The fibroblast integrin ␣11␤1 is a key receptor for fibrillar collagens. To study the potential function of ␣11 in vivo, we generated a null allele of the ␣11 gene. Integrin ␣11 ؊/؊ mice are viable and fertile but display dwarfism with increased mortality, most probably due to severely defective incisors. Mutant incisors are characterized by disorganized periodontal ligaments, whereas molar ligaments appear normal. The primary defect in the incisor ligament leads to halted tooth eruption. ␣11␤1-defective embryonic fibroblasts displayed severe defects in vitro, characterized by (i) greatly reduced cell adhesion and spreading on collagen I, (ii) reduced ability to retract collagen lattices, and (iii) reduced cell proliferation. Analysis of matrix metalloproteinase in vitro and in vivo revealed disturbed MMP13 and MMP14 synthesis in ␣11 ؊/؊ cells. We show that ␣11␤1 is the major receptor for collagen I on mouse embryonic fibroblasts and suggest that ␣11␤1 integrin is specifically required on periodontal ligament fibroblasts for cell migration and collagen reorganization to help generate the forces needed for axial tooth movement. Our data show a unique role for ␣11␤1 integrin during tooth eruption.Integrins constitute a family of multifunctional cell adhesion receptors involved in a variety of biological processes. In higher vertebrates the integrin family is composed of 18 ␣ subunits and 8 ␤ subunits. Out of the 24 integrin heterodimers, ␣1␤1, ␣2␤1, ␣10␤1, and ␣11␤1 act as primary receptors for native collagens. The ␣3␤1 integrin, initially described as a collagen receptor, was later shown to act as a receptor for laminin-5 and does not display any measurable affinity for collagen I (21). The observed role of ␣v␤3 integrin in collagen lattice remodeling in vitro (13, 33) and in vivo (33) may be related to indirect binding to RGD ligands which are locally deposited in the collagen matrix.Collagen-binding integrins bind native collagens via their ␣I domain, recognizing a GFOGER motif (30, 52) or similar sequences with varying specificities and affinities depending on the collagen type and fibrillar status (27). In addition to mediating cell adhesion, cell spreading, and cell migration (22), collagen-binding integrins regulate collagen turnover (32) and take part in assembling (31, 49) and reorganizing three-dimensional collagen matrices (23).Fibroblasts express characteristic collagen receptor repertoires in a tissue-specific manner, partly reflecting their different embryonic origins. We have previously demonstrated that ␣11␤1 is the only detectable collagen-binding integrin in the incisor periodontal ligament (PDL) fibroblasts of mice (38). The PDL in the mouse incisor is composed of a relatively dense connective tissue on the side facing the tooth and a loose connective tissue region rich in blood vessels on the side facing the bone. The odontogenic ectomesenchyme is the source of the cells populating these two domains in the PDL, which are sometimes referred to as tooth-associated fibroblasts and bone-associated...

Integrin ␣11 (ITGA11/␣11) is localized to stromal fibroblasts and commonly overexpressed in non-small-cell lung carcinoma (NSCLC). We hypothesized that stromal ␣11 could be important for the tumorigenicity of NSCLC cells. SV40 immortalized mouse embryonic fibroblasts established from wild-type (WT) and Itga11-deficient [knockout (KO)] mice were tested for their tumorigenicity in immune-deficient mice when implanted alone or coimplanted with the A549 human lung adenocarcinoma cells. A549 coimplanted with the fibroblasts showed a markedly enhanced tumor growth rate compared with A549, WT, or KO, which alone formed only small tumors. Importantly, the growth was significantly greater for A549؉WT compared with A549؉KO tumors. Reexpression of human ␣11 cDNA in KO cells rescued a tumor growth rate to that comparable with the A549؉WT tumors. These findings were validated in two other NSCLC cell lines, NCI-H460 and NCI-H520. Gene expression profiling indicated that IGF2 mRNA expression level was >200 times lower in A549؉KO compared with A549؉WT tumors. Stable short-hairpin RNA (shRNA) down-regulation of IGF2 in WT (WT shIGF2) fibroblasts resulted in a decreased growth rate of A549؉WTshIGF2, compared with A549؉WT tumors. The results indicate that ␣11 is an important stromal factor in NSCLC and propose a paradigm for carcinoma-stromal interaction indirectly through interaction between the matrix collagen and stromal fibroblasts to stimulate cancer cell growth.cancer-associated fibroblast ͉ tumor microenvironment ͉ tumor progression ͉ tumor-stromal interaction ͉ paracrine signaling

We assessed the prevalence of common altered brain proteins in 296 cognitively unimpaired subjects ranging from age 50 to 102 years. The incidence and the stage of hyperphosphorylated-τ (HPτ), β-amyloid, α-synuclein (αS), and transactive response DNA (TDP) binding protein 43 (TDP43)-immunoreactivity (-IR) increased with age. HPτ-IR was observed in 98% of the subjects; the locus coeruleus was solely affected in 46%, and 79% of the subjects were in Braak stages a to II. β-Amyloid was seen in 47% of subjects and the Thal phase correlated with the HPτ Braak stage and age. Intermediate Alzheimer disease-related pathology (ADRP) was seen in 12%; 52% of the subjects with HPτ-IR fulfilled criteria for definite primary age-related tauopathy (PART). The incidence of concomitant pathology (αS, TDP43) did not differ between those with PART and those with ADRP but the former were younger. TDP43-IR was observed in 36%; the most frequently affected region was the medulla; αS-IR was observed in 19% of subjects. In 41% of the subjects from 80 to 89 years at death, 3 altered proteins were seen in the brain. Thus, altered proteins are common in the brains of cognitively unimpaired aged subjects; this should be considered while developing diagnostic biomarkers, particularly for identifying subjects at early stages of neurodegenerative diseases.

Fibrotic tissue is characterized by an overabundance of myofibroblasts. Thus, understanding the factors that induce myofibroblast differentiation is paramount to preventing fibrotic healing. Previous studies have shown that mechanical stress derived from the integrin-mediated interaction between extracellular matrix and the cytoskeleton promotes myofibroblast differentiation. Integrin ␣11␤1 is a collagen receptor on fibroblasts. To determine whether ␣11␤1 can act as a mechanosensor to promote the myofibroblast phenotype, mouse embryonic fibroblasts and human corneal fibroblasts were utilized. We found that ␣11 mRNA and protein levels were up-regulated in mouse embryonic fibroblasts grown in attached three-dimensional collagen gels and conversely down-regulated in cells grown in floating gels. ␣11 up-regulation could be prevented by manually detaching the collagen gels or by cytochalasin D treatment. Furthermore, SB-431542, an inhibitor of signaling via ALK4, ALK5, and ALK7, prevented the up-regulation of ␣11 and the concomitant phosphorylation of Smad3 under attached conditions. In attached gels, TGF-␤1 was secreted in its inactive form but surprisingly not further activated, thus not influencing ␣11 regulation. However, inhibition of activin A attenuated the up-regulation of ␣11. To determine the role of ␣11 in myofibroblast differentiation, human corneal fibroblasts were transfected with small interfering RNA to ␣11, which decreased ␣-smooth muscle actin expression and myofibroblast differentiation. Our data suggest that ␣11␤1 is regulated by cell/matrix stress involving activin A and Smad3 and that ␣11␤1 regulates myofibroblast differentiation.

AimsIn 2010, four subtypes (classical, proneural, mesenchymal, and neural) of glioblastoma multiforme (GBM) were defined by molecular genetic analyses. The objective of this study was to assess whether gliomas, independently of the type and grade, could be subdivided into protein-based subtypes.Methods and resultsA tissue microarray (TMA) approach was applied to incorporate tissue samples of low-grade and high-grade gliomas into five TMAs. High expression levels of epidermal growth factor receptor (EGFR), CD44, c-MER proto-oncogene tyrosine kinase (MERTK), platelet-derived growth factor receptor α, p53, oligodendrocyte transcription factor 2 (OLIG2) and isocitrate dehydrogenase 1 with the R132H mutation were assessed using immunohistochemistry (IHC). Glioma could be subdivided into four subtypes by IHC. The majority of the low-grade gliomas were of the proneural subtype, i.e. high p53 expression (63% of grade II). The classical subtype, with high EGFR and low p53 expression, was most common in GBMs (39%), followed by the proneural (29%) and mesenchymal (with high CD44 and MERTK expression) (29%) subtypes, a frequency that is in line with previously published data based on molecular genetics.ConclusionsAssessment of the expression of the five proteins EGFR, CD44, MERTK, p53 and OLIG2 is sufficient for subtyping gliomas, and can be recommended for implementation in clinical practice for both low-grade and high-grade gliomas.