Indiana University-Purdue University Indianapolis (IUPUI) / Papillomaviruses (PVs) are small, double-stranded DNA viruses. Hundreds of species have evolved to replicate in mammals, birds, and reptiles. Approximately two hundred species are estimated to infect humans alone, and these human papillomaviruses (HPVs) cause diseases ranging from benign warts to anogenital and oropharyngeal cancers. While vaccination is effective at preventing the majority of these infections and their disease outcomes, there are no successful treatments for existing infections; thus, exploration of novel therapeutic targets is warranted. PVs control expression and function of their gene products through alternative splicing, alternate start codons, and post-translational modification (PTM). The viral E2 protein regulates transcription, replication, and genome maintenance in infected cells, and PTMs have been demonstrated for E2 proteins from multiple papillomavirus types. Serine phosphorylation events were reported to influence E2 stability, and our laboratory was the first to describe in vitro acetylation events with implications for E2 transcription function. Here we report confirmation of these acetylation events in vivo and additional data elucidating the role of these PTMs in viral transcription. Moreover, we present a novel phosphorylation site for bovine papillomavirus type 1 (BPV-1) E2 at tyrosine 102 (Y102). Using phospho-deficient and phospho-mimetic point mutants, we found that this site influences E2-mediated transcription and replication, and we hypothesize that phosphorylation at Y102 regulates these activities by interrupting the association of E2 with its binding partners. We also report interaction of BPV-1 E2 and HPV-31 E2 with different receptor tyrosine kinases (TKs), most notably members of the fibroblast growth factor receptor family. We hypothesize that Y102 phosphorylation by these receptors occurs early in infection to limit viral replication and gene expression. Further studies will cement the role of RTKs in PV biology and could reveal novel therapeutic strategies.

Indiana University-Purdue University Indianapolis (IUPUI) / Internal tandem duplications in FMS-like receptor tyrosine kinase (FLT3-ITDs) are seen in approximately 25% of all acute myeloid leukemia (AML) patients. FLT3-ITDs induce FLT3 ligand (FL)-independent cellular hyperproliferation, promiscuous and aberrant activation of STAT5, and confer a poor prognosis in patients; however, the molecular mechanisms contributing to FLT3-ITD-induced malignancy remain largely unknown. The protein tyrosine phosphatase, Shp2, is important for normal hematopoiesis as well as hematopoietic stem cell (HSC) differentiation, engraftment, and self-renewal. Furthermore, FLT3-ITD- or constitutive active STAT5-expressing CD34+ cells demonstrate enhanced hematopoietic stem cell self-renewal. Together with the previous findings that Shp2 is critical for normal hematopoiesis, that dysregulated Shp2 function contributes to myeloid malignancies, and that Shp2 has been shown to interact with WT-FLT3 tyrosine 599, which is commonly duplicated in FLT3-ITDs, a positive role for Shp2 in FLT3-ITD-induced signaling and leukemogenesis is implied. I demonstrated that Shp2 is constitutively associated with the reported FLT3-ITDs, N51-FLT3 and N73-FLT3, compared to WT-FLT3; therefore, I hypothesized that increased Shp2 recruitment to N51-FLT3 or N73-FLT3 contributes to hyperproliferation and hyperactivation of STAT5. I also hypothesized that Shp2 cooperates with STAT5 to activate STAT5 transcriptional targets contributing to the up-regulation of pro-leukemic proteins. Finally, I hypothesized that reduction of Shp2 would result in diminished N51-FLT3-induced hyperproliferation and activation of STAT5 in vitro, and prevent FLT3-ITD-induced malignancy in vivo. I found that genetic disruption of Ptpn11, the gene encoding Shp2, or pharmacologic inhibition of Shp2 with the novel Shp2 inhibitor, II-B08, resulted in significantly reduced FLT3-ITD-induced hematopoietic cell hyperproliferation and STAT5 hyperphosphorylation. I also demonstrated a novel role of Shp2 in the nucleus of FLT3-ITD-expressing hematopoietic cells where Shp2 and STAT5 co-localized at the promoter region of STAT5-transcriptional target and pro-survival protein, Bcl-XL. Furthermore, using a Shp2flox/flox;Mx1Cre+ mouse model, I demonstrated that reduced Shp2 expression in hematopoietic cells resulted in an increased latency to and reduced severity of FLT3-ITD-induced malignancy. Collectively, these findings demonstrate that Shp2 plays an integral role in FLT3-ITD-induced malignancy and suggest that targeting Shp2 may be a future therapeutic option for treating FLT3-ITD-positive AML patients.

No description available.

Chronic Lymphocytic Leukemia is the primary lymphoid neoplasm in adults and and it is especially manifested in the elderly. Because it is a heterogeneous disease it awakens great interest regarding its prognosis. Rai and Binet developed staging systems to predict the evolution of the disease and currently, the analysis of expression of CD38 and Zap-70 has been investigated as a prognostic factor for indicating presence or absence of the mutation in the gene IgVH, so, the objective of this study was to analyze the clinical and laboratory profiles of patients with Chronic Lymphocytic Leukemia taking as reference the clinical staging of Rai and Binet and quantification of CD38 and Zap-70 expression as prognosis factors. We searched the medical records of 64 patients treated at University Hospital of Santa Maria and the variables considered were swollen lymph nodes, presence or absence of hepatomegaly and / or splenomegaly, hematological evaluation of peripheral blood and immunophenotype. The data obtained were correlated with the staging of Rai (1975) and Binet (1981), the expression of CD38 and Zap-70 and clinical stage. The results showed no association between ataging Rai and Binet and the expression of CD38, Zap-70 and Binet clinical staging. / A Leucemia Linfocítica Crônica é a principal neoplasia linfóide em adultos e se manifeta principalmente em indivíduos idosos. Por ser uma doença heterogênea, desperta grande interesse quanto ao seu prognóstico. Rai e Binet desenvolveram sistemas de estadiamento capazes de prever a evolução da doença e atualmente, a análise da expressão de CD38 e Zap- 70 tem sido investigada como fator prognóstico por indicar presença ou ausência da mutação no gene IgVH, assim, o objetivo deste estudo foi analisar o perfil clínico-laboratorial dos pacientes com Leucema Linfocítica Crônica, tomando como referência os estadiamentos clínicos de Rai e Binet e a quantificação da expressão de CD38 e Zap-70 como fatores prognóstico. Foram pesquisados 64 prontuários médicos de pacientes atendidos no Hospital Universitário de Santa Maria e as variáveis consideradas foram aumento de linfonodos, presença ou ausência de hepatomegalia e/ou esplenomegalia, avaliação hematológica de sangue periférico e imunofenótipo. Os dados obtidos foram correlacionados com o estadiamento de Rai (1975) e Binet (1981), a expressão de CD38 e Zap-70 com o estádio clínico de Binet. Os resultados demonstraram que não há associação entre o estadiamento de Raí e Binet e a expressão de CD38, Zap-70 com o estadiamento clínico de Binet.

Indiana University-Purdue University Indianapolis (IUPUI) / Bone is a dynamic organ that responds to its external environment. Cell signaling cascades are initiated within bone cells when changes in mechanical loading occur. To describe these molecular signaling networks that sense a mechanical signal and convert it into a transcriptional response, we proposed the mechanosome model. “GO” and “STOP” mechansomes contain an adhesion-associated protein and a nucleocytoplasmic shuttling transcription factor. “GO” mechanosomes functions to promote the anabolic response of bone to mechanical loading, while “STOP” mechanosomes function to suppress the anabolic response of bone to mechanical loading. While much work has been done to describe the molecular mechanisms that enhance the anabolic response of bone to loading, less is known about the signaling mechanisms that suppress bone’s response to loading. We studied two adhesion-associated proteins, Src and Pyk2, which may function as “STOP” mechanosomes. Src kinase is involved in a number of signaling pathways that respond to changes in external loads on bone. An inhibition of Src causes an increase in the expression of the anabolic bone gene osteocalcin. Additionally, mechanical stimulation of osteoblasts and osteocytes by fluid shear stress further enhanced expression of osteocalcin when Src activity was inhibited. Importantly, fluid shear stress stimulated an increase in nuclear Src activation and activity. The mechanism by which Src participates in attenuating anabolic gene transcription remains unknown. The studies described here suggest Src and Pyk2 increase their association in response to fluid shear stress. Pyk2, a protein-tyrosine kinase, exhibits nucleocytoplasmic shuttling, increased association with methyl-CpG-binding protein 2 (MBD2), and suppression of osteopontin expression in response to fluid shear stress. MBD2, known to be involved in DNA methylation and interpretation of DNA methylation patterns, may aid in fluid shear stress-induced suppression of anabolic bone genes. We conclude that both Src and Pyk2 play a role in regulating bone mass, possibly through a complex with MBD2, and function to limit the anabolic response of bone cells to fluid shear stress through the suppression of anabolic bone gene expression. Taken together, these data support the hypothesis that “STOP” mechanosomes exist and their activity is simulated in response to fluid shear stress.

Indiana University-Purdue University Indianapolis (IUPUI) / Murine double minute (Mdm2) is a highly modified and multi-faceted protein that is overexpressed in numerous human malignancies. It engages in many cellular activities and is essential for development since deletion of mdm2 is lethal in early stages of embryonic development. The most studied function of Mdm2 is as a negative regulator of the tumor suppressor protein p53. Mdm2 achieves this regulation by binding to p53 and inhibiting p53 transcriptional activity. Mdm2 also functions as an E3 ubiquitin ligase that signals p53 for destruction by the proteasome. Interestingly recent evidence has shown that Mdm2 can also function as an E3 neddylating enzyme that can conjugate the ubiquitin-like molecule, nedd8, to p53. This modification results in inhibition of p53 activity, while maintaining p53 protein levels. While the signaling events that regulate Mdm2 E3 ubiquitin ligase activity have been extensively studied, what activates the neddylating activity of Mdm2 has remained elusive. My investigations have centered on understanding whether tyrosine kinase signaling could activate the neddylating activity of Mdm2. I have shown that c-Src, a non-receptor protein tyrosine kinase that is involved in a variety of cellular processes, phosphorylates Mdm2 on tyrosines 281 and 302. This phosphorylation event increases the half-life and neddylating activity of Mdm2 resulting in a neddylation dependent reduction of p53 transcriptional activity. Mdm2 also has many p53-independent cellular functions that are beginning to be linked to its role as an oncogene. There is an emerging role for Mdm2 in tumor metastasis. Metastasis is a process involving tumor cells migrating from a primary site to a distal site and is a major cause of morbidity and mortality in cancer patients. To date, the involvement of Mdm2 in breast cancer metastasis has only been correlative, with no in vivo model to definitively define a role for Mdm2. Here I have shown in vivo that Mdm2 enhances breast to lung metastasis through the up regulation of multiple angiogenic factors, including HIF-1 alpha and VEGF. Taken together my data provide novel insights into important p53-dependent and independent functions of Mdm2 that represent potential new avenues for therapeutic intervention.

Les anomalies du tube neural (ATN) sont des anomalies développementales où le tube neural reste ouvert (1-2/1000 naissances). Afin de prévenir cette maladie, une connaissance accrue des processus moléculaires est nécessaire. L’étiologie des ATN est complexe et implique des facteurs génétiques et environnementaux. La supplémentation en acide folique est reconnue pour diminuer les risques de développer une ATN de 50-70% et cette diminution varie en fonction du début de la supplémentation et de l’origine démographique. Les gènes impliqués dans les ATN sont largement inconnus. Les études génétiques sur les ATN chez l’humain se sont concentrées sur les gènes de la voie métabolique des folates du à leur rôle protecteur dans les ATN et les gènes candidats inférés des souris modèles. Ces derniers ont montré une forte association entre la voie non-canonique Wnt/polarité cellulaire planaire (PCP) et les ATN. Le gène Protein Tyrosine Kinase 7 est un membre de cette voie qui cause l’ATN sévère de la craniorachischisis chez les souris mutantes. Ptk7 interagit génétiquement avec Vangl2 (un autre gène de la voie PCP), où les doubles hétérozygotes montrent une spina bifida. Ces données font de PTK7 comme un excellent candidat pour les ATN chez l’humain. Nous avons re-séquencé la région codante et les jonctions intron-exon de ce gène dans une cohorte de 473 patients atteints de plusieurs types d’ATN. Nous avons identifié 6 mutations rares (fréquence allélique <1%) faux-sens présentes chez 1.1% de notre cohorte, dont 3 sont absentes dans les bases de données publiques. Une variante, p.Gly348Ser, a agi comme un allèle hypermorphique lorsqu'elle est surexprimée dans le modèle de poisson zèbre. Nos résultats impliquent la mutation de PTK7 comme un facteur de risque pour les ATN et supporte l'idée d'un rôle pathogène de la signalisation PCP dans ces malformations. / Neural tube defects (NTDs) are among the most common congenital defects with a high incidence of 1-2 per 1000 births, causing a heavy burden to both the families and society. Various types of NTDs result from defects happening in the neurulation process during vertebrate embryonic development. In order to prevent the occurrence of NTDs, understanding the underlying mechanism is a prerequisite. The etiology of NTDs is complex involving environmental and genetic factors. Folic acid supplementation was proven to efficiently decrease the frequency of NTDs by 50-70% depending on the time point of this supplementation and demographic background. Gene identification studies in NTDs have adopted mainly a candidate gene approach investigating folate-related genes and genes derived from animal models. In particular, studies in mouse models have demonstrated a strong association between the non canonical Wnt/Planar Cell Polarity (PCP) pathway and NTDs. Protein Tyrosine Kinase 7 (PTK7) is a member of the PCP pathway and was shown to cause a very severe form of NTDs called craniorachischisis in a mouse model. Ptk7 genetically interacts with a core PCP member Vangl2 where double heterozygotes suffer from spina bifida. These data make PTK7 a strong candidate for NTDs in humans. We sequenced the coding region and the exon-intron junctions of PTK7 in a cohort of 473 patients affected with various forms of open and closed NTDs. Novel and rare variants (<1%) were genotyped in a cohort of 473 individuals. Their pathogenic effect was predicted in silico and functionally in an overexpression assay in a well established zebrafish model. We identified in our cohort 6 novel rare mutations, 3 of which are absent in all public databases, in 1.1% of our NTD cohort. One variant, p.Gly348Ser, acted as a hypermorph when overexpressed in the zebrafish model. Our findings implicate mutation of PTK7 as a risk factor for NTDs and provide additional evidence for a pathogenic role of PCP signaling in these malformations.

O STI (imatinib, Glivec) é um inibidor da tirosina quinase BCR-ABL, responsável pela patogênese da leucemia mielóide crônica (LMC). Um total de 110 pacientes com LMC na fase crônica (FC) que falharam ou foram intolerantes ao tratamento com interferon, fase acelerada (FA) e crise blástica (CB) foram tratados com imatinibe entre dezembro de 2000 e setembro de 2003. Resposta hematológica completa e resposta citogenética maior foram observadas em 95,9% e 69,4% respectivamente em pacientes em FC e 93,2% e 36,4% em FA. Apenas 2 pacientes na CB estão vivos. O imatinib foi bem tolerado com altas taxas de resposta. / STI571 (Imatinib, Glevec) is an inhibitor of the Bcr-Abl tyrosine kinase that is central to the pathogenesis of chronic myelogenous leukemia (CML). A total of 110 patients with CML chronic phase (CP) who failed or were intolerant to interferon, accelerated phase (AP) and blastic crisis (BC) were treated with imatinib from December 2000 until September 2003. Complete hematologic response and major cytogenetic response were observed in 95,9% and 69,4% respectively of patients in CP and 93,2% and 36,4% in AP. Only 2 patients are alive in BC. Imatinib is well tolerated with high rates of response

O STI (imatinib, Glivec) é um inibidor da tirosina quinase BCR-ABL, responsável pela patogênese da leucemia mielóide crônica (LMC). Um total de 110 pacientes com LMC na fase crônica (FC) que falharam ou foram intolerantes ao tratamento com interferon, fase acelerada (FA) e crise blástica (CB) foram tratados com imatinibe entre dezembro de 2000 e setembro de 2003. Resposta hematológica completa e resposta citogenética maior foram observadas em 95,9% e 69,4% respectivamente em pacientes em FC e 93,2% e 36,4% em FA. Apenas 2 pacientes na CB estão vivos. O imatinib foi bem tolerado com altas taxas de resposta. / STI571 (Imatinib, Glevec) is an inhibitor of the Bcr-Abl tyrosine kinase that is central to the pathogenesis of chronic myelogenous leukemia (CML). A total of 110 patients with CML chronic phase (CP) who failed or were intolerant to interferon, accelerated phase (AP) and blastic crisis (BC) were treated with imatinib from December 2000 until September 2003. Complete hematologic response and major cytogenetic response were observed in 95,9% and 69,4% respectively of patients in CP and 93,2% and 36,4% in AP. Only 2 patients are alive in BC. Imatinib is well tolerated with high rates of response

Tyrphostine stellen eine Klasse synthetischer Protein-Tyrosin-Kinase (PTK)-Hemmer, die sich strukturell vom Tyrosin ableiten und dazu dienen, spezifisch Substratphosphorylierungen zu verhindern. Tyrphostin AG126 zeigte entzündungshemmende Eigenschaften in zahlreichen Tiermodellen von Erkrankungen. Dies schließt den septischen Schock ein, der durch Lipopolysaccharid (LPS) Gram-negativer Bakterien induziert werden kann, sowie die durch Zellwandstrukturen Gram-positiver Bakterien ausgelöste bakterielle Meningitis. Wir zeigen nun positive AG126-Effekte in einer weiteren ZNS-Komplikation, der experimentellen autoimmunen Enzephalomyelitis (EAE) als einem Modell der Multiplen Sklerose, wo AG126-Behandlung die klinischen Symptome und Myelinschäden mildert. Auf zellulärer Ebene beeinflusst AG126 eine Vielzahl von Funktionen der Mikroglia, der ZNS-Makrophagen, die durch Aktivierung von Toll-like-Rezeptoren (TLR s) ausgelöst werden. Diese Rezeptoren der angeborenen Immunität erkennen mikrobielle Strukturen sowie Faktoren, die durch Gewebeverletzungen generiert werden. Mit dem Fokus auf Mikroglia untersuchte die vorliegende Arbeit erstmals molekulare Zielstrukturen und Mechanismen des AG126. AG126 beeinflusst besonders Geninduktionen, die vom Adaptorprotein MyD88, einem der zwei TLR-Signalwege, abhängen. Bruton s Tyrosin-Kinase (BTK), eine MyD88-assoziierte PTK, kann von AG126 in molekularen und zellbasierten Assays gehemmt werden. Diese Hemmung kann allerdings nicht das gesamte Spektrum der AG126-Effekte erklären. Daher müssen alternative, sogar PTK-unabhängige Mechanismen, in Betracht gezogen werden, basierend auf strukturellen und funktionellen Ähnlichkeiten zu Tyrosin-abgeleiteten und/oder mikrogliaaktiven Molekülen. Diese alternativen Mechanismen umfassen Prinzipien, die für Antioxidantien, adrenerge Agonisten, Glukokortikoide oder Entkoppler der oxidativen Phosphorylierung bekannt sind. Tatsächlich zeigen Analysen auf der Grundlage von Kernspinresonanzspektroskopie, dass AG126 in die Hauptprodukte 3-Hydroxy-4-Nitroben zaldehyd (BZ) und Malononitril (MN) zerfallen kann, von denen MN, aber nicht BZ, die AG126-Effekte in Mikroglia imitiert. Ein ähnliches Verhalten zeigen weitere Tyrphostine, die ebenfalls das kritische MN-Strukturmotiv aufweisen. Tierexperimente zeigen schließlich, dass nur AG126 als Ausgangstruktur, nicht aber MN oder BZ, das Gesamtspektrum protektiver Effekte in der EAE vermittelt. Die Identifizierung des eigentlichen von AG126 bzw. von MN beeinflussten Targets könnte somit einen wesentlichen Mechanismus für die Entwicklung von entzündungshemmenden Verbindungen offenlegen.