A endometriose, caracterizada por crescimento de tecido endometrial fora da cavidade uterina, é responsável por sintomas álgicos com grande impacto na qualidade de vida da paciente. Várias linhas de medicações têm sido estudadas para essa o tratamento da endometriose, já que a cirurgia não é o tratamento de escolha sempre e, quando realizado, não é um tratamento definitivo. O conhecimento da patogenia da endometriose é fundamental para o estudo de novas classes de medicações. Uma delas, os fatores inibitórios da angiogênese, tem papel fundamental no estabelecimento e crescimento de lesões de endometriose. Neste estudo, buscamos a influência da Bevacizumab, droga anti-fator de crescimento endotelial (anti-VEGF), utilizada em duas dosagens diferentes, em endometriose peritoneal induzida em ratas, modelo animal já bem estabelecido para o estudo de endometriose. As ratas permaneceram sob tratamento durante 4 semanas, após as quais foram sacrificadas, sendo as lesões e o corno uterino remanescente retirados para posterior avaliação. Foi realizada avaliação da área das lesões de cada rata, da presença de tecido endometrial à microscopia, da positividade para o anticorpo antiVEGF na imunohistoquímica e da expressão gênica de PCNA, MMP9, Tp63 e VEGFA. O bevacizumab atuou reduzindo a área das lesões nos grupos que receberam medicação (p=0,002) e reduzindo a expressão gênica para Tp63 nas lesões (p=0,04). Não houve resultado significativo nas outras avaliações / Endometriosis, characterized by growth of endometrial tissue outside the uterine cavity, is responsible for painful symptoms with great impact on the quality of life of women. Several lines of medications have been studied for endometriosis\'s treatment, since surgery is not always the treatment of choice and, when done, it is not a definitive treatment. Knowing the pathogenesis of this disease is fundamental for the study of new classes of medications. One of them, the inhibitory factors of angiogenesis, plays a fundamental role in the establishment and growth of endometriosis lesions. In this study, we sought the influence of Bevacizumab, an anti-endothelial growth factor (anti-VEGF) drug, used in two different dosages, in peritoneal endometriosis induced in rats, an animal model well established for the study of endometriosis. The rats remained under treatment for 4 weeks, after which they were sacrificed, with the remaining lesions and uterine horn being removed for further evaluation. An evaluation of the lesion area of each rat, the presence of endometrial tissue under microscopy, the positivity of the anti-VEGF antibody in immunohistochemistry and the gene expression of PCNA, MMP9, Tp63 and VEGFA were performed. Bevacizumab worked by reducing the area of the lesions in the groups receiving medication (p = 0.002) and reducing the gene expression for Tp63 in the lesions (p = 0.04). There was no significant result in the other evaluations

Our laboratory delineated a role for alternative pre-mRNA splicing (AS) in triple negative breast cancer (TNBC). We found the translational regulator cytosolic polyadenylation element binding protein 2 (CPEB2) which has two isoforms, CPEB2A and CPEB2B, is alternatively spliced during acquisition of anoikis resistance (AnR) and metastasis. The splicing event which determines the CPEB2 isoform is via inclusion/ exclusion of exon four in the mature mRNA transcript. The loss of CPEB2A with a concomitant increase in CPEB2B is required for TNBC cells to metastasize in vivo. We examined RNAseq profiles of TNBC cells which had CPEB2 isoforms specifically downregulated to examine the mechanism by which CPEB2 isoforms mediate opposing effects on cancer-related phenotypes. Downregulation of the CPEB2B isoform inhibited pathways driving the epithelial-to-mesenchymal transition (EMT) and hypoxic response, whereas downregulation of the CPEB2A isoform did not have this effect. Specifically, CPEB2B functioned as a translational activator of TWIST1 and HIF1a. Functional studies showed that specific downregulation of either HIF1α or TWIST1 inhibited the ability of CPEB2B to induce AnR and drive metastasis. The mechanism governing inclusion/ exclusion of exon 4 was determined to be serine/ arginine-rich splicing factor 3 (SRSF3). Binding of SRSF3 to a consensus sequence within CPEB2 exon 4 promoted its inclusion in the mature mRNA, and mutation of this sequence abolished association of SRSF3 with exon 4. SRSF3 expression was upregulated in TNBC cells upon acquisition of AnR correlating with a reduction in the CPEB2A/B ratio. Importantly, downregulation of SRSF3 by siRNA in these cells induced the exclusion of exon 4. Downregulation of SRSF3 also reversed the CPEB2A/B ratio in a wild-type CPEB2 exon 4 minigene construct, but not a mutant CPEB2 minigene with the SRSF3 RNA cis-element ablated. Physiologic studies demonstrated SRSF3 downregulation ablated AnR in TNBC cells, and was “rescued” by ectopic expression of CPEB2B. Importantly, biostatistical analysis of The Cancer Genome Atlas database showed a positive relationship between alterations in SRSF3 expression and lower overall survival in TNBC. Overall, this study demonstrates that SRSF3 modulates CPEB2 AS to induce the expression of the CPEB2B isoform that drives TNBC phenotypes correlating with aggressive human breast cancer.

Tissue engineering strategies represent exciting potential therapies to repair cartilage injuries; however, difficulty regenerating the complex extracellular matrix (ECM) organization of native cartilage remains a significant challenge. Cartilaginous ECM molecules, specifically chondroitin sulfate (CS) glycosaminoglycan, may possess the ability to promote and direct MSC differentiation down a chondrogenic lineage. CS may interact with the stem cell microenvironment through its highly negative charge, generation of osmotic pressure, and sequestration of growth factors; however, the role of CS in directing differentiation down a chondrogenic lineage remains unclear. The overall goal of this dissertation was to develop versatile biomaterial platforms to control CS presentation to mesenchymal stem cells (MSCs) in order to improve understanding of the interactions with CS that promote chondrogenic differentiation. To investigate chondrogenic response to a diverse set of CS materials, progenitor cells were cultured in the presence of CS proteoglycans and CS chains in a variety of 2D and 3D material systems. Surfaces were coated with aggrecan proteoglycan to alter cell morphology, CS-based nano- and microspheres were developed as small particle carriers for growth factor delivery, and desulfated chondroitin hydrogels were synthesized to examine electrostatic interactions with growth factors and the role of sulfation in the chondrogenic differentiation of MSCs. Together these studies provided valuable insight into the unique ability of CS-based materials to control cellular microenvironments via morphological and material cues to promote chondrogenic differentiation in the development of tissue engineering strategies for cartilage regeneration and repair.

Spermatogenesis is a complex process of male germ cell development in which the diploid spermatogonia undergo series of mitotic divisions and differentiation steps culminating into the preleptotene spermatocytes which then enter into the meiotic prophase following a single replication cycle. This phase is characterized by meiotic recombination and is followed by reduction division resulting in haploid round spermatids. These cells then undergo extensive morphological and nuclear changes to form a unique cell, spermatozoa. This entire germ cell differentiation process occurs in a unique environment present inside the seminiferous tubules which is created by the Sertoli cells, the somatic cells in the tubules by forming junctions with each other thus providing unique milieu to the developing germ cells. Within the tubule, the germ cells are also arranged in an orderly manner called stages of spermatogenesis indicating a complex mechanism of germ cell differentiation. This complex differentiation process is a consequence of developmentally and precisely regulated differential gene expression (Eddy, 2002). Unraveling the molecular mechanisms involved in the male germ cell development is an uphill task due to the complexity of the cyto-architecture existing in the tubules and further complicated by unavailability of established germ cell lines and lack of cell culture systems that facilitate the germ cell differentiation in vitro. Comparative gene expression analysis of spermatogenesis in nematodes, flies and rodents revealed highly conserved transcriptomes and have provided some insights into its regulation (Schlecht and Primig, 2003). However, these data fail to represent the genetic and biological complexity of human spermatogenesis. In the present study, an attempt has been made to identify the genes that are differentially expressed in human tetraploid and haploid germ cells and to investigate the mechanism of regulation of the genes expressed in the post-meiotic germ cells. To identify the cell type specific genes, expression profiling of the human tetraploid and haploid germ cells was carried out using cDNA microarray. These cells were purified by centrifugal elutriation (Meistrich et al., 1981; Shetty et al., 1996) from the human testicular tissues obtained from the patients undergoing orchidectomy as treatment for prostate cancer. Purity of the enriched population of the germ cells was ascertained by DNA flow cytometry and by RT-PCR analysis using the known cell-specific markers and ruling out contamination of the somatic cells such as the Sertoli cells and the Leydig cells. Microarray experiments were carried out with the RNA isolated from each cell type and labeling the cDNA with Cy3/Cy5-dUTP and hybridizing to the human 19K array chip (University Health Network, Toronto, Canada) containing 19,200 ESTs. Two independent hybridizations were carried out using the germ cells isolated from two individuals and the microarray data were analyzed using Avadis 3.1 software (Strand Life Sciences, India). Analysis of the microarray data following normalization revealed that 723 transcripts showed higher expression in the meiotic cells whereas 459 transcripts showed higher expression in the post-meiotic germ cells. Microarray data were validated further by RT-PCR analysis of some of the differentially regulated genes. The DAVID analysis (Database for Annotation, Visualization and Integrated Discovery; http://david.abcc.ncifcrf.gov/) of these genes revealed that many genes associated with diverse functions and pathways appeared to be differentially expressed in both cell types. It is known that many biological systems exhibit distinct temporal gene expression profiles during different processes related to cell cycle, stress response and differentiation. Similarly, there are sets of genes, which respond to specific stimuli, appear to be synchronized in their expression. Such ‘synexpressed’ genes have been shown to be regulated by common transcription regulatory processes and have similar upstream transcription factor binding sites (Niehrs and Pollet, 1999). And therefore, having identified genes that appeared to be differentially expressed in the haploid and the tetraploid germ cells, attempt was made to analyze transcription factor binding sites in the promoter of those genes. In silico promoter analysis of several genes showing higher post-meiotic expression was carried out in order to identify the common regulatory motifs. Analysis of the annotated promoters (available from Eukaryotic Promoter Database; http://www.epd.isb-sib.ch/) of about forty genes highly expressed in the post-meiotic germ cells using TFSEARCH program (http://www.cbrc.jp/ research/db/TFSEARCH.html) confirmed that many genes had common transcription factor binding sites. Interestingly, almost all of the analyzed genes harbored SRY (Sex determining Region in Y)/SOX (SRY-box containing) binding motifs. In addition, the promoters of genes such as Protamine 1 and 2, Transition protein 1 and 2, A kinase (PRKA) anchor protein 4 that are known to be expressed post-meiotically, also harbor SRY binding sites suggesting that SRY may be one of the key regulators of the post-meiotic gene expression. SRY is a HMG-box containing member of Sox-family of architectural transcription factors. SRY is encoded by the Y chromosome and was first discovered as the testis-determining factor in mammals (Koopman et al., 1991). SRY HMG-box is eighty amino acids conserved motif that binds to the minor groove of the DNA in a sequence-dependent manner resulting in its bending and thus regulating the gene expression. The RT-PCR analysis of the human haploid and tetraploid germ cells showed very high expression of SRY in the post-meiotic cells further suggesting key role of SRY in the post-meiotic gene regulation. Role of SRY in the post-meiotic gene expression was investigated by determining the effect of SRY on human Protamine 1 (PRM1) promoter, a gene known to be exclusively expressed in the round spermatids and as indicated above, harbors many SRY binding sites in its promoter. SRY cDNA was cloned into the mammalian expression vector, pcDNA3.1 and the PRM1 promoter was cloned into the promoter-less pGL3 Basic vector upstream of the Luciferase reporter gene. Co-transfection of both constructs led to up-regulation of PRM1 promoter activity in both HeLa cells and LNCaP cells in a dose-dependent manner clearly demonstrating the role of SRY in PRM1 gene expression. Sequential deletion of the SRY binding sites in the PRM1 promoter led to the identification of the critical SRY binding motif important for SRY-mediated upregulation of PRM1 gene expression. This was confirmed by demonstrating in vitro binding of SRY to its critical binding site in the PRM1 promoter by gel shift assay using the nuclear extract of the HeLa cells transfected with FLAG-tagged SRY. The human SRY is an atypical transcription factor that binds DNA through its HMG, but unlike the mouse Sry and other Sox proteins, lacks the trans-activation domain and therefore requires other factors for its actions. Recently, the glutamine-rich, zinc-finger containing transactivator, Specificity protein 1 (Sp1) has been identified as one such interacting partner (Wissmuller et al., 2006). RT-PCR analysis showed that human SP1 is highly expressed in the haploid germ cells and could up-regulate PRM1 expression which harbors two SP1 binding sites in its promoter. When co-transfected, SRY and SP1 up-regulated PRM1 promoter in co-operative manner suggesting that SP1 may act in coordination with SRY in regulating PRM1. All these data taken together clearly signifies a critical role of SRY in post-meiotic germ cell gene expression. Recent reports suggest that SRY is also expressed in the adult human brain and prostate. However, its role in these tissues is not clearly understood. The Y chromosome has been shown to be frequently lost in prostate cancer and has also been shown to suppress the tumorigenicity of the PC-3 prostate cancer cells suggesting that the Y chromosome encoded genes may be involved in tumor suppression. SRY can physically interact with the androgen receptor (AR) and thereby interfere in its downstream signaling (Yuan et al., 2001). Since the prostate tumors show initial androgen-dependency, it was interesting to look at the role of SRY in the prostate cancer. To decipher the effect of SRY on the androgen-responsive LNCaP cells, stable clones of LNCaP expressing human SRY were generated. These clones showed significant decrease in growth in response to 5α-dihydrotestosterone (DHT) compared to the vector transfected or the parental LNCaP cells. In the soft agar colony formation assay, the SRY expressing LNCaP formed smaller colonies as compared to the controls in presence of DHT. Preliminary experiments in male athymic nude mice demonstrated that one of the SRY expressing clones showed reduced tumor growth compared to control cells suggesting that SRY may play a role in prostate cancer progression by decreasing the sensitivity to DHT. To summarize, the present study has identified several genes differentially expressed in the human haploid and tetraploid germ cells and further showed that SRY may be one of the key regulators of the post-meiotic gene expression.

The developmental processes of lymphopoiesis generate mature B lymphocytes from hematopoietic stem cells through increasingly restricted intermediates. Networks of transcription factors regulate these cell fate choices and are composed of both ubiquitously expressed and B lineage-specific factors. E-protein transcription factors are encoded by the three genes E2A, E2-2 (SEF2-1), and HEB. The E2A gene is required for B cell development and encodes the alternatively spliced proteins E12 and E47. During B lymphocyte development, the cells have to pass several checkpoints verifying the functionality of their antigen receptors. Early in the development, the expression of a pre-B cell receptor (pre-BCR) with membrane-bound immunoglobulin (Ig) heavy chain protein associated with surrogate light chain (SLC) proteins is a critical checkpoint that monitors for functional Ig heavy chain rearrangement. Signaling from the pre-BCR induces survival and a limited clonal expansion. Here it is shown that pre-BCR signaling rapidly down-regulates the SLCs l5 and VpreB and also the co-receptor CD19. Ca2+ signaling and E2A were shown to be essential for this regulation. E2A mutated in its binding site for the Ca2+ sensor protein calmodulin (CaM), and thus with CaM-resistant DNA binding, makes l5, VpreB and CD19 expression resistant to the inhibition following pre-BCR stimulation. Thus, Ca2+ down-regulates SLC and CD19 gene expression upon pre-BCR stimulation through inhibition of E2A by Ca2+/CaM. A general negative feedback regulation of the pre-BCR proteins as well as many co-receptors and proteins in signal pathways from the receptor was also shown. After the ordered recombination of Ig heavy chain gene segments, also Ig light chain gene segments are recombined together to create antibody diversity. The recombinations are orchestrated by the recombination activating gene (RAG) enzymes, other enzymes that cleave/mutate/assemble DNA of the Ig loci, and the transcription factor Pax5. A key feature of the immune system is the concept that one lymphocyte has only one antigen specificity that can be selected for or against. This requires that only one of the alleles of genes for Ig chains is made functional. The mechanism of this allelic exclusion has however been an enigma. Here pre-BCR signaling was shown to down-regulate several components of the recombination machinery including RAG1 and RAG2 through CaM inhibition of E2A. Furthermore, E2A, Pax5 and the RAGs were shown to be in a complex bound to key sequences on the IgH gene before pre-BCR stimulation and instead bound to CaM after this stimulation. Thus, the recombination complex is directly released through CaM inhibition of E2A. Upon encountering antigens, B cells must adapt to produce a highly specific and potent antibody response. Somatic hypermutation (SH), which introduces point mutations in the variable regions of Ig genes, can increase the affinity for antigen, and antibody effector functions can be altered by class switch recombination (CSR), which changes the expressed constant region exons. Activation-induced cytidine deaminase (AID) is the mutagenic antibody diversification enzyme that is essential for both SH and CSR. The AID enzyme has to be tightly controlled as it is a powerful mutagen. BCR signaling, which signals that good antibody affinity has been reached, was shown to inhibit AID gene expression through CaM inhibition of E2A.  SH increases the antigen binding strength by many orders of magnitude. Each round of SH leads to one or a few mutations, followed by selection for increased affinity. Thus, BCR signaling has to enable selection for successive improvements in antibodies (Ab) over an extremely broad range of affinities. Here the BCR is shown to be subject to general negative feedback regulation of the receptor proteins as well as many co-receptors and proteins in signal pathways from the receptor. Thus, the BCR can down-regulate itself to enable sensitive detection of successive improvements in antigen affinity. Furthermore, the feedback inhibition of the BCR signalosome and most of its protein, and most other gene regulations by BCR stimulation, is through inhibition of E2A by Ca2+/CaM. Differentiation to Ab-secreting plasmablasts and plasma cells is antigen-driven. The interaction of antigen with the membrane-bound Ab of the BCR is critical in determining which clones enter the plasma cell response. Genome-wide analysis showed that differentiation of B cells to Ab-secreting cell is induced by BCR stimulation through very fast regulatory events, and induction of IRF-4 and down-regulation of Pax5, Bcl-6, MITF, Ets-1, Fli-1 and Spi-B gene expressions were identified as immediate early events. Ca2+ signaling through CaM inhibition of E2A was essential for these rapid down-regulations of immediate early genes after BCR stimulation in initiation of plasma cell differentiation.

No description available.

Die progrediente, muskuloskelettale Erkrankung Ostheoarthrose wird aufgrund der immer älter werdenden Weltbevölkerung im Jahre 2020 einer der häufigsten Invaliditätsgründe sein. Koelling et al. beschrieb 2009 eine migrierende, chondrogene Progenitorzelllinie (CPC) im Reparaturgewebe der fortgeschrittenen Gonarthrose des Menschen, die Stammzelleigenschaften besitzt. Sie sind multipotent, klonal und besitzen ein osteochondrogenes Expressionsmuster, wodurch sie sich für neue Behandlungsmöglichkeiten bei der Ostheoarthrosetherapie eignen könnten. In dieser Arbeit wurden in vitro drei Klone einer humanen CPC-Population aus osteoarthrotisch verändertem Knorpel hinsichtlich ihrer multipotenten Eigenschaften, Proliferationsgeschwindigkeit und unterschiedlicher Phänotypen gegenübergestellt, da sich bei anderen Stammzelllinien Zusammenhänge zwischen diesen Eigenschaften zeigen, die mit fortgeschrittener Ausdifferenzierung der Stammzellen begründet wird. Die drei Klone IF-8, IIB-6 und IID-4 wurden 12 Tage unter Standardbedingungen in 2D-Flaschenkultur gehalten und anschließend ihr normaler Phänotyp ausgewertet. Dabei zeigte sich, dass IF-8 und IIB-6 eher einen fibroblastenartigen Phänotyp ausbildeten, während sich bei IID-4 erst kugelige Zellen bildeten, die später teils in eine längliche Form übergingen. Die fibroblastenartige Form entsprach der von CPCs aus heterogenen Kulturen, wohingegen der Phänotyp von IID-4 auf Dedifferenzierung oder fortgeschrittenere Differenzierung schließen ließ. Die Klone für die Differenzierungsversuche wurden mit zwei verschiedenen Zelldichten ausgesät, um auch eventuelle Einflüsse der Zelldichte mit in die Untersuchung einzubeziehen. Es wurde pro Well einmal die Anfangskonzentration von 1000 Zellen gewählt und einmal 3000 Zellen pro Well. Nach sechs Tagen wurden morphologische Veränderungen unter dem Mikroskop ausgewertet. Die Differenzierung in Adipozyten und Osteoblasten erfolgte insgesamt über zehn Tage mit anschließendem Differenzie- rungsnachweis mittels Oil-Red-Färbung von Adipozyten, bzw. der Alkalischen-Phosphatase-Reaktion der Osteoblasten. Es wurde zusätzlich mit der Immunfluoreszenzzytochemie kontrolliert, ob in den differenzierten Zellen auch spezifische Proteine exprimiert wurden und sich zwischen den Klonen ein quantitativer Unterschied ergibt, der auf einen veränderten Differenzierungsgrad der Klone schließen konnte. Für die Adipozyten wurden Antikörper gegen dieLipoproteinlipase und PPARγ gewählt, bei den Osteoblasten kamen Antikörper gegen Osteocalcin und den osteogenen Transkriptionsfaktor runx-2 zum Einsatz. Allen Differenzierungsversuchen wurden jeweils Kontrollgruppen gegenübergestellt. Die Ergebnisse zeigten morphologische Unterschiede zwischen den Klonen und den verschiedenen Zelldichten, die bei der osteogenen Differenzierung nicht so stark ausgeprägt waren wie bei der adipogenen. Der Klon-IID-4 zeigte auch hier die am Stärksten ausgeprägtesten morphologischen Unterschiede zwischen den Zellen selber und der verschiedenen Dichtegrade. Die quantitative Auswertung mittels Oil-Red und Alkalischer-Phosphatase, bzw. die Ergebnisse der Immunzytochemie ergaben hingegen keine Abweichungen zwischen den Klonen und keine Veränderung in Abhängigkeit zur Zelldichte. Dadurch konnte gezeigt werden, dass bei den CPCs ein veränderter Phänotyp kein Hinweis auf eine fortgeschrittene Zellalterung und verminderte Differenzierbarkeit ist. Auch die Zelldichte nimmt auf die Differenzierung in andere Zelllinien keinen positiven oder negativen Einfluss. Deutliche Unterschiede zwischen den Klonen zeigten sich hinsichtlich ihrer Proliferationsgeschwindigkeit und ihres osteochondrogenen Grundmusters. Für das Proliferationsassay wurden über den Zeitraum von sieben Tagen die Zellzahlen gemessen. Dabei wurde festgestellt, dass sich Klon-IF-8 am langsamsten teilte, danach folgte IID-4 und am Ende IIB-6. Im Zusammenhang mit dem Western-Blot, bei dem der osteogene Transkriptionsfaktor runx-2 und der chondrogene Transkrip-tionsfaktor sox-9 miteinander verglichen wurden, konnte eine Beziehung zwischen Proliferationsgeschwindigkeit und der Ausprägung der Transkriptionsfaktoren festgestellt werden. Mit Abnahme der Proliferationsgeschwindigkeit nimmt die Expression von runx-2 zu, während die Expression von sox-9 abnimmt. Dadurch konnte nachgewiesen werden, dass die CPCs mit abnehmender Zellteilung in einen vermehrt osteogenen Zustand übergehen und ihren osteochondrogenen Charakter verlieren. Dieser Übergang hat jedoch keinen Einfluss auf ihre multipotenten Eigenschaften. Mit den Ergebnissen konnte gezeigt werden, dass sich CPCs, ähnlich wie andere Progenitorzellen auch, in ihrer Entwicklung weiter ausdifferenzieren und sich dadurch innerhalb einer Population verschiedene Entwicklungszustände ergeben, die eine genauere Charakterisierung der CPCs weiter erschweren.

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Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.