Thesis (M.S.)--University of Michigan, 2006. / Includes bibliographical references (leaves 81-89).

Epithelial folding is an important morphogenetic process that is essential in transforming simple sheets of cells into complex three-dimensional tissues and organs during animal development (Davidson, 2012). Epithelial folding has been shown to rely on constriction forces generated by the apical actomyosin network (Martin et al., 2009; Roh-Johnson et al., 2012; Sawyer et al., 2010). However, the contributions of mechanical forces acting along lateral and basal cell surfaces to epithelial folding remain poorly understood. Here we combine live imaging with force measurements of epithelial mechanics to analyze the formation of two epithelial folds in the Drosophila larval wing imaginal disc. We show that these two neighboring folds form via two distinct mechanisms. These two folds are driven either by decrease of basal tension or increase of lateral tension, none of them depends on apical constriction. In the first fold, a local decrease in extracellular matrix (ECM) density in prefold cells results in a reduction of mechanical tension on the basal cell surface, leading to basal expansion and fold formation. Consistent with that, a local reduction of ECM by overexpression of Matrix metalloproteinase II is sufficient to induce ectopic folding. In the second fold a different mechanism is at place. Here basal tension is not different with neighboring cells, but pulsed dynamic F-actin accumulations along the lateral interface of prefold cells lead to increased lateral tension, which drives cell shortening along the apical-basal axis and fold formation. In this thesis I described two distinct mechanisms driving epithelial folding, both basal decrease and lateral increase in tension can generate similar morphological changes and promote epithelial folding in the Drosophila wing discs. / Die Faltung von Epithelien ist ein wichtiger morphogenetischer Prozess, der die Entstehung komplexer, dreidimensionaler Gewebe und Organe aus einfachen Zellschichten ermöglicht (Davidson, 2012). Es ist bekannt, dass Kräfte erzeugt durch das apikale Aktomyosin-Netzwerk wichtig sind für die erfolgreiche Faltung von Epithelien (Martin et al., 2009; Roh-Johnson et al., 2012; Sawyer et al., 2010). Die Rolle von mechanischen Kräften, die entlang der lateralen und basalen Seite wirken, ist jedoch kaum verstanden. Wir verbinden Lebendmikroskopie mit der Messung von mechanischen Eigenschaften, um die Entstehung von 2 Epithelfalten in den Imaginalscheiben von Drosophila zu verstehen. Wir können dadurch zeigen, dass die beiden Falten durch unterschiedliche Mechanismen entstehen. Sie entstehen entweder durch eine Verringerung der Spannung auf der basalen Seite oder durch eine Erhöhung der Spannung auf der lateralen Seite, aber keine von beiden entsteht durch zusammenziehende Kräfte auf der apikalen Seite. Die erste Falte entsteht durch eine lokale Verringerung der extrazellulären Matrix in den Vorläuferzellen, was zu einer Reduktion der Spannung auf der basalen Seite und zur Ausbildung der Falte führt. Die zweite Falte wird durch einen anderen Mechanismus ausgebildet. Hier ist nicht die Spannung auf der basalen Seite reduziert sondern dynamische Anreicherungen von F-Aktin auf der lateralen Seite resultieren in einer erhöhten lateralen Spannung, die zu einer Verkürzung der Zellen und damit zur Ausbildung einer Falte führt. In meiner Arbeit zeige ich 2 neue Mechanismen zur Entstehung von Epithelfalten auf, durch Absenken der Spannung auf der basalen oder Erhöhen auf der lateralen Seite.

Le cancer du sein est une pathologie hétérogène au plan clinique et au moins 5 sous-types moléculaires ont pu être définis sur la base de différences d’expression ARNm. Ces sous-types présentent des différences de profils d’anomalies génomiques et de méthylation des cytosines. Ces différences génétiques et épigénétiques s’expliqueraient par des types cellulaires d’origines distincts au sein de l’épithélium mammaire, toutefois, ceci n’a pas été confirmé clairement à ce jour. Alternativement, il a été proposé que l’activation de voies oncogéniques différentes pouvait avoir un impact significatif sur les modifications génétiques ou épigénétiques. Dans ce travail nous avons voulu vérifier cette hypothèse en l’appliquant à un modèle de cellules épithéliales mammaires normales primaires humaines, que nous avons isolé des à partir de glandes mammaires. Ces cellules ont été transformées en deux étapes par transduction avec (i) un shARN ciblant TP53, (ii) un oncogène. Nous avons sélectionné 3 oncogènes qui activent des voies de signalisations distinctes CCNE1, HRAS-v12 et WNT1. Nous avons établi un modèle de transformation tumorale en trois étapes, cellules normales, immortalisées et transformées, permettant de suivre les modifications moléculaires associées à chaque étape et de vérifier si l’activation de voies oncogéniques distinctes produisait des profils d’anomalies différents. Les différents modèles ont été analysés par CGH-array, RRBS, transcriptome et miRNA à des temps de culture définis.Nos résultats montrent que l’activation de la voie RAS aboutit à des profils d’anomalies génétiques et de méthylation des CpG radicalement différents de ceux obtenus après surexpression des gènes CCNE1 et WNT1. Ces différences apparaissent très rapidement après transduction des oncogènes alors que les profils des cellules CCNE1 et WNT1 divergent plus tardivement. Enfin, l’inactivation de p53 n’induit pas par elle-même une instabilité élevée, mais produit un contexte de plasticité favorable aux modifications génétiques et épigénétique.Par ailleurs, nous avons noté des différences phénotypiques entre les HMEC RAS (mésenchymateuses) et les HMEC CCNE1 et les HMEC WNT1 (épithéliales). Dans ce travail, je montre que les HMEC shp53 immortalisées présentent une plasticité phénotypique, une partie des cellules entrant en EMT spontanément, l’autre restant épithéliales. J’ai montré que la transduction RAS sélectionnait les cellules ayant effectué une EMT, alors que la transduction de CCNE1 ou WNT1 sélectionnait les cellules épithéliales. J’ai cherché à identifier les déterminants de ces changements phénotypiques et mes résultats suggèrent qu’ils résultent d’une balance entre une signalisation TGFB1/BMP1, qui favorise l’EMT, et BMP4/WNT7 qui favorise la MET. / Breast cancer is a heterogeneous pathology. Based on the differences of mRNA expression, at least five molecular subtypes have been defined. These subtypes show differences in profiles of genomic abnormalities and CpG methylation. These molecular subtypes are thought to originate from different cell lineages in the mammary gland. However, this has not yet been clearly demonstrated. Alternatively, it has been proposed that the activation of different oncogenic pathways could have a significant impact on genetic or epigenetic changes.We wanted to verify this hypothesis by applying it to a normal primary human mammary epithelial cells (HMEC) model, which we isolated from normal mammary explants. These cells were transformed in two step process by sequential transduction of (i) a shRNA targeting TP53, (ii) an oncogene. We selected 3 oncogenes that activate distinct signaling pathways CCNE1, HRAS-v12 and WNT1. Our tumor transformation model was established in three-step, normal, immortalized and transformed cells, allowing us to monitor the molecular changes associated with each step and to verify whether the activation of distinct oncogenic pathways produced different profiles of genetic and epigenetic modifications. The different models were analyzed at defined culture times by CGH-array, RRBS, transcriptome and miRNA. Our results show that genetic abnormalities and CpG methylation profiles are different between cells where the RAS pathway was activated and cells overexpressing WNT1 or CCNE1. These differences appear rapidly after oncogene transduction, whereas the profiles of the CCNE1 and WNT1 cells diverged later. Finally, inactivation of p53 by itself does not induce high instability, but produces a context of plasticity favorable to genetic and epigenetic changes.In addition, we noted phenotypic differences between HMEC RAS (mesenchymal) and HMEC CCNE1 and HMEC WNT1 (epithelial). In this work, I show that the immortalized HMEC shp53 exhibit a phenotypic plasticity, where some cells enter a spontaneous EMT and the others remain epithelial. I showed that RAS transduction selected cells that are undergoing an EMT, whereas transduction with CCNE1 or WNT1 selected the epithelial cells. I have sought to identify the determinants of these phenotypic changes and my results suggest that a balance exists between TGFβ1 / BMP1 signaling, which promotes EMT, and BMP4 / WNT7a which promotes TEM.

A naphthoquinone, 7-methyljuglone and some of its 5-hydroxy, 5-acetoxy-, 5-alkoxy- and 1,2,4,5-tetra-O-acetate derivatives were tested for their activity in four human cancer cell lines: breast adenocarcinoma, cervical epithelial carcinoma, oesophageal carcinoma and prostate epithelial carcinoma. Compound 2,5-dihydroxy-7-methyl-1,4-naphthoquinone was found to be the most effective one (exhibited a fifty percent inhibitory concentration (IC50) in the range of 5.3 to 14.7 μM), while the parent compound 7-methyljuglone was less active than several of these derivatives. The IC50 values of 5-hydroxy-6-methyl-1,4-naphthoquinone were found to be between 19.1 and 15.4 μM on the four cell lines. However this compound showed toxicity on peripheral blood mononuclear cells. Six derivatives were selected for mechanistic studies. Considering the findings from cell cycle analysis, caspase 3/7 activation and annexinV-FITC dual labelling, 5-hydroxy-6-methyl-1,4-naphthoquinone was found to have antitumour effect by inducing apoptosis. Two derivatives namely, ‘8-fluoro-5-hydroxy-7- methyl-1,4-naphthoquinone’ and ‘2,5-dihydroxy-7-methyl-1,4-naphthoquinone’ were found to be not toxic on peripheral blood mononuclear cells suggesting their action is specific for tumour cells. Compound 2,5-dihydroxy-7-methyl-1,4-naphthoquinone was found to induce apoptosis through caspase 3/7 activation. In view of the enhanced potencies associated with these derivatives, these analogues may hold considerable therapeutic potential for the treatment of leukaemia cancers. The ethanol extracts of seven plant species (ethnobotanically selected) were also tested for their cytotoxicity, assayed by the XTT assay, against four human cancer cell lines at concentrations ranging from 0.78 to 100 μg/ml. Of all the ethanol extracts, Foeniculum vulgare was found to have the best activity on HeLa cells, which exhibited an IC50 value of 19.97± 0.048 μg/ml. Therefore, it was selected for isolation of the bioactive principles. The extract of Foeniculum vulgare was fractionated using column chromatography with hexane and ethyl acetate at different ratios as eluent. Two known compounds, ‘4-methoxycinnamyl alcohol’ and ‘syringin’ were isolated. The IC50 values of ‘4-methoxycinnamyl alcohol’ and ‘syringin’ were found to be 7.82 ± 0.28 μg/ml and 10.26 ± 0.18 μg/ml respectively on HeLa cells. Both compounds were tested for their cytotoxicity against U937 cells and also on peripheral blood mononuclear cells. At the concentrations of 10 and 100 μg/ml ‘4- methoxycinnamyl alcohol’ showed similar cell proliferation as that of the positive control ‘cisplatin’. ‘Syringin’ however, had much lower cytotoxicity on the U937 cells than ‘4- methoxycinnamyl alcohol’. IC50 was found to be 91.14 ± 0.63 μg/ml. Both ‘syringin’ and ‘4- methoxycinnamyl alcohol’ were not cytotoxic at concentrations of 1 and 10 μg/ml on the PBMCs as compared to cisplatin. ‘4-Methoxycinnamyl alcohol’ was selected based on its activity on the cancer cells, for further investigation with regard to its mechanism of action. On gel electrophoresis it did not show a typical ladder pattern, instead a characteristic smear resulted which indicated necrosis. Two best derivatives of 7-methyljuglone (‘8-fluoro-5-hydroxy-7-methyl-1,4-naphthoquinone’ and ‘2,5-dihydroxy-7-methyl-1,4-naphthoquinone’) and the ethanol extract of F. vulgare warrant further investigation to be considered for their potential as anticancer agents. / Dissertation (MSc)--University of Pretoria, 2011. / Plant Science / unrestricted

No / Thymic epithelial cells (TECs) are the main component of the thymic stroma, which supports T-cell proliferation and repertoire selection. Here, we demonstrate that Cbx4, a Polycomb protein that is highly expressed in the thymic epithelium, has an essential and non-redundant role in thymic organogenesis. Targeted disruption of Cbx4 causes severe hypoplasia of the fetal thymus as a result of reduced thymocyte proliferation. Cell-specific deletion of Cbx4 shows that the compromised thymopoiesis is rooted in a defective epithelial compartment. Cbx4-deficient TECs exhibit impaired proliferative capacity, and the limited thymic epithelial architecture quickly deteriorates in postnatal mutant mice, leading to an almost complete blockade of T-cell development shortly after birth and markedly reduced peripheral T-cell populations in adult mice. Furthermore, we show that Cbx4 physically interacts and functionally correlates with p63, which is a transcriptional regulator that is proposed to be important for the maintenance of the stemness of epithelial progenitors. Together, these data establish Cbx4 as a crucial regulator for the generation and maintenance of the thymic epithelium and, hence, for thymocyte development.

[Truncated abstract] Atopic asthma pathogenesis is driven by the combined effects of airway inflammation generated during responses to viral infections and aeroallergens, and both of these pathways are regulated by dendritic cells (DC) that differentiate locally from monocytic precursors. These DC normally exhibit a sentinel phenotype characterised by active antigen sampling but attenuated presentation capability, which limits the intensity of local expression of adaptive immunity. How this tight control of airway DC functions is normally maintained and why it breaks down in some atopics leading to immunopathological changes in airway tissues, is unknown. In the airway mucosa, DC are intimately associated with airway epithelial cells (AEC), which are a source of a range of both pro- and anti-inflammatory mediators. A few studies have previously examined the effects of AEC-derived surface-expressed and soluble mediators upon the function of pre-differentiated DC, although there is a dearth of information as to the extent of AEC-conditioning of DC during their generation from incoming monocytic precursors within the airways. Therefore, this study was designed to test the hypothesis that signals from adjacent AEC contribute to regulation of local differentiation of airway mucosal DC, especially in the context of allergic airway disease. A direct co-culture model was developed containing the AEC line 16HBE 14o- as a surrogate for primary AEC, and purified peripheral blood monocytes derived from atopic patients in a GM-CSF/IL-4-enriched cytokine milieu. Cells were cultured for 5 days, at which time the phenotype and functional attributes of the monocyte-derived DC (MDDC) generated in the presence of AEC (AEC-MDDC) were compared to the control MDDC population generated without AEC contact (Ctrl- MDDC). ... In parallel, an attenuation of mRNA boosting for 7 out of 12 selected Th2-asscociated genes as well as IL-13 protein, was observed in AEC-MDDC supplemented cultures compared to ctrl-MDDC supplemented cultures. The data collected in the initial characterisation of the AEC-MDDC in Chapter 3 and further analysis of their gene expression profiles by microarray suggest a number of DC-associated factors could be involved in directing a potential bias against Th2 immunity within the T-cell recall response. These include increased expression of IL- 12 subunit mRNA and the enhanced levels of surface MHC Class II, CD80, ICAM-1 and SLAM. Further to Th1/Th2 modulation, a number of T-regulatory (Treg) genes were differentially expressed in the AEC-MDDC-re-activated CD4+ T-cells, and members of the chemokine and metallothionein families were elevated in the same population. Collectively the results of this study suggest that in the context of the atopic airway microenvironment where there is an abundance of Th2-related mediators, healthy AEC arm locally maturing DC with an arsenal of anti-microbial defences that can be rapidly employed in response to encounter with inhaled pathogens, in particular viruses. In this way, the DC are maintained in an ideal functional phenotype to efficiently mobilise both innate and Th1-polarised adaptive immune defences against infection, whilst achieving tight control of potentially-damaging Th2 immunity to aeroallergens, thus contributing to the maintenance of immunological homeostasis within the respiratory tract.

The thesis describes the effects of various plant flavonoids (curcumin, epigallocatechin-3-gallate [EGCG], luteolin, apigenin, myricetin, quercetin, and cyanidin) on the physiological properties and viability of cultured human retinal pigment epithelial (RPE) cells. It is described that, with the exception of EGCG, all flavonoids tested decrease dose-dependently the RPE cell proliferation, migration, and secretion of VEGF. Luteolin, apigenin, myricetin, and quercetin decreased the viability of RPE cells at higher concentrations, by triggering cellular necrosis. Curcumin decreased the viability of RPE cells via induction of early necrosis and delayed apoptosis. The cytotoxic effect of curcumin involved activation of caspase-3 and calpain, intracellular calcium signaling, mitochondrial permeability, oxidative stress, and increased phosphorylation of p38 MAPK and decreased phosphorylation of Akt protein. Myricetin caused caspase-3 independent RPE cell necrosis mediated by free radical generation and activation of calpain and phospholipase A2. The myricetin- and quercetin-induced RPE cell necrosis was partially inhibited by necrostatin-1, a blocker of programmed necrosis. The author concludes that the intake of curcumin, luteolin, apigenin, myricetin, and quercetin as supplemental cancer therapy or in the treatment of retinal diseases should be accompanied by careful monitoring of the retinal function. Possible beneficial effects of EGCG and cyanidin in the treatment of retinal diseases should be examined in further investigations.

The mineralocorticoid hormone, aldosterone, classically acts via the Mineralocorticoid Receptor (MR) to promote sodium transport in aldosterone target tissues, such as the kidney, thereby controlling long-term electrolyte homeostasis and blood pressure (BP). Aldosterone biosynthesis by the adrenal gland is regulated by a negative feedback loop called the Renin Angiotensin Aldosterone System (RAAS). The glucocorticoid cortisol (corticosterone in rodents), which has a very similar structure to aldosterone, shares with aldosterone an equal affinity for the MR. Typically, plasma cortisol levels are approximately 1000-fold higher than plasma aldosterone, and so the ligand specificity for aldosterone must be imposed on MR by other, non-structural, means. This specificity is important in order to retain electrolyte and BP balance within the control of the RAAS. The co-localisation of the enzyme 11β-Hydroxysteroid Dehydrogenase Type 2 (11β-HSD2) with the MR in aldosterone target tissues provides the MR with the aldosterone specificity it inherently lacks. 11β-HSD2 achieves this by converting active cortisol to its inactive 11-keto metabolite, cortisone (dehydrocorticosterone in rodents). In humans with the monogenetic Syndrome of Apparent Mineralocorticoid Excess (SAME), inactivating mutations in the HSD11B2 gene allows cortisol unregulated access to the MR. Resultant symptoms include severe hypertension and life-threatening hypokalemia. Individuals heterozygous for SAME display no overt phenotypes. However, some studies have associated SAME heterozygosity and loss-of-function polymorphisms within the HSD11B2 gene with essential and/or salt-sensitive hypertension in the general population. Targeted disruption of the Hsd11b2 gene in mice (Hsd11b2-/-) faithfully reproduces with all the major phenotypes of SAME patients. Mice heterozygote for the targeted gene (Hsd11b2+/-) have no phenotype and display a normal BP. In the present study, Hsd11b2+/- mice were used to explore the relationship between reduced 11β-HSD2 enzyme activity and salt-sensitive hypertension. On a high salt diet, Hsd11b2+/- mice were found to have increased BP and impaired natriuresis, compared to wild-type controls (Hsd11b2+/+). Further studies used pharmacological blockade of the Epithelial Sodium Channel (ENaC) and MR to ascertain the contributions of these pathways towards the observed phenotypes. These identified a deregulation of ENaC activity pertaining to an inability to regulate sodium appropriately. Investigations into the contributions of the RAAS and the Hypothalamus Pituitary Adrenal (HPA) axis have revealed valuable insights into their roles in this model. There is an implication that the RAAS has increased sensitivity in Hsd11b2+/-, further exacerbated by increased dietary sodium, and that the regulation of corticosteroids may also be altered. Novel observations have suggested that oxidative stress in response to a high salt diet could also be involved, as a study administering an antioxidant drug in conjunction with a high salt diet prevented the manifestation of a phenotype in Hsd11b2+/-. Finally, the generation of a floxed Hsd11b2 targeting construct for tissue-specific deletion of 11β-HSD2 will allow future studies into the contributions of specific 11β-HSD2 expression sites (such as the kidney) towards the phenotypes of both homozygous and heterozygous mice.

Epithelial-mesenchymal transition (EMT) is an evolutionarily conserved process during which cells lose epithelial characteristics and gain a migratory phenotype. Although downregulation of epithelial cadherins by Snail and other transcriptional repressors is generally considered a prerequisite for EMT, recent studies have challenged this view. Here we investigate the relationship between E-cadherin and P-cadherin expression and localization, Snail function and EMT during gastrulation in chicken embryos. Expression analyses show that while E-cadherin transcripts are detected in the epiblast but not in the primitive streak or mesoderm, P-cadherin mRNA and protein are present in the epiblast, primitive and mesoderm. Antibodies that specifically recognize E-cadherin are not presently available. During EMT, P-cadherin relocalizes from the lateral surfaces of epithelial epiblast cells to a circumferential distribution in emerging mesodermal cells. Cells electroporated with an E-cadherin expression construct undergo EMT and migrate into the mesoderm. An examination of Snail function showed that reduction of Slug (SNAI2) protein levels using a morpholino fails to inhibit EMT, and expression of human or chicken Snail in epiblast cells fails to induce EMT. In contrast, cells expressing the Rho inhibitor peptide C3 rapidly exit the epiblast without activating Slug or the mesoderm marker N-cadherin. Together, these experiments show that epiblast cells undergo EMT while retaining P-cadherin, and raise questions about the mechanisms of EMT regulation during avian gastrulation.

Human adenoviruses (HAdVs) are common viruses often associated withgastrointestinal, ocular and respiratory infections. They can infect a widevariety of cells, both dividing and non-dividing. HAdVs attach to and infecttarget cells through interactions with cellular receptors. It has also beenshown that HAdVs can use soluble host components in body fluids forindirect binding to target cells, a feature that enables the usage of new typesof receptors resulting in a more efficient HAdV infection. We thereforeevaluated the influence of soluble components from four different bodyfluids on HAdV infection of epithelial cells, representing the respiratory andocular tropism of most HAdVs. We found that plasma, saliva, and tear fluidpromote binding and infection of HAdV-5 (species C) and that plasmapromotes infection of HAdV-31 (species A). Further binding and infectionexperiments identified coagulation factor IX (FIX) and X (FX) as thecomponents of plasma responsible for increase of HAdV-5 infection whileFIX alone mediates increase of HAdV-31 infection. We found that as little as1% of the physiological concentration of these factors is required to facilitatemaximum binding. The effect of coagulation factors on HAdV infection was thereafterextended to include all species A HAdVs: HAdV-12, -18 and -31. Species AHAdVs normally cause infections involving the airways and/or the intestine.These infections are often mild but species A HAdVs in general, and HAdV-31 in particular, have been shown to cause severe and life-threateninginfections in immunocompromised patients. We show here that FIXefficiently increase HAdV-18 and -31 (but not HAdV-12) binding andinfection of human epithelial cells, representing the respiratory andgastrointestinal tropism. FIX was shown to interact with the hexon proteinof HAdV-31 and surface plasmon resonance analysis revealed that theHAdV-31:FIX interaction is slightly stronger than that of the HAdV-5:FIX/FX interactions, but more interestingly, the half-lives of theseinteractions are profoundly different. By performing binding and infectionexperiments using cells expressing specific glycosaminoglycans (GAGs) and ivGAG-cleaving enzymes we found that the HAdV-31:FIX and HAdV-5:FIX/FX complexes bind to heparan sulfate-containing GAGs on targetcells, but we could also see a difference in GAG dependence and specificitybetween these complexes.We conclude that the use of coagulation factors might be of moreimportance than previously recognized and that this may affect not only theliver tropism seen when administering adenovirus vectors into thecirculation but also regulate primary infections by wild-type viruses of theirnatural target cells. We also believe that our findings may contribute tobetter design of HAdV-based vectors for gene and cancer therapy and thatthe interaction between the HAdV-31 hexon and FIX may serve as a targetfor antiviral treatment. HAdV vectors are mainly based on HAdV-5 and several problems haverecently become evident when using these vectors. Major challenges withHAdV-5 based vectors include pre-existing neutralizing antibodies, pooraccess to the receptor CAR (coxsackie and adenovirus receptor), and offtarget effects to the liver due to interactions with coagulation factors. Theneed for new HAdV vectors devoid of these problems is evident.HAdV-52 is one of only three HAdVs that are equipped with two differentfiber proteins, one long and one short. We show here, by means of bindingand infection experiments, that HAdV-52 can use CAR as a cellular receptor,but that most of the binding is dependent on sialic acid-containingglycoproteins. Flow cytometry, ELISA and surface plasmon resonanceanalyses revealed that the terminal knob domain of the long fiber (52LFK)binds to CAR, and the knob domain of the short fiber (52SFK) binds tosialylated glycoproteins. X-ray crystallographic analysis of 52SFK in complexwith sialic acid revealed a new sialic acid binding site compared to otherknown adenovirus:glycan interactions. Moreover, glycan array analysisidentified α2,8-linked oligosialic acid, mimicking the naturally occurringpolysialic acid (PSia), as a potential sialic acid-containing glycan receptor for52SFK. ELISA and surface plasmon resonance confirmed the ability of52SFK to interact with PSia. Flow cytometry analysis also showed a fivefold vincrease in binding of 52SFK to PSia-expressing cells compared to controlcells. X-ray crystallographic analysis of 52SFK in complex with oligo-PSiarevealed engagement at the non-reducing end of oligo-PSia to the canonicalsialic acid-binding site, but also suggested the presence of a 'steering rim'consisting of positively charged amino acids contributing to the contact bylong-range electrostatic interactions. PSia is nearly absent on cells in healthy adults but can be expressed inhigh amounts on several types of cancers including: glioma, neuroblastomaand lung cancer. We show here that the short fiber of HAdV-52 bindsspecifically to PSia. Taking into account that HAdV-52 has a supposedly lowseroprevalence and is incapable of interacting with coagulation factors webelieve that HAdV-52 based vectors can be useful for treatment of cancertypes with elevated PSia expression.