La phase de l'épithélialisation de la réparation cutanée se déroule en impliquant plusieurs processus dynamiques et interactifs pendant lesquels les kératinocytes migrent, prolifèrent et se différentient afin de reconstruire la fonction de la barrière. La migration des kératinocytes est l'événement qui détermine l'efficacité du processus entier. Le comportement migratoire est contrôlé au même temps au niveau extracellulaire et intracellulaire et dépend d'interactions dynamiques entre les cellules et leur environnement extracellulaire, des facteurs de croissance et des cytokines. Parmi les protéines de la matrice extracellulaire, la laminine 332 est un substrat d'adhésion majeur des kératinocytes qui joue un rôle important au cours de la migration des kératinocytes, travers son domaine LG4/5 localisé à l'extrémité carboxy-terminale de sa chaine a. Des études récentes ont rapporté que l'induction de la migration des kératinocytes par LG4/5 est dépendante des Métalloprotéinases Matricielles pro-migratoires (MMP)-9 et -1 qui jouent des rôles essentiels au cours de la cicatrisation et surtout pendant la ré-épithélialisation. Etant donné que des travaux antérieurs du laboratoire ont montré que le domaine LG4/5 participe à la dynamique du cytosquelette et à la motilité cellulaire au travers de liaisons avec les récepteurs de type de protéoglycanes à heparane sulfate, syndécan-1 et -4 on a regardé l'implication potentielle de ces récepteurs au processus. Afin d'analyser la participation possible des syndecans dans ce processus, nous avons développé une approche de mutagénèse dirigée dans la protéine LG4/5 recombinante pour altérer les sites de liaison aux syndécan-1 ou -4. Notre analyse PCR et nos résultats de zymographie ont révélé une différence du profile d'activation des MMPs en fonction de la mutation produite et donc de la capacité de la protéine à recruter le syndécan-1 ou le syndécan-4, ainsi que le syndécan-1, et pas la syndécan-4, est impliqué dans l'activation de la production de la MMP-9 par LG4/5. Nous avons ensuite confirmé ces résultats en réduisant l'expression du syndécan-1 dans des kératinocytes et on a pu aussi montrer que le traitement avec des cytokines telles que TNFalpha et IL-1beta, connues pour leur capacité d'induire l'activation de la MMP-9, a produit le même résultat dans ce systéme. L'addition de l'héparine dans nos experiences a inhibé l'activation de l'expression de MMP-9 suggerant que les heparanes sulfates dans syndecan-1 sont impliqué au mécanisme. Pour confirmer ces résultats des experiences avec des séries de syndecan-1 mutés sont en cours. Pour conclure, nos résultats montrent pour la première fois un rôle important de syndecan-1 à l'expression de MMP-9 suggérant que sa re-distribution au front des kératinocytes migratoires puisse éventuellement être liée au clivage ou à la dégradation des protéines de la matrice extracellulaire. En plus, nos résultats proposent que le domain LG4/5 de la laminin 332 libéré soit capable d'affecter la balance de l'expression de la MMP-9 lors de la migration des kératinocytes en leur permettant de traverser le caillot de fibrine / During skin repair, the epithelialization phase occurs by an orderly series of events whereby keratinocytes migrate, proliferate, and differentiate to restore the barrier function. Keratinocyte migration determines the efficiency of the overall wound repair process. The migratory behaviour is governed at both the extracellular and intracellular levels and depends on the carefully balanced dynamic interactions of the cells with ECM components, growth factors and cytokines. Among extracellular matrix proteins, laminin 332, known as a major adhesion substrate for keratinocytes was shown to contribute to skin reepithelialization through its a3 chain C-terminal domains LG45. Recent studies have reported that LG45 induces keratinocyte migration, an event that relies on the involvement of the pro-migratory matrix metalloproteinases-1 and -9, two MMPs known to play a role in the reepithelialization phase of wound healing. As findings from our laboratory have reported that LG45 domains participate in cytoskeleton dynamic and cell movement through binding of the heparan sulphate proteoglycans syndecan-1 and -4, we analyzed the potential involvement of these receptors in this process. To that end, we have developed a site-directed mutagenesis approach within a recombinant LG45 protein to alter either the syndecan-1 or syndecan-4 binding site. Our PCR analysis and zymography results revealed that depending on the mutants, syndecan-1 or syndecan-4 recruitment induced different MMP activation profile and suggested that syndecan-1 plays a role in LG45 induced MMP-9 expression and activation. We confirmed these results by down regulating syndecans expression in keratinocytes and revealed that this phenomenon also occurred when cells were treated with TNFalpha or IL1beta, two cytokines known to up-regulate MMP-9 expression. Addition of heparin in these experiments abolished MMP-9 expression activation suggesting that syndecan-1 heparan sulfate moieties are involved in this mechanism. Confirming experiments using a series of mutated syndecan-1 in their ectodomain (lacking glycosaminoglycan chains) or in their cytoplasmic tail are ongoing in the lab. Taken together, our data demonstrate for the first time that syndecan-1 plays a pivotal role in MMP-9 expression, suggesting that its re-distribution at the front edge of migrating keratinocyte may have a role to play in the cleavage or degradation of extracellular matrix proteins. Our results further suggest that the released laminin 332 LG45 domain has the ability to impact the MMP9 expression balance during keratinocyte migration therefore facilitating their path through the fibrin clot

We describe here for the first time an efficient high yield production method for clinical grade recombinant human Oncofetal Antigen/immature laminin receptor protein (OFA/iLRP). We also demonstrate significant antitumor activity for this protein when administered in liposomal delivery form in a murine model of syngeneic fibrosarcoma. OFA/iLRP is a therapeutically very promising universal tumor antigen that is expressed in all mammalian solid tumors tested so far. We have cloned the human OFA/iLRP cDNA in a bacterial expression plasmid which incorporates a 6x HIS-tag. Large scale cultures of the plasmid transformed Escherichia coli were performed and the crude HIS-tagged OFA/iLRP was isolated as inclusion bodies and solubilized in guanidine chloride. The protein was then purified by successive passage through three column chromatography steps of immobilized metal affinity, anion exchange, and gel filtration. The resulting protein was 94% pure and practically devoid of endotoxin and host cell protein. The purified OFA/iLRP was tested in mice for safety and efficacy in tumor rejection with satisfactory results. This protein will be used for loading onto autologous dendritic cells in an FDA approved phase I/II human cancer vaccine trial in OFA/iLRP-positive breast cancer patients.

The laminin-binding integrin (LBI) family are cell adhesion molecules that are essential for invasion and metastasis of human epithelial cancers and cell adhesion mediated drug resistance. We investigated whether copy number alteration (CNA) or mutations of a five-gene signature (ITGB4, ITGA3, LAMB3, PLEC, and SYNE3), representing essential genes for LBI adhesion, would correlate with patient outcomes within human epithelial-type tumor data sets currently available in an open access format.

Background: Large-scale expansion of myogenic progenitors is necessary to support the development of high-throughput cellular assays in vitro and to advance genetic engineering approaches necessary to develop cellular therapies for rare muscle diseases. However, optimization has not been performed in order to maintain the differentiation capacity of myogenic cells undergoing long-term cell culture. Multiple extracellular matrices have been utilized for myogenic cell studies, but it remains unclear how different matrices influence long-term myogenic activity in culture. To address this challenge, we have evaluated multiple extracellular matrices in myogenic studies over long-term expansion. Methods: We evaluated the consequence of propagating mouse and human myogenic stem cell progenitors on various extracellular matrices to determine if they could enhance long-term myogenic potential. For the first time reported, we comprehensively examine the effect of physiologically relevant laminins, laminin 211 and laminin 521, compared to traditionally utilized ECMs (e.g., laminin 111, gelatin, and Matrigel) to assess their capacity to preserve myogenic differentiation potential. Results: Laminin 521 supported increased proliferation in early phases of expansion and was the only substrate facilitating high-level fusion following eight passages in mouse myoblast cell cultures. In human myoblast cell cultures, laminin 521 supported increased proliferation during expansion and superior differentiation with myotube hypertrophy. Counterintuitively however, laminin 211, the native laminin isoform in resting skeletal muscle, resulted in low proliferation and poor differentiation in mouse and human cultures. Matrigel performed excellent in short-term mouse studies but showed high amounts of variability following long-term expansion. Conclusions: These results demonstrate laminin 521 is a superior substrate for both short-term and long-term myogenic cell culture applications compared to other commonly utilized substrates. Since Matrigel cannot be used for clinical applications, we propose that laminin 521 could possibly be employed in the future to provide myoblasts for cellular therapy directed clinical studies.

Die Spinale Muskelatrophie (SMA) ist eine häufige autosomal-rezessiv vererbte Erkrankung des motorischen Nervensystems bei Kindern. Ursache der Degeneration von spinalen Motoneuronen ist der homozygote Verlust des SMN- (survival of motoneuron) Gens und ein dadurch bedingter Mangel an SMN-Protein. Untersuchungen an Motoneuronen von Smn-defizienten Mäusen ergaben Störungen des axonalen Längenwachstums aufgrund einer Fehlverteilung des Zytoskelettproteins beta-Aktin und seiner mRNA in den Axonterminalen. Das Axonwachstum wird durch Aktin-Polymerisierung im Wachstumskegel gesteuert. beta-Aktin-mRNA findet sich auch in Axonen, und die lokale Proteinsynthese kann durch neuronale Aktivierung gesteigert werden. Das SMN-Protein ist am axonalen Transport von beta-Aktin beteiligt. In der vorliegenden Arbeit ergaben Western Blot-Analysen in neuralen Stammzellen (NSC) sowie spinalen Motoneuronen in vitro eine Steigerung der SMN-Proteinexpression durch 8-CPT-cAMP. Zur Untersuchung der Auswirkungen der erhöhten SMN-Proteinmenge auf die Pathologie der Motoneurone wurde ein in-vitro-Assay entwickelt, mit dessen Hilfe gezeigt werden konnte, dass eine Behandlung mit 100 µM 8-CPT-cAMP die axonalen Veränderungen isolierter embryonaler Smn-defizienter Motoneurone kompensieren kann. Motoneurone von 14 Tage alten Smn-defizienten und Kontroll-Mausembryonen wurden über sieben Tage hinweg auf einer Matrix aus Poly-Ornithin und Laminin-111 bzw. Laminin-121/221 kultiviert und mit 100µM cAMP und neurotrophen Faktoren behandelt. Nach Fixierung wurden die Zellen mit Antikörpern gegen Islet-1/2, tau und beta-Aktin gefärbt, mit Hilfe eines konfokalen Mikroskops fotografiert und digital vermessen. 8-CPT-cAMP erhöht den beta-Aktin-Gehalt in den axonalen Wachstumskegeln von Smn-defizienten Motoneuronen. Die Größe der Wachstumskegel nimmt durch die Behandlung um das 2-3fache zu und erreicht normale Werte. Auf Laminin-111 bleibt das Längenwachstum der Axone durch 100µM 8-CPT-cAMP unbeeinflusst, auf Laminin-121/221 wird das Längenwachstum normalisiert. Die beta-Aktin-Verteilung innerhalb der Axone und Wachstumskegel von Smn-defizienten Motoneuronen erscheint durch die cAMP-Behandlung nahezu normalisiert. Die Wiederherstellung der beta-Aktin-Verteilung in Wachstumskegeln durch cAMP kann große Auswirkungen auf die Funktionalität der Motoneurone haben. Die Ergebnisse sind möglicherweise ein erster Schritt auf dem Weg zu einer Therapie für die Spinale Muskelatrophie. / Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by loss of alpha-motoneurons in the spinal chord due to low levels of the survival motor neuron (SMN) protein. The genetic cause is the homozygous loss or mutation of the telomeric SMN1 gene and retention of the centromeric SMN2 gene, whose transcripts consist of about 90% truncated and unstable and only 10% functional protein. Motoneurons of Smn-deficient SMN2 transgenic mouse embryos cultured on laminin-1 show abnormalities compared to wildtype controls such as shorter axons, smaller growth cones and a ß-actin protein and mRNA deficit in the distal part of the axon. ß-actin plays a major role in growth cone motility and transmitter release at the presynapse. In addition, SMN works in a complex to transport ß-actin mRNA, which is known to be localized and locally translated in axons and growth cones, along the axon. Local ß-actin protein synthesis can be stimulated by increased neuronal activation. We determined the effects of cAMP on ß-actin localisation in axons as well as on axonal growth parameters in Smn-deficient primary motoneurons. Motoneurons of 14 days old Smn-/-, SMN2 transgenic and wildtype mouse embryos were cultured on laminin for 7 days with 100µM 8-CPT-cAMP and neurotrophic factors BDNF and CNTF. Fluorescence staining and digital measurements revealed a major effect of cAMP treatment on ß-actin distribution and growth cone size, which were restored to normal. Neurite lengths on laminin-111 remained unaffected but were normalized on substrate containing a synapse-specific ß2-laminin isoform. Western blots with neural stem cells (NSC) and heterozygous Smn+/-; SMN2 transgenic motoneurons treated with 100µM cAMP showed a marked upregulation of Smn protein expression. These data point to an important role for cAMP as a possible target of SMA drug therapy.

Erlangen, Nürnberg, Universiẗat, Diss., 2007. / Enth. 1 Sonderabdr. aus: Journal of investigative dermatology ; 124. 2005. - Beitr. teilw. dt., teilw. engl.

Nerve autografts are widely used clinically to repair nerve grafts. However, nerve grafts have many limitations, such as, availability of donor nerve grafts, and loss of function at donor site. To overcome these problems, we have used a tissue engineering approach to design three-dimensional (3D) agarose scaffolds containing gradients of laminin-1 (LN-1) and nerve growth factor (NGF) to mimic in vivo conditions to promote nerve regeneration in rats. To determine the effect of LN-1 gradients on neurite extension in vitro, dorsal root ganglia (DRG) from chick embryos were cultured in 3D hydrogels. A gradient of LN-1 molecules in agarose gels was made by diffusion technique. LN-1 was then immobilized to the agarose hydrogels using a photo-crosslinker, Sulfo-SANPAH (Sulfosuccinimidyl-6-[4-azido-2-nitrophenylamino] hexanoate). Anisotropic scaffolds with three different slopes of LN-1 gradients were used. Isotropic scaffolds with uniform concentrations of LN-1, at various levels, were used as a positive control. DRG cultured in anisotropic scaffolds with optimal slope of LN-1 gradient extended neurites twice as fast as DRG in optimal concentration in isotropic scaffolds. Also, in the anisotropic scaffolds the faster growing neurites were aligned along the direction of LN-1 gradient. To promote nerve regeneration in vivo, tubular polysulfone guidance channels containing agarose hydrogels with gradients of LN-1 and NGF (anisotropic scaffolds) were used to bridge 20-mm nerve gaps in rats. Nerve autografts were used as positive controls and isotropic scaffolds, with uniform concentration of LN-1 and NGF, were used as negative controls. After 4-months, the rats were sacrificed and nerve histology was done to test for nerve regeneration. Only anisotropic scaffolds and nerve autografts contained evidence of axonal regeneration. Both groups had similar numbers of myelinated axons and similar axonal-diameter distribution. However, nerve graft group performed better in functional outcome as measured by relative gastrocnemius muscle weight (RGMW) and electrophysiology. Optimization of performance of anisotropic scaffolds by varying the LN-1 and NGF concentration gradients might lead to development of scaffolds that can perform as well as nerve auotgrafts for nerve regeneration over long nerve gaps.

It is well established that failure of the lamellar basement membrane (BM) occurs during the development of equine laminitis. This is due to loss of the crucial BM components; laminins and collagens along with loss of attachment complex, the hemidesmosome, of the basal cell to the underlying BM. Previous studies have suggested that Ln-332 may be the primary protein involved in lamellar failure. However, the details of the progression and mechanism involved in this pathology are not currently fully known. This thesis aimed to refine the proteolytic processes and mechanisms occurring during the development of oligofructose induced laminitis. Through the use of novel temporal lamellar biopsies obtained during the development of laminitis induction, it was determined that loss of both Ln-332 and collagen type IV occurs as early as 12 hours post induction. This loss of reactivity initially occurred in a focal pattern with increasing loss as the disease progressed in severity. At the later stages of laminitis, separation of the basal epithelial cell from the dermal tissue was also observed, however at these points the BM still appeared intact. This suggests that more than one mechanism may be involved in disease pathology; one resulting in fragmentation of the BM while a second results in loss of the cell attachment allowing the intact BM to slip away. Immunohistochemical analysis of lamellar tissue revealed a unique pattern of reactivity for the Ln-332 γ2 antibody D4B5, in which no reactivity was observed in normal lamellar tissue, yet the epitope recognized by this antibody becomes apparent during disease development. This initially led to the hypothesis that cleavage of the γ2 subunit and the release of biologically active fragments may occur. However, at the molecular level, no γ2 fragments were detected by western blotting. In vitro cleavage of partially purified equine Ln-332 revealed that both MMP-2 and MT1-MMP were able to process the molecule to produce fragments corresponding to the biologically active counterparts. This suggests that the change in reactivity with this antibody may be due to other mechanisms such as decreased interaction of Ln-332 with other BM components resulting in loss of structural stability of the BM allowing for a change in the orientation of Ln-332. Increased MMP-2, MMP-9 and MT1-MMP expression has been demonstrated in laminitis and this was assumed to be the causative agent resulting in tissue destruction and failure. However, work in this thesis found no increase in gene expression of MMP- 2 and MT1-MMP, as well as no activation of pro MT1-MMP. Increased pro MMP-9 gene and protein expression was observed early in the disease progression yet no MMP- 9 activation occurred. Additionally, activation of MMP-2 was found to occur late in laminitis progression at least 12 hours following BM degradation, thus MMP-2 activation is a secondary effect of laminitis development. Thus, other proteases are expected to result in BM processing. Gene expression of the metalloprotease ADAMTS-4, was observed to increase early during laminitis development, suggesting this is a putative factor involved in intensifying the degradation of the lamellar BM. Work in this thesis also revealed that both Ln-332 and collagen type IV are widely distributed throughout organs in the equine body and localized primarily to BM structures. A novel finding of this thesis is that not only does BM degradation occur in the lamellar BM, it also occurs in organs remote from the hoof. At both the onset of lameness and the acute phase of laminitis, fragmentation of both Ln-332 and collagen type IV also occurs in both the skin and stomach. Recent studies have indicated that both leukocyte emigration and increased cytokine expression occurs in the lamellar tissue during laminitis. Work in this thesis added to this knowledge as leukocyte infiltration into the lamellar tissue occurs early during oligofructose laminitis induction as does increased IL-6 gene expression. Overall, work conducted in this thesis has added to the knowledge of the events occurring during laminitis development. Even though the complete mechanism of tissue destruction and lamellar failure was not established, the progression of events is now more clear in that BM degradation is one of the first events to occur, while MMP-2 activation occurs secondarily. Thus, other mechanisms must be at work early during laminitis development and discovering what they are must remain a research priority for the realization of effective therapeutic strategies.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 7 uppsatser.

Orientador: Maria José Soares Mendes Giannini / Banca: Alexandre Melo Bailão / Banca: Christiane Pienna Soares / Resumo: Paracoccidioides brasiliensis (Pb) é o agente etiológico da paracoccidioidomicose, micose sistêmica de grande importância no Brasil, país que possui a maior concentração de áreas endêmicas para essa doença no mundo. Uma das estratégias possivelmente utilizadas pelo patógeno seria a expressão de genes envolvendo adaptação às condições do hospedeiro, que pode também estar relacionadas à captação de micronutrientes. A matriz extracelular (MEC) desempenha um papel importante na regulação da adesão celular, diferenciação, migração e proliferação das células. Este estudo propõe uma análise de transcritos e de proteínas expressas em condições de depleção de cobre, na presença de quatro matrizes extracelulares - laminina, fibronectina e colágeno I e IV, mimetizando as condições de infecção por P. brasiliensis por meio das técnicas de RDA (Representational Difference Analysis) e eletroforese bidimensional. Para isso, o isolado Pb01 foi cultivado por 3 horas no meio quimicamente definido (MVM), depletado de cobre (Cu) e a seguir colocado em contato com os quatro diferentes componentes da MEC e a adesão foi avaliada por citometria de fluxo. Um aumento significativo (p ≤ 0,05) na adesão frente a todos os componentes da MEC foi observado quando o fungo foi cultivado sem Cu. Então, o RNA e os extratos protéicos foram obtidos de Pb sem Cu e Pb sem Cu em contato com os diferentes componentes da MEC. Ensaios de RDA foram realizados para demonstrar os genes envolvidos neste processo. Duas hibridizações foram realizadas nas proporções de 1:10 e 1:100 de tester e driver, respectivamente, com um excesso de driver para remover as seqüências comuns em ambas condições. Os produtos diferencialmente expressos foram amplificados, resultando em padrões distintos que foram seqüenciados... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Paracoccidioides brasiliensis (Pb) is the etiologic agent of paracoccidioidomycosis, a systemic mycosis of great importance in Brazil, which has the highest concentration of endemic areas for this disease in the world. One of the strategies used by the pathogen may be the expression of proteins related to the adaptation to the host conditions, which may also be related to the uptake of micronutrients. Extracellular matrix (ECM) plays an important role in the regulation of cell adhesion, differentiation, migration and proliferation of cells. This study proposes an analysis of transcripts and proteins expressed in condition of copper depletion in the presence of four components of extracellular matrix - laminin, fibronectin and collagen I and IV, mimicking the conditions of infection by P. brasiliensis, using techniques of RDA (Representational Difference Analysis) and two-dimensional electrophoresis. For this, we cultured the Pb 01 strain at 3 hours in a chemically defined media (MVM) with depletion copper (Cu). After, the fungus was placed at contact with the four differents ECM components and the adhesion was evaluated by flow cytometry. A significant increase of binding (p ≤ 0,05) to all ECM components was observed when the fungal was cultured without Cu. So RNA and protein extracts were obtained of Pb without Cu, and Pb without Cu in contact with the differents ECM components. RDA assay was developed to demonstrate the genes involved in this process. Two hybridizations were performed in the proportions of 1:10 and 1:100 of tester and driver respectively, with an excess of driver to remove the common sequences in both conditions. The differentially expressed products were amplified, resulting in distinct patterns that were sequenced revealing genes involved in differents process like virulence (25%), protein synthesis... (Complete abstract click electronic access below) / Mestre