PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Slit Homolog 2 Protein”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2005

Magic roundabout, a tumor endothelial marker: expression and signaling.

Molecular signals that guide blood vessels to specific paths are not fully deciphered, but are thought to be similar to signals that mediate neuronal guidance. These cues are not only critical for normal blood vessel development, but may also play a major role in tumor angiogenesis. In this study, we have demonstrated the tumor endothelial specific expression of a Robo family member, magic roundabout (MRB), functionally characterized its role in endothelial cell migration and defined a signaling pathway that might mediate this function. We show that MRB is differentially over-expressed in tumor endothelial cells versus normal adult endothelial cells in numerous solid tumors. Moreover, over-expression of MRB in endothelial cells activates MRB in a ligand-independent fashion, and activation of MRB via Slit2, a putative ligand, results in inhibition of VEGF and FGF induced migration. We also demonstrate that MRB induced inhibition of endothelial migration is partially mediated by the Ras-Raf-Mek-Erk signaling pathway. We therefore hypothesize that expression of MRB is involved in regulating the migration of endothelial cells during tumor angiogenesis.

Biomarkers, Tumor↗
PubMed2000

Slit2 is a repellent for retinal ganglion cell axons.

We set out to isolate inhibitory guidance cues that affect retinal ganglion cell (RGC) axons in vitro and that could potentially be involved in RGC pathfinding decisions. Here we describe the biochemical purification of an RGC growth cone collapsing factor from bovine brain membranes and its identification as Slit2. Recombinant human Slit2 collapses and repels RGC growth cones from all quadrants of the chick retina. In the developing mouse visual system, slit2 is expressed in the eye, in the optic stalk, and in the ventral diencephalon. Slit2 expression is strong in anterior ventral diencephalic structures but is absent from the ventral midline where the optic chiasm forms. The putative receptors for Slits, robo1 and robo2, are expressed in the inner retinal layer in which RGCs are located. A comparison of the expression patterns of Slit2 and retinal axon trajectories suggests that slit2 acts as a short range repellent for retinal ganglion cell axons.

Animals↗
PubMed2004

Multiple roles for slits in the control of cell migration in the rostral migratory stream.

The subventricular zone (SVZ) contains undifferentiated cells, which proliferate and generate olfactory bulb (OB) interneurons. Throughout life, these cells leave the SVZ and migrate along the rostral migratory stream (RMS) to the OB where they differentiate. In vitro, the septum and the choroid plexus (CP) secrete repulsive factors that could orient the migration of OB precursors. Slit1 and Slit2, two known chemorepellents for developing axons, can mimic this effect. We show here that the Slit receptors Robo2 and Robo3/Rig-1 are expressed in the SVZ and the RMS and that Slit1 and Slit2 are still present in the adult septum. Using Slit1/2-deficient mice, we found that Slit1 and Slit2 are responsible for both the septum and the CP repulsive activity in vitro. In adult mice lacking Slit1, small chains of SVZ-derived cells migrate caudally into the corpus callosum, supporting a role for Slits in orienting the migration of SVZ cells. Surprisingly, in adult mice, Slit1 was also expressed by type A and type C cells in the SVZ and RMS, suggesting that Slit1 could act cell autonomously. This hypothesis was tested using cultures of SVZ explants or isolated neurospheres from Slit1-/- or Slit1+/- mice. In both types of cultures, the migration of SVZ cells was altered in the absence of Slit1. This suggests that the regulation of the migration of OB precursors by Slit proteins is complex and not limited to repulsion.

Animals↗
PubMed2006

Heparan sulphation patterns generated by specific heparan sulfotransferase enzymes direct distinct aspects of retinal axon guidance at the optic chiasm.

Retinal ganglion cell (RGC) axons from each eye execute a series of maneuvers as they converge on the ventral surface of the brain at the optic chiasm for sorting into the optic tracts. Heparan sulfate proteoglycans (HSPGs) are extracellular glycoproteins involved in cell-surface interactions. HSPGs exhibit massive structural diversity, conferred partly by extensive post-translational modification including differential sulfation. Here we examine the roles of HSPG sulfation in RGC axon guidance at the chiasm. We identified different axon navigation phenotypes in two heparan sulfate sulfotransferase (Hst) mutant embryos, Hs2st-/- and Hs6st1-/-, each lacking an enzyme that catalyzes a particular HSPG modification. Hs2st-/- embryos display axon disorganization at the chiasm. Hs6st1-/- embryos exhibit prolific inter-retinal innervation. We show that RGCs express Hs2st and Hs6st1 and that navigation errors made by their axons coincide with regions of high Hs2st and/or Hs6st1 expression at the chiasm. Slit proteins are expressed at particular locations in the retina and around the chiasm and are normally deployed to prevent axons entering inappropriate territories. We show that Hs2st and/or Hs6st1 expression coincides with Slit expression domains at locations where RGC axons make navigation errors in Hs2st-/- and Hs6st1-/- mutants and that Hs6st1-/- RGC axons are less sensitive to Slit2 repulsion than their wild-type counterparts in vitro. We suggest that (1) Hs2st and Hs6st1 are each deployed to generate distinct patterns of heparan sulfation on RGCs and at the optic chiasm and (2) this differential sulfation directs retinal axons through the chiasm, at least in part by modulating the response of the navigating growth cone to Slit proteins.

Alleles↗
PubMed1999

Chemorepulsion of neuronal migration by Slit2 in the developing mammalian forebrain.

Newborn cerebral cortical neurons migrate along radial glia to the cortical plate. Experiments using a collagen gel assay revealed that the choroid plexus repelled cerebral cortical neurons and olfactory interneuron precursors, which were mimicked by Neuro-2A cells. Fractionation of Neuro-2A-conditioned medium identified a protein of 190 kDa, equivalent to full-length Slit proteins. Indeed, it cross-reacted with an antibody against Slit2, suggesting that it is either Slit2 or another Slit protein. Further, Slit2, expressed in COS cells, repelled cerebral cortical neurons and olfactory interneuron precursors. Thus, Slit2, which is expressed by the choroid plexus and the septum, acts as a chemorepulsive factor for neuronal migration. These results suggest chemorepulsion as a guidance mechanism for neuronal migration in the developing forebrain.

Animals↗
PubMed1998

Distinct but overlapping expression patterns of two vertebrate slit homologs implies functional roles in CNS development and organogenesis.

The Drosophila slit gene (sli) encodes a secreted leucine-rich repeat-containing protein (slit) expressed by the midline glial cells and required for normal neural development. A putative human sli homolog, SLIT1, has previously been identified by EST database scanning. We have isolated a second human sli homolog, SLIT2, and its murine homolog Slit2. Both SLIT1 and SLIT2 proteins show approximately 40% amino acid identity to slit and 60% identity to each other. In mice, both genes are expressed during CNS development in the floor plate, roof plate and developing motor neurons. As floor plate represents the vertebrate equivalent to the midline glial cells, we predict a conservation of function for these vertebrate homologs. Each gene shows additional but distinct sites of expression outside the CNS suggesting a variety of functions for these proteins.

Amino Acid Sequence↗
PubMed2004

[Study of expression of slit2 mRNA in rats of different age after sciatic nerve injury].

OBJECTIVE: To determine the age-related expression features of slit2 mRNA at various intervals at the proximal and distal parts of sciatic nerve during re-innervation after severance injury, and to investigate the molecular biological reason why co-contraction occurs more commonly in the young rats than in the adults after peripheral nerve injury. METHODS: The right sciatic nerve was transected sharply at the midthigh in the young and adult rats, 28 in each group. The proximal and distal stumps were inserted into a medical silicone tube with a gap of 3 mm. Before the injury, and 1, 3 and 7 days (6 rats at each interval) after sciatic nerve severance injury, both stumps of the sciatic nerve were harvested. Reverse transcription polymerase chain reaction (RT-PCR) was use to examine the expression of slit2 mRNA in the young and adult group rats. In situ hybridization was done to detect the cell location of slit2 mRNA expression in young and adult rats, 4 rats in each group, 2 rats used before the injury and 2 rats used on the postoperative third day. RESULTS: RT-PCR results suggested that slit2 mRNA at both stumps was significantly lower in the young group of rats than in the adult except that at the proximal part on the postoperative 7th day. There was statistically significant difference (P < 0.01). In situ hybridization studies indicated that the slit2 mRNA was specifically expressed in the cytoplasm of Schwann cells both in the young and adult rats before injury and 3 days after injury. CONCLUSION: The expression of slit2 mRNA by Schwann cells in the young rats is lower than that in the adult rats after peripheral nerve injury. These findings suggests the lower expression of chemotactic factor (slit2) by Schwann cells in the young group is likely to be the molecular biological reason for the higher incidence of co-contraction between agonists and antagonists in the younger rats.

Age Factors↗
PubMed2004

SLIT2 promoter methylation analysis in neuroblastoma, Wilms' tumour and renal cell carcinoma.

The 3p21.3 RASSF1A tumour suppressor gene (TSG) provides a paradigm for TSGs inactivated by promoter methylation rather than somatic mutations. Recently, we identified frequent promoter methylation without somatic mutations of SLIT2 in lung and breast cancers, suggesting similarities between SLIT2 and RASSF1A TSGs. Epigenetic inactivation of RASSF1A was first described in lung and breast cancers and subsequently in a wide range of human cancers including neuroblastoma, Wilms' tumour and renal cell carcinoma (RCC). These findings prompted us to investigate SLIT2 methylation in these three human cancers. We analysed 49 neuroblastomas (NBs), 37 Wilms' tumours and 48 RCC, and detected SLIT2 promoter methylation in 29% of NB, 38% of Wilms' tumours and 25% of RCC. Previously, we had demonstrated frequent RASSF1A methylation in the same tumour series and frequent CASP8 methylation in the NB and Wilms' tumour samples. However, there was no significant association between SLIT2 promoter methylation and RASSF1A or CASP8 methylation in NB and RCC. In Wilms' tumour, there was a trend for a negative association between RASSF1A and SLIT2 methylation, although this did not reach statistical significance. No associations were detected between SLIT2 promoter methylation and specific clinicopathological features in the tumours analysed. These findings implicate SLIT2 promoter methylation in the pathogenesis of both paediatric and adult cancers and suggest that further investigations of SLIT2 in other tumour types should be pursued. However, epigenetic inactivation of SLIT2 is less frequent than RASSF1A in the tumour types analysed.

Adult↗
PubMed2005

Comparative genomics on SLIT1, SLIT2, and SLIT3 orthologs.

SLIT1 gene at human chromosome 10q24.1, SLIT2 gene at 4p15.31, and SLIT3 gene at 5q34-q35.1 encode large secreted proteins functioning as ligands for Roundabout (Robo) receptors. SLIT-ROBO signaling pathway is implicated in neurogenesis, angiogenesis, and immune response through the regulation of axonal guidance, endothelial cell migration, and denderitic cell migration, respectively. GREMLIN (CKTSF1B1 or GREM1) and DANTE (CKTSF1B3 or GREM3) are secreted antagonists for BMPs and SLITs. Here, comparative integromics analyses on SLIT1, SLIT2, and SLIT3 orthologs were performed by using bioinformatics. Rat Slit2 gene, consisting of 36 exons, was located within rat genome sequences AC098362.4 and AC111627.6. Mouse Slit3 complete coding sequence was determined by assembling BB634238 EST, AF144629 cDNA, and AK129223 cDNA. Leucine-rich repeats with nine conserved cysteine (LRRCC) domains and SLIT C-terminal cysteine-rich (SLITCCR) domain were identified in this study. CPxxCxCxxxxVxCxxxxLxxxPxxxPx(10~58) Nx(19,20)LxxNx(9)Fx(8)LxLxxNxxxCxxxxxFxxLxxx xxLxLxxNx(9)Fx(13)NxxxCxCxxxWLx(15)CxxPx(17)C was the consensus sequence of LRRCC domain. Mammalian SLIT1, SLIT2 and SLIT3 orthologs were large secreted proteins with four LRRCC domains, nine EGF domains, Laminin G (LamG) domain, and SLITCCR domain. SLIT1 mRNA was expressed in fetal brain, infant brain, anaplastic oligodendroglioma, and Jurkat T cells. SLIT2 and SLIT3 mRNAs were co-expressed in embryonic stem (ES) cells with embryoid body formation, and diffuse type gastric cancer with signet ring cell features. Double TCF/LEF and bHLH-binding sites were conserved among mammalian SLIT1 promoters. FOXJ2, E47, ETS1, and FOXA2-binding sites and CCAAT box were conserved among mammalian SLIT3 promoters. Mammalian SLIT1 orthologs were identified as evolutionarily conserved targets of the WNT/beta-catenin signaling pathway.

Amino Acid Sequence↗
PubMed2000

Slit inhibition of retinal axon growth and its role in retinal axon pathfinding and innervation patterns in the diencephalon.

We have analyzed the role of the Slit family of repellent axon guidance molecules in the patterning of the axonal projections of retinal ganglion cells (RGCs) within the embryonic rat diencephalon and whether the slits can account for a repellent activity for retinal axons released by hypothalamus and epithalamus. At the time RGC axons extend over the diencephalon, slit1 and slit2 are expressed in hypothalamus and epithalamus but not in the lateral part of dorsal thalamus, a retinal target. slit3 expression is low or undetectable. The Slit receptors robo2, and to a limited extent robo1, are expressed in the RGC layer, as are slit1 and slit2. In collagen gels, axon outgrowth from rat retinal explants is biased away from slit2-transfected 293T cells, and the number and length of axons are decreased on the explant side facing the cells. In addition, in the presence of Slit2, overall axon outgrowth is decreased, and bundles of retinal axons are more tightly fasciculated. This action of Slit2 as a growth inhibitor of retinal axons and the expression patterns of slit1 and slit2 correlate with the fasciculation and innervation patterns of RGC axons within the diencephalon and implicate the Slits as components of the axon repellent activity associated with the hypothalamus and epithalamus. Our findings suggest that in vivo the Slits control RGC axon pathfinding and targeting within the diencephalon by regulating their fasciculation, preventing them or their branches from invading nontarget tissues, and steering them toward their most distal target, the superior colliculus.

Animals↗
PubMed2006

Signaling mechanisms underlying Slit2-induced collapse of Xenopus retinal growth cones.

Slits mediate multiple axon guidance decisions, but the mechanisms underlying the responses of growth cones to these cues remain poorly defined. We show here that collapse induced by Slit2-conditioned medium (Slit2-CM) in Xenopus retinal growth cones requires local protein synthesis (PS) and endocytosis. Slit2-CM elicits rapid activation of translation regulators and MAP kinases in growth cones, and inhibition of MAPKs or disruption of heparan sulfate blocks Slit2-CM-induced PS and repulsion. Interestingly, Slit2-CM causes a fast PS-dependent decrease in cytoskeletal F-actin concomitant with a PS-dependent increase in the actin-depolymerizing protein cofilin. Our findings reveal an unexpected link between Slit2 and cofilin in growth cones and suggest that local translation of actin regulatory proteins contributes to repulsion.

Actin Depolymerizing Factors↗
PubMed2002

Slit1 and Slit2 cooperate to prevent premature midline crossing of retinal axons in the mouse visual system.

During development, retinal ganglion cell (RGC) axons either cross or avoid the midline at the optic chiasm. In Drosophila, the Slit protein regulates midline axon crossing through repulsion. To determine the role of Slit proteins in RGC axon guidance, we disrupted Slit1 and Slit2, two of three known mouse Slit genes. Mice defective in either gene alone exhibited few RGC axon guidance defects, but in double mutant mice a large additional chiasm developed anterior to the true chiasm, many retinal axons projected into the contralateral optic nerve, and some extended ectopically-dorsal and lateral to the chiasm. Our results indicate that Slit proteins repel retinal axons in vivo and cooperate to establish a corridor through which the axons are channeled, thereby helping define the site in the ventral diencephalon where the optic chiasm forms.

Animals↗
PubMed2004

Convergent and divergent signaling mechanisms of growth cone collapse by ephrinA5 and slit2.

EphrinA5 and slit2 are important repulsive guidance cues in the developing retinotectal system. Both ephrinA5 and slit2 cause growth cone collapse of embryonic chick retinal ganglion growth cones cultured on EHS laminin. However, the signaling mechanism that these guidance cues initiate to cause collapse remains unclear. Here we provide evidence that while both ephrinA5 and slit2 cause collapse in morphologically similar ways, the intracellular signaling leading to the collapse involves shared as well as divergent paths. Pharmacological inhibition of either phosphatidylinositol 3-kinase (PI3K) or src family kinases prevented both ephrinA5-mediated and slit2-mediated growth cone collapse. In contrast, the inhibition of nonclassical protein kinase C (PKC) isoforms blocked ephrinA5-mediated collapse, but did not interfere with slit2-mediated collapse. PI3K was copurified by affinity chromatography with either the ephrinA5 receptors (ephAs) or the slit2 receptor (roundabout). Colocalization studies have also shown that src family kinase members are recruited to the ephA and roundabout receptors upon activation. In contrast, PKC members are recruited to the ephA receptors, but not to the roundabout receptors, upon activation. This demonstrates distinct points of convergence and divergence between the two signaling molecules, ephrinA5 and slit2, and their repulsive guidance in the chick retinotectal system.

Analysis of Variance↗
PubMed2006

Nck adaptor proteins link nephrin to the actin cytoskeleton of kidney podocytes.

The glomerular filtration barrier in the kidney is formed in part by a specialized intercellular junction known as the slit diaphragm, which connects adjacent actin-based foot processes of kidney epithelial cells (podocytes). Mutations affecting a number of slit diaphragm proteins, including nephrin (encoded by NPHS1), lead to renal disease owing to disruption of the filtration barrier and rearrangement of the actin cytoskeleton, although the molecular basis for this is unclear. Here we show that nephrin selectively binds the Src homology 2 (SH2)/SH3 domain-containing Nck adaptor proteins, which in turn control the podocyte cytoskeleton in vivo. The cytoplasmic tail of nephrin has multiple YDxV sites that form preferred binding motifs for the Nck SH2 domain once phosphorylated by Src-family kinases. We show that this Nck-nephrin interaction is required for nephrin-dependent actin reorganization. Selective deletion of Nck from podocytes of transgenic mice results in defects in the formation of foot processes and in congenital nephrotic syndrome. Together, these findings identify a physiological signalling pathway in which nephrin is linked through phosphotyrosine-based interactions to Nck adaptors, and thus to the underlying actin cytoskeleton in podocytes. Simple and widely expressed SH2/SH3 adaptor proteins can therefore direct the formation of a specialized cellular morphology in vivo.

Actins↗
PubMed1994

A Drosophila homolog of cadherin associated with armadillo and essential for embryonic cell-cell adhesion.

We have identified a Drosophila homolog of vertebrate classic cadherins. A monoclonal antibody to Drosophila alpha-catenin (D alpha-catenin) copurifies a 150-kDa glycoprotein (gp150) along with the alpha-catenin. To further characterize this protein, we generated monoclonal antibodies to gp150 and isolated its cDNAs using the antibodies. Predicted sequences of the encoded product revealed that it is a transmembrane protein with similarity to vertebrate classic cadherins, and so we designated this molecule DE-cadherin. The extracellular domain has six cadherin-specific repeats, although the first repeat seems to be cleaved off upon maturation, and the cytoplasmic domain shows significant identity to that of vertebrate classic cadherins. DE-cadherin is distinguishable from its vertebrate counterparts by a large insertion with local sequence similarity to Fat, laminin A chain, Slit, and neurexin I at the proximal region of the extracellular domain. Despite such differences, DE-cadherin is functionally similar to vertebrate classic cadherins. For example, it is associated with alpha-catenin and beta-catenin (Armadillo), and protected from trypsin digestion only in the presence of Ca2+, as is the case for many of classic cadherins. Transfection of S2 cells with the DE-cadherin cDNA enhances their Ca(2+)-dependent cell aggregation. Antibodies to this molecule inhibited aggregation of not only the transfectants but also early embryonic cells. DE-cadherin is concentrated at the apical poles of epithelial cell-cell junctions. All these results suggest that DE-cadherin is a homolog of vertebrate classic cadherins and that the vertebrate and invertebrate share common mechanisms for regulation of cell-cell adhesion.

Amino Acid Sequence↗
PubMed2004

Identification of novel human neuronal leucine-rich repeat (hNLRR) family genes and inverse association of expression of Nbla10449/hNLRR-1 and Nbla10677/hNLRR-3 with the prognosis of primary neuroblastomas.

To search for novel prognostic indicators, we previously cloned >2,000 novel genes from primary neuroblastoma (NBL) cDNA libraries and screened for differential expression between the subsets with favorable (stage 1 or 2 with a single copy of MYCN) and unfavorable (stage 3 or 4 with amplification of MYCN) prognosis. From them, we have identified 3 genes of human neuronal leucine-rich repeat protein (NLRR) family: Nbla10449/hNLRR-1, Nbla00061/hNLRR-2/GAC1 and Nbla10677/hNLRR-3. An additional family member, hNLRR-5, was also found by homology search against public database. NLRR family proteins have been proposed to function as a neuronal adhesion molecule or soluble ligand binding receptor like Drosophila toll and slit with multiple domains including 11 sets of extracellular leucine-rich repeat (LRR)-motifs. However, the functional role of the NLRR protein family has been elusive. Our present study shows that hNLRR mRNAs are preferentially expressed in nervous system and/or adrenal gland. In cancer cell lines, hNLRR-1, hNLRR-3 and hNLRR-5 are expressed at high levels in the neural crest-derived cells. Most remarkably, in primary NBLs, hNLRR-1 is significantly expressed at high levels in unfavorable subsets as compared to favorable ones, whereas the expression pattern of hNLRR-3 and hNLRR-5 is the opposite. In order to understand the function of these receptors, we have used newborn mouse superior cervical ganglion (SCG) cells which are dependent on nerve growth factor (NGF) for their survival. Expression of the mouse counterparts of hNLRR-2 and hNLRR-3 is up-regulated after NGF-induced differentiation and down-regulated after NGF depletion-induced apoptosis. On the other hand, expression of hNLRR-1 and hNLRR-5 is inversely regulated in the same system. These results have suggested that the regulation of the hNLRR family genes may be associated with NGF signaling pathway in both SCG cells and neuroblastoma. Our quantitative real-time RT-PCR analysis using 99 primary NBLs has revealed that high levels of hNLRR-1 expression are significantly associated with older age (>1 year, p=0.0001), advanced stages (p=0.0007), low expression of TrkA (p=0.011), and MYCN amplification (p=0.0001), while those of hNLRR-3 expression are significantly correlated with the favorable prognostic indicators. Furthermore, multivariate analysis reveals that expression of hNLRR-1 is an independent prognostic indicator in human neuroblastoma. Thus, our results demonstrate that, despite being members of the same family, hNLRR-1 and hNLRR-3 may share different biological function among the NBL subsets, and that their expression level becomes novel prognostic indicators of NBL.

Adrenal Glands↗