Are you Peter E. Hall?

Claim your profile

Publications (17)

  • Justin D Lathia · Meizhang Li · Peter E Hall · [...] · Jeremy N Rich
    [Show abstract] [Hide abstract] ABSTRACT: Glioblastomas (GBMs) are lethal cancers that display cellular hierarchies parallel to normal brain. At the apex are GBM stem cells (GSCs), which are relatively resistant to conventional therapy. Interactions with the adjacent perivascular niche are an important driver of malignancy and self-renewal in GSCs. Extracellular matrix (ECM) cues instruct neural stem/progenitor cell-niche interactions, and the objective of our study was to elucidate its composition and contribution to GSC maintenance in the perivascular niche. We interrogated human tumor tissue for immunofluorescence analysis and derived GSCs from tumor tissues for functional studies. Bioinformatics analyses were conducted by mining publicly available databases. We find that laminin ECM proteins are localized to the perivascular GBM niche and inform negative patient prognosis. To identify the source of laminins, we characterized cellular elements within the niche and found that laminin α chains were expressed by nonstem tumor cells and tumor-associated endothelial cells (ECs). RNA interference targeting laminin α2 inhibited GSC growth and self-renewal. In co-culture studies of GSCs and ECs, laminin α2 knockdown in ECs resulted in decreased tumor growth. Our studies highlight the contribution of nonstem tumor cell-derived laminin juxtracrine signaling. As laminin α2 has recently been identified as a molecular marker of aggressive ependymoma, we propose that the brain vascular ECM promotes tumor malignancy through maintenance of the GSC compartment, providing not only a molecular fingerprint but also a possible therapeutic target. ANN NEUROL 2012;72:766-778.
    Article · Nov 2012 · Annals of Neurology
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: During embryogenesis, the neural stem cells (NSC) of the developing cerebral cortex are located in the ventricular zone (VZ) lining the cerebral ventricles. They exhibit apical and basal processes that contact the ventricular surface and the pial basement membrane, respectively. This unique architecture is important for VZ physical integrity and fate determination of NSC daughter cells. In addition, the shorter apical process is critical for interkinetic nuclear migration (INM), which enables VZ cell mitoses at the ventricular surface. Despite their importance, the mechanisms required for NSC adhesion to the ventricle are poorly understood. We have shown previously that one class of candidate adhesion molecules, laminins, are present in the ventricular region and that their integrin receptors are expressed by NSC. However, prior studies only demonstrate a role for their interaction in the attachment of the basal process to the overlying pial basement membrane. Here we use antibody-blocking and genetic experiments to reveal an additional and novel requirement for laminin/integrin interactions in apical process adhesion and NSC regulation. Transient abrogation of integrin binding and signalling using blocking antibodies to specifically target the ventricular region in utero results in abnormal INM and alterations in the orientation of NSC divisions. We found that these defects were also observed in laminin alpha2 deficient mice. More detailed analyses using a multidisciplinary approach to analyse stem cell behaviour by expression of fluorescent transgenes and multiphoton time-lapse imaging revealed that the transient embryonic disruption of laminin/integrin signalling at the VZ surface resulted in apical process detachment from the ventricular surface, dystrophic radial glia fibers, and substantial layering defects in the postnatal neocortex. Collectively, these data reveal novel roles for the laminin/integrin interaction in anchoring embryonic NSCs to the ventricular surface and maintaining the physical integrity of the neocortical niche, with even transient perturbations resulting in long-lasting cortical defects.
    Full-text Article · Sep 2009 · PLoS Biology
  • Source
    Dataset: Figure S5
    [Show abstract] [Hide abstract] ABSTRACT: Intraventricular co-electroporation/injection of β1 integrin blocking antibody reveals detached cells. (A) Schematic representation of the delamination analysis including orthogonal sections to view the cortex from apical to basal surface followed by volumetric reconstruction and counting of the number of apical processes and cell bodies. (B) 3-D reconstruction pictures of CAG-RFP electroporated cells (in red) at the VZ surface (labelled with phalloidin in green) of E15.5 β1 integrin blocking antibody-injected brain. (C) Confocal fluorescence micrographs of E16 telencephalon stained with PH3 (C2, green) following β1 integrin blocking antibody and electroporation with CAG-RFP (C1, red) at E15.5. Note the co-expression of CAG-RFP and PH3 in a cell (yellow, C3, C4) away from the ventricular surface. Scale bar represents 50 µm. (10.08 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Figure S4
    [Show abstract] [Hide abstract] ABSTRACT: Cell differentiation is not affected after disruption of β1 integrin signalling at the ventricular surface. (A, B) Fluorescence micrographs of Tbr2 expression (green) after ITC (control, A) or β1 integrin blocking (B) antibody injection at E12.5. (C, D) Quantification of Tbr2+ cells in a dorsal (C) and ventral (D) 200 µm×100 µm (width×height) area of the VZ shows that the number of intermediate progenitors is not modified by the blockade of β1 integrin in the VZ. (E, F) Fluorescence micrographs of β3 tubulin expression (red, dapi-counterstained nuclei in blue) after antibody injection at E12.5. Note the lack of β3 tubulin expression within 100 µm of the ventricular surface; scale bar represents 50 µm. (7.92 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Video S3
    [Show abstract] [Hide abstract] ABSTRACT: Time lapse imaging of organotypic brain slice prepared 24 h after in utero electroporation with eGFP-F DNA into a wild-type E14.5 embryo and incubated in the presence of a drop of β1 integrin blocking antibody-containing growth factor–reduced matrigel in the lateral ventricle. Automated multipoint scanning using a multiphoton laser (850 nm) was used to monitor the behavior of the eGFP-F+ cells. In presence of β1 blocking antibody, the neuroepithelial organization of the VZ appears to be progressively disrupted because of an alteration of the radial morphology of the NSC cells whose both basal and apical processes appear bowed and exhibit detachment of their ventricular end feet. Scale bar represents 25 µm. (1.04 MB MPG)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Figure S3
    [Show abstract] [Hide abstract] ABSTRACT: Both β1 blocking antibody-injected and laminin α2-deficient forebrains exhibit a lower proportion of horizontal mitotic cleavages in the VZ throughout neurogenesis. (A) Graph illustrating the results of the ordinal regression analysis of the frequency of cleavage plane angle strata in the β1 integrin blocking antibody injected forebrain versus ITC by region (see Materials and Methods). Note the proportion of horizontally dividing VZ cells (0–30 degrees) is lower at the medial and caudal levels of β1 integrin blocking antibody injected forebrain compared to controls. (B) Graph illustrating results of the ordinal regression analysis of the frequency of cleavage plane angle strata in Lnα2−/− forebrain versus wild type by region. Note the proportion of horizontally dividing VZ cells is lower at the medial level of Lnα2−/− forebrain compared to wild-type littermates, as with the embryos injected with β1 integrin blocking antibody. n = 3 wild-type and 4 Lnα2−/− embryos from one litter, ±SEM (standard error of the mean). (8.04 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Figure S6
    [Show abstract] [Hide abstract] ABSTRACT: Analysis of the mobility/diffusion of the β1 integrin blocking antibody in growth factor-reduced matrigel during time lapse imaging experiments. (A, B) Fluorescent micrographs of 300-µm-thick neocortical E14.5 slices stained with dapi (blue) and containing a drop of ITC-(A) or FITC- conjugated β1 integrin blocking antibody (B) growth factor-reduced matrigel (GFRM) within their ventricular space. (C ,D) Intensity profile graphs illustrating the distribution of pixel intensity on both blue (dapi) and green (FITC antibody) channels from the VZ surface (bin 0) towards the pial surface (bin 5) with both ITC- (C) and β1 integrin blocking antibody FITC-conjugated (D) GFRM. Each bin represents 20% of the neocortical wall. Note that a green peak (green arrow) is only detected in the first bin of the β1 integrin blocking antibody FITC-conjugated GFRM (D), whereas a blue peak (blue arrows) corresponding to dapi at the apical surface of the neocortical slices is detected in both conditions. (E) Graph illustrating the average of green channel pixel intensity summed for each bin along the neocortical wall in β1 integrin blocking antibody FITC-conjugated GFRM (red line) compared to controls (blue line). Note that the pixel intensity in the first bin (corresponding at the apical surface) is significantly higher with the β1 integrin blocking antibody than in the control confirming that the antibody can diffuse into at least in the first 20% of the thickness of the neocortical wall. Conversely, the levels of antibody are not different from the control (noise/background) in bin 5 (that corresponds to the pial surface) indicating that the β1 integrin blocking antibody does not reach the pial surface. n = 6 cortices for ITC; n = 10 for β1 blocking antibody, ±SEM, *, p<0.05; unpaired two-tailed t-test. Scale bar represent 50 µm. (8.14 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Figure S2
    [Show abstract] [Hide abstract] ABSTRACT: In utero intraventricular injection of β1 integrin blocking antibody results in specific targeting of the ventricular surface and decreased β1 integrin signalling in the VZ. (A, B) Fluorescence micrographs of the E14 telencephalon following an intraventricular injection of a β1 integrin FITC-conjugated blocking antibody (green) show that the antibody does not penetrate as far as the pial surface (white dashed line) but is present in the VZ (B) (negative control [PBS], A), (dapi-counterstained nuclei in blue). (C) Western blot analysis showing levels of phospho (p) and total (T) Akt 1 and actin in E12.5 and E15.5 embryos 30 min after injection with an ITC or β1 integrin blocking antibody. (8.58 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Figure S1
    [Show abstract] [Hide abstract] ABSTRACT: β1 integrin is localized basally to adherens junctions. (A) Colabelling of β1 integrin and actin in E14 neocortical VZ reveals the basal localization of β1 integrin staining relative to actin-based adherens junctions. The white arrow points to the apical process (identified by the accumulation of actin staining at the tip) along which the fluorescence intensity profile presented in the graph below (B) was determined for each marker. To facilitate the comparison of β1 integrin positioning relative to actin, dotted lines were drawn at the peak of staining intensity for each marker and the actin position taken as the position of reference. (B) The graph shows that β1 integrin is located more basally than actin-based adherens junctions. (8.92 MB TIF)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Video S1
    [Show abstract] [Hide abstract] ABSTRACT: Interactive Quick Time VR video of CAG-RFP electroporated cells (in red) at the E16 VZ surface labelled with phalloidin (in green) following simultaneous β1 integrin blocking antibody injection and CAG-RFP electroporation at E15.5. (4.50 MB MPG)
    Full-text Dataset · Aug 2009
  • Source
    Dataset: Video S2
    [Show abstract] [Hide abstract] ABSTRACT: Time lapse imaging of organotypic brain slice prepared 24 h after in utero electroporation with eGFP-F DNA into a wild-type E14.5 embryo and incubated in the presence of a drop of ITC antibody-containing growth factor–reduced matrigel in the lateral ventricular space. Automated multipoint scanning using a multiphoton laser (850 nm) was used to monitor the behavior of the eGFP-F+ cells in presence of ITC control antibody. During the 10 h recording the bipolar eGFP-F+ cells maintain straight processes and end-feet attached to the ventricular surface. Scale bar represents 25 µm. (1.50 MB MPG)
    Full-text Dataset · Aug 2009
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Human neural stem cells (hNSC) have the potential to provide novel cell-based therapies for neurodegenerative conditions such as multiple sclerosis and Parkinson's disease. In order to realise this goal, protocols need to be developed that allow for large quantities of hNSC to be cultured efficiently. As such, it is important to identify factors which enhance the growth of hNSC. In vivo, stem cells reside in distinct microenvironments or niches that are responsible for the maintenance of stem cell populations. A common feature of niches is the presence of the extracellular matrix molecule, laminin. Therefore, this study investigated the effect of exogenous laminin on hNSC growth. To measure hNSC growth, we established culture conditions using B27-supplemented medium that enable neurospheres to grow from human neural cells plated at clonal densities. Limiting dilution assays confirmed that neurospheres were derived from single cells at these densities. Laminin was found to increase hNSC numbers as measured by this neurosphere formation. The effect of laminin was to augment the proliferation/survival of the hNSC, rather than promoting the undifferentiated state. In agreement, apoptosis was reduced in dissociated neurospheres by laminin in an integrin beta1-dependent manner. The addition of laminin to the culture medium enhances the growth of hNSC, and may therefore aid their large-scale production.
    Full-text Article · Jul 2008 · BMC Neuroscience
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Comparison of the effect different laminin concentrations on mouse neurosphere numbers. Mouse neurospheres were dissociated and plated at 500 cells/well in medium containing 5–20 μg/ml laminin. After 7 days, the number of neurospheres formed was quantified. Compared to wells with no added laminin, significant increases were observed for all concentrations (p < 0.01). However, whilst 10 μg/ml laminin produced significantly more neurospheres than 5 μg/ml (p < 0.01), no significant difference was found between 10 or 20 μg/ml laminin. Therefore, 10 μg/ml laminin was used for all experiments on human cells. Statistics were determined by a one-way ANOVA with Tukey post-test, with 8 technical replicates performed within a single experiment.
    Full-text Dataset · Jul 2008
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: TS2/16 does activate integrin beta 1 signalling. (A) Platelet adhesion assay, demonstrating that the activating-β1 integrin antibody, TS2/16, stimulates adhesion to pepsin-digested collagen I at the concentrations of 5 μg/ml, relative to medium alone or to an isotype control antibody. (B) Western blot showing that 10 μg/ml TS2/16 stimulates focal adhesion kinase (FAK) phosphorylation on tyrosine 397 (pY397) after 10 min of treatment. 'Iso. Cont.', isotype control antibody (10 μg/ml). *p < 0.01, relative to the isotype control or medium alone, as determined by a one-way ANOVA with Tukey post-test; n = 2.
    Full-text Dataset · Jul 2008
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Additional methods.
    Full-text Dataset · Jul 2008
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Laminin increases mouse neurosphere formation in an α6β1-dependent manner. (A) Mouse neurospheres were dissociated and plated in medium containing 10 μg/ml laminin ('Medium+Laminin'), resulting in augmented primary neurosphere formation after 7 days in culture. (B) However, this difference was not maintained upon passaging in medium alone (secondary neurosphere formation). (C) Graph demonstrating that the effect of laminin on primary neurosphere formation is mediated by integrin β1. In medium alone, neither an isotype control antibody ('Iso. cont.') nor an integrin β1-blocking antibody ('β1 block'; 1 μg/ml) affected neurosphere formation. Significantly, though, in the presence of laminin the β1 integrin-blocking antibody reduced neurosphere formation to control levels. (D) Similarly, an α6 blocking antibody ('α6 block'; 20 μg/ml) inhibited the effect of laminin ('Laminin') on neurosphere formation, although blocking another laminin-binding integrin, α7 ('α7 block'; 10 μg/ml) did not. ITC, isotype control (A) *p < 0.0001, as determined by Student's t-test; n = 3. (C, D) *p < 0.001, as determined by a one-way ANOVA with Tukey post-test; n = 3.
    Full-text Dataset · Jul 2008
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: The identification of markers for the isolation of human neural stem cells (hNSCs) is essential for studies of their biology and therapeutic applications. This study investigated expression of the integrin receptor family by hNSCs as potential markers. Selection of alpha6(hi) or beta1(hi) cells by fluorescence-activated cell sorting led to an enrichment of human neural precursors, as shown by both neurosphere forming assays and increased expression of prominin-1, sox2, sox3, nestin, bmi1, and musashi1 in the beta1(hi) population. Cells expressing high levels of beta1 integrin also expressed prominin-1 (CD133), a marker previously used to isolate hNSCs, and selection using integrin beta1(hi) cells or prominin-1(hi) cells was found to be equally effective at enriching for hNSCs from neurospheres. Therefore, integrin subunits alpha6 and beta1 are highly expressed by human neural precursors and represent convenient markers for their prospective isolation.
    Full-text Article · Oct 2006 · Stem Cells