Gerhard Sengle / Raimund Wagener / Mats Paulsson - C 14

Extracellular microfibrillar systems in disease pathogenesis: functional interactions in cytokine regulation, cellular differentiation and tissue homeostasis

New strategies for treating congenital musculoskeletal disorders are needed. Current treatments are limited and aim to prolong ambulation and survival.Cellular microenvironments such as stem cell niches in muscle and bone are defined by extracellular microfibrillar networks (EMFN) which are required for tissue structure and function. EMFN made of fibrillin-1 and -2, and collagen VI with associated ligands are of particular interest since human mutations in EMFN components result in disorders with overlapping clinical features.

Introduction

The molecular mechanisms by which perturbed cellmatrix interactions lead to musculoskeletal disorders are not well understood, and common or shared pathogenetic mechanisms have not yet been uncovered. From genetic evidence in humans and mice it becomes clear that EMFN together with their associated ligands are controlling homeostasis of multiple tissues. However, the underlying molecular pathways remain obscure. Our previous investigations have identified EMFN consisting of fibrillins as regulators/ modulators of growth factor activity. This corroborates the emerging concept that extracellular matrix proteins are actively regulating growth factor activity and bioavailability.
This concept opens novel treatment avenues for a wide range of connective tissue diseases which were thought to be incurable due to defects in proteins of purely architecturalnature.

EMILIN-1 is required for extracellular matrix deposition of fibulin-4

Elastin-Microfibril-Interface-Located-proteINs, the EMILIN, comprise a family of three structurally homologous extracellular matrix (ECM) glycol-proteins that serve as versatile regulators of cell adhesion, migration, and proliferation, but also as unique modulators of extracellular signalling pathways. EMILINs were found to influence pro-TGF-βprocessing, modulate Wnt and Hedgehog signaling, activate death receptor mediated apoptosis, and communicate with cells via α4β1 and α9β1 integrin mediated signalling. We recently found that EMILINs are targeted to fibrillin microfibrils implicating them in the disease pathogenesis of fibrillin-related disorders. Recently, we showed that EMILIN-1 directly interacts with fibulin-4 and is required for its ECM deposition within specialized cellular microenvironments (Schiavinato et al., 2017). Fibulin-4 mutations lead to flexion contractures in patients and mice. Mutations in fibrillin-2 also result in flexion contractures of the large joints in Beals Syndrome patients. 

Assessment of structurally impaired fibrillin microfibrils by Raman microspectroscopy in a mouse model of Marfan Syndrome

Mutations in building blocks of the EMFN manifest in connective tissue disorders such as Marfan syndrome (MFS) characterized by long bone overgrowth, aortic aneurysm formation, and muscle weakness. Understanding how structural changes induced by fibrillin-1 mutation impact the architecture of fibrillin microfibrils (FMF), which then translates into an altered activation state of targeted growth factors, represents a huge challenge in elucidating the genotype-phenotype correlations in MFS. In collaboration with the group of Katja Schenke-Layland (University of Tübingen) we could show that Raman microspectroscopy is able to reveal structural changes in fibrillin-1 microfibrils and elastic fiber networks and to discriminate between normal and diseased networks in vivo and in vitro (Brauchle et al., 2017).
For this purpose we analyzed a Marfan mouse model in which the C-terminal half of fibrillin-1 is truncated. Skin biopsies and organotypic co-cultures from isolated primary fibroblasts were utilized for Raman measurements. In our study, structural elements in an area of 400 × 700 nm were scanned based on the volume of the Raman laser spot. Given the length of fibrillin-1 monomers of 150 nm and a 50-80 nm periodicity Raman microspectroscopy is able to pick up structural changes of FMF on the molecular level. Therefore Raman microspectroscopy may be utilized as a non-invasive and sensitive diagnostic tool to identify connective tissue disorders and monitor their disease progression.

New mechanisms controlling growth factor release from the ECM 

The short most C-terminal domain of the collagen VI α3 chain, was recently proposed to be released as an adipokine enhancing tumor progression, fibrosis, inflammation and insulin resistance, and therefore named “endotrophin”. We showed that the metalloproteinase BMP-1 is involved in the release of endotrophin. Moreover, we provided evidence that a variety of endotrophin-containing fragments are present in various tissues and body fluids (Heumüller et al., 2019). Among these, a large C2-C5 fragment containing endotrophin, is released by furin-like proprotein convertase cleavage. This detailed information on the processing of the collagen VI α3 chain therefore provides a basis to unravel the function of endotrophin (C5) and larger endotrophin-containing fragments and to refine their use as circulating biomarkers of disease progression.
In addition, we showed in collaboration with the group of Clair Baldock (University of Manchester) that genetic ablation of the metalloproteinase ADAMTS10 in mice ressembles recessive Weill-Marchesani syndrome (WMS). WMS mice have an increased skeletal muscle mass and more myofibres which correlated with increased expression of growth differentiation factor (GDF8) and BMPs (Mularczyk et al., 2018). Furthermore, our collaborative work addressed the question how modulators such as BMPER exert their function in the extracellular microenvironment (Lockhart-Cairns et al., 2019).  

Perspectives

This project has the potential to provide a comprehensive and fundamental understanding of the molecular pathomechanisms caused by mutations in EMFN components which will lay the foundation for future translational approaches of congenital musculoskeletal disorders

Selected publications

1. Brauchle, E., Bauer, H., Fernes, P., Zuk, A., Schenke-Layland, K., and Sengle, G. (2017). Raman microspectroscopy as a diagnostic tool for the non-invasive analysis of fibrillin-1 deficiency in the skin and in the in vitro skin models.Acta Biomater. 52: 41-48.

2. Heumüller SE, Talantikite M, Napoli M, Armengaud J, Mörgelin M, Hartmann U, Sengle GPaulsson M, Moali C, Wagener R. C-terminal proteolytic cleavage of the collagen VI α3 chain by BMP-1 and proprotein convertase(s): Endotrophin is released in fragments of different size, JBC 2019, in press.

3. Lockhart-Cairns MP, Lim KTW, Zuk A, Godwin ARF, Cain SA, Sengle G, Baldock C. Internal cleavage and synergy with twisted gastrulation enhance BMP inhibition by BMPER. Matrix Biol. (2019); 77: 73-86. 

4. Mularczyk EJ, Singh M, Godwin ARF, Galli F, Humphreys N, Adamson AD, Mironov A, Cain SA, Sengle G, Boot-Handford RP, Cossu G, Kielty CM, Baldock C. ADAMTS10-mediated tissue disruption in Weill-Marchesani syndrome. Hum Mol Genet. (2018); 27: 3675-3687. 

5. Schiavinato, A., Keene, D.R., Imhof, T., Doliana, R., Sasaki, T., and Sengle G. (2017). Fibulin-4 deposition requires EMILIN-1 in the extracellular matrix of osteoblasts. Sci Rep. 7: 5526.


Prof. Dr. Gerhard Sengle

Institute for Biochemistry II

Prof. Dr. Gerhard Sengle

Principal Investigator C 14

gsengle@uni-koeln.de

Work +49 221 478 97260

Fax (Work) +49 221 478 6977

Institute for Biochemistry II
Joseph-Stelzmann-Str. 52
50931 Cologne

http://www.uni-koeln.de/med-fak/biochemie/staff/sengle/

Publications - Gerhard Sengle

Link to PubMed


Prof. Dr. Raimund Wagener

Institute for Biochemistry II

Prof. Dr. Raimund Wagener

Co-Principal Investigator C 14

raimund.wagener@uni-koeln.de

Work +49 221 478 6990

Fax (Work) +49 221 478 6977

Institute for Biochemistry II
Joseph-Stelzmann-Str. 52
50931 Cologne

http://www.uni-koeln.de/med-fak/biochemie/staff/wagener/

Publications - Raimund Wagener

Link to PubMed


Prof. Dr. Mats Paulsson

Institute for Biochemistry II

Prof. Dr. Mats Paulsson

Co-Principal Investigator C 14
Executive Board Member

mats.paulsson@uni-koeln.de

Work +49 221 478 6997

Fax (Work) +49 221 478 6977

Institute for Biochemistry II
Joseph-Stelzmann-Str. 52
50931 Cologne

http://www.uni-koeln.de/med-fak/biochemie/biomed2/

Publications - Mats Paulsson

Link to PubMed

Group Members

Katrin Hildebrandt (Doctoral student)
Stefanie Heumüller (Doctoral student)

Figure 1

CMMC Research Odenthal

Localization of EMFN in specialized cellular microenvironments. Top panel: Confocal immunefluorescence microscopy showing EMILIN-1 and -2, together with fibrillin-2 localization in transverse sections from newborn mouse tail. Each protein showed a specific dis-tribution pattern among the different tissues present in the tail. The inset in the merged panel shows a higher magnification of the annulus fibrosus, where EMILIN-1 and fibrillin-2 fibers show co-localization. Bottom panel: siRNA mediated knock-down of EMILIN-1 abolished ECM deposition of fibulin-4 in MC3T3-E1osteoblasts.Scale bar: 75 μm.