Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 148-171). Also available on the Internet.

Ageing tissue is characterised by an alteration in mechanical properties, with tissues becoming increasingly fragile, stiff and less resilient over time. This can lead to a loss of function in tissues which undergo a high degree of stretch and recoil, such as the skin, blood vessels and lungs. These changes are attributed to remodelling of the dermal extra cellular matrix (ECM) proteins which endow tissue with its mechanical properties. Principally the fibrillar collagens provide tensile strength, complemented by the elastic fibres which confer resilience and allow tissues to recoil following deformation. Intriguingly, at the time of menopause, which sees the cessation of the majority of circulating estrogen, skin undergoes accelerated ageing. This strongly suggests a direct link between circulating estrogen and youthful skin. Using an ovariectomised (Ovx) mouse model of human menopause the link between ageing, estrogen deficiency and the dermal ECM proteins was explored. Mechanical testing revealed a significant reduction in the tensile strength, Young’s modulus and stress relaxation time of estrogen deprived tissue, indicating postmenopausal skin would be weaker, more lax and less able to withstand sustained force. Corresponding histological analysis highlighted the elastic fibres are dramatically reduced by estrogen deprivation with seemingly little effects on the fibrillar collagen abundance or alignment. Direct comparison between Ovx and age, reveals age affects mechanical properties in a completely opposing way, with aged tissue higher in tensile strength, Young’s modulus and stress relaxation time compared to control and Ovx. Proteomic analysis by mass spectrometry confirmed elastic fibres to be highly sensitive to estrogen levels. Additionally small leucine rich proteoglycans (SLRP’s) were also significantly reduced by estrogen deficiency, which could affect collagen fibrillogenesis and leave tissue weaker and more susceptible to damage. Despite the opposing effects on mechanical properties, ageing and estrogen deficiency had comparable effects on ECM abundance, suggesting the amount of ECM is not a predictor of mechanical properties; however disparity may be in part due to increased advanced glycation end product crosslinking. Further investigation suggests the mechanism for elastic fibre degradation may be via significant subcutaneous adipose hypertrophy and/or increased gelatinase activity. Both estrogen replacement and stimulation of estrogen receptor α with the agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (PPT) were found to prevent elastic fibre degradation and adipose hypertrophy. Additionally these treatments were also found to induce key elastic fibre proteins in both the mouse model and cultured human dermal fibroblasts. A deeper understanding of estrogen mediated ECM remodelling offers opportunities for targeted pharmacological intervention to slow the effects of menopause and ageing.

Human adult mesenchymal stem cells (MSCs) derived from bone marrow have the capacity to self-renew and to differentiate into a variety of cells and tissues. They can leave their niche to migrate to remote tissues where they play a critical role in angiogenesis, wound repair and tissue regeneration. A major goal in adult stem cell research is to define how MSC fate is controlled by the pericellular extracellular matrix (ECM) and soluble factors that largely constitute their tissue-specific niches. Defining crucial regulatory signals that control the fate and function of MSCs in vitro will contribute to the development of therapeutic strategies to improve tissue regeneration. The objective of this study was to investigate the molecular relationships between cell-ECM integrin receptors and platelet-derived growth factor receptor (PDGFR) tyrosine kinases, which are crucial in modulating MSC expansion, recruitment, and differentiation towards a number of different cell lineages. This study reports that ECM-directed cross-talk between PDGFR-β and alpha5β1 integrin controls the migration of MSCs. Cell adhesion to fibronectin induced integrin alpha5β1-dependent phosphorylation of PDGFR-β in the absence of growth factor stimulation. Phosphorylated PDGFR-β co-immunoprecipitated with integrin alpha5 and co-localised with alpha5β1 in a transient tidemark of focal adhesions. Adhesion to fibronectin also strongly potentiated platelet-derived growth factor (PDGF)-BB-stimulated PDGFR-β phosphorylation, in an alpha5β1-dependent manner. PDGFR-β-activated phosphatidylinositol 3 ́-kinase (PI3-kinase) and Akt activity, actin reorganisation and cell migration were all regulated by fibronectin engagement of alpha5β1 integrin. This synergistic relationship between integrin alpha5β1 and PDGFR-β is a fundamental determinant of mesenchymal cell migration. Thus, fibronectin-rich matrices can prime PDGFR-β to recruit mesenchymal cells at sites of tissue remodelling.

The composition and conformational state of biological molecules have a profound influence on cell behavior and large-scale processes including development and disease progression. Fibronectin fibers are a prevalent component of the extracellular matrix that are believed to adopt a wide array conformations with different functions. Two factors that are hypothesized to regulate fibronectin conformation, and hence fibronectin biological function, are allosteric regulators, such as heparan sulfates, and mechanical strain. However, the relative influence of allosteric regulators and mechanical forces on fibronectin conformation has not been determined. This conformational regulation is especially important in the context of the heparin 2 binding domain (modules III12 to III14), which is known to bind and present numerous growth factors, such as vascular endothelial growth factor, to cells. This thesis will highlight three contributions to this field. First, a new, and remarkably simple technique was developed that permits the detection of the non-equilibrium fibronectin conformations. This technique is founded on the identification of monoclonal antibodies that have altered affinities for fibronectin based on heparin treatment or mechanical strain dependence, or that bind fibronectin equally well in all conditions. Second, the impact of both heparin and mechanical strain on the binding of VEGF to the hep2 region of fibronectin was investigated. It was discovered that both strain and heparin co-regulate VEGF binding. Finally, studies of cell attachment and migration on single fibers of fibronectin with controlled strain states provided the first direct evidence that mechanical strain regulates cell attachment, spreading, and migration on a fibronectin matrix. This body of work demonstrating that the conformational changes in fibronectin lead to altered biological activity has broad impact in a number of fields due to the ubiquitous presence and requirement of fibronectin in cell and tissue function.

Adipose tissue is an organ that plays an important role in energy storage, nutritional balance and thermogenesis. White and brown adipose tissues have distinct cell morphology and metabolic functions. White adipose tissue (WAT) with unilocular lipid droplets serves as a major site of energy storage, while brown adipose tissue (BAT) with multilocular lipid droplets plays an important role in thermogenesis via a mitochondrial protein, uncoupling protein 1 (UCP1). These cells are derived from mesenchymal stem cells (MSCs). Newly discovered beige adipocytes are derived from the same MSC precursors as WAT but resemble BAT due to expression of UCP1. Due to side effects of drugs for treating obesity, activation of UCP1 positive beige adipocytes in WAT has become a new therapeutic target. The interaction of extracellular matrix (ECM) with integrin was found to regulate cell specification of mesenchymal stem cells (MSCs) via intracellular signaling. However, the role of individual ECM proteins in beige adipogenesis in WAT remains unknown. Therefore, we established a system for culturing stromal vascular fraction (SVF) cells from inguinal WAT on ECM protein coated plates and differentiating the cells into either white or beige adipocytes. We found that cells cultured on type I collagen had more round cell morphology and higher mRNA expression of thermogenic genes, UCP1 and type II iodothyronine deiodinase (DIO2),which was further enhanced in myocardin-related transcription factor A (MRTFA) knockout SVF cells. MRTFA has been reported to regulate beige adipogenesis in BMP-ROCK signaling pathway. Based on our data, we found that type I collagen-integrin signaling regulates beige adipogenesis by controlling the activity of MRTFA in MSCs. Our study has provided an insight into developing therapeutic drugs to enhance beige adipocytes formation in WAT for reducing obesity in the future.

Orientador: Benedicto de Campos Vidal / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T09:50:51Z (GMT). No. of bitstreams: 1 Rodrigues_MarcelaAldrovani_D.pdf: 1521761 bytes, checksum: 9a7ab4633d89c9a2a2caa5f1bc35ce53 (MD5) Previous issue date: 2007 / Resumo: Diabetes mellitus é uma doença crônica que afeta o metabolismo de lipídios, carboidratos e proteínas. Sua principal característica é a hiperglicemia devido à produção insuficiente de insulina ou a defeitos na resposta à insulina pelos tecidos periféricos. A hiperglicemia, quando muito acentuada, induz glicosilação não-enzimática de proteínas, que é responsável pela formação de produtos finais de glicosilação não-enzimática (AGEs) e de ligações cruzadas intermoleculares. Neste estudo, organização supramolecular, orientação espacial e propriedades ópticas foram investigadas em proteínas extracelulares da córnea e da aorta de camundongos diabéticos não-obesos (NOD) e não diabéticos (BALB/c). CÓRNEAS: Birrefringência e dicroísmo linear foram investigados em fibras colágenas do estroma corneal de camundongos NOD/Uni e BALB/c/Uni. A contribuição de proteoglicanos do estroma para as anisotropias da córnea também foi investigada. Retardo óptico foi medido em fibras colágenas de córneas intactas e seccionadas com 8 µm de espessura (sem coloração). Dicroísmo linear e índices dicróicos foram investigados em cortes de córnea corados com ponceau SS pH 2.5 e azul de toluidina pH 4.0, usando microespectrofotômetro de varredura e diferentes comprimentos de onda obtidos com régua monocromática. Análise morfológica das birrefringências revelou que fibras colágenas de camundongos NOD e BALB/c estão intercruzadas em vários planos espaciais e orientadas em mais que uma direção ao longo da trajetória corneal. Córneas de NOD apresentaram maiores valores de retardo óptico das birrefringências que o controle. Fibras colágenas coradas com ponceau SS apresentaram valores positivos de dicroísmo linear e índice dicróico. Esses valores foram maiores para as córneas de NOD. Após coloração com azul de toluidina, córneas de NOD e BALB/c apresentaram reação metacromática devido à presença de grupamentos aniônicos (glicosaminoglicanos de proteoglicanos) no estroma; e valores negativos de dicroísmo linear e índice dicróico. Não foi verificada diferença significativa entre córneas de NOD e BALB/c coradas com azul de toluidina. Esses resultados sugerem que o diabetes foi capaz de alterar as anisotropias ópticas da córnea, possivelmente por aumentar o empacotamento molecular das fibras colágenas. Entretanto, o diabetes não alterou a organização espacial dos proteoglicanos do estroma. AORTAS: Ocorrência de glicosilação não-enzimática foi verificada em aortas abdominais de camundongos NOD/Uni, usando azul de nitro-tetrazólio (NBT). Alterações moleculares e estruturais foram investigadas em lâminas elásticas e fibras colágenas, após colorações com cloreto de danzila e anilino-sulfato naftaleno (ANS). Alterações em auto-fluorescência e birrefringência arterial foram investigadas em aortas sem coloração. Proliferação de células musculares lisas também foi investigada em amostras coradas com a reação de Feulgen, usando microscopia confocal e análise de imagem. NBT demonstrou a formação de produtos de glicosilação (frutosamina) na matriz extracelular da aorta de NOD. Lâminas elásticas e fibras colágenas da aorta de NOD apresentaram fluorescência menos intensa que o controle, após colorações com cloreto de danzila e ANS. Entretanto, a auto-fluorescência arterial foi maior nos camundongos NOD. Análise da birrefringência revelou alterações no empacotamento molecular das fibras colágenas da aorta NOD. Nenhuma evidência de proliferação de células musculares lisas foi observada em aortas NOD coradas com a reação de Feulgen / Abstract: Diabetes mellitus is a chronic disorder of the carbohydrate, lipids and protein metabolism. A characteristic feature of this disorder is the hyperglycemia due to a deficient insulin production or to metabolic defects on its response in peripheral tissues. Hyperglycemia induces non-enzymatic glycosylation of proteins, which is responsible for advanced glycosylation end-products (AGEs), and intermolecular crosslinks reactions. In this study, supramolecular organization, spatial orientation and optical properties were investigated in extracellular proteins of the cornea and of the abdominal aorta from nonobese diabetic (NOD) mice and non-diabetic mice (BALB/c). CORNEAS: Birefringence and linear dichroism were investigated in corneal stroma collagen fibers from nonobese NOD/Uni mice and BALB/c/Uni mice. The contribution of stroma proteoglycans to optical anisotropies of the cornea was also investigated in NOD and BALB/c mice. Birefringence optical retardations were measured in stroma collagen fibers of unstained whole and sectioned (8 µm) corneas. Linear dichroism and dichroic ratios were investigated in cornea sections stained with ponceau SS pH 2.5 and toluidine blue pH 4.0, using scanning microspectrophotometer and different wavelengths that were obtained with a monochromator filter ruler. Morphological analysis of the birefringences revealed that NOD and BALB/c stroma collagen fibers are intercrossed in different spatial planes and oriented in more that one direction along the corneal trajectories. NOD corneas showed higher birefringence optical retardation values than the control. Ponceau SS-complexed collagen fibers showed positive linear dichroism and dichroic ratios values that were higher for NOD corneas. After staining with toluidine blue, NOD and BALB/c corneas showed metachromatic reaction verifying the presence of anionic groups (proteoglycan glycosaminoglycans) in the stroma, and negative linear dichroism values. No significant difference was observed between NOD and BALB/c corneas stained with toluidine blue. These results demonstrate that diabetes was capable of altering the optical anisotropies of the cornea, possibly to increase the number of intermolecular crosslinks in stroma collagen fibers, making them more crystalline and aggregate than the control. However, diabetes did not affect the spatial organization of the stroma proteoglycans. Nonenzymatic glycosylation was assessed in aorta extracellular matrix from NOD/Uni mice, using nitroblue tetrazolium (NBT). Molecular and structural changes were investigated in elastic lamellae and collagen fibers of diabetic mice aortas, after staining with dansyl chloride and anilinonaphthalene sulfonate (ANS). Alterations in arterial autofluorescence and birefringence of collagen fibers were investigated in unstained aortas. Smooth muscle cells proliferation was also investigated by confocal microscopy and image analysis, after Feulgen reaction. Assessment of nonenzymatic glycosylation demonstrated glycosylation products formation in the aorta extracellular matrix from NOD mice. Elastic lamellae and collagen fibers from diabetic aortas presented less intense fluorescence after staining with dansyl chloride and ANS when compared to controls. However unstained NOD aortas showed more intense autofluorescence when compared to controls. Birefringence analysis suggests alterations in the higher molecular packing of the arterial collagen fibers in diabetic aortas. In aortas stained by Feulgen reaction no evidence of smooth muscle cells proliferation was observed in diabetic aortas / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

Orientador: Jose Mauro Granjeiro / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T11:41:57Z (GMT). No. of bitstreams: 1 Demarchi_AnaClaudiaCardosodeOliveira_D.pdf: 5748533 bytes, checksum: fc7f80117afc19afea7b65b54245cd3e (MD5) Previous issue date: 2007 / Resumo: As fissuras orais exercem uma profunda influência sobre a vida de seus portadores. Esses indivíduos apresentam, desde o nascimento, dificuldades na alimentação, disturbios ósseos maxilar e mandibular, na arcada dentária, na fala e, em alguns casos, na audição. Além disto, fissurados e seus familiares enfrentam sérios problemas psicológicos decorrentes do comprometimento estético causado pela anomalia. Sem dúvida alguma, a morfogênese do palato secundário é um dos pontos mais críticos na formação da face e do palato. Depende de uma sequência complexa de eventos que possuem em comum o remodelamento de matriz extracelular (MEC), regulado, principalmente, pelas metaloproteinases de matriz (MMPs). Esta éa primeira vez que RECK, uma proteína indutora da reversão tumoral, rica em cisteína e com motivos kazal, é pesquisada neste processo. O primeiro objetivo deste estudo foi investigar se há expressão de RECK durante os eventos envolvidos na formação do palato secundário em camundongos. A partir dos resultados obtidos, indicando a presença de RECK nesses eventos, objetivou-se estabelecer um padrão temporal e espacial dessa expressão, assim como analisar o padrão de distribuição de MMP-2 e MMP-9, comparando os resultados obtidos entre si. Para tanto, cabeças inteiras e palatos dissecados de embriões de camundongos com 13; 14; 14,5 e 15 dias de desenvolvimento embrionário (DE) foram submetidos a reações de PCR em tempo real, hibridização in situ, imunoistoquímica e zimografia. As reações de PCR em tempo real indicaram a presença de mRNA de RECK (mRECK) em todos os períodos analisados, os níveis do transcrito aumentaram gradativamente e foram significativamente diferentes entre 13 e 15DE e entre 14 e lSDE. Os resultados de hibridização in situ e imunoistoquímica apontaram, consecutivamente, um padrão variável de distribuição de mRECK e da proteína RECK no mesênquima, epitélio e linha de junção (LI) formada entre as paredes palatais, no transcorrer dos períodos analisados. Com relação ao padrão de expressão das MMPs, a análise imunoistoquímica revelou a presença de MMP-2 no mesênquima, epitélio e LI em todos os períodos. A MMP-9 foi expressa no 14DE, 14,SDE e lSDE na LI e mesênquima palatal. A análise zimográfica confirmou a atividade de MMP-2 e MMP-9. Dessa forma, concluímos que RECK está presente nos principais eventos de formação do palato secundário, apresentando um padrão de expressão variável no tempo e espaço, que quando compar~o ao padrão de " expressão de MMP-2 e MMP-9 apresentam, na maioria das vezes, similaridades entre si. Esses , achados sugerem um provável envolvimento dessas moléculas na organogênese do palato secundário e uma possível interação/modulação entre elas / Abstract: The oral clefts show a great influence in the size of their hosts. They have, since birthy, difficulties in alimentation, problems in the maxilar bones, in dental arch, in speech, and in some cases, in hearing. In addition, the hosts and their families have serious psychological problems due to the esthetic lenght caused by anomalia. With no doubt, the formations of the secondary palate is one of the most critial phases during the formation of the surface and of the palate. Depending on a sequente of complex events that have in common the remodeling of the extracellular matrix (ECM), mainly regulated by matrix metalloproteinases (MMPs). This is first time that the presence of RECK, a reversion-inducing cystein-rich protein with kazal motifs, this is process is researched. The first objective of this study was to investigate the RECK expression during events involved in formation of the secondary palate in mice. Based on the results obtained, which indicated the presence of RECK in these events, the objective was to establish a temporal and spatial pattern of such expression, as well as to analyze the pattern of distribution of MMP-2 and MMP-9, comparing the results obtained to each other. For that purpose, whole heads and dissected palates of mice aged 13, 14, 14.5 and 15 days of embryonic development (ED) were submitted to real-time PCR, in situ hybridization, immunohistochemistry and zymography. The real-time PCR indicatedthe presence of mRNA of RECK (mRECK) in all periods analyzed; the transcript levels were gradually increased and were significant1y different between 13 and 15ED and between 14 and 15ED. The results of in situ hybridization and immunohismchemistry consecutively indicated a variable pattern of distribution of mRECK and RECK protein in the mesenchyme, epithelium and in midline edge seam (MES) formed between the palatal shelves during the study periods. With regard to the pattern of expression of MMPs, immunohistochemical analysis revealed the presence of MMP- 2 in the mesenchyme, epithelium and MES in all periods. The MMP-9 was expressed in the MES and palatal mesenchyme at 14ED, 14.5ED and 15ED. Zymographic analysis confirmed the activity of MMP- 2 and MMP-9. Therefore, it was concluded that RECK is present in the main events of formation of the secundary pala te, presenting a variable pattern of expression along time and space, which often present similarities to each other compared to the pattern of expression of MMP-2 and MMP-9. These findings suggest probable .involvement of these molecules in the formation of the secondary palate and possible interaction/modulation among them / Doutorado / Bioquimica / Doutor em Biologia Funcional e Molecular

Abstract Numerous adverse effects and health problems are associated with smoking, but the mechanisms of the adverse effects of smoking on skin are not well documented. The aim of the present study was to elucidate the effects of smoking on the structure, metabolism and appearance of skin. The study population consisted of 98 Finnish males, of whom 47 were current smokers and 51 non-smokers. The main parameters under evaluation were the appearance and physical qualities of skin, including skin wrinkling, thickness and elasticity. Biochemical analyses were performed to assess the rate of type I and III collagen biosynthesis as well as the degradation of the extracellular matrix (ECM) of skin in terms of matrix metalloproteinase levels (MMPs). To compare the morphology of skin between the groups, histological and immunohistological studies were performed, including assessments of the proportional area and width of dermal elastic fibres. The results revealed decreased synthesis of type I and III collagens in smokers as well as changes in the regulatory mechanisms which control the turnover of these and other extracellular matrix proteins. The level of matrix metalloproteinase -8 (collagenase-2), a protease degrading both type I and type III collagen, in suction blister fluid was significantly higher in smokers, indicating enhanced degradation of these collagens. In skin tissue samples, the levels of the active forms of MMP-8 and MMP-9 were significantly lower in smokers compared to non-smokers. Serum levels of MMP-8 were slightly but not significantly higher in smokers, whereas the levels of the matrix metalloproteinases MMP-2 and MMP-9 (72-kDa and 92-kDa gelatinase, respectively) were significantly higher in smokers compared to non-smokers. Salivary MMP-8 and MMP-9 were lower in smokers compared to non-smokers, but only the latter showed a statistically significant difference. The levels of the tissue inhibitor of matrix metalloproteinases (TIMP-1) were significantly lower in the suction blister fluid of smokers compared to non-smokers. In general, there were no significant differences in skin thickness and elasticity or regeneration of barrier function, nor in the amount or width of elastic fibres between the groups. We did not observe significant differences in skin wrinkling between smokers and non-smokers, but smokers looked older than their age compared to non-smokers. It can be concluded that the rate of type I and III collagen synthesis in skin is decreased and the regulation of ECM turnover is altered in smokers, which may lead to deterioration of the tensile strength and resiliency of skin in the long term, even though no morphological changes were detected in the present study.

Abstract The complete exon-intron organization of the gene coding for the mouse α1(XIII) collagen chain, Col13a1, was characterized from genomic clones and multiple transcription initiation points were determined. Detailed comparison of the human and mouse genes showed that the exon-intron structures are completely conserved between the species, and both genes have their 5' untranslated region preceded by a highly conserved putative promoter region. The chromosomal location of the mouse gene was determined to be at chromosome 10, band B4, between markers D10Mit5 – (2.3 ± 1.6 cM) – Col13a1 – (3.4 ± 1.9 cM) – D10Mit15. The location of the genes for both the catalytically important α-subunit of prolyl 4-hydroxylase (P4HA) and human type XIII collagen (COL13A1) were previously mapped to 10q21.3-23.1. Prolyl-4-hydroxylase catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of peptide-bound proline and plays a crucial role in the synthesis of these proteins. The order and transcriptional orientation of the COL13A1 and P4HA was determined. These two genes were found to lie at tail to tail orientation on chromosome 10 and the distance between these genes was determined to be about 550 kbp. To study the function of type XIII collagen we used gene targeting in ES cells to generate a mouse line that carries a mutated type XIII collagen gene. Instead of normal protein, mutant mice express type XIII collagen with an altered amino-terminus in which the cytosolic and the transmembrane domains have been replaced with an unrelated sequence. The homozygous mice are fertile and viable but they show alterations in skeletal muscles, mainly wavy sarcolemma and increased variation in muscle fiber diameter. Ultrastructural studies revealed additional abnormalities such as streaming of z-disks, accumulation and enlargement of mitochondria, and disorganized myofilaments. The basement membranes of the muscle cells showed areas of detachment from the plasma membrane and the fibrillar matrix of the cells was less compact than in control animals. Fibroblasts cultured from mutant mice had normal levels of type XIII collagen but exhibited decreased adhesion to substratum which might be explained by a reduced anchoring strength of the altered protein.

Abstract Type XIII collagen is a transmembrane protein consisting of a short intracellular portion, a transmembrane anchor, and a long extracellular domain with a mainly collagenous sequence. Histochemical and cell biological studies have revealed that type XIII collagen has a wide distribution in various tissues and that it is mostly localized to cell-cell and cell-matrix contacts. In order to study type XIII collagen at the molecular level, the protein was expressed in insect cells as a homotrimer. The recombinant protein was found to reside in the plasma membrane of insect cells with its N-terminus intracellular and C-terminal part extracellular, i. e. in a type II orientation. The trimerization of type XIII collagen chains was initiated by 21 amino acid residues adjacent to the transmembrane domain on the extracellular side, and this sequence was found to be conserved in several other collagenous transmembrane proteins. In addition to the transmembrane form, the ectodomain of type XIII collagen was secreted into the cell culture medium, a result of proteolytic cleavage by furin-like proteases at the non-collagenous NC1 domain. The ectodomain was purified from the insect cell culture medium with a typical collagenous composition and conformation, and it showed as a 150 nm-long rod in rotary shadowing electron microscopy. Furthermore, the recombinant ectodomain showed high affinity binding to several extracellular matrix proteins, e. g. fibronectin, nidogen-2, and perlecan, as well as to heparin. The type XIII collagen ectodomain also showed selective recognition to collagen receptor integrins. Integrin α1 and α11 I domains bind to type XIII collagen with a high affinity, and both integrins α1β1 and α11β1 mediate cell attachment to type XIII collagen. The present results suggest that type XIII collagen shares common aspects with other collagenous transmembrane proteins in terms of chain association and ectodomain shedding. However, it is notably distinct in its structure and binding specificity compared to other types of collagen and cell-surface proteins. The data imply that type XIII collagen might participate in multiple cell-cell and cell-matrix interactions.