chain) can induce immune targeting of insulin and islets in normal Balb/c mice. The insulin autoantibodies induced react with insulin and not the immunizing peptide. Oral administration of insulin as well as subcutaneous insulin can sensitize to insulin.

Identification of integrin beta subunit mutations that alter heterodimer function in situ

We conducted a genetic screen for mutations in myospheroid, the gene encoding the Drosophila betaPS integrin subunit, and identified point mutants in all of the structural domains of the protein. Surprisingly, we find that mutations in very strongly conserved residues will often allow sufficient integrin function to support the development of adult animals, including mutations in the ADMIDAS site and in a cytoplasmic NPXY motif. Many mutations in the I-like domain reduce integrin expression specifically when betaPS is combined with activating alphaPS2 cytoplasmic mutations, indicating that integrins in the extended conformation are unstable relative to the inactive, bent heterodimers. Interestingly, the screen has identified alleles that show gain-of-function characteristics in cell culture, but have negative effects on animal development or viability. This is illustrated by the allele mys(b58); available structural models suggest that the molecular lesion of mys(b58), V409>D, should promote the "open" conformation of the beta subunit I-like domain. This expectation is supported by the finding that alphaPS2betaPS (V409>D) promotes adhesion and spreading of S2 cells more effectively than does wild-type alphaPS2betaPS, even when betaPS is paired with alphaPS2 containing activating cytoplasmic mutations. Finally, comparisons with the sequence of human beta8 suggest that evolution has targeted the "mys(b58)" residue as a means of affecting integrin activity.

Analysis of the Drosophila betaPS subunit indicates that regulation of integrin activity is a primal function of the C8-C9 loop

Integrin-ligand interactions can be influenced by the sequence in a disulfide-bridged loop between the 8th and 9th beta subunit cysteines. Previous experiments are consistent with C8-C9 loop residues being involved in direct ligand-integrin interactions and/or being important in heterodimer regulation. In betaPS from Drosophila melanogaster and three other dipterans, the C8-C9 loop consists of only two amino acids, and exists in two forms that arise by differential splicing of exon 4. In these species, the betaPS4A isoform has an acidic residue in the first loop position (C8+1), with an alanine or proline in the corresponding position of betaPS4B. Mutations in both isoforms (in combination with alphaPS2) can reduce cell spreading during normal growth, but function is generally restored under conditions that enhance integrin activation. Replacement of the betaPS4A acidic residue with a basic lysine has relatively modest effects on integrin function. Spread cells bearing C8-C9 mutations tend to become less elongated, with reduced frequencies of actin stress fibers. The results indicate that even a minimal, two-residue C8-C9 loop contains structural information that can differentially regulate integrin activity and/or integrin signaling, and that this regulation does not rely on direct molecular interactions involving the variable C8+1 side chains.

Delayed behavioural aging and altered mortality in Drosophila beta integrin mutants

The genetic basis for aging is being intensely investigated in a variety of model systems. Much of the focus in Drosophila has been on the molecular-genetic determinants of lifespan, whereas the molecular-genetic basis for age-related functional declines has been less vigorously explored. We evaluated behavioural aging and lifespan in flies harbouring loss-of-function mutations in myospheroid, the gene that encodes betaPS, a beta integrin. Integrins are adhesion molecules that regulate a number of cellular processes and developmental events. Their role in aging, however, has received limited attention. We report here that age-related declines in locomotor activity are ameliorated and that mean lifespan is increased in myospheroid mutants. The delayed functional senescence and altered mortality in myospheroid flies are independent of changes in body size, reproduction or stress resistance. Our data indicate that functional senescence and age-dependent mortality are influenced by beta integrins in Drosophila.

Essential roles for ecdysone signaling during Drosophila mid-embryonic development

Although functions for the steroid hormone ecdysone during Drosophila metamorphosis have been well established, roles for the embryonic ecdysone pulse remain poorly understood. We show that the EcR-USP ecdysone receptor is first activated in the extraembryonic amnioserosa, implicating this tissue as a source of active ecdysteroids in the early embryo. Ecdysone signaling is required for germ band retraction and head involution, morphogenetic movements that shape the first instar larva. This mechanism for coordinating morphogenesis during Drosophila embryonic development parallels the role of ecdysone during metamorphosis. It also provides an intriguing parallel with the role of mammalian extraembryonic tissues as a critical source of steroid hormones during embryonic development.

Posterior migration of the salivary gland requires an intact visceral mesoderm and integrin function

The final overall shape of an organ and its position within the developing embryo arise as a consequence of both its intrinsic properties and its interactions with surrounding tissues. Here, we focus on the role of directed cell migration in shaping and positioning the Drosophila salivary gland. We demonstrate that the salivary gland turns and migrates along the visceral mesoderm to become properly oriented with respect to the overall embryo. We show that salivary gland posterior migration requires the activities of genes that position the visceral mesoderm precursors, such as heartless, thickveins, and tinman, but does not require a differentiated visceral mesoderm. We also demonstrate a role for integrin function in salivary gland migration. Although the mutations affecting salivary gland motility and directional migration cause defects in the final positioning of the salivary gland, most do not affect the length or diameter of the salivary gland tube. These findings suggest that salivary tube dimensions may be an intrinsic property of salivary gland cells.

Forces for morphogenesis investigated with laser microsurgery and quantitative modeling

We investigated the forces that connect the genetic program of development to morphogenesis in Drosophila. We focused on dorsal closure, a powerful model system for development and wound healing. We found that the bulk of progress toward closure is driven by contractility in supracellular "purse strings" and in the amnioserosa, whereas adhesion-mediated zipping coordinates the forces produced by the purse strings and is essential only for the end stages. We applied quantitative modeling to show that these forces, generated in distinct cells, are coordinated in space and synchronized in time. Modeling of wild-type and mutant phenotypes is predictive; although closure in myospheroid mutants ultimately fails when the cell sheets rip themselves apart, our analysis indicates that beta(PS) integrin has an earlier, important role in zipping.

Myopodia (postsynaptic filopodia) participate in synaptic target recognition

Synaptic partner cells recognize one another by utilizing a variety of molecular cues. Prior to neuromuscular synapse formation, Drosophila embryonic muscles extend dynamic actin-based filopodia called "myopodia." In wild-type animals, myopodia are initially extended randomly from the muscle surface but become gradually restricted to the site of motoneuron innervation, a spatial redistribution we call "clustering." Previous experiments with prospero mutant embryos demonstrated that myopodia clustering does not occur in the absence of motoneuron outgrowth into the muscle field. However, whether myopodia clustering is due to a general signal from passing axons or is a result of the specific interactions between synaptic partners remained to be investigated. Here, we have examined the relationship of myopodia to the specific events of synaptic target recognition, the stable adhesion of synaptic partners. We manipulated the embryonic expression of alphaPS2 integrin and Toll, molecules known to affect synaptic development, to specifically alter synaptic targeting on identified muscles. Then, we used a vital single-cell labeling approach to visualize the behavior of myopodia in these animals. We demonstrate a strong positive correlation between myopodia activity and synaptic target recognition. The frequency of myopodia clustering is lowered in cases where synaptic targeting is disrupted. Myopodia clustering seems to result from the adherence of a subset of myopodia to the innervating growth cone while the rest are eliminated. The data suggest that postsynaptic cells play a dynamic role in the process of synaptic target recognition.

Interaction between apterous and early expression of vestigial in formation of the dorso-ventral compartments in the Drosophila wing disc

BACKGROUND

Compartment formation is a developmental process that requires the existence of barriers against intermixing between cell groups. In the Drosophila wing disc, the dorso-ventral (D/V) compartment boundary is defined by the expression of the apterous (ap) selector gene in the dorsal compartment. AP activity is under control of dLMO which destabilizes the formation of the AP-CHIP complex.

RESULTS

We report that D/V boundary formation in the wing disc also depends on early expression of vestigial (vg). Our data suggest that vg is already required for wing cell proliferation before D/V compartmentalization. In addition, we show that over-expression of vg can, to some extent, rescue the effect of the absence of ap on D/V boundary formation. Early VG product regulates AP activity by inducing dLMO and thus indirectly regulating ap target genes such as fringe and the PSalpha1 and PSalpha2 integrins.

CONCLUSION

Normal cell proliferation is necessary for ap expression at the level of the D/V boundary. This would be mediated by vg, which interacts in a dose-dependent way with ap.

Collagen-binding I domain integrins--what do they do?

Collagens are the most abundant proteins in the mammalian body and it is well recognized that collagens fulfill an important structural role in the extracellular matrix in a number of tissues. Inactivation of the collagen alpha 1(I) gene in mice results in embryonic lethality and collagen mutations in humans cause defects leading to disease. Integrins constitute a major group of receptors for extracellular matrix components, including collagens. Currently four collagen-binding I domain-containing integrins are known, namely alpha 1 beta 1, alpha 2 beta 1, alpha 10 beta 1 and alpha 11 beta 1. Unlike the undisputed role of collagens as structural elements, the biological importance of integrin mediated cell-collagen interactions is far from clear. This is in part due to the limited information available on the most recent additions of the integrin family, alpha 10 beta 1 and alpha 11 beta 1. Future studies using gene inactivation of individual and multiple integrin genes will allow testing of the hypothesis that collagen-binding integrins have redundant functions but will also shed light on their importance in pathological conditions. In this review we will describe what is currently known about the collagen-binding integrins and discuss their biological functions.

Alteration in expression of beta 2 integrins on lamina propria lymphocytes in ulcerative colitis and Crohn's disease

We have previously demonstrated by immunohistochemistry that mucosal expression of beta 2 integrins was enhanced in Crohn's disease and ulcerative colitis as compared to normal controls. We aimed, therefore, to determine whether there was a corresponding alteration in the expression of CD11a/CD18 (LFA-1), the primary lymphocyte beta 2 integrin, among the principal subsets of lamina propria lymphocytes (LPLs). Accordingly, LPLs were extracted from surgical resection specimens derived from patients with Crohn's colitis, ulcerative colitis, and from noninflamed controls. Following immunofluorescent staining, three-color flow-cytometry analysis identified LPLs on the basis of CD45 side scatter gating, which in turn, were further subdivided into CD4(+), CD8(+), and CD19(+) cells to account for the predominant T and B cells in the lamina propria. Expression patterns of CD11a, the alpha-subunit of LFA-1; CD18, the beta-subunit of LFA-1; and alpha d, a novel alpha-subunit of the beta 2 integrin family were assessed for each of these lymphocyte subsets. In Crohn's disease and ulcerative colitis there was an increased mean percentage expression of CD4(+) cells and CD11a(+) cells compared with noninflamed controls. CD11a was more likely to be expressed on CD4(+) cells in both Crohn's disease and ulcerative colitis and compared with controls and less expressed on CD19(+) cells. It is likely that an influx of CD4(+)11a(+) cells into the lamina propria accounted for these changes. These results suggest that although currently there is great interest in harnessing alpha 4 beta 7 in treatment of inflammatory bowel disease, further consideration should be given to the role of CD11a in these disease states.

Hoxa 11 is upstream of Integrin alpha8 expression in the developing kidney

Mutation of the functionally redundant Hoxa 11/Hoxd 11 genes gives absent or rudimentary kidneys resulting from a dramatic reduction of the growth and branching of the ureteric bud. To understand better the molecular mechanisms of Hoxa 11/Hoxd 11 function in kidney development, it is necessary to identify the downstream target genes regulated by their encoded transcription factors. To this end, we conducted a screen for Hoxa 11-responsive genes in two kidney cell lines. HEK293 cells, which usually do not express Hoxa 11, were modified to allow inducible Hoxa 11 expression. The mK10 cells, derived specifically for this study from Hoxa 11/Hoxd 11 double-mutant mice, were also modified to give cell populations with and without Hoxa 11 expression. Differential display, Gene Discovery Arrays, and Affymetrix genechip probe arrays were used to screen for genes up- or down-regulated by Hoxa 11. Nine genes, PDGF A, Cathepsin L, annexin A1, Mm.112139, Est2 repressor factor, NrCAM, ZNF192, integrin-associated protein, and GCM1, showed reproducible 3-fold or smaller changes in gene expression in response to Hoxa 11. One gene, the Integrin alpha8, was up-regulated approximately 20-fold after Hoxa 11 expression. The Integrin alpha8 gene is expressed together with Hoxa 11 in metanephric mesenchyme cells, and mutation of Integrin alpha8 gives a bud-branching morphogenesis defect very similar to that observed in Hoxa 11/Hoxd 11 mutant mice. In situ hybridizations showed a dramatic regional reduction in Integrin alpha8 expression in the developing kidneys of Hoxa 11/Hoxd 11 mutant mice. This work suggests that the Integrin alpha8 gene may be a major effector of Hoxa 11/Hoxd 11 function in the developing kidney.

Disruption of C-terminal cytoplasmic domain of betaPS integrin subunit has dominant negative properties in developing Drosophila

We have analyzed a set of new and existing strong mutations in the myospheroid gene, which encodes the betaPS integrin subunit of Drosophila. In addition to missense and other null mutations, three mutants behave as antimorphic alleles, indicative of dominant negative properties. Unlike null alleles, the three antimorphic mutants are synthetically lethal in double heterozygotes with an inflated (alphaPS2) null allele, and they fail to complement very weak, otherwise viable alleles of myospheroid. Two of the antimorphs result from identical splice site lesions, which create a frameshift in the C-terminal half of the cytoplasmic domain of betaPS. The third antimorphic mutation is caused by a stop codon just before the cytoplasmic splice site. These mutant betaPS proteins can support cell spreading in culture, especially under conditions that appear to promote integrin activation. Analyses of developing animals indicate that the dominant negative properties are not a result of inefficient surface expression, or simple competition between functional and nonfunctional proteins. These data indicate that mutations disrupting the C-terminal cytoplasmic domain of integrin beta subunits can have dominant negative effects in situ, at normal levels of expression, and that this property does not necessarily depend on a specific new protein sequence or structure. The results are discussed with respect to similar vertebrate beta subunit cytoplasmic mutations.

Analysis of the roles of RGD-binding integrins, alpha(4)/alpha(9) integrins, alpha(6) integrins, and CD9 in the interaction of the fertilin beta (ADAM2) disintegrin domain with the mouse egg membrane

Fertilin beta (also known as ADAM2), a mammalian sperm protein that mediates gamete cell adhesion during fertilization, is a member of the ADAM protein family whose members have disintegrin domains with homology to integrin ligands found in snake venoms. Fertilin beta utilizes an ECD sequence within its disintegrin domain to interact with the egg plasma membrane; the Asp is especially critical. Based on what is known about different integrin subfamilies and their ligands, we sought to characterize fertilin beta binding sites on mouse eggs, focusing on integrin subfamilies that recognize short peptide sequences that include an Asp residue: the alpha(5)/alpha(8)/alpha(v)/alpha(IIb) or RGD-binding subfamily (alpha(5)beta(1), alpha(8)beta(1), alpha(V)beta(1), alpha(V)beta(3), alpha(V)beta(5), alpha(V)beta(6), alpha(V)beta(8), and alpha(IIb)beta(3)) and the alpha(4)/alpha(9) subfamily (alpha(4)beta(1), alpha(9)beta(1), and alpha(4)beta(7)). We tested peptide sequences known to perturb interactions mediated by these integrins in two different assays for fertilin beta binding. Peptides with the sequence MLDG, which perturb alpha(4)/alpha(9) integrin-mediated interactions, significantly inhibit fertilin beta binding to eggs, which suggests a role for a member of this integrin subfamily as a fertilin beta receptor. RGD peptides, which perturb alpha(5)/alpha(8)/alpha(v)/alpha(IIb) integrin-mediated interactions, have partial inhibitory activity. The anti-alpha(6) antibody GoH3 has little or no inhibitory activity. An antibody to the integrin-associated tetraspanin protein CD9 inhibits the binding of a multivalent presentation of fertilin beta (immobilized on beads) but not soluble fertilin beta, which we speculate has implications for the role of CD9 in the strengthening of fertilin beta-mediated cell adhesion but not in initial ligand binding.

Flow cytometry of peripheral blood and bone marrow cells from patients with hairy cell leukemia: phenotype of hairy cells, lymphocyte subsets and detection of minimal residual disease after treatment

By flow cytometry (FC) and an extensive panel of markers we characterized leukemia cells from the peripheral blood (PB) and bone marrow (BM) of 13 symptomatic patients with hairy cell leukemia (HCL). Hairy cells (HCs) identified in the large cell gate always expressed B-cell markers - CD19, CD20, CD22, HLA-DR, and 'HCL-restricted' markers - CD22+CD11c, CD25 and CD103. Other markers, not followed regularly, were occasionally expressed, such as CD34, CD38, CD71, CD15, CD10 and kappa/lambda light chains. Furthermore, in one patient with suspect but not proved HCL in PB or BM, neither morphologically nor immunologically, we confirmed the diagnosis of HCL. Only the immunophenotyping of splenic cells after splenectomy confirmed HCL diagnosis. Flow cytometry was repeated at 3-5 month intervals, after treatment with 2-Chlorodeoxyadenosine (CdA) or less frequently alpha-interferon (IFN). We investigated serially lymphocyte subsets after treatment and we found profound and persistent CD4+ lymphopenia in majority of studied patients after CdA treatment. Simultaneously we investigated the value of FC to detect minimal residual disease (MRD) and to establish, whether MRD+ could predict relapse. Detection of MRD in our series predicted hematological relapse only in one case with persistent MRD+, in majority of cases with occasionally found MRD+ phenotype, did not. Using quantitative immunophenotyping we observed significantly higher values of molecule numbers of hairy cell B-cell markers, comparing to B-cells in nonleukemic gate of the same sample. Our study showed 1) the diagnostic value of FC in management of HCL patients, 2) long-lasting response in the majority of patients after CdA, 3) a profound and persistent CD4+ lymphopenia in CdA treated patients, 4) some correlation between persistent MRD staining and hematological relapse, and 5) further, till now not described activated feature of HCs, given by the increased values of molecular numbers (molecules of equivalent soluble fluoresceine - MESF) in B-cell antigens of HCL.

The alpha8 integrin chain affords mechanical stability to the glomerular capillary tuft in hypertensive glomerular disease

In the kidney, the alpha8 integrin chain is expressed in glomerular mesangial cells. The alpha8 integrin plays a role in early nephrogenesis but its functional role in the adult kidney is unknown. We tested the hypothesis that alpha8 integrin-mediated cell-matrix interactions are important to maintain the integrity of the glomerulus in arterial hypertension. Desoxycorticosterone (DOCA)-salt hypertension was induced in mice homozygous for a deletion of the alpha8 integrin chain and wild-type mice. Blood pressure, albumin excretion, total renal mass, and glomerular filtration in DOCA-treated alpha8-deficient mice were comparable to DOCA-treated wild types. DOCA-treated wild types showed increased glomerular immunostaining for alpha8 integrin compared to salt-loaded and untreated controls, whereas the glomeruli of alpha8-deficient mice always stained negative. Morphometric studies revealed similar degrees of glomerulosclerosis in DOCA-treated alpha8-deficient and DOCA-treated wild-type mice. However, DOCA-treated alpha8-deficient mice had a higher score of capillary widening (mesangiolysis) than DOCA-treated wild-type mice, which was confirmed in two additional wild-type strains. Moreover, in DOCA-treated alpha8-deficient mice, glomerular fibrin deposits were more frequent than in DOCA-treated wild types. The results show that lack of alpha8 is associated with increased susceptibility to glomerular capillary destruction in DOCA salt hypertension, whereas it does not seem to play a major role in the development of fibrosis or glomerulosclerosis. Our findings indicate that mesangial alpha8 integrin contributes to maintain the integrity of the glomerular capillary tuft during mechanical stress, eg, in hypertension.

Dystroglycan is not required for localization of dystrophin, syntrophin, and neuronal nitric-oxide synthase at the sarcolemma but regulates integrin alpha 7B expression and caveolin-3 distribution

Dystroglycan is part of the dystrophin-associated protein complex, which joins laminin in the extracellular matrix to dystrophin within the subsarcolemmal cytoskeleton. We have investigated how mutations in the components of the laminin-dystroglycan-dystrophin axis affect the organization and expression of dystrophin-associated proteins by comparing mice mutant for merosin (alpha(2)-laminin, dy), dystrophin (mdx), and dystroglycan (Dag1) using immunohistochemistry and immunoblots. We report that syntrophin and neuronal nitric-oxide synthase are depleted in muscle fibers lacking both dystrophin and dystroglycan. Some fibers deficient in dystroglycan, however, localize dystrophin at the cell surface at levels similar to that in wild-type muscle. Nevertheless, these fibers have signs of degeneration/regeneration including increased cell surface permeability and central nuclei. In these fibers, syntrophin and nitric-oxide synthase are also localized to the plasma membrane, whereas the sarcoglycan complex is disrupted. These results suggest a mechanism of membrane attachment for dystrophin independent of dystroglycan and that the interaction of sarcoglycans with dystrophin requires dystroglycan. The distribution of caveolin-3, a muscle-specific component of caveolae recently found to bind dystroglycan, was affected in dystroglycan- and dystrophin-deficient mice. We also examined alternative mechanisms of cell-extracellular matrix attachment to elucidate how the muscle basement membrane may subsist in the absence of dystroglycan, and we found the alpha(7B) splice variant of the alpha(7) integrin receptor subunit to be up-regulated. These results support the possibility that alpha(7B) integrin compensates in mediating cell-extracellular matrix attachment but cannot rescue the dystrophic phenotype.

CD4(+)CD25(+) immunoregulatory T cells: gene expression analysis reveals a functional role for the glucocorticoid-induced TNF receptor

CD4(+)CD25(+) immunoregulatory T cells represent a unique lineage of thymic-derived cells that potently suppress both in vitro and in vivo effector T cell function. We analyzed CD4(+)CD25(+) and CD4(+)CD25(-) T cells by DNA microarray, identifying 29 genes differentially expressed in the resting subpopulations, and 77 that were differentially expressed following activation. Most of these genes were elevated in the CD4(+)CD25(+) population, suggesting a previously activated phenotype. Among these were a number of genes that antagonize signaling, including members of the SOCS family, which may contribute to their anergic phenotype. Multiple cell surface receptors also had increased expression in CD4(+)CD25(+) cells, including GITR, a member of the TNF receptor superfamily. Importantly, antibodies to GITR abrogated suppression, demonstrating a functional role for this receptor in regulating the CD4(+)CD25(+) T cell subset.

Branch-specific migration cues in the Drosophila tracheal system

The Drosophila tracheal system forms by highly stereotyped migration of the tracheal cells, generating an elaborate network of interconnected tubes supplying oxygen to all tissues. A major guiding system in the migration process of all branches is the dynamic and localized expression of Branchless (Bnl), an FGF-like molecule. Bnl triggers the activation of the FGF receptor Breathless (Btl) locally in all tracheal cells. Is this the only guiding cue, or do additional local signals provide distinct inputs to each branch? Several recent papers identify such local signals, relying on contacts with specific cell types and with the matrix encountered by the migrating tracheal branches. In particular, the paper by Boube et al(1) demonstrates a role for PS integrins in promoting migration of a specific tracheal branch.

Transforming growth factor-beta1 mediates coexpression of the integrin subunit alphaE and the chymase mouse mast cell protease-1 during the early differentiation of bone marrow-derived mucosal mast cell homologues

BACKGROUND

Mucosal mast cells (MMC) play a central role in gut hypersensitivities and inflammation. They are morphologically, biochemically and functionally distinct from their connective tissue counterparts. Massive hyperplasia of MMC occurs 7-10 days after intestinal infection with nematodes but it has never been possible to replicate this phenomenon in vitro.

OBJECTIVE

(1) To determine whether mouse bone marrow-derived mast cells (mBMMC) grown in the presence of transforming growth factor (TGF)-beta1 could develop over the same time frame (7-10 days) as MMC in parasitized mice. (2) To compare the early expression of surface receptors (integrins alphaE and beta7, c-kit and FcepsilonR) with that of the MMC-specific granule chymase mouse mast cell protease-1 (mMCP-1).

METHODS

Mouse bone marrow cells were cultured in the presence of IL-9, IL-3 and Stem Cell Factor (SCF) with or without TGF-beta1. mBMMC were quantified after toluidine blue or Leishmans' staining. Expression of MMC-specific mouse mast cell proteases was analysed by ELISA, immunohistochemistry and RT-PCR. Surface antigen expression was characterized by flow cytometry and confocal microscopy.

RESULTS

TGF-beta1 promotes the development of abundant MMC-like mBMMC from bone marrow progenitor cells with kinetics, which closely parallel that seen in vivo. mRNA transcripts encoding mMCP-1 and -2 are readily detectable by day 4 ex vivo in cultures grown in the presence of TGF-beta1. Between 30 and 40% and 75-90% of the cells in these cultures on days 4 and 7, respectively, have typical mast cell morphology, are c-kit+, FcepsilonR+, integrin alphaEbeta7+, and express and secrete abundant mMCP-1. The integrin alphaE subunit is coexpressed with mMCP-1.

CONCLUSION

The kinetics of mMCP-1+/alphaE+ mBMMC development, regulated by TGF-beta1, are consistent with that seen in vivo in the parasitized intestine. The normally down-regulatory functions of TGF-beta1 in haematopoiesis are superseded in this culture system by its ability to promote the early expression of alphaE and mMCP-1.

Characterization of a feline homologue of the alphaE integrin subunit (CD103) reveals high specificity for intra-epithelial lymphocytes

The characteristics of a feline homologue of the alphaE integrin (CD103), defined by two murine monoclonal antibodies, Fe7.1B8 (IgG1) and Fe7.2D8 (IgG1), are described. These antibodies recognized 75% of intra-epithelial (range 59-88%) and 40% of lamina proprial (range 28-46%) T cells of the intestinal mucosal tissue of the small intestine in contrast with approximately 2% of peripheral blood lymphocytes. Both antibodies immunoprecipitated a 180 kDa protein from biotinylated feline intra-epithelial mucosal leukocytes consistent with the alphaE integrin subunit in conjunction with a 120 kDa protein consistent with the beta7 subunit. The nucleotide sequence of feline alphaE integrin, generated from molecular cloning of the feline alphaE encoding cDNA, is also reported. This feline molecule shares 72% sequence homology with human and 69% homology with murine and rat counterparts. Homology includes the presence of an X (extra) domain, that appears unique to alphaE molecules as described for human, rat and mouse, as well as areas of homology common to other alpha integrins. Of note is a typical I (inserted) domain, the presence of seven repeat regions, and highly conserved sequences in the cytoplasmic tail. Transfection studies demonstrated that both antibodies recognized an extracellular component which encompassed the X and I domains of the cloned alphaE integrin subunit. These studies demonstrate that the pattern of tissue distribution, biochemical characteristics, and cDNA sequence of the feline alphaE integrin subunit are largely similar to that described for other species.

Cervicovaginal lamina propria lymphocytes: phenotypic characterization and their importance in cytotoxic T-lymphocyte responses to simian immunodeficiency virus SIVmac251

Most human immunodeficiency virus (HIV) type 1 infections occur by the mucosal route. Thus, it is important to assess the immune responses to HIV in the vaginal, cervical, and rectal compartments. Here we quantitated the virus-specific CD8+ T-cell response and characterized the phenotype of lymphocytes in the genital tracts of naive macaques, macaques acutely or chronically infected with simian immunodeficiency virus SIVmac251, and macaques chronically infected with chimeric simian/human immunodeficiency virus SHIV(KU2.) Vaginal biopsy samples or samples obtained at the time of euthanasia were used in this analysis. The percentage of Gag-specific, tetramer-positive T cells was as high as 13 to 14% of the CD3+ CD8+ T-cell population in the vaginal and cervical laminae propriae of both SIVmac251 and SHIV(KU2) chronically infected macaques. In most cases, the frequency of this response in the cervicovaginal compartment far exceeded the frequency in the blood or the draining iliac lymph node. Vaginal laminae propriae of naive macaques contained 55 to 65% CD3+ CD8+ cells and 28 to 34% CD3+ CD4+ cells, while the majority of intraepithelial cells were CD8+ T cells (75 to 85%). For the same cells, the surface expression of CD62L was low whereas that of alphaEbeta7 was high. No difference in the expression of CD45RA on CD8+ T cells was observed in the chronic stage of SIVmac251 infection. Although no decrease in the percentage of CD4+ cells in the genital tract was observed within the first 12 days of infection, by 6 weeks from SIVmac251 infection and thereafter the percentage of CD4+ T cells was decreased in the laminae propriae of the vagina and cervix. Expression of CD45RA did not differ in naive and acutely SIVmac251 infected macaques. Information on the quality and quantity of local immune responses may help in the design of vaccine strategies aimed at containing viral replication at the site of viral encounter.

Selective binding of collagen subtypes by integrin alpha 1I, alpha 2I, and alpha 10I domains

Four integrins, namely alpha(1)beta(1), alpha(2)beta(1), alpha(10)beta(1), and alpha(11)beta(1), form a special subclass of cell adhesion receptors. They are all collagen receptors, and they recognize their ligands with an inserted domain (I domain) in their alpha subunit. We have produced the human integrin alpha(10)I domain as a recombinant protein to reveal its ligand binding specificity. In general, alpha(10)I did recognize collagen types I-VI and laminin-1 in a Mg(2+)-dependent manner, whereas its binding to tenascin was only slightly better than to albumin. When alpha(10)I was tested together with the alpha(1)I and alpha(2)I domains, all three I domains seemed to have their own collagen binding preferences. The integrin alpha(2)I domain bound much better to fibrillar collagens (I-III) than to basement membrane type IV collagen or to beaded filament-forming type VI collagen. Integrin alpha(1)I had the opposite binding pattern. The integrin alpha(10)I domain was similar to the alpha(1)I domain in that it bound very well to collagen types IV and VI. Based on the previously published atomic structures of the alpha(1)I and alpha(2)I domains, we modeled the structure of the alpha(10)I domain. The comparison of the three I domains revealed similarities and differences that could potentially explain their functional differences. Mutations were introduced into the alphaI domains, and their binding to types I, IV, and VI collagen was tested. In the alpha(2)I domain, Asp-219 is one of the amino acids previously suggested to interact directly with type I collagen. The corresponding amino acid in both the alpha(1)I and alpha(10)I domains is oppositely charged (Arg-218). The mutation D219R in the alpha(2)I domain changed the ligand binding pattern to resemble that of the alpha(1)I and alpha(10)I domains and, vice versa, the R218D mutation in the alpha(1)I and alpha(10)I domains created an alpha(2)I domain-like ligand binding pattern. Thus, all three collagen receptors appear to differ in their ability to recognize distinct collagen subtypes. The relatively small structural differences on their collagen binding surfaces may explain the functional specifics.

Distribution of lymphocytes of the alpha(E)beta(7) phenotype and E-cadherin in normal human urothelium and bladder carcinomas

The primary aim of this work was to survey normal urothelium and transitional cell carcinoma (TCC) for the presence of T lymphocytes expressing the intraepithelial, CD103(+) phenotype. This antigen defines the alpha(E)beta(7)-integrin. The adhesive counter-receptor for alpha(E)beta(7) is E-cadherin, which is down-regulated during cancer progression. The secondary aim was to determine the pattern of distribution of CD103(+) lymphocytes in relation to E-cadherin expression in bladder cancer. Cryostat sections of normal bladder and TCC were treated with antibodies specific for human CD103, CD3, CD8 and E-cadherin. Visualization was performed by immunoperoxidase or alkaline phosphatase development with light and confocal microscopy. Dual staining and serial sections were used to assess the relationship between these antigens. Four samples of normal bladder and 26 TCC samples were assessed. Occasional T lymphocytes (CD3(+)) were seen in normal urothelium and lamina propria. In the urothelium the majority of these T lymphocytes (71%) were also CD8(+) and of these 68% expressed the CD103 marker. In the lamina propria 62% of the T lymphocytes were CD8(+) and 56% of these expressed the CD103 marker. In carcinomas significantly greater numbers of CD103(+) T lymphocytes were present in the surrounding stroma rather than infiltrating the carcinomas (P = 0.0006). Of those T lymphocytes infiltrating the tumours, 71% were CD8(+) and of these 58% expressed CD103. In the surrounding stroma 52% of lymphocytes were CD8(+) and 82% of this subset expressed CD103. Infiltration by CD103(+) lymphocytes was not related to the intensity of E-cadherin expression. T lymphocytes of the CD103(+) phenotype are present in normal urothelium where they may play a role in immunosurveillance. Rather than infiltrating into carcinomas, these cells predominate in the surrounding stroma which could suggest a failure of immune function.

Characterization of the mouse integrin subunit alpha10 gene and comparison with its human homologue. Genomic structure, chromosomal localization and identification of splice variants

Alpha10beta1 is a collagen-binding integrin expressed by chondrocytes [Camper et al. (1998) J. Biol. Chem. 273: 20383-20389]. In the present study, the mouse alpha10 gene was isolated from a sCos1 SVJ library and the genomic structure and chromosomal localization was determined. The alpha10 gene consists of 30 translated exons spanning a region of approximately 18 kb genomic DNA. The sequences of all exon/intron borders follow the consensus "gt-ag" rule. A transcription start site, determined by primer extension analysis, was located 38 nucleotides upstream of the initiation ATG site. The 5' flanking region of the transcription start site lacked a TATA-box. The first exon contained, in addition to 38 untranslated nucleotides, the ATG translation start site and the major part of the signal peptide. The alpha10 gene was mapped to mouse chromosome 3 by fluorescence in situ hybridization and is the only integrin subunit localized to this chromosome. When we investigated the expression of alpha10 by PCR we found that both mouse and human articular chondrocytes express extracellular splice variants of the alpha10 subunit. In mouse, exon 26 was extended into the intron by 62 nt, generating a truncated alpha10-chain. In human, exon 25 consisted of 114 nt which were alternately spliced in or out.

CD103+ CTL accumulate within the graft epithelium during clinical renal allograft rejection

BACKGROUND

We have previously reported that activated CD8+TCRalphabeta+ cells that express high levels of the beta7 integrin CD103 (formerly alphaE, MLA) are present at the graft site during clinical renal allograft rejection. This observation potentially provides new insight into the mechanisms underlying renal allograft destruction because the ligand of CD103 is the epithelial cell-specific molecule E-cadherin, which is known to be expressed by critical graft functional elements such as the renal tubular epithelium. We herein used combined fluorescence-activated cell sorter (FACS) and immunohistochemical (IHC) analyses of transplant nephrectomy (TN) specimens to demonstrate that CD103+ cytolytic T lymphocytes (CTLs) specifically home to the graft epithelium during rejection episodes.

METHODS

Serial sections of TN specimens undergoing histologically confirmed cellular rejection (n=7) were stained with anti-CD8 or anti-CD103 and were scored for the presence of positively stained cells within the tubular basement membrane. Freshly isolated graft-infiltrating lymphocytes were subjected to three-color FACS analyses to define the extended phenotypic characteristics of CD103+ cells detected by IHC.

RESULTS

CD103+ cells in all specimens were biased towards an intratubular localization. On average, the percentage of CD103+ cells with an intraepithelial localization was 52.2+/-13.1 compared to 12.0+/-3.5 for pan CD8+ cells (mean+/-SE, n=5). FACS analyses confirmed that CD103+ cells detected by IHC exhibited the salient characteristics of CD8+ CTLs (large CD8+TCRalphabeta+CD62L-CD11a(hi)perforin+). The CD103- subset of graft-infiltrating CD8 cells also exhibited a CTL phenotype, but these were predominantly restricted to the graft interstitium.

CONCLUSIONS

These data implicate CD103 as a homing receptor that targets graft-infiltrating CD8+ CTLs to the graft epithelium. Given the strong association of tubulitis with clinical rejection, these data are consistent with a role for the CD103+ CTL subset as an effector mechanism in renal allograft destruction.

zipper Nonmuscle myosin-II functions downstream of PS2 integrin in Drosophila myogenesis and is necessary for myofibril formation

Nonmuscle myosin-II is a key motor protein that drives cell shape change and cell movement. Here, we analyze the function of nonmuscle myosin-II during Drosophila embryonic myogenesis. We find that nonmuscle myosin-II and the adhesion molecule, PS2 integrin, colocalize at the developing muscle termini. In the paradigm emerging from cultured fibroblasts, nonmuscle actomyosin-II contractility, mediated by the small GTPase Rho, is required to cluster integrins at focal adhesions. In direct opposition to this model, we find that neither nonmuscle myosin-II nor RhoA appear to function in PS2 clustering. Instead, PS2 integrin is required for the maintenance of nonmuscle myosin-II localization and we show that the cytoplasmic tail of the beta(PS) integrin subunit is capable of mediating this PS2 integrin function. We show that embryos that lack zygotic expression of nonmuscle myosin-II fail to form striated myofibrils. In keeping with this, we demonstrate that a PS2 mutant that specifically disrupts myofibril formation is unable to mediate proper localization of nonmuscle myosin-II at the muscle termini. In contrast, embryos that lack RhoA function do generate striated muscles. Finally, we find that nonmuscle myosin-II localizes to the Z-line in mature larval muscle. We suggest that nonmuscle myosin-II functions at the muscle termini and the Z-line as an actin crosslinker and acts to maintain the structural integrity of the sarcomere.

Intestinal mast cell progenitors require CD49dbeta7 (alpha4beta7 integrin) for tissue-specific homing

Mast cells (MCs) are centrally important in allergic inflammation of the airways, as well as in the intestinal immune response to helminth infection. A single lineage of bone marrow (BM)-derived progenitors emigrates from the circulation and matures into phenotypically distinct MCs in different tissues. Because the mechanisms of MC progenitor (MCp) homing to peripheral tissues have not been evaluated, we used limiting dilution analysis to measure the concentration of MCp in various tissues of mice deficient for candidate homing molecules. MCp were almost completely absent in the small intestine but were present in the lung, spleen, BM, and large intestine of beta7 integrin-deficient mice (on the C57BL/6 background), indicating that a beta7 integrin is critical for homing of these cells to the small intestine. MCp concentrations were not altered in the tissues of mice deficient in the alphaE integrin (CD103), the beta2 integrin (CD18), or the recombination activating gene (RAG)-2 gene either alone or in combination with the interleukin (IL)-receptor common gamma chain. Therefore, it is the alpha4beta7 integrin and not the alphaEbeta7 integrin that is critical, and lymphocytes and natural killer cells play no role in directing MCp migration under basal conditions. When MCp in BALB/c mice were eliminated with sublethal doses of gamma-radiation and then reconstituted with syngeneic BM, the administration of anti-alpha4beta7 integrin, anti-alpha4 integrin, anti-beta7 integrin, or anti-MAdCAM-1 monoclonal antibodies (mAbs) blocked the recovery of MCp in the small intestine. The blocking mAbs could be administered as late as 4 d after BM reconstitution with optimal inhibition, implying that the MCp must arise first in the BM, circulate in the vasculature, and then translocate into the intestine. Inasmuch as MCp are preserved in the lungs of beta7 integrin-deficient and anti-alpha4beta7 integrin-treated mice but not in the small intestine, alpha4beta7 integrin is critical for tissue specific extravasation for localization of MCp in the small intestine, but not the lungs.

Dentate hilar mossy cells and somatostatin-containing neurons are immunoreactive for the alpha8 integrin subunit: characterization in normal and kainic acid-treated rats

Integrins are heterodimeric cell surface receptors composed of different alpha and beta subunits that mediate cell-cell and cell-extracellular matrix interactions. They have been implicated in the regulation of neuronal migration, differentiation, process outgrowth, and plasticity. The alpha8 integrin subunit associates exclusively with the beta1 subunit to form a receptor (alpha8beta1) for fibronectin, vitronectin, tenascin, and osteopontin. In a previous study, we demonstrated that hippocampal dentate hilar neurons are immunoreactive for alpha8. The present study identifies the major types of alpha8-immunoreactive hilar neurons and characterizes the effects of kainic acid-induced seizures on alpha8-immunoreactivity in these cells. Examination of the hilus in normal rats revealed alpha8-immunoreactivity in the somatodendritic compartments of large hilar neurons identified as mossy cells, including a subset of dendritic thorny excrescences that were contacted by large mossy fiber terminals. alpha8-immunoreactivity also was found in approximately 71% of somatostatin-containing hilar cells. Kainic acid-induced seizures dramatically and rapidly altered the levels and distribution of alpha8-immunoreactivity in hilar neurons. After 1.5 h of seizures, alpha8-immunoreactivity in their dendrites was reduced greatly. One day after kainic acid treatment, labeling was diminished throughout the somatodendritic compartments of most hilar cells. This decrease appeared to be transient, since alpha8 labeling returned to normal levels in surviving hilar neurons within 2 weeks of treatment. In addition, many alpha8-immunoreactive hilar neurons, particularly in caudal dentate regions, were lost 3-5 weeks after kainic acid treatment. Our findings suggest that alpha8beta1 may mediate adhesive interactions of the dendritic processes of mossy cells and somatostatin-containing hilar neurons with other cellular elements or with extracellular matrix components. They also suggest that alpha8 may be susceptible to activity-dependent proteolysis that could modulate its function in the somatodendritic compartment of these cells.

Trophoblast-specific expression and function of the integrin alpha 7 subunit in the peri-implantation mouse embryo

For implantation and placentation to occur, mouse embryo trophoblast cells must penetrate the uterine stroma to make contact with maternal blood vessels. A major component of the uterine epithelial basement membrane and underlying stromal matrix with which they interact is the extracellular matrix protein laminin. We have identified integrin alpha 7 beta 1 as a major receptor for trophoblast-laminin interactions during implantation and yolk sac placenta formation. It is first expressed by trophectoderm cells of the late blastocyst and by all trophectoderm descendants in the early postimplantation embryo through E8.5, then disappears except in cells at the interface between the allantois and the ectoplacental plate. Integrin alpha 7 expression is a general characteristic of the early differentiation stages of rodent trophoblast, given that two different cultured trophoblast cell lines also express this integrin. Trophoblast cells interact with at least three different laminin isoforms (laminins 1, 2/4, and 10/11) in the blastocyst and in the uterus at the time of implantation. Outgrowth assays using function-blocking antibodies show that alpha 7 beta 1 is the major trophoblast receptor for laminin 1 and a functional receptor for laminins 2/4 and 10/11. When trophoblast cells are cultured on substrates of these three laminins, they attach and spread on all three, but show decreased proliferation on laminin 1. These results show that the alpha 7 beta 1 integrin is expressed by trophoblast cells and acts as receptor for several isoforms of laminin during implantation. These interactions are not only important for trophoblast adhesion and spreading but may also play a role in regulating trophectoderm proliferation and differentiation.

Binding of Paxillin to the alpha 9 Integrin Cytoplasmic Domain Inhibits Cell Spreading

alpha(9)beta(1) integrin is a member of the beta(1) integrin family, plays an important role in extravasation of neutrophils at sites of acute inflammation, and is required for the normal development of the lymphatic system. The alpha(9) and alpha(4) integrin subunits are most closely related and form a subfamily of integrin alpha subunits. Previously, we have reported that the alpha(4) cytoplasmic domain directly and tightly binds paxillin, an intracellular signaling adaptor molecule. This interaction accounts for some of the unusual functional responses to alpha(4) integrin-mediated cell adhesion, including stimulation of cell migration and inhibition of cell spreading and focal adhesion formation. In the current studies, we have examined the interaction between the alpha(9) cytoplasmic domain and paxillin. Here we report that the alpha(9) cytoplasmic domain binds paxillin directly and tightly and that the alpha(9)-paxillin association inhibits cell spreading. We have identified amino acid residues in the alpha(9) cytoplasmic domain, Trp(999) and Trp(1001), that are critical for paxillin binding, and alanine substitution of either Trp(999) or Trp(1001) blocks paxillin binding. Furthermore, these mutations also reverse the effect of the alpha(9) cytoplasmic domain on cell spreading. Thus, the alpha(9) and alpha(4) integrin subunits form a paxillin-binding subfamily of integrin alpha subunits, and direct binding of paxillin to the alpha(9) cytoplasmic domain mediates some of the biological activities of the alpha(9)beta(1) integrin.

Distribution of the collagen-binding integrin alpha10beta1 during mouse development

We have previously identified and characterised the collagen type II-binding integrin subunit alpha10, which is a member of the beta1 family and is expressed by chondrocytes. In the present study, we examined the expression of the alpha10 integrin in various mouse tissues. Immunohistochemical analysis of alpha10 on cryosections from 3-day-old mice demonstrated that alpha10beta1 was present in the hyaline cartilage of joints, vertebral column, trachea and bronchi. In addition, alpha10 was found in the ossification groove of Ranvier, in the aortic and atrioventricular valves of the heart and in the fibrous tissue lining skeletal muscle and ligaments. Overall, the distribution was distinct from that of the collagen-binding integrins alpha1beta1 and alpha2beta1. We also found that alpha10beta1was the dominating collagen-binding integrin during cartilage development. Expression of alpha10 appeared at embryonic day 11.5 (E11.5) at the same time as chondrogenesis started as judged by collagen type II expression. At E13.5, alpha10 was present throughout the anlage as well as in the perichondrium and in mesenchyme just outside the perichondrium, where it localised with collagen type I. Four weeks after birth, alpha10 was prominent both at the articular surface and in the growth plate. In conclusion, we found that integrin alpha10beta1 was a major collagen-binding integrin during cartilage development and in mature hyaline cartilage. In addition, we found that alpha10beta1 was present in some fibrous tissues.

The cytoplasmic domain of the integrin alpha9 subunit requires the adaptor protein paxillin to inhibit cell spreading but promotes cell migration in a paxillin-independent manner

The integrin alpha9 subunit forms a single heterodimer, alpha9beta1. The alpha9 subunit is most closely related to the alpha4 subunit, and like alpha4 integrins, alpha9beta1 plays an important role in leukocyte migration. The alpha4 cytoplasmic domain preferentially enhances cell migration and inhibits cell spreading, effects that depend on interaction with the adaptor protein, paxillin. To determine whether the alpha9 cytoplasmic domain has similar effects, a series of chimeric and deleted alpha9 constructs were expressed in Chinese hamster ovary cells and tested for their effects on migration and spreading on an alpha9beta1-specific ligand. Like alpha4, the alpha9 cytoplasmic domain enhanced cell migration and inhibited cell spreading. Paxillin also specifically bound the alpha9 cytoplasmic domain and to a similar level as alpha4. In paxillin(-/-) cells, alpha9 failed to inhibit cell spreading as expected but surprisingly still enhanced cell migration. Further, mutations that abolished the alpha9-paxillin interaction prevented alpha9 from inhibiting cell spreading but had no effect on alpha9-dependent cell migration. These findings suggest that the mechanisms by which the cytoplasmic domains of integrin alpha subunits enhance migration and inhibit cell spreading are distinct and that the alpha9 and alpha4 cytoplasmic domains, despite sequence and functional similarities, enhance cell migration by different intracellular signaling pathways.