Functional changes in bladder tissue from type III collagen-deficient mice.
ABSTRACT Collagen fibers impart tensile strength and transfer tension from bladder smooth muscle cells. We have previously shown that fibrotic bladders are characterized by an increased type III:type I collagen ratio. To determine the effect of decreased type III collagen on bladder function, type III collagen-deficient mice (COL3A1) were studied physiologically.
Bladders from wild-type (+/+) and heterozygous (+/-) COL3A1 mice were biochemically characterized to determine total collagen (hydroxyproline analysis) and collagen subtype concentration (cyanogen bromide digestion and ELISA). Alterations in collagen fiber diameter were assessed by electron microscopy. Bladder muscle strips were used to assess physiologic function.
Hydroxyproline content decreased in heterozygous bladders, which had 50% less type III collagen. Wild-type bladders had a biphasic distribution of collagen fiber sizes, whereas heterozygous bladder collagen fibers spanned a broad range. Physiologically, there were no differences in contractile responses between wild-type and heterozygotes when stimulated with ATP, carbachol or KCl, indicating normal contraction via purinergic and muscarinic receptors, and in response to direct membrane depolarization. In contrast, tension generation in heterozygotes was decreased after field stimulation (FS), indicating decreased synaptic transmission. Length-tension studies showed that the heterozygote muscle strips generated less tension per unit length, indicating that they were more compliant than wild-type controls.
Critical levels of type III collagen appear to be a requirement for normal bladder tension development and contraction. Our data show that a decrease in the type III:type I collagen ratio, and altered fiber size, results in a more compliant bladder with altered neurotransmitter function.
- SourceAvailable from: Susan Volk[Show abstract] [Hide abstract]
ABSTRACT: The repair of cutaneous wounds in the postnatal animal is associated with the development of scar tissue. Directing cell activities to efficiently heal wounds while minimizing the development of scar tissue is a major goal of wound management and the focus of intensive research efforts. Type III collagen (Col3), expressed in early granulation tissue, has been proposed to play a prominent role in cutaneous wound repair, although little is known about its role in this process. To establish the role of Col3 in cutaneous wound repair, we examined the healing of excisional wounds in a previously described murine model of Col3 deficiency. Col3 deficiency (Col3+/-) in aged mice resulted in accelerated wound closure with increased wound contraction. In addition, Col3-deficient mice had increased myofibroblast density in the wound granulation tissue as evidenced by an increased expression of the myofibroblast marker, α-smooth muscle actin. In vitro, dermal fibroblasts obtained from Col3-deficient embryos (Col3+/- and -/-) were more efficient at collagen gel contraction and also displayed increased myofibroblast differentiation compared to those harvested from wild-type (Col3+/+) embryos. Finally, wounds from Col3-deficient mice also had significantly more scar tissue area on day 21 post-wounding compared to wild-type mice. The effect of Col3 expression on myofibroblast differentiation and scar formation in this model suggests a previously undefined role for this ECM protein in tissue regeneration and repair.Cells Tissues Organs 01/2011; 194(1):25-37. DOI:10.1159/000322399 · 2.14 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Background: While urothelial signals, including sonic hedgehog (Shh), drive bladder mesenchyme differentiation, it is unclear which pathways within the mesenchyme are critical for its development. Studies have shown fibroblast growth factor receptor 2 (Fgfr2) is necessary for kidney and ureter mesenchymal development. Objective: To determine the role of Fgfr2 in bladder mesenchyme.. Methods: We used Tbx18cre mice to delete Fgfr2 in bladder mesenchyme (Fgfr2(BM-/-)). We performed three dimensional (3D) reconstructions, real time PCR (qPCR), in situ hybridization, immunolabeling, ELISAs, immunoblotting, void stain on paper (VSOP), ex vivo bladder sheet assays, and in vivo decerebrated cystometry. Results: Compared to controls, embryonic day (E) 16.5 Fgfr2(BM-/-) bladders have thin muscle layers with less alpha smooth muscle actin (aSMA) and thickened lamina propria with increased collagen Ia and IIIa that intrude into the muscle. The reciprocal changes in mutant layer thicknesses appear due partly to a cell fate switch. P1 to P30, Fgfr2(BM-/-) bladders demonstrate progressive muscle loss and increased collagen expression. Postnatal Fgfr2(BM-/-) bladder sheets exhibit decreased agonist mediated contractility and increased passive stretch tension vs. controls. Cystometry revealed high baseline and threshold pressures and shortened intercontractile intervals in Fgfr2(BM-/-) bladders vs. controls. Mechanistically, while Shh expression appears normal, mRNA and protein readouts of hedgehog activity are increased in E16.5 Fgfr2(BM-/-) bladders vs. controls. Moreover, E16.5 Fgfr2(BM-/-) bladders exhibit higher levels of Cdo and Boc, hedgehog co-receptors that enhance sensitivity to Shh, compared with controls. Conclusion: Loss of Fgfr2 in bladder mesenchyme leads to abnormal bladder morphology and decreased compliance and contractility. Copyright © 2014, American Journal of Physiology - Renal Physiology.American journal of physiology. Renal physiology 02/2015; 308(8):ajprenal.00624.2014. DOI:10.1152/ajprenal.00624.2014 · 3.30 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Type III collagen (Col3) has been proposed to play a key role in tissue repair based upon its temporospatial expression during the healing process of many tissues, including bone. Given our previous finding that Col3 regulates the quality of cutaneous repair, as well as our recent data supporting its role in regulating osteoblast differentiation and trabecular bone quantity, we hypothesized that mice with diminished Col3 expression would exhibit altered long-bone fracture healing. To determine the role of Col3 in bone repair, young adult wild-type (Col3 + / +) and haploinsufficent (Col3 +/ -) mice underwent bilateral tibial fractures. Healing was assessed 7, 14, 21, and 28 days following fracture utilizing microcomputed tomography (microCT), immunohistochemistry and histomorphometry. MicroCT analysis revealed a small but significant increase in bone volume fraction in Col3 + /- mice at day 21. However, histological analysis revealed that Col3 + /- mice have less bone within the callus at days 21 and 28, which is consistent with the established role for Col3 in osteogenesis. Finally, a reduction in fracture callus osteoclastic activity in Col3 + /- mice suggests Col3 also modulates callus remodeling. Although Col3 haploinsufficiency affected biological aspects of bone repair, it did not affect the regain of mechanical function in the young mice that were evaluated in this study. These findings provide evidence for a modulatory role for Col3 in fracture repair and support further investigations into its role in impaired bone healing. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.Journal of Orthopaedic Research 01/2015; 33(5). DOI:10.1002/jor.22838 · 2.97 Impact Factor