The exon encoding the fibronectin type III-9 repeat is constitutively included in the mRNA from chick limb mesenchyme and cartilage

Previous studies have shown that several forms of the glycoprotein tenascin are present in the embryonic extracellular matrix. These forms are the result of alternative splicing, which generates tenascin variants with different numbers of fibronectin type III repeats. We have used degenerate primers and PCR to isolate a novel tenascin exon from an avian genomic library. Genomic clones contained a sequence encoding a fibronectin type III repeat that corresponds to repeat ‘C’ from the variable domain of human tenascin. To demonstrate that tenascin containing repeat ‘C’ is actually synthesized by avian cells, a monospecific antiserum was raised against a repeat ‘C’ fusion protein. This antiserum recognized a novel high-molecular-weight variant on immunoblots of tenascin isolated from chicken embryo fibroblast-conditioned medium, and stained tendons on frozen sections of chicken embryos. A cDNA probe specific for mRNA encoding repeat ‘C’ was used for in situ hybridization. This probe hybridized in a subset of the embryonic tissues labelled with a universal tenascin probe, including tendons, ligaments and mesenchyme at sites of epithelial-mesenchymal interactions. Finally, we provide evidence that additional fibronectin type III repeats, one corresponding to a recently discovered human repeat as well as one entirely novel sequence, also exists in chicken tenascin mRNA. These data indicate that tenascin is present in the embryonic matrix in a multitude of forms and that these forms have distinctive distributions that may reflect more than one function for tenascin in development.

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Interaction of CREB and PGC-1α Induces Fibronectin Type III Domain-Containing Protein 5 Expression in C2C12 Myotubes

Cellular Physiology and Biochemistry ◽

10.1159/000494655 ◽

2018 ◽

Vol 50 (4) ◽

pp. 1574-1584 ◽

Cited By ~ 6

Author(s):

Xiu-ying Yang ◽

Margaret C.L. Tse ◽

Xiang Hu ◽

Wei-hua Jia ◽

Guan-hua Du ◽

...

Keyword(s):

Skeletal Muscle ◽

Molecular Mechanisms ◽

Metabolic Effects ◽

Hek293 Cells ◽

Metabolic Phenotype ◽

C2c12 Myotubes ◽

Type Iii ◽

Fibronectin Type Iii ◽

Fibronectin Type Iii Domain ◽

Fibronectin Type

Background/Aims: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. Methods: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). Results: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. Conclusion: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.

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Peer Review #1 of "Expression, refolding and spectroscopic characterization of fibronectin type III (FnIII)-homology domains derived from human fibronectin leucine rich transmembrane protein (FLRT)-1, -2, and -3 (v0.1)"

10.7287/peerj.3550v0.1/reviews/1 ◽

2017 ◽

Keyword(s):

Peer Review ◽

Transmembrane Protein ◽

Spectroscopic Characterization ◽

Type Iii ◽

Fibronectin Type Iii ◽

Human Fibronectin ◽

Fibronectin Type ◽

Homology Domains

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Target-Binding Proteins Based on the 10th Human Fibronectin Type III Domain (10Fn3)

Methods in Enzymology - Protein Engineering for Therapeutics, Part B ◽

10.1016/b978-0-12-396962-0.00006-9 ◽

2012 ◽

pp. 135-156 ◽

Cited By ~ 54

Author(s):

Shohei Koide ◽

Akiko Koide ◽

Daša Lipovšek

Keyword(s):

Binding Proteins ◽

Type Iii ◽

Fibronectin Type Iii ◽

Human Fibronectin ◽

Target Binding ◽

Fibronectin Type Iii Domain ◽

Fibronectin Type

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Domains of tenascin involved in glioma migration

Journal of Cell Science ◽

10.1242/jcs.111.8.1095 ◽

1998 ◽

Vol 111 (8) ◽

pp. 1095-1104

Author(s):

G.R. Phillips ◽

L.A. Krushel ◽

K.L. Crossin

Keyword(s):

Cell Migration ◽

Matrix Protein ◽

Glioma Cells ◽

C6 Glioma ◽

Extracellular Matrix Protein ◽

C6 Glioma Cells ◽

Dependent Manner ◽

Type Iii ◽

Fibronectin Type Iii ◽

Fibronectin Type

Tenascin (TN) is an extracellular matrix protein found in areas of cell migration during development and expressed at high levels in migratory tumor cells. TN was previously shown to support the attachment and migration of glioma cells in culture. To determine the domains responsible for glioma migration and attachment, we produced recombinant fusion proteins that collectively span the majority of the molecule including its epidermal growth factor-like repeats, fibronectin type III repeats and fibrinogen domain. These domains were tested for their ability to support migration of C6 glioma cells in an aggregate migration assay. A recombinant fusion protein including fibronectin type III (FNIII) repeats 2–6 (TNfn2-6) was the only fragment found to promote migration of C6 glioma cells at levels similar to that promoted by intact TN. Evaluation of smaller segments and individual FNIII repeats revealed that TNfn3 promoted migration and attachment of glioma cells and TNfn6 promoted migration but not attachment. While TNfn3 and TNfn6 promoted migration individually, the presence of both TNfn3 and TNfn6 was required for migration on segments of the FNIII region that included TNfn5. TNfn5 inhibited migration in a dose dependent manner when mixed with TNfn3 and also promoted strong attachment and spreading of C6 glioma cells. TNfn3 and TNfn6 promote cell migration and may function cooperatively to overcome the inhibitory activity of TNfn5. Additional cell attachment studies suggested that both beta1 integrins and heparin may differentially influence the attachment of glioma cells to TN fragments. Together, these findings show that C6 glioma cells integrate their response upon binding to at least three domains within TN.

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