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

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 7 uppsatser.

The equity crowdfunding market has since the financial crisis in 2008 become an important source of alternative financing in Sweden. The equity crowdfunding platforms constitute the market and are responsible for governing the investment relationships. However, the market is not regulated, and in the spring of 2018 the Swedish government proposed regulatory changes for the platforms to impact the problem of information asymmetry. There are different approaches on how to impact the problem, and therefore the thesis sets out to understand how the equity crowdfunding platforms within the Swedish market work to impact information asymmetry.  Empirical data has been collected from five different Swedish equity crowdfunding platforms. Semi-structured interviews were conducted with individuals whose work is connected to governing and impacting information asymmetry. The analysis of the empirical findings identifies five main reasons for the arise of information asymmetry and the platforms work to control and reduce information asymmetry by mitigation strategies, investor communication and effective signaling. The findings indicate that there is a trade-off between controlling information asymmetry and making the financing method accessible within the market. This study contributes to the understanding of how equity crowdfunding platforms work to impact information asymmetry within the Swedish market.

The transition to flowering is an important decision for plants since seed-setting and the survival of the progeny depend on the environmental conditions prevalent during this transition. Therefore, to ensure maximum reproductive success, plants have evolved several regulatory mechanisms to enable them flower at the most appropriate time. Environmental parameters such as light, temperature and nutrient availability as well as endogenous factors such as age and hormonal status of the plant profoundly affect floral transition (Boss et al., 2004; Srikanth and Schmid, 2011). Studies in Arabidopsis and other model plant species have identified several distinct genetic pathways that integrate the information from the endogenous and environmental cues to regulate flowering (Boss et al., 2004; Srikanth and Schmid, 2011). Many components and gene regulatory networks identified in Arabidopsis are conserved in other commercially important species including rice, maize, sorghum, potato and tomato. Therefore, it is important to understand the basic mechanisms that modulate the flowering response in model plants such as Arabidopsis thaliana, the knowledge from which can be used to develop better adapted and high-yielding varieties of crop plants in the wake of challenges like global warming and increasing food demand. In the present study, we have studied the function of VLB1 and VLB2, genes that code for plant-specific Zn-finger transcription factors. Previous studies from our laboratory (Pratibha Choudhary, Ph.D thesis, 2011) and by other research groups have reported that VLBs redundantly promote flowering in A. thaliana (Yasui et al., 2012; Celesnik et al., 2013). However, the underlying mechanism of this regulation is not well understood. Our data suggests that VLBs redundantly promote the transition to flowering specifically in the photoperiod pathway, the major floral induction pathway in A. thaliana. CO, which is the 93 key regulatory gene in this pathway, is regulated by various factors at the transcriptional as well as post-transcriptional level (Suarez-Lopez et al., 2001; Yanovsky and Kay, 2002; Srikanth and Schmid, 2011). Using genetics, we show that VLBs and CO function together to promote flowering in the photoperiod pathway. Further, our BiFC results reveal that VLBs and CO interact physically. Nevertheless, the physical interaction between VLBs and CO needs to be further validated by in vitro and in vivo by co-immunoprecipitation experiments. We hypothesize that the interaction between VLBs and CO is important to regulate FT expression and hence, flowering. However, whether VLBs interact with CO and promote the CO-stability, or facilitates its recruitment to the FT promoter region, still needs to be determined. Apart from its role in flowering, VLBs have been recently shown to regulate biotic and abiotic responses in Arabidopsis (Nakai et al., 2013a; Nakai et al., 2013b). Also, even though it has been demonstrated that VLBs code for transcription factors, no direct targets of VLBs have been reported till date. We performed a whole genome trancriptome-profiling and found that several important classes of genes including WRKY, RLPs, NBS-LRR and JAZs were affected suggesting that, in addition to their role in floral transition, VLBs have important functions in other plant processes as well. In fact, vlb1vlb2 mutant showed an early senescence phenotype and many senescence-associated genes (SAGs) were up-regulated in our microarray experiments, which was further validated by qRT-PCR analysis. By comparing the differentially-regulated genes and PatMatch analysis, we have identified 82 putative direct targets of VLBs in the Arabidopsis genome which need to be validated by chromatin immunoprecipitation (ChIP) assay and functional studies. 94 Results of global transcriptome analysis revealed that the expression of several JA-signaling and response genes was significantly down-regulated. JA is an important phytohormone involved in plant defense and other developmental processes such as stamen development, root growth and senescence (Wasternack, 2007). Results from the JA-induced expression analysis and root inhibition assay confirmed that JA-signaling and response are indeed compromised in the vlb1vlb2 double mutant. Moreover, in vitro DNA-binding assay showed that MYC2, the key transcriptional regulator of JA-responsive gene expression, is a direct transcriptional target of VLB2. A recent study reported that loss-of-function of VLB genes impairs plant defense while their overexpression confers biotic stress tolerance in Arabidopsis (Nakai et al., 2013a; Nakai et al., 2013b). Compromised JA signaling in the vlb1vlb2 double mutant might partly explain this reduced tolerance to pathogens. However, whether VLBs are associated with the MYC2 promoter in planta needs to be tested by performing ChIP and other in vivo assays. In conclusion, our study shows that VLBs have important regulatory roles in diverse processes including control of flowering time, senescence and JA signaling in Arabidopsis. The validation and functional characterization of the direct targets of VLBs will shed more light on the role of VLBs. Since VLBs are conserved in vascular plants, it will be interesting to see if the function of VLBs is also conserved across species and what might be its ancestral function in evolution.

Mycobacterium are important human pathogens and their strength lies in establishing acute infections, latent infections as well as co-existing with other dreadful infectious agents like HIV. The success of mycobacterium infection often relies in its ability to evade immune-surveillance mechanisms mediated by sentinels of host immunity by modulating host signal transduction pathways and expression of immune regulatory molecules. In this scenario, the role of pattern recognition receptors (PRRs) in orchestrating host immune responses assumes central importance. Of the PRRs, the Toll-like receptors (TLRs) or intracellular surveillance receptors such as retinoic acid-inducible gene 1 (RIG-I)-like receptors (RLRs) govern key immune-surveillance mechanisms in recognition as well as control of mycobacterial or viral infections. The first part of this study illustrates the role of SHH signaling in macrophage induced neutrophil recruitment during mycobacterial infections. The present investigation demonstrates that, in response to mycobacterium infection, macrophages displayed robust activation of TLR2 dependent SHH signaling. By utilizing the well-documented experimental air pouch model, we show that the ability of pathogenic mycobacterium infected macrophages to recruit polymorph nuclear leukocytes (PMNs) like neutrophils to the infected site was dependent on SHH signaling. The activated SHH signaling differentially regulated the expression of proteolytic enzymes, MMP-9 and MMP-12 that would contribute to PMN migration. Interestingly, SHH-responsive krüppel-like family (KLF) of transcription factors, KLF4 and KLF5 were found to modulate these chemokine effectors to regulate neutrophil recruitment. Subsequent chapters describe novel functions of SHH signaling during RIG-I mediated anti-viral immunity and RIG-I mediated modulation of TLR2 anti-inflammatory signature in mycobacteria infected macrophages. In this perspective, we demonstrate that RIG-I ligand robustly induces the activation of SHH signaling via the phosphatidylinositide 3-kinase (PI3K) pathway in macrophages. Furthermore, we show that the sustained inhibition of PKA-GSK-3β-SUFU negative regulatory axis upon RIG-I engagement with 5'3pRNA is critical for the activation of SHH signaling. Gain or loss of function studies implicate the necessity of RIG-I triggered MAVS-TBK1 canonical axis in the inhibition of PKA-GSK-3β-SUFU negative regulatory axis that contributes to SHH signaling activation. The RIG-I activated SHH signaling drives the production of anti-viral type 1 interferons leading to the inhibition Japanese encephalitis virus (JEV) replication. Further, RIG-I-mediated anti-viral type 1 interferon production and subsequent control of viral replication suggested the involvement of two transcriptional factors, IRF3 and YY1 in the response along a SHH axis. Further, mounting evidence clearly depicts a significant cross talk among the molecular events initiated by given TLRs and RLRs like RIG-I. Clearly, these studies present an interesting challenge in delineating the events during polymicrobial infection of host immune cells like macrophages or DCs. Altogether, our results improve our understanding of mycobacteria associated confections’ and may add significantly to the current knowledge of the delicate balance that determines a successful mycobacterial infection.

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Background: RGS9-deficient mice show drug-induced dyskinesia but normal locomotor activity under unchallenged conditions. Results: Genes related to Ca2+ signaling and their functions were regulated in RGS9-deficient mice. Conclusion: Changes in Ca2+ signaling that compensate for RGS9 loss-of-function can explain the normal locomotor activity in RGS9-deficient mice under unchallenged conditions. Significance: Identified signaling components may represent novel targets in antidyskinetic therapy. The long splice variant of the regulator of G-protein signaling 9 (RGS9-2) is enriched in striatal medium spiny neurons and dampens dopamine D2 receptor signaling. Lack of RGS9-2 can promote while its overexpression prevents drug-induced dyskinesia. Other animal models of drug-induced dyskinesia rather pointed towards overactivity of dopamine receptor-mediated signaling. To evaluate changes in signaling pathways mRNA expression levels were determined and compared in wild-type and RGS9- deficient mice. Unexpectedly, expression levels of dopamine receptors were unchanged in RGS9-deficient mice, while several genes related to Ca2+ signaling and long-term depression were differentially expressed when compared to wild type animals. Detailed investigations at the protein level revealed hyperphosphorylation of DARPP32 at Thr34 and of ERK1/2 in striata of RGS9-deficient mice. Whole cell patch clamp recordings showed that spontaneous synaptic events are increased (frequency and size) in RGS9-deficient mice while long-term depression is reduced in acute brain slices. These changes are compatible with a Ca2+-induced potentiation of dopamine receptor signaling which may contribute to the drug-induced dyskinesia in RGS9-deficient mice.:Introduction; Materials and methods; Results; Discussion

Cardiovascular disease is a leading cause of death in the United States. Toll-like receptor (TLR)-mediated pathways have been demonstrated to play a role in myocardial ischemia/reperfusion (I/R) injury. We and others have shown that PI3K/Akt signaling is involved in regulating cellular survival and protecting the myocardium from I/R induced injury. In this dissertation, we provide compelling evidence that miR-125b serves to “fine tune” TLR mediated NF-kB responses by repressing TNF-a and TRAF6 expression. We constructed lentiviral expressing miR-125b, delivered it into the myocardium. The data showed that delivery of lentivirus expressing miR-125b significantly reduces myocardial infarct size and improves cardiac function in I/R hearts. Mechanistic studies demonstrated that miR-125b negatively regulates TLR mediated NF-kB activation pathway by repressing TNF-a and TRAF6 expression in the myocardium. We also observed that transfection of the myocardium with lentivirus expressing miR-214 markedly attenuates I/R induced myocardial infarct size and cardiac dysfunction. We demonstrated that miR-214 activates PI3K/Akt signaling by targeting PTEN expression in the myocardium. We also investigated the role of TLR3 in neonatal heart repair and regeneration following myocardial infarction (MI). Wild type (WT) neonatal mice showed fully cardiac functional recovery and small infarct size, while TLR3 deficient mice exhibited impaired cardiac functional recovery and large infarct area after MI. Poly (I:C), a TLR3 ligand, administration significantly enhances glycolysis, YAP1 activation and the proliferation of WT neonatal cardiomyocytes. 2-deoxyglucose (2-DG), a glycolysis inhibitor treatment abolished cardiac functional recovery and YAP1 activation in neonatal mice after MI. In vitro either inhibition of glycolysis by 2-DG or inhibition of YAP1 activation prevents Poly (I:C) induced YAP1 activation and neonatal cardiomyocyte proliferation. Importantly, YAP1 activation increases miR-152 expression, leading to cardiomyocyte proliferation through suppression P27kip1 and DNMT1 expression. We conclude that microRNAs play an important role in TLR modulation induced protection against myocardial I/R injury by increasing the activation of PI3K/Akt signaling pathway, decreasing TLR/NF-kB mediated inflammatory response, and suppressing activation of apoptotic signaling following myocardial I/R injury. In addition, TLR3 is an essential for neonatal heart repair and regeneration after myocardial infarction. TLR3 modulation could be a novel strategy for heart regeneration and repair.

This dissertation is divided into three chapters, each discussing the study of different regulatory molecules involved in sensory neurogenesis occurring in the trigeminal placode. Chapter one is a spatiotemporal description of Notch pathway genes in chick opV placode by stage-specific expression analysis, showing expression of many Notch pathway genes and effectors in the opV placode. Notch pathway gene expression is primarily confined to the ectoderm with highest expression of these genes at the beginning stages of peak neuronal differentiation. This information preceded studies of the functional roles that Notch signaling has in the opV placode and how it may affect the transcription factor, Pax3. Chapter two is a study of the transcription factor Pax3 and its role in opV placode development and sensory neuron differentiation. Pax3 is known to activate or repress gene transcription, and its activity may be dependent on the splice variant or isoform present. We show through RT-PCR that alternative splice forms of Pax3 are present at stages of chick development corresponding to cellular competence, cellular differentiation and ingression, and cellular aggregation. We have named these splice forms, Pax3V1 and Pax3V2. Using quantitative RT-PCR we show that Pax3V2 is consistently expressed at lower levels compared to Pax3 during cellular competence and differentiation. In order to determine the function of the three splice forms, we misexpressed them in the opV placode and analyzed the effect on neurogenesis. We looked at markers for neuronal differentiation of targeted cells after in ovo electroporation of Pax3, Pax3V1, and Pax3V2, which showed a significant difference between the control and each construct, but not between the groups of constructs. To enhance the process of neurogenesis we exposed the electroporated embryos to DAPT, a Notch signaling inhibitor that enhances sensory neurogenesis. Using this method we found that misexpression of Pax3 and Pax3V1 resulted in cells failing to differentiate, while Pax3V2 misexpression more closely resembles the neuronal differentiation seen in controls. These results show that the Pax3V2 isoform allows for neuronal differentiation of opV placodal cells after misexpression, while the Pax3 isoform and the Pax3V1 isoform block neuronal differentiation. Chapter three is a study of the necessity of Wnt signaling originating from the neural tube to induce Pax3 expression in the opV placode. A double knockout of Wnt1 and Wnt3a was produced to determine the necessity of these genes in opV placode development. Pax3 expression in the opV placode at E8.5 and E9.5 was markedly reduced in the double mutants when compared to wild type mice. This study shows that Wnt1 and Wnt3a genes are necessary for normal Pax3 expression, but that other signals may contribute to its induction.

Editorial on the Research Topic. Purinergic Signaling 2020: The State-of-The-Art Commented by the Members of the Italian Purine Club.