Análise da influência de proteínas da matriz extracelular e fibrinogênio na formação de biofilme por cepas de Enterococcus faecalis isoladas de infecção endodôntica primária / Analysis of influence of extracellular matrix proteins and fibrinogen in biofilm formation by Enterococcus faecalis strains isolated from primary endodontic infection

Enterococcus faecalis é um patógeno oportunista com peculiar potencial para a manutenção da infecção perirradicular endodôntica após o preparo químico-mecânico do sistema de canais radiculares. Adicionalmente, possui aptidão para desenvolver-se em biofilme e apresenta em sua parede celular adesinas compatíveis com substratos colagênicos, como a composição da matriz extracelular da dentina e dos túbulos dentinários. Esse estudo propôs-se a caracterizar geneticamente 23 amostras de E faecalis isoladas de infecções endodônticas primárias através da técnica da reação em cadeia da polimerase (PCR, do inglês Polymerase Chain Reaction) e investigar a influência de COL I (colágeno tipo I), FN (fibronectina) e fibrinogênio (FBG) na formação de biofilme em superfície abiótica. Assim, após a sensibilização de ¾ dos poços de placas de poliestireno estéreis com 50 µl da solução de proteína de matriz (COL I, FN e FBG) na concentração de 1mg/ml, transferiu-se 50µl de suspensão bacteriana (1,5 x 108 bact/mL) correspondente a cada amostra, de modo a preencher tanto os poços sensibilizados como os não sensibilizados. A quantificação da formação de biofilme foi realizada por meio de leitura por densidade óptica, cujos resultados revelaram que houve formação de biofilme por todas as em superfície abiótica, porém com diferentes graus de intensidade. Todas as cepas foram identificadas geneticamente como Enterococcus faecalis e a presença do gene gelE foi dominante. Contudo, nenhuma apresentou amplificação para os genes esp e agg, e, apesar de 73,9% das amostras amplificarem para o gene ace, apenas 2 cepas (P7 e P75) isoladas de infecções endodônticas primárias tiveram aumento de formação de biofilme na presença de COL I (P<0,05). Embora a presença de FBG não forneça subsídio estatisticamente significante para a formação de biofilme, COL I e FN influenciaram na redução da formação do biofilme para a maior parte das amostras. É possível que a capacidade de formação de biofilme inerente ao E. faecalis e a afinidade para FN e COL I através da expressão gênica de ace contribuam substancialmente para a manutenção desse micro-organismo no ambiente radicular mesmo após o tratamento endodôntico minucioso.

Enterococcus faecalis is an opportunistic pathogen with peculiar potential to maintain the periradicular endodontic infection even after chemical-mechanical preparation of the root canal system. In addition, it has the ability to develop into biofilms and presents in your cell wall adhesins compatible with collagenous substrates, as the composition of the extracellular matrix of the dentine and dentinal tubules. This study aims to characterize genetically 23 samples of E. faecalis isolated from primary endodontic infections by Polymerase Chain Reaction (PCR) technique and investigate the influence of collagen type I (COL I), fibronectin (FN) and fibrinogen (FBG) in biofilm formation on abiotic surface. Thus, after the sensitization of ¾ the wells of sterile microtiter plates with 50 ul of matrix protein solution (COL I and FN FBG) at a concentration of 1mg / ml, was transferred 50mL of bacterial suspension (1.5 x 108 bact / ml) corresponding to each sample in order to fill both wells sensitized and non-sensitized. Quantification of biofilm formation was performed by optical density, so the results showed that there were biofilm formation by all strains on abiotic surface, but with different degrees of intensity. All strains were genetically identified as Enterococcus faecalis and the presence of gelE gene was prevalent. However, none showed amplification for the esp and agg gene, and, while 73.9% of the samples for amplifying ace gene, only 2 strains (P7 and P75) isolated from primary endodontic infections they had increased biofilm formation in the presence of COL I (P <0.05). Although the presence of FBG no provides significant support for the biofilm formation, COL I and FN were relevant influence in the reduction of biofilm formation for most of the samples. It is possible that the biofilm-forming ability inherent in E. faecalis and affinity for FN and COL I through ace gene expression contribute substantially to maintain of this microorganism in the root environment even after thorough endodontic treatment.

Autophagy impairment: a crossroad between neurodegeneration and tauopathies.

Most neurodegenerative diseases involve the accumulation of misfolded proteins in the nervous system. Impairment of protein degradation pathways such as autophagy is emerging as a consistent and transversal pathological phenomenon in neurodegenerative diseases, including Alzheimer's, Huntington's, and Parkinson's disease. Genetic inactivation of autophagy in mice has demonstrated a key role of the pathway in maintaining protein homeostasis in the brain, triggering massive neuronal loss and the accumulation of abnormal protein inclusions. However, the mechanism underlying neurodegeneration due to autophagy impairment remains elusive. A paper in Molecular Neurodegeneration from Abeliovich's group now suggests a role for phosphorylation of Tau and the activation of glycogen synthase kinase 3ß (GSK3ß) in driving neurodegeneration in autophagy-deficient neurons. We discuss the implications of this study for understanding the factors driving neurofibrillary tangle formation in Alzheimer's disease and tauopathies.

A feasibility study for the analysis of reparative dentinogenesis in pOBCol3.6GFPtpz transgenic mice.

AIM: To examine the feasibility of using the pOBCol3.6GFPtpz [3.6-green fluorescent protein (GFP)] transgenic mice as an in vivo model for studying the biological sequence of events during pulp healing and reparative dentinogenesis. METHODOLOGY: Pulp exposures were created in the first maxillary molar of 12-16-week-old 3.6-GFP transgenic mice with CD1 and C57/Bl6 genetic background. Direct pulp capping on exposed teeth was performed using mineral trioxide aggregate followed by restoration with a light-cured adhesive system (AS) and composite resin. In control teeth, the AS was placed in direct contact with the pulp. Animals were euthanized at various time points after pulp exposure and capping. The maxillary arch was isolated, fixed and processed for histological and epifluorescence analysis to examine reparative dentinogenesis. RESULTS: Analysis of teeth immediately after pulp exposure revealed absence of odontoblasts expressing 3.6-GFP at the injury site. Evidence of reparative dentinogenesis was apparent at 4 weeks in 3.6-GFP mice in CD1 background and at 8 weeks in 3.6-GFP mice with C57/Bl6 background. The reparative dentine with both groups contained newly formed atubular-mineralized tissue resembling a dentine bridge and/or osteodentine that was lined by cells expressing 3.6-GFP as well as 3.6-GFP expressing cells embedded within the atubular matrix. CONCLUSION: This study was conducted in a few animals and did not allow statistical analysis. The results revealed that the 3.6-GFP transgenic animals provide a unique model for direct analysis of cellular and molecular mechanisms of pulp repair and tertiary dentinogenesis in vivo. The study also shows the effects of the capping material and the genetic background of the mice in the sequence and timing of reparative dentinogenesis.

Astrocytes treated by lysophosphatidic acid induce axonal outgrowth of cortical progenitors through extracellular matrix protein and epidermal growth factor signaling pathway.

Lysophosphatidic acid (LPA) plays important roles in many biological processes, such as brain development, oncogenesis and immune functions, via its specific receptors. We previously demonstrated that LPA-primed astrocytes induce neuronal commitment of cerebral cortical progenitors (Spohr et al. 2008). In the present study, we analyzed neurite outgrowth induced by LPA-treated astrocytes and the molecular mechanism underlying this event. LPA-primed astrocytes increase neuronal differentiation, arborization and neurite outgrowth of developing cortical neurons. Treatment of astrocytes with epidermal growth factor (EGF) ligands yielded similar results, suggesting that members of the EGF family might mediate LPA-induced neuritogenesis. Furthermore, treatment of astrocytes with LPA or EGF ligands led to an increase in the levels of the extracellular matrix molecule, laminin (LN), thus enhancing astrocyte permissiveness to neurite outgrowth. This event was reversed by pharmacological inhibitors of the MAPK signaling pathway and of the EGF receptor. Our data reveal an important role of astrocytes and EGF receptor ligands pathway as mediators of bioactive lipids action in brain development, and implicate the LN and MAPK pathway in this process.

Collagen fibril organization in the pregnant endometrium of decorin-deficient mice.

In the pregnant mouse endometrium, collagen fibrillogenesis is characterized by the presence of very thick collagen fibrils which are topographically located exclusively within the decidualized stroma. This dynamic biological process is in part regulated by the small leucine-rich proteoglycans decorin and biglycan. In the present study we utilized wild-type (Dcn(+/+)) and decorin-deficient (Dcn(-/-)) time-pregnant mice to investigate the evolution of non-decidualized and decidualized collagen matrix in the uterine wall of these animals. Ultrastructural and morphometric analyses revealed that the organization of collagen fibrils in the pregnant endometrium of both non-decidualized and decidualized stroma showed a great variability of shape and size, regardless of the genotype. However, the decidualized endometrium from Dcn(-/-) mice contained fibrils with larger diameter and more irregular contours as compared to the wild-type littermates. In the Dcn(-/-) animals, the proportion of thin (10-50 nm) fibrils was also higher as compared to Dcn(+/+) animals. On day 7 of pregnancy, biglycan was similarly localized in the decidualized endometrium in both genotypes. Lumican immunostaining was intense both in decidualized and non-decidualized stroma from Dcn(-/-) animals. The present results support previous findings suggesting that decorin participates in uterine collagen fibrillogenesis. In addition, we suggest that the absence of decorin disturbs the process of lateral assembly of thin fibrils, resulting in very thick collagen fibrils with irregular profiles. Our data further suggest that decorin, biglycan and lumican might play an interactive role in collagen fibrillogenesis in the mouse endometrium, a process modulated according to the stage of pregnancy.

Heparan sulfate proteoglycans: structure, protein interactions and cell signaling.

Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.

Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.

Proteoglicanos de heparam sulfato são encontrados tanto superfície celular quanto na matriz extracelular em todas as espécies animais. Esta revisão tem enfoque nas características estruturais dos proteoglicanos de heparam sulfato e nas interações destes proteoglicanos com proteínas que levam à sinalização celular. As cadeias de heparam sulfato, devido a sua variedade estrutural, são capazes de se ligar e interagir com ampla gama de proteínas, como fatores de crescimento, quimiocinas, morfógenos, componentes da matriz extracelular, enzimas, entreoutros. Existe uma especificidade estrutural que direciona as interações dos heparam sulfatos e proteínas alvo. Esta especificidade está relacionada com a estrutura da cadeia do polissacarídeo e os motivos conservados da cadeia polipeptídica das proteínas envolvidas nesta interação. Os heparam sulfatos possuem papel na sinalização celular como receptores ou coreceptores para diferentes ligantes. Esta ligação dispara vias de sinalização celular levam à fosforilação de diversas proteínas citosólicas ou com ou sem interações diretas com o citoesqueleto, culminando na regulação gênica. O papel dos proteoglicanos de heparam sulfato na sinalização celular e vias de captação endocítica também são discutidas nesta revisão.

[Axonal growth inhibition by chondroitin sulfate proteoglycans in the central nervous system]. / Inhibición del crecimiento axonal por proteoglicanos de condroitin sulfato en el sistema nervioso central.

Chondroitin sulphate proteoglycans (CSPG) are components of the extracellular matrix, consisting of peptides chemically attached covalently to chains of glycosaminoglycans. There are 4 families of CSPG including lecticans, which are found mainly in the central nervous system (CNS) of vertebrates. In vitro studies have shown a negative effect of these proteoglycans on axonal growth, mediated by depolymerization of actin filaments in the neuronal cytoskeleton. In some neurodegenerative diseases, and especially after traumatic injuries of adult CNS, there are increased levels of CSPG expression. Axonal growth inhibition by CSPG has been observed also in vivo, and therefore a strategy aimed to counteract the inhibition of axonal growth might lead to new therapies designed to restore neural circuits. There is compelling in vivo evidence that CSPG degradation by Chondroitinase ABC allows both axonal growth and functional recovery in models of injury in the mammalian CNS. These data suggest that manipulation of the response to damage could result in effective ways to promote recovery of nerve functions in neurological disorders that affect humans, such as spinal cord lesions or Parkinson disease.

The impact of infectious diseases upon neuroendocrine circuits.

During infectious diseases, neuroendocrine and immune networks act in concert, facilitating host response. It is known that infections cause profound immune changes, but the impact upon immunoendocrine circuits has been less studied. Disorders in the hypothalamic-pituitary-adrenal (HPA) axis were frequently observed associated with infections, and these changes often occur in parallel to alterations in the systemic cytokine network. Explanations for the infection-associated immunoendocrine disturbances include several and not mutually exclusive possibilities. Changes in cytokine levels can enhance or suppress the HPA axis, by acting at the hypothalamus-pituitary unit and/or at the adrenal glands. In situ inflammatory reactions or structural changes like vascular alterations or an enhanced extracellular matrix deposition in the endocrine microenvironment may also lead to a transient HPA dysfunction. Lastly, a microbe-related effect by means of pathogen infiltration or exploitation of the host's hormonal microenvironment may be involved as well. A better understanding of the relevance of immunoendocrine communication during infectious diseases, and how disturbances in the flux of information lead to neuroendocrine immune-related disorders will provide important insights into mechanisms underlying the disease pathology.

TGF-beta1 induces transendothelial migration of the pathogenic fungus Sporothrix schenckii by a paracellular route involving extracellular matrix proteins.

Sporotrichosis, a mycosis caused by Sporothrix schenckii, is characterized by lymphocutaneous lesions. In immunocompromised hosts, this fungus may invade the bloodstream and disseminate to other tissues, such as lung and bone. Our group previously showed that S. schenckii yeasts adhere to endothelial monolayers and that this interaction is modulated by cytokines. Using 3.0 mum-pore culture inserts, the present work shows that transforming growth factor (TGF)-beta1 led to a 80+/-26 % increase in fungal migration across endothelial monolayers and inhibited fungus internalization by 55+/-23.5 %, when compared to untreated cells. The major surface endothelial molecules recognized by S. schenckii were not modulated by TGF-beta1. These data suggested that a paracellular route is preferentially used by S. schenckii during the transmigration of cultured endothelial cells. It was further observed that TGF-beta1 increased the subendothelial matrix exposure and that anti-fibronectin (anti-FN) and anti-laminin (anti-LM) antibodies abolished the increase in S. schenckii association with endothelial monolayers induced by TGF-beta1. These antibodies also inhibited (38.2+/-4.29 % and 50.8+/-17.3 %, respectively) the adhesion of S. schenckii to freshly prepared native endothelial matrices. Furthermore, transendothelial migration of S. schenckii was blocked by anti-FN and anti-LM antibodies. These data indicate that TGF-beta1-induced S. schenckii adhesion to endothelial monolayers results from the increased exposure of the subendothelial extracellular matrix and that this event may contribute to the enhancement of transendothelial migration.

[Therapeutical targets for revert liver fibrosis]. / Blancos terapéuticos potenciales para revertir la cirrosis hepática.

Liver fibrosis is the common response to chronic liver injury, ultimately leading to cirrhosis and its complications: portal hypertension, liver failure, hepatic encephalopathy, and hepatocellular carcinoma and others. Efficient and well-tolerated antifibrotic drugs are still lacking, and current treatment of hepatic fibrosis is limited to withdrawal of the noxious agent. Efforts over the past decade have mainly focused on fibrogenic cells generating the scarring response, although promising data on inhibition of parenchymal injury or reduction of liver inflammation have also been obtained. A large number of approaches have been validated in culture studies and in animal models, and several clinical trials are underway or anticipated for a growing number of molecules. This review highlight recent advances in the molecular mechanisms of liver fibrosis and discusses mechanistically based strategies that have recently emerged.

The extracellular matrix of the lung and its role in edema formation.

The extracellular matrix is composed of a three-dimensional fiber mesh filled with different macromolecules such as: collagen (mainly type I and III), elastin, glycosaminoglycans, and proteoglycans. In the lung, the extracellular matrix has several functions which provide: 1) mechanical tensile and compressive strength and elasticity, 2) low mechanical tissue compliance contributing to the maintenance of normal interstitial fluid dynamics, 3) low resistive pathway for an effective gas exchange, d) control of cell behavior by the binding of growth factors, chemokines, cytokines and the interaction with cell-surface receptors, and e) tissue repair and remodeling. Fragmentation and disorganization of extracellular matrix components comprises the protective role of the extracellular matrix, leading to interstitial and eventually severe lung edema. Thus, once conditions of increased microvascular filtration are established, matrix remodeling proceeds fairly rapidly due to the activation of proteases. Conversely, a massive matrix deposition of collagen fiber decreases interstitial compliance and therefore makes the tissue safety factor stronger. As a result, changes in lung extracellular matrix significantly affect edema formation and distribution in the lung.

The extracellular matrix of the lung and its role in edema formation

The extracellular matrix is composed of a three-dimensional fiber mesh filled with different macromolecules such as: collagen (mainly type I and III), elastin, glycosaminoglycans, and proteoglycans. In the lung, the extracellular matrix has several functions which provide: 1) mechanical tensile and compressive strength and elasticity, 2) low mechanical tissue compliance contributing to the maintenance of normal interstitial fluid dynamics, 3) low resistive pathway for an effective gas exchange, d) control of cell behavior by the binding of growth factors, chemokines, cytokines and the interaction with cell-surface receptors, and e) tissue repair and remodeling. Fragmentation and disorganization of extracellular matrix components comprises the protective role of the extracellular matrix, leading to interstitial and eventually severe lung edema. Thus, once conditions of increased microvascular filtration are established, matrix remodeling proceeds fairly rapidly due to the activation of proteases. Conversely, a massive matrix deposition of collagen fiber decreases interstitial compliance and therefore makes the tissue safety factor stronger. As a result, changes in lung extracellular matrix significantly affect edema formation and distribution in the lung.

A matriz extracelular é um aglomerado tridimensional demacromoléculas composta por: fibras colágenas (principalmente, tipos I e III), elastina, glicosaminoglicanos e proteoglicanos. No pulmão, a matriz extracelular tem várias funções, tais como: 1) promover estresse tensil e elasticidade tecidual, 2) contribuir para a manutenção da dinâmica de fluidos no interstício, 3) propiciar efetiva troca gasosa, 4) controlar a função celular através de sua ligação com fatores de crescimento, quimiocinas, citocinas e interação com receptores de superfície, e 5) remodelamento e reparo tecidual. A fragmentação e a desorganização da matriz extracelular pode acarretar edema intersticial e, eventualmente, edema alveolar grave. Logo, quando há aumento da filtração microvascular ocorre rápido remodelamento da matriz por ativação de proteases. Destarte, a deposição de fibras colágenas reduz a complacência intersticial limitando o edema. Em conclusão, modificações na matriz extracelular podem afetar a formação e distribuição do edema no pulmão.

Blancos terapéuticos potenciales para revertir la cirrosis hepática / Therapeutical targets for revert liver fibrosis

Liver fibrosis is the common response to chronic liver injury, ultimately leading to cirrhosis and its complications: portal hypertension, liver failure, hepatic encephalopathy, and hepatocellular carcinoma and others. Efficient and well-tolerated antifibrotic drugs are still lacking, and current treatment of hepatic fibrosis is limited to withdrawal of the noxious agent. Efforts over the past decade have mainly focused on fibrogenic cells generating the scarring response, although promising data on inhibition of parenchymal injury or reduction of liver inflammation have also been obtained. A large number of approaches have been validated in culture studies and in animal models, and several clinical trials are underway or anticipated for a growing number of molecules. This review highlight recent advances in the molecular mechanisms of liver fibrosis and discusses mechanistically based strategies that have recently emerged.

Novel fibroblast growth factor receptor 1 mutations in patients with congenital hypogonadotropic hypogonadism with and without anosmia.

CONTEXT: Kallmann syndrome is a clinically and genetically heterogeneous disorder. To date, loss-of-function mutations in the genes encoding anosmin-1 (KAL1) and fibroblast growth factor receptor 1 (FGFR1) have been described in the X-linked and autosomal dominant forms of this syndrome, respectively. OBJECTIVE: The objective was to investigate genetic defects in the KAL1 and FGFR1 genes in patients with congenital isolated hypogonadotropic hypogonadism (IHH). PATIENTS: Eighty patients (71 males and nine females) with IHH were studied, of which 30 were familial. Forty-six of them had olfactory abnormalities. METHODS: The coding regions of both KAL1 and FGFR1 genes were amplified and automatically sequenced. The KAL1 mutations were investigated only in patients with olfactory abnormalities, whereas FGFR1 was studied in the entire group. RESULTS: Two novel KAL1 mutations, an intragenic deletion of exons 3-6 and a splicing mutation IVS7 + 1G>A, were identified in two of 46 patients with Kallmann syndrome. Eight novel heterozygous FGFR1 mutations (G48S, L245P, R250W, A343V, P366L, K618fsX654, P722S, and V795I) were identified in nine of 80 patients with IHH. Eight of them had olfactory abnormalities. Interestingly, the G48S mutation was identified in a normosmic IHH patient. Two unrelated females, who carried FGFR1 mutations, had anosmia and normal reproductive function. CONCLUSION: We identified novel mutations in KAL1 and FGFR1 genes in IHH patients. FGFR1 mutations were identified in 17% of the patients with olfactory abnormalities and in one of 34 normosmic IHH patients. In addition, isolated anosmia was identified in two unrelated females as a partial phenotypic manifestation of FGFR1 defects.

The extracellular matrix provides directional cues for neuronal migration during cerebellar development

Normal central nervous system development relies on accurate intrinsic cellular programs as well as on extrinsic informative cues provided by extracellular molecules. Migration of neuronal progenitors from defined proliferative zones to their final location is a key event during embryonic and postnatal development. Extracellular matrix components play important roles in these processes, and interactions between neurons and extracellular matrix are fundamental for the normal development of the central nervous system. Guidance cues are provided by extracellular factors that orient neuronal migration. During cerebellar development, the extracellular matrix molecules laminin and fibronectin give support to neuronal precursor migration, while other molecules such as reelin, tenascin, and netrin orient their migration. Reelin and tenascin are extracellular matrix components that attract or repel neuronal precursors and axons during development through interaction with membrane receptors, and netrin associates with laminin and heparan sulfate proteoglycans, and binds to the extracellular matrix receptor integrins present on the neuronal surface. Altogether, the dynamic changes in the composition and distribution of extracellular matrix components provide external cues that direct neurons leaving their birthplaces to reach their correct final location. Understanding the molecular mechanisms that orient neurons to reach precisely their final location during development is fundamental to understand how neuronal misplacement leads to neurological diseases and eventually to find ways to treat them.

The extracellular matrix provides directional cues for neuronal migration during cerebellar development.

Normal central nervous system development relies on accurate intrinsic cellular programs as well as on extrinsic informative cues provided by extracellular molecules. Migration of neuronal progenitors from defined proliferative zones to their final location is a key event during embryonic and postnatal development. Extracellular matrix components play important roles in these processes, and interactions between neurons and extracellular matrix are fundamental for the normal development of the central nervous system. Guidance cues are provided by extracellular factors that orient neuronal migration. During cerebellar development, the extracellular matrix molecules laminin and fibronectin give support to neuronal precursor migration, while other molecules such as reelin, tenascin, and netrin orient their migration. Reelin and tenascin are extracellular matrix components that attract or repel neuronal precursors and axons during development through interaction with membrane receptors, and netrin associates with laminin and heparan sulfate proteoglycans, and binds to the extracellular matrix receptor integrins present on the neuronal surface. Altogether, the dynamic changes in the composition and distribution of extracellular matrix components provide external cues that direct neurons leaving their birthplaces to reach their correct final location. Understanding the molecular mechanisms that orient neurons to reach precisely their final location during development is fundamental to understand how neuronal misplacement leads to neurological diseases and eventually to find ways to treat them.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling.

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Glyceraldehyde-3-phosphate dehydrogenase of Paracoccidioides brasiliensis is a cell surface protein involved in fungal adhesion to extracellular matrix proteins and interaction with cells.

The pathogenic fungus Paracoccidioides brasiliensis causes paracoccidioidomycosis, a pulmonary mycosis acquired by inhalation of fungal airborne propagules, which may disseminate to several organs and tissues, leading to a severe form of the disease. Adhesion to and invasion of host cells are essential steps involved in the infection and dissemination of pathogens. Furthermore, pathogens use their surface molecules to bind to host extracellular matrix components to establish infection. Here, we report the characterization of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of P. brasiliensis as an adhesin, which can be related to fungus adhesion and invasion. The P. brasiliensis GAPDH was overexpressed in Escherichia coli, and polyclonal antibody against this protein was obtained. By immunoelectron microscopy and Western blot analysis, GAPDH was detected in the cytoplasm and the cell wall of the yeast phase of P. brasiliensis. The recombinant GAPDH was found to bind to fibronectin, laminin, and type I collagen in ligand far-Western blot assays. Of special note, the treatment of P. brasiliensis yeast cells with anti-GAPDH polyclonal antibody and the incubation of pneumocytes with the recombinant protein promoted inhibition of adherence and internalization of P. brasiliensis to those in vitro-cultured cells. These observations indicate that the cell wall-associated form of the GAPDH in P. brasiliensis could be involved in mediating binding of fungal cells to fibronectin, type I collagen, and laminin, thus contributing to the adhesion of the microorganism to host tissues and to the dissemination of infection.