| 1. |
- Aripaka, Karthik, 1986-
(författare)
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Studies on the biological functions of interaction between components in Wnt, TGF-β and HIF pathways for cancer progression
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cancer is a disease that involves aggressive changes in the genome and aberrant signals between the living cells. Signalling pathways such as TGF-β (Transforming growth factor-β), Wnt, EGF (epidermal growth factor) and HIF (Hypoxia-inducible factor) evolved to regulate growth and development in mammals. These factors are also implicated for tumorigenesis due to failure or aberrant expression of components in these pathways. Cancer progression is a multistep process, and these steps reflect genetic alterations driving the progressive transformation of healthy human cells into highly malignant derivatives. Many types of cancers are diagnosed in the human population, such as head & neck, cervical, brain, liver, colon, prostate, uterine, breast, and renal cell cancer.Prostate cancer is the second most common cancer and one of the foremost leading cancer-related deaths in men in the world. Aberrant Wnt3a signals promote cancer progression through the accumulation of β-Catenin. In the first paper, we have elucidated intriguing functions for Tumour necrosis factor receptor-associated factor 6 (TRAF6) as a coregulatory factor for the expression of Wnt-target genes which was confirmed in vivo by using CRISPR/Cas9 genomic editing, in zebrafish. Our data suggest that Wnt3a promotes TRAF6 interaction with Wnt components, and TRAF6 is required for gene expression of β-Catenin as well as for the Wnt-ligand co-receptor LRP5. From the in vivo studies, we elucidated positive regulation of TRAF6, which is crucial for survival and development of zebrafish. This study identifies TRAF6 as an evolutionary conserved co-regulatory protein in the Wnt pathway that also promotes the progression of prostate and colorectal cancer due to its positive effects on Wnt3a signalling.Hypoxia is a condition due to O2 deprivation, and Hypoxia-inducible factors (HIF) transcription factors are responsible for the maintenance of oxygen homeostasis in living cells. Irregularities in these HIF transcription factors trigger pathological cellular responses for initiation and progression of malignant cancers. Renal cell carcinoma, malignant cancer arising in renal parenchyma and renal pelvis and, hypoxia plays a vital role in its progression. In the second paper, we have investigated the clinicopathological relevance of several hypoxic and TGF-β component proteins such as HIF-1α/2α/3α, TGF-β type 1 receptor (ALK5-FL) and the intracellular domain of ALK5 (ALK5-ICD), SNAI1 and PAI-1 with patient survival in clear cell renal cell carcinoma (ccRCC). We showed that HIF-2α associated with low cancer-specific survival. HIF-2α and SNAI1 positively correlated with ALK5-ICD, pSMAD2/3, PAI-1 and SNAI1 with HIF-2α; HIF-1α positively correlated with pSMAD2/3. Further, under normoxic conditions, our data suggest that ALK5 interacts with HIF-1α and HIF-2α, and promotes their expression and target genes such as GLUT1 and CA9, in a VHL dependent manner through its kinase activity. These findings shed light on the critical aspect of cross-talk between TGF-β signalling and hypoxia pathway, and also the novel finding of an interaction between ALK5 and HIF-α might provide a more in-depth understanding of mechanisms behind tumour progressionIn the third paper, an ongoing study, we investigated the role of HIF-3α in the progression of Renal cell carcinoma and its association with the components of TGF-β and HIF pathways. We have observed increased levels of HIF-3α in ccRCC and pRCC (papillary renal cell carcinoma) which are associated with advanced tumour stage, metastasis and larger tumours. Also, we found HIF-3α show a significant positive association with pro-invasive gene SNAI1, which is a crucial regulator of epithelial to mesenchymal transition. TRAF6 an E3 ligase known to be a prognostic marker in RCC and we observed HIF-3α associates with TRAF6.
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| 2. |
- Mendoza-Garcia, Patricia, 1988-
(författare)
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Harnessing the power of model systems to investigate regulation of Anaplastic Lymphoma Kinase function
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The anaplastic lymphoma kinase (ALK), initially identified as a translocation partner in anaplastic large cell lymphoma (ALCL), has been described in a number of tumors such as neuroblastoma. Neuroblastoma is a neural crest derived malignancy of the sympathetic nervous system. Therefore, understanding regulation of ALK transcription and activity in the context of normal neural crest development might highlight abnormal events contributing to neuroblastoma initiation. The use of vertebrate model systems has been very important for studying in detail the pathways activated during neural crest development, their contribution to neuroblastoma and the identification of therapeutic targets.Using a yeast one-hybrid approach, we identified Odd-paired (Opa) as a potential transcription factor modulating Alk expression in the Drosophila visceral mesoderm (VM) (Paper I). Opa promotes Alk expression in the VM in combination with Bagpipe (Bap) and Biniou (Bin) through binding to the here identified AlkEB9 enhancer region.In a subsequent paper, we identified ALKAL1 and ALKAL2 as the activating ligands for the human ALK (Paper II). Using a combination of in vitro and cell culture assays we show that the ALKAL proteins can bind and activate human ALK. Moreover, ALKAL proteins can “super-activate” mutant ALK, highlighting a putative role for the ALKALs/ALK axis in neuroblastoma.The third paper shows in vivo evidence of ALKAL activity during zebrafish neural crest development (Paper III). We identified and characterized three zebrafish Alkal proteins and demonstrated their ability to activate human and zebrafish ALK family RTKs. Zebrafish Alkals activate the ALK-related receptor leukocyte tyrosine kinase (LTK) in the neural crest to promote iridophore development.In the last paper, we employed the DamID approach on the Drosophila VM and identified the transcription factor Kahuli (Kah) as an Alk transcriptional target in this tissue (Paper IV). We also addressed the in vivo iv Kah role during embryogenesis and showed that Kah is required for normal midgut invaginations and formation of the body wall musculature.Together, this thesis highlights the importance of ALK receptor signaling during development in vertebrate and invertebrate models. Further, it shows that ALKAL signaling via the activation of the ALK family receptors are involved in neural crest development.
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| 3. |
- Hugosson, Fredrik, 1972-
(författare)
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Deciphering the Alk signaling pathway in Drosophila
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Drosophila melanogaster the visceral mesoderm (VM) develops during embryogenesis in a process where myoblasts become specified to generate two distinct cell types, the founder cells (FCs) and the fusion competent myoblasts (FCMs) that consequently fuses. The cell specification is dependent on cell signaling mediated by the receptor tyrosine kinase (RTK) Anaplastic lymphoma kinase (Alk) and its ligand Jelly belly (Jeb), how this further sets up different identity programs that drive myoblasts to differentiate into FCs and FCMs is still not well understood.We have analysed whether the Midkine (MDK)/Pleiotrophin (PTN) homologues in Drosophila, Miple1 and Miple2 activate the Alk RTK in vivo. Earlier results from cell culture experiments suggested that vertebrate MDK/PTN is capable of activating ALK, findings that have become controversial with other studies showing contradictory results. We wanted to use Drosophila that have conserved homologues of both MDK/PTN and ALK, to address the question in vivo. We analysed the contribution of Miple in Alk dependent developmental processes such as visceral mesoderm (VM) specification during embryogenesis and in body size regulation of adult flies. Specification of VM as well as body size are not effected by loss of Miple proteins, and over expression of Miple proteins do not effect VM specification or body size. All together we conclude that there is no evidence that Miple1 or Miple2 can activate Alk in vivo. We found that loss of Miple protein effect the median lifespan of the fly which is reduced, interestingly the over expression of Miple proteins can promote an increased median life span in Drosophila.We have also analysed how Alk RTK signaling regulates the Gli-like transcription factor Lame duck (Lmd) in vivo on a post-translational level. It has already been reported that Lmd plays an essential role in specification of FCMs in the somatic mesoderm during embryogenesis. We detect Lmd protein exclusively in FCMs of VM in control embryos, but in Alk mutants Lmd protein is present in all cells of VM and opposite to this when Alk is activated in all cells in VM by over expression of Jeb this results in total loss of Lmd protein. This suggests that Alk signaling is regulating Lmd, and we additionally show that Lmd persist in FCMs in mutants where VM is specified but where myoblast fusion do not occur, supporting that Alk activity in FCs is regulating the downregulation of Lmd in FCMs upon fusion.Finally we have characterised the Rap1GEF C3G in vivo in Drosophila. In cell culture systems, the GTPase Rap1 has been identified to mediate Alk signaling and that this is regulated by the GEF C3G and interestingly the Drosophila C3G is expressed in the FCs of VM. We generated deletion mutants of C3G which exhibit semi-lethality and reduced life span, but no defects in visceral mesoderm development during embryogenesis. Instead we detected distinct phenotypes in somatic muscles of 3rd instar mutant larvae, with detachment and mistargeting of muscles, which effect localisation of integrins. We suggest that Drosophila C3G regulates Rap1 via inside out signaling of integrins which in turn effects cell adhesion in vivo in Drosophila larval muscles.
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| 4. |
- Yao, Liqun, 1985-
(författare)
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Genome-wide identification of Grainy head target genes and their functions in Drosophila embryos
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The transcription factor Grainy head (Grh) is conserved from Drosophila to humans. Drosophila Grh plays important roles in epithelial differentiation and regeneration. To investigate the mechanisms of Grh function, we performed ChIP-sequencing and microarray gene expression analysis and identified Grh target genes in Drosophila embryos at a genome-wide scale. We found Grh ChIP peaks in the proximity of 3754 genes and showed that Grh acts both as an activator and as a repressor. Grh regulates distinct genes in different contexts. During wound healing, Grh transcriptionally activates stitcher (stit), a gene encoding a receptor tyrosine kinase. We show that Stit activates two distinct pathways, including Src kinases and extracellular signal-regulated kinase (ERK), after injury. The tyrosine residue Y762 mediates Stit binding to the SH2 domains of Src42A, Src64B, or Drk. Src family kinases and Drk act as downstream effectors of Stit in the activation of wound response enhancers. Src family kinases control re-epithelialization, but fail to induce the dpERK accumulation after injury. In contrast, Drk is dispensable in re-epithelialization, but can induce the activation of ERK, which can therefore link RTKs to ERK-mediated Grh-dependent activation of wound response genes. In airways, Grh regulates 1152 target genes encoding various enzymes, signaling proteins, and transcription factors. Grh represses the POU-domain transcription factor Vvl (Ventral veinless). Vvl interacts with Grh and can regulate a set of Grh target genes. Grh and Vvl antagonize each other during airway maturation and tracheal tube elongation. The analysis of Grh-responsive enhancers during embryonic development and in wound healing indicates that Grh cooperates with other transcription factors, such as Vvl, to regulate target gene expression.In addition, we identify a novel grh PO isoform expressed predominantly in the central nervous system, epidermis, and trachea. Unlike the canonical grh (grh PI) that can regulate endogenous grh PI and grh PO, Grh PO fails to regulate the grh gene transcriptionally. Further functional analysis in the trachea suggests that Grh PO may act as a partial dominant-negative regulator of Grh.
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| 5. |
- Evangelou, Evangelos, et al.
(författare)
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Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits.
- 2018
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 50:10, s. 1412-1425
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Tidskriftsartikel (refereegranskat)abstract
- High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future.
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