1.
Lindberg, Frida A.
(författare)
The Biological Importance of the Amino Acid Transporter SLC38A10 : Characterization of a Knockout Mouse
2022
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The biggest group of transporters, the solute carriers (SLCs), has more than 400 members, and about 30% of these are still orphan. In order to decipher their biological function and possible role in disease, there is a need for characterization of these. Around 25% of SLCs are estimated to have amino acids as substrates, including transporters belonging to the SLC38 family. The SLC38 members are sometimes referred to their alternative name: sodium-coupled neutral amino acid transporters (SNATs). One of these transporters, SNAT10 (or SLC38A10), has been characterized as a bidirectional transporter of glutamate, glutamine, alanine and aspartate, as well as having an efflux of serine, and is ubiquitously expressed in the body. However, its biological importance is not yet understood. The aim with this thesis was to characterize a mouse model deficient in SNAT10 protein in order to find the biological importance of this transporter. In paper I, this is done by using a series of behavioral tests, including the open field test, elevated plus maze, rotarod and Y-maze, among others. The SNAT10 knockout mouse was found to have an increased risk-taking behavior, but no motor or spatial working memory impairments. Furthermore, the knockout mouse was found to have a decreased body weight. In paper II, an additional behavioral characterization was performed by using the multivariate concentric square field™ (MCSF) test. The MCSF test is an arena with different zones associated to different behavioral traits, which generates a behavioral profile depending on where the mouse spends its time. The result from this test implies that the SNAT10 deficient mouse has a lower explorative behavior than its wild type littermates. In paper III, gene expression was studied in whole brain and some genes related to cell cycle regulation and p53 expression were found to be differentially expressed in the knockout brain. Additional gene expression was studied in kidney, liver, lung and muscle, but no changes were found. Plasma levels of histidine and threonine were altered in males, but no altered amino acid levels were found in knockout females, suggesting a possible sex-specific effect. These studies together imply that SNAT10 might be involved in processes related to risk-taking and explorative behavior in the open field and MCSF tests. SNAT10 deficiency also affected amino acid levels in plasma, indicating a disrupted amino acid homeostasis.
2.
Chebli, Jasmine
(författare)
Physiological roles of amyloid precursor protein in vivo - zebrafish as a model
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Amyloid-beta precursor protein (APP) is an evolutionarily conserved transmembrane protein expressed in many different tissues. APP belongs to a gene family consisting of two other APP-like proteins (APLP1 and APLP2). APP has been shown to be involved in biological processes such as neurite outgrowth, neuronal migration, synapse formation and plasticity, and cell-cell interactions. APP also plays a central role in the development of Alzheimer's disease (AD). APP's physiological role has been difficult to understand and despite all research is not yet completely understood. The purpose of this thesis was to study the role of APP during early development with zebrafish as the main model system. We have focused on the zebrafish's Apps and have tried to understand their function with the help of genetic knockout models created using the CRISPR / Cas9 method. We report that appb mutants have weakened cell adhesions that give rise to changes in cell organization. We also report that the appb mutants are smaller but develop into fertile and healthy adult individuals. We also found defects in the formation of the trigeminal ganglia (TG) and that Appb seems to have a role in cell-cell interaction. The more widespread TG also consisted of fewer nerve cells, indicating that Appb promotes nerve cell formation. Furthermore, our studies demonstrate APP expression in cilia on sensory nerve cells and ependymal cells covering the brain chambers. The conserved expression of APP in ependymal cilia in mice and humans suggest an important and preserved function. Zebrafish with mutated App were found to have defects in the formation of both cilia and cerebral ventricles. To identify new signalling pathways through which Appb controls these functions, we studied protein changes in appb mutants using mass spectrometry. These studies highlight changes that both confirm known and suggest new regulations by appb, especially in neural development, cell adhesion and in gene regulation. Finally, we tried to answer the underlying mechanisms behind compensation within the App family. We found that mutations in the app genes activate expression of homologous genes via so-called transcriptional adaptation. In conclusion, the findings reported in this thesis showed that App is implicated already in early cellular adhesion and sensory neuronal differentiation processes and is located to several sensory cilia in vivo. The use of zebrafish as a model organism allowed us to gain valuable knowledge on the physiological roles of App.
3.
Rodriguez, Juan, 1983
(författare)
Targeting apoptosis-inducing factor as a novel therapeutic strategy for preventing perinatal brain injury
2020
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Perinatal complications such as asphyxia can cause brain injuries that are often associated with subsequent neurological deficits. The mechanisms of perinatal brain injury are not fully understood, but mitochondria play a prominent role, not only due to their central function in metabolism, but also because many proteins with apoptosisrelated functions are located in the mitochondrion. Among these proteins, CHCHD4 and apoptosis-inducing factor (AIF) have already been shown to make important contributions to neuronal cell death upon hypoxia-ischemia (HI), but a better understanding of the mechanisms behind these processes is required for the development of improved treatments. By inducing HI in 9-day-old mice, leading to moderate brain injury, we studied these mechanisms from multiple perspectives. First, we determined the effect of chchd4 haploinsufficiency, and we showed that neonatal mice with this genotype experienced less brain damage due to reduced translocation of AIF and Cytochrome c from the mitochondrion. Second, we characterized the role of a newly discovered AIF isoform (AIF2), which is only expressed in the brain and the functions of which are unknown. By using Aif2 knockout mice, we showed that under physiological conditions there is an increase in Aif1 expression (the ubiquitously expressed isoform) due to a compensatory effect of loss of Aif2 expression. As a result, these mice showed a higher degree of brain damage after HI and were more vulnerable to oxidative stress. Third, we used another transgenic mouse in which Aif was overexpressed by knocking in a proviral insertion of Aif, leading to an increased expression of Aif1 without affecting the expression of Aif2. This mouse also showed a higher degree of brain damage and higher levels of oxidative stress. Finally, we used a peptide designed to block the apoptotic function of AIF. The results in young mice showed that the neuroprotective effect of the peptide was greater in male mice than in female mice. In summary, this PhD project has opened new perspectives in the comprehension of the mechanisms by which CHCHD4 and AIF are crucial proteins for brain damage after HI, and it has showed that AIF is a promising therapeutic target for improving outcome after perinatal brain injury.
4.
5.
Skovgård, Katrine
(författare)
Models and biomarkers of motor and neuropsychiatric complications in Parkinson’s disease
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterised by typicalmotor symptoms that are caused by severe dopamine depletion in the cortico-basalganglia network. Parkinsonian motor symptoms are improved by dopaminergicmedications, the most effective being the dopamine precursor L-DOPA. Thiscompound exerts its motor effects by stimulating dopamine D1 and D2 receptors,whose expression are segregated between the movement-promoting and movement-suppressing pathways of the basal ganglia circuitry. As the disease progresses,treatment with L-DOPA give rise to involuntary movements (dyskinesia), whichlimits its utility. Drugs that directly stimulate dopamine receptors, referred to asdopamine agonists, are commonly used to delay the use of L-DOPA or reduce itsdosage. Although less prone to induce dyskinesia, dopamine agonists have a highliability to induce neuropsychiatric side effects, in particular, impulsive-compulsivebehaviours. However, it remains to be established whether pharmacotherapiescombining L-DOPA and dopamine agonists give rise to specific profiles of motorand non-motor complications.The overarching aim of this thesis is to develop improved experimental modelsto advance translational research on the motor and neuropsychiatric complicationsof PD therapy. Both well-established and new experimental models are used todefine correlations and causal links between regimens of dopaminergic treatment,behavioural changes, and biomarkers of network and cellular dysfunction in thecortico-basal ganglia system.Using in vivo local field potential recordings to study biomarkers of networkdysfunctions, we show that changes in broad-band oscillatory activities of cortico-striatal circuits are correlated to ongoing motions and do not reflect parkinsonian-specific states. Moreover, we demonstrate that dyskinesias induced by D1 receptorstimulation are associated with prominent narrowband cortico-striatal oscillationsin the high gamma range (70-110 Hz). Following treatment with a D2 agonist, thesenarrowband gamma oscillations are less pronounced, whereas this treatment inducesprominent theta oscillations (5-10 Hz) in the deep basal ganglia nuclei. Thus, thecomposition of the dopaminergic therapies might affect these neurophysiologicalbiomarkers and should be considered in future investigations.Next, using a set of pharmacological tools and markers of cellular dysfunctions,we show that adjuvant treatment with D2/3 agonists alters the pattern of dopamine-related neuroplasticity in the basal ganglia compared to L-DOPA monotherapy,despite similar dyskinetic behaviours. The antidyskinetic effects of compounds modulating D1 receptor signalling were stronger in L-DOPA-treated animals, whileNMDA receptor antagonists produced markedly larger effects in the combinedtreatment group. Thus, adjuvant dopamine agonist treatment has a significantimpact on the neuroplasticity and pharmacological response profiles of L-DOPA-induced dyskinesia. In a last study, we show that treatment with a D2/3 agonistinduces compulsive behaviours and impulsive decision-making in both intact andpartially dopamine-depleted rats regardless of L-DOPA coadministration.Taken together, the findings of this thesis shed new light on the maladaptivecellular changes and network dynamics through which dopaminergic pharmacotherapies for PD affects motor behaviours. Moreover, this thesis work reveals the importance of including realistic models of combined therapies in future translational research on L-DOPA-induced dyskinesia.
6.
Vieira, João
(författare)
Profiling Plasma Metabolite Alterations in Diet-Induced Obesity and Diabetes Using NMR Metabolomics
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Diets rich in saturated fat and sedentary lifestyles markedly contribute to obesity and metabolic syndrome-related diseases, including type 2 diabetes mellitus (T2D). Metabolite profiling plays a pivotal role in understanding these metabolic diseases. This thesis comprises insights from four distinct studies to illuminate metabolic imbalances induced by diet-induced obesity (DIO), covering topics related to the duration of dietary regimens, potential benefits of dietary interventions on the brain and metabolism, and the impact of underlying T2D on post-stroke recovery. Using a combination of proton nuclear magnetic resonance (1H-NMR) spectroscopy and mass spectrometry (MS), study I initially demonstrated the superiority of the combined approach in characterizing the effects of DIO on plasma metabolites. The robustness of this method was further validated in a human cohort, underscoring its translational potential in unravelling metabolic imbalances. In study II, female mice exposed to high-fat diet (HFD) exhibited brain metabolism alterations and memory deficits, which were mitigated by taurine and N-acetylcysteine (NAC) supplementation. These supplements not only ameliorated HFD-induced memory impairment but also elicited distinct effects on metabolic alterations within the hippocampus. Systemically, 1H-NMR metabolomics data in study III revealed that NAC and taurine treatments impacted plasma metabolites. Ultimately, as explored in study IV using 1H-NMR metabolomics, unique metabolite changes in male mice with T2D following transient middle cerebral artery occlusion were reported. Specifically, metabolite changes that link T2D to poor neurological outcomes after stroke were observed. In summary, this thesis underscores the significance of metabolite profiling in elucidating the complexities of metabolic diseases, memory impairment, and post-stroke recovery in DIO mouse models. It also emphasizes the translational character of such findings to human pathophysiology.
7.
Titulaer, Joep
(författare)
Finding improved drug strategies for schizophrenia : Preclinical studies on lumateperone and sodium nitroprusside
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Schizophrenia is a severe psychiatric disorder affecting approximately 20 million people worldwide. The disease consists of positive symptoms e.g. hallucinations, negative symptoms such as anhedonia, and cognitive deficits, e.g. impaired episodic memory. Most of the currently available treatment options for schizophrenia only target the positive symptoms, possess severe side effects and do not work for a large group of patients. In this thesis, the unique antipsychotic drug lumateperone and adjunctive treatment of sodium nitroprusside (SNP) to sub-maximal doses of conventional antipsychotic drugs are investigated in preclinical tests as novel treatment options for schizophrenia In paper I we showed that SNP enhances the antipsychotic-like effect of a sub-effective dose of risperidone in the conditioned avoidance response (CAR) test in rats. Moreover, by using microdialysis we showed that SNP significantly enhances risperidone-induced dopamine release in the rat medial prefrontal cortex (mPFC) but not in the nucleus accumbens, indicating that adjunct SNP could be used to improve the efficacy of antipsychotic drugs, while reducing their dose and subsequently lower the risk of side effects.In paper II we used microdialysis combined to the behavioral novel object recognition test in rats to show that the release of both dopamine and norepinephrine is increased in the ventral hippocampus in response to a novel object, suggesting that dopamine and norepinephrine may play a crucial role in recognition memory. In paper III we showed that SNP significantly enhanced the antipsychotic-like effect of sub-effective doses of olanzapine in the CAR test, but not of clozapine, this could be explained by the developed tolerance towards clozapine after repeated administrations.In paper IV we used enzyme-coated microelectrode arrays to show that lumateperone significantly increased cortical glutamate release in the mPFC of anaesthetized rats. By using electrophysiology, we also show that lumateperone facilitates NMDA and AMPA-mediated currents in a dopamine D1 dependent manner in layer V/VI pyramidal neurons in the mPFC of rats. Moreover, lumateperone increases dopamine release in the mPFC of freely moving rats as shown by using microdialysis. These mechanisms may improve cognitive deficits and contribute to the clinically demonstrated antidepressant effects of lumateperone. Taken together, these results show that lumateperone is a promising novel treatment option for schizophrenia, and that adjunct SNP treatment may allow for improved efficacy at maintained or even reduced dosage of conventional antipsychotic medication.
8.
Tripathi, Rekha, PhD student, 1985-
(författare)
Unlocking the Role Of Orphan Solute Carrier SLC38A10 In Brain Metabolism : The SLC38A10 transporter in nutrient and metabolic regulation
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Membrane transporters are the primary gatekeepers of cells and regulate the transport of nutrients, metabolites, ions, water, and neurotransmitters into and across the human cells. The solute carrier transporters (SLCs) are the most prominent transporters, comprising 430 members divided into 65 subfamilies. SLCs are located on the plasma membrane and organelles such as mitochondria, vesicles, peroxisomes, endoplasmic reticulum, Golgi, and lysosomes. This thesis aimed to study SLCs of the SLC38 family under nutrient stress, focused particularly on the orphan SLC38A10 transporter.In Paper I, regulation of members of SLC38 family transporter, after amino acid starvation in mouse hypothalamic cells and primary cortex cells, was studied using microarrays and qPCR. We found several members of the SLC38 family that were strongly affected under amino acid starvation and showing a potential role in amino acid signaling in the brain. In Paper II, we performed a cellular and tissue localization and functional study of SLC38A10 transporter and revealed that SLC38A10 was expressed in both excitatory and inhibitory neurons in the mouse brain and has a unique subcellular localization in the ER and Golgi membrane. Furthermore, knockdown of the SLC38A10 gene resulted in reduced nascent protein synthesis in PC12 cells. Further, to unlock the biological function of the SLC38A10 transporter, in Paper III and Paper IV, we used SLC38A10 knockout mouse model.In Paper III, the goal was to uncover the role of SLC38A10 in acute glutamate and oxidative stress. Here, we found that a loss of SLC38A10 KO resulted in changes in the p53 levels and affected the mitochondrial function. Thus, this study established a possible role of SLC38A10 in cell survival, linked with p53, in mouse primary cortex cells. In Paper IV, we examined the role of SLC38A10 in amino acid metabolism and nutrient sensing in the mTOR signaling pathway. We performed complete amino acid starvation and refeed experiment on SLC38A10 knockout primary cortex cells. We concluded that SLC38A10 acts as a transceptor and regulates mTOR-dependent protein and lipid synthesis in brain cells, corroborating the findings from Paper II. To summarize, the present work has uncovered the function of SLC38A10 in the brain. It also provides knowledge of SLC38A10’s role in amino acid metabolism and signaling pathway(s). The findings of this thesis will enhance an understanding of SLC38A10 transporter and provide insight into future disease targeted drug studies focused on metabolic disorder and neurodegenerative disease.
9.
Falk Erhag, Hanna, et al.
(författare)
A Multidisciplinary Approach to Capability in Age and Ageing
2022
Bok (övrigt vetenskapligt/konstnärligt) abstract
This open access book provides insight on how to interpret capability in ageing – one’s individual ability to perform actions in order to reach goals one has reason to value – from a multidisciplinary approach. With for the first time in history there being more people in the world aged 60 years and over than there are children below the age of 5, the book describes this demographic trends as well as the large global challenges and important societal implications this will have such as a worldwide increase in the number of persons affected with dementia, and in the ratio of retired persons to those still in the labor market. Through contributions from many different research areas, it discussed how capability depends on interactions between the individual (e.g. health, genetics, personality, intellectual capacity), environment (e.g. family, friends, home, work place), and society (e.g. political decisions, ageism, historical period). The final chapter by the editors summarizes the differences and similarities in these contributions. As such this book provides an interesting read for students, teachers and researchers at different levels and from different fields interested in capability and multidisciplinary research.
10.
Garcia, Megg Gonzales
(författare)
Neuroinflammation and amyloid-β in early Alzheimer’s disease. Insight into the earliest events using mouse models
2023
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Alzheimer’s disease (AD) is the leading cause of dementia and most common neurodegenerative disease worldwide, but there currently exists no effective treatment that can stop nor slow the progression of the disease. The current dogma in the field postulates that the appearance of extracellular amyloid-beta (Aβ) plaques, a histopathological hallmark of the disease, is the trigger for downstream, detrimental events, including neuronal loss, extensive neuroinflammation and cognitive decline. However, increasing evidence suggests that neuroinflammatory alterations and synaptic and neuronal dysfunction occur already before plaque deposition, which we have also noted in previous work done by our groups. In addition, we have found that Aβ aggregates intracellularly, especially within neurons, before plaque appearance and that this has the ability to impair synaptic function. Therefore, we wonder whether there is an interplay between the neuroinflammatory system, neuronal and synaptic alterations, and intracellular Aβ in the earliest stages of the disease. To address this, we utilize mouse-based models in vivo, primarily the 5xFAD transgenic mouse model, and in vitro neuronal culture models. In the scientific papers included in this thesis work, we explore aspects related to mechanisms and modulations related to early AD. This includes looking at the prion-like spread and properties of intracellular Aβ, identifying sex-specific effects of early-life stress on inflammatory systems as well as neurons and Aβ, and investigating the interaction between neuroinflammatory cells and early aggregated Aβ. Taken together, we have worked to elucidate the earliest events in the disease, including factors that can modulate pathogenesis and the underlying mechanisms. By fostering a greater understanding of AD, we attempt to aid efforts towards the development of an effective disease-modifying treatment.
