8 research outputs found
Genetic alterations in epilepsy: the cases of Unverricht- Lundborg disease, Fragile X and B1 null mutation
No full textGenetic mechanisms are estimated to underlie about 40% of epilepsies and may present with
different manifestations and syndromes. In this thesis, three different cases of genetic implications
in epilepsy have been studied: Unverricht-Lundborg disease (ULD), a monogenic Progressive
Myoclonic Epilepsy in which disruption of the cystatin B gene results in the manifestation of the
pathology; Fragile X, the most frequent genetic mental retardation disease which associates to
epileptic seizures in about 25% of the cases; and involvement of the bradykinin system in epilepsy,
a possible cause of latent hyper-excitability.
The study on ULD revealed increased brain excitability in mice deficient for cystatin B, the genetic
defect associated with the pathology. This hyperexcitability seems to be related to a decreased
inhibitory cell number and/or to the activation of microglia. Our findings on Fragile-X reveal that,
after a chemically induced epileptic event (pilocarpine status epilepticus), active synapses
accumulate Fmr1 mRNA and its protein, FMRP. This phenomenon may account for an involvement
in activity-dependent synaptic plasticity and epileptogenesis. Finally, we studied bradykinin
involvement in brain excitability, and found that electrical (kindling) and chemical (kainate)
epileptic insults exacerbate a latent tissue hyper-excitability in B1 null mice.
These findings are examples of how genetic alterations may alter brain function, directly or
indirectly leading to epilepsy manifestations. In depth, investigation of the different aspects of the
genetic mechanisms of epilepsy is very important to identify key factors that, in the end, may allow
discovering new therapeutic targets and new treatments. Moreover, study of the basic mechanisms
underpinning pathological events may also shed light on the normal brain function
Thermodynamic analyses of different scenarios in a CCHP system with micro turbine - Absorption chiller, and heat exchanger
No full textAçıkkalp, Emin (Bilecik, Author)Distributed generation as a viable solution to the energy crisis has gained popularity in recent years due to reduced transmission losses and improved efficiency. In this study, nine scenarios are considered to analyze and evaluate a cogeneration system in various conditions. The cogeneration system that includes a gas turbine, absorption chillers, boilers, and heat exchangers is modeled in EES software. The system is studied in multiple scenarios. Values of energy efficiency (EE), used energy (UE), and utility fuel ratio (UFR) are calculated to assess the system. In addition, the amount of CO2 production is also investigated for each of the scenarios. It is found that the system used in scenario No. 5 which consists of two absorption chillers installed in series, with UFR of 45325.50 kJ/kg has the optimum performance in terms of simultaneous electricity and cooling generation. For electricity and heating generation, scenario No. 7 in which heat can be completely recovered, with UFR of 39541.90 kJ/kg is the optimum configuration. It is monitored that scenario No. 1 and scenario No. 6 have the highest amount of carbon dioxide production among the studied scenarios, 88.18 kg/s.National Natural Science Foundation of China - 5157620
Crosstalk between c-Jun and TAp73alpha/beta contributes to the apoptosis–survival balance
No full textThe p53-family member p73 plays a role in various cellular signaling pathways during development and growth control and it can have tumor suppressor properties. Several isoforms of p73 exist with considerable differences in their function. Whereas the functions of the N-terminal isoforms (TA and delta Np73) and their opposing pro- and antiapoptotic roles have become evident, the functional differences of the distinct C-terminal splice forms of TAp73 have remained unclear. Here, we characterized the global genomic binding sites for TAp73alpha and TAp73beta by chromatin immunoprecipitation sequencing as well as the transcriptional responses by performing RNA sequencing. We identified a specific p73 consensus binding motif and found a strong enrichment of AP1 motifs in close proximity to binding sites for TAp73alpha. These AP1 motif-containing target genes are selectively upregulated by TAp73alpha, while their mRNA expression is repressed upon TAp73beta induction. We show that their expression is dependent on endogenous c-Jun and that recruitment of c-Jun to the respective AP1 sites was impaired upon TAp73beta expression, in part due to downregulation of c-Jun. Several of these AP1-site containing TAp73alpha-induced genes impinge on apoptosis induction, suggesting an underlying molecular mechanism for the observed functional differences between TAp73alpha and TAp73beta
Early growth response genes -2 and -3 are essential for optimal immune responses
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Early Growth Response Genes (EGR) is a family of four transcription factors containing a unique zinc finger domain. EGR-2 and EGR-3 are important for hindbrain development and myelination. These transcription factors are also necessary for lymphocyte function however, the mechanisms are still unclear. Previous findings have shown that EGR-2cKO mice develop lupus-like autoimmune disease with high levels of pro-inflammatory cytokines despite showing normal T and B cell proliferation after mitogenic stimulation. Therefore we established the CD2-EGR-2-/-EGR-3-/- mouse model to explore the phenotype, susceptibility to autoimmune disease and relevant lymphocyte function. We discovered that CD2-EGR-2-/-EGR-3-/- mice developed severe systemic autoimmune disease and expressed high levels of inflammatory cytokines. More importantly we discovered a novel finding that CD2-EGR-2-/-EGR-3-/- T and B cells had impaired cell proliferation after mitogenic stimulation. Further investigations revealed that the molecular mechanism defected in the T cell receptor signalling pathway is due to a dysfunction in Activator Protein-1 (AP-1). AP-1 is a heterodimeric protein composed of AP-1 family members including Jun, Atf and Fos. Our data shows that EGR-2 and EGR-3 directly bind with the Atf family member Batf, which prevents Batf’s inhibitory function on AP-1 activation. This research demonstrates that EGR-2 and EGR-3 intrinsically regulate chronic inflammation and also positively regulate antigen receptor activation. In conclusion EGR-2 and EGR-3 are essential for providing optimal immune responses, whilst limiting inflammatory immunopathology. We propose that this new model could be used for studying autoimmune disease
iRHOM2 in skin disease and oesophageal cancer
No full textPhDMutations in RHBDF2, the gene encoding inactive rhomboid protein iRHOM2, result in the dominantly inherited condition Tylosis with oesophageal cancer (TOC). TOC causes plamoplantar keratoderma, oral precursor lesions and up to a 95 % life-time risk of oesophageal squamous cell carcinoma (SCC). The role of iRHOM2 in the epidermis is not well characterised, although we previously showed dysregulated epidermal growth factor receptor (EGFR) signalling and accelerated migration in TOC keratinocytes, and a role for iRHOM2 was shown in trafficking the metalloproteinase ADAM17. Substrates of ADAM17 include EGFR ligands and adhesion molecules.
iRHOM2 localisation and function were investigated in frozen sections and keratinocyte cell lines from control and TOC epidermis. Although iRHOM2 was predicted to be an ER-membrane protein, it showed cell-surface expression in control epidermis, with variable localisation in TOC. Increased processing and activation of ADAM17 was seen in TOC keratinocytes compared with control cells, suggesting that increased ADAM17-mediated processing of EGFR ligands may cause the changes in EGFR signalling. Downstream of iRHOM2-ADAM17, Eph/Ephrin and NOTCH signalling also appeared affected. Additionally, desmosomes in TOC epidermis lacked the electron-dense midline of the mature desmosomes seen in normal skin; this was accompanied by increased processing of desmoglein 2, a substrate of ADAM17. Expression and localisation of iRHOM2 was also investigated in TOC and sporadic SCC. iRHOM2 expression varied between SCC cell lines, and appeared to correlate with ADAM17 and NOTCH1 expression in oesophageal SCC and head and neck SCC cells.
In summary, iRHOM2 mutations in TOC appear to be gain-of-function in nature, resulting in increased ADAM17 processing and enhanced EGFR signalling. Questions remaining include the reason why iRHOM2 is found at the plasma membrane. Future study of the iRHOM2-ADAM17 pathway may provide additional insight into the mechanism of epidermal wound healing and the pathogenesis of oesophageal SCC.British Skin Foundatio
Molecular Characterization of ‘p53 Family Network’ in Human Head and Neck Cancer and Anti-EGFR Therapy
No full textUnderstanding of p53 family protein (p53, p63 and p73) networks in head and neck squamous cell carcinoma (HNSCC), can positively influence in cancer screening, diagnosis, treatment and prevention. P53 family proteins are regulating diverse cell signalling pathways at diverse conditions to determine cell fate. At each condition of cells state, how these proteins are controlling cell fate is more complexed due to the presense of several isoforms for each p53 family proteins and their multifaceted interactions. Like other solid tumours, the p53 pathway is disabled by several mechanisms in HNSCC. Despite of the convincing evidence of a high frequency of p53 mutations in HNSCC, a subset of cancers arise in the absence of mutations. The molecular mechaninsms through which p53 lacking mutations subvert its tumor supressor functions in HNSCC still remain uncertain. In fact, some cancers and established cancer cell lines are over-expressing wild type p53 protein makes questionable of p53 role as only a tumor suppressor or it has some other additional functions, even in cancer cells. For an answer of this hypothesis, we have performed detailed molecular characterization, in an invitro model of head and neck cancer, in a broad panel of 12 newly established HNSCC cell lines. In our studies, we found that some head and neck cancer cell lines are accumulating wild p53 protein hyperphosphorylated at serine15 and 392 and it leads to the over expression of DNp73, the mechanism already reported from our laboratory in HPV38 immortalized keratinocytes. To better understand the functions of accumulated wild p53 role in HPV positive and negative cancer cell lines, we have performed p53 knock down by siRNA and the results have showed that p53 knock down inhibited cell proliferation in both HPV positive and negative cancer cells. Moreover, p53 knock down induced significant morphological changes and senescence associated beta galactosidase activity in these cells. Our results pinpoint, wild-type p53 protein accumulated in transformed cell lines has an additional role in cell proliferation other than its well known tumor supressor activity. Moreover, the key role of p53 family network in modulating epidermal growth factor receptor (EGFR) expression and in controlling cell proliferation and apoptosis arises the question of whether p53 family proteins status influences the efficacy of EGFR inhibitors, investigating its ability to reduce cell growth, to induce apoptosis and to modulate cell cycle and various EGFR pathwayrelated targets in head and neck cancer. Because, recently improved understanding of the pathogenesis of human head and neck squamous cell carcinoma has led to the development of new, molecular based therapeutic strategies, one of the most promising is the utilization of tyrosine kinase (TK) inhibitors, targeting EGFR. The comparison between the targets analysed and gefitinib effectiveness evidenced the absence of a clear relationship, exluding them as predictive factors for gefitinib efficacy. Our results confirmed the in vitro efficacy of an anti-EGFR approach, but other targets than those analysed here should be characterized in order to identify valid predictive factors for gefitinib utilization in head and neck cancer. We have also performed chemoresistance analysis in our invitro model of HNSCC cell lilnes and found that p53 family network has less predictive role in HNSCC chemoresistance but ABCG2, a multidrug resistance protein, has over-expressed in HNSCC
Climate and Bioinvasives drivers of change on South African Rocky shores?
No full textIncludes abstract.Includes bibliographical references.The overall aims of the thesis were to assess spatio-temporal change in macro species assemblages at sites located around the South African coast. Detected changes were considered in parallel with regional patterns of bioinvasion and climate change driven shifts in temperature trends over comparable time scales
