| 1. |
- Guipponi, Michel, et al.
(författare)
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Galanin pathogenic mutations in temporal lobe epilepsy
- 2015
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 24:11, s. 3082-3091
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Tidskriftsartikel (refereegranskat)abstract
- Temporal lobe epilepsy (TLE) is a common epilepsy syndrome with a complex etiology. Despite evidence for the participation of genetic factors, the genetic basis of TLE remains largely unknown. A role for the galanin neuropeptide in the regulation of epileptic seizures has been established in animal models more than two decades ago. However, until now there was no report of pathogenic mutations in GAL, the galanin-encoding gene, and therefore its role in human epilepsy was not established. Here, we studied a family with a pair of monozygotic twins affected by TLE and two unaffected siblings born to healthy parents. Exome sequencing revealed that both twins carried a novel de novo mutation (p.A39E) in the GAL gene. Functional analysis revealed that the p.A39E mutant showed antagonistic activity against galanin receptor 1 (GalR1)-mediated response, and decreased binding affinity and reduced agonist properties for GalR2. These findings suggest that the p.A39E mutant could impair galanin signaling in the hippocampus, leading to increased glutamatergic excitation and ultimately to TLE. In a cohort of 582 cases, we did not observe any pathogenic mutations indicating that mutations in GAL are a rare cause of TLE. The identification of a novel de novo mutation in a biologically-relevant candidate gene, coupled with functional evidence that the mutant protein disrupts galanin signaling, strongly supports GAL as the causal gene for the TLE in this family. Given the availability of galanin agonists which inhibit seizures, our findings could potentially have direct implications for the development of anti-epileptic treatment.
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| 2. |
- Bademci, Guney, et al.
(författare)
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FOXF2 is required for cochlear development in humans and mice.
- 2019
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Ingår i: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 28:8, s. 1286-1297
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Tidskriftsartikel (refereegranskat)abstract
- Molecular mechanisms governing the development of the human cochlea remain largely unknown. Through genome sequencing, we identified a homozygous FOXF2 variant c.325A > T (p.I109F) in a child with profound sensorineural hearing loss associated with incomplete partition type I anomaly of the cochlea. This variant is not found in public databases or in over 1,000 ethnicity-matched control individuals. I109 is a highly conserved residue in the forkhead box (Fox) domain of FOXF2, a member of the Fox protein family of transcription factors that regulate the expression of genes involved in embryogenic development as well as adult life. Our in vitro studies show that the half-life of mutant FOXF2 is reduced compared to that of wildtype. Foxf2 is expressed in the cochlea of developing and adult mice. The mouse knockout of Foxf2 shows shortened and malformed cochleae, in addition to altered shape of hair cells with innervation and planar cell polarity defects. Expressions of Eya1 and Pax3, genes essential for cochlear development, are reduced in the cochleae of Foxf2 knockout mice. We conclude that FOXF2 plays a major role in cochlear development and its dysfunction leads to sensorineural hearing loss and developmental anomalies of the cochlea in humans and mice.
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| 3. |
- Silberberg, Gilad, et al.
(författare)
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Deregulation of the A-to-I RNA editing mechanism in psychiatric disorders
- 2012
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 21:2, s. 311-321
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia and bipolar disorder (BPD) are common neurodevelopmental disorders, characterized by various life-crippling symptoms and high suicide rates. Multiple studies support a strong genetic involvement in the etiology of these disorders, although patterns of inheritance are variable and complex. Adenosine-to-inosine RNA editing is a cellular mechanism, which has been implicated in mental disorders and suicide. To examine the involvement of altered RNA editing in these disorders, we: (i) quantified the mRNA levels of the adenosine deaminase acting on RNA (ADAR) editing enzymes by real-time quantitative polymerase chain reaction, and (ii) measured the editing levels in transcripts of several neuroreceptors using 454 high-throughput sequencing, in dorsolateral-prefrontal cortices of schizophrenics, BPD patients and controls. Increased expression of specific ADAR2 variants with diminished catalytic activity was observed in schizophrenia. Our results also indicate that the I/V editing site in the glutamate receptor, ionotropic kainate 2 (GRIK2) transcript is under-edited in BPD (type I) patients (45.8 versus 53.9%, P= 0.023). GRIK2 has been implicated in mood disorders, and editing of its I/V site can modulate Ca(+2) permeability of the channel, consistent with numerous observations of elevated intracellular Ca(+2) levels in BPD patients. Our findings may therefore, at least partly, explain a molecular mechanism underlying the disorder. In addition, an intriguing correlation was found between editing events on separate exons of GRIK2. Finally, multiple novel editing sites were detected near previously known sites, albeit most with very low editing rates. This supports the hypothesis raised previously regarding the existence of wide-spread low-level 'background' editing as a mechanism that enhances adaptation and evolvability.
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| 4. |
- Adhikari, Deepak, et al.
(författare)
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Cdk1, but not Cdk2, is the sole Cdk that is essential and sufficient to drive resumption of meiosis in mouse oocytes
- 2012
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 21:11, s. 2476-2484
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian oocytes are arrested at the prophase of meiosis I during fetal or postnatal development, and the meiosis is resumed by the preovulatory surge of luteinizing hormone. The in vivo functional roles of cyclin-dependent kinases (Cdks) during the resumption of meiosis in mammalian oocytes are largely unknown. Previous studies have shown that deletions of Cdk3, Cdk4 or Cdk6 in mice result in viable animals with normal oocyte maturation, indicating that these Cdks are not essential for the meiotic maturation of oocytes. In addition, conventional knockout of Cdk1 and Cdk2 leads to embryonic lethality and postnatal follicular depletion, respectively, making it impossible to study the functions of Cdk1 and Cdk2 in oocyte meiosis. In this study, we generated conditional knockout mice with oocyte-specific deletions of Cdk1 and Cdk2. We showed that the lack of Cdk1, but not of Cdk2, leads to female infertility due to a failure of the resumption of meiosis in the oocyte. Re-introduction of Cdk1 mRNA into Cdk1-null oocytes largely resumed meiosis. Thus, Cdk1 is the sole Cdk that is essential and sufficient to drive resumption of meiosis in mouse oocytes. We also found that Cdk1 maintains the phosphorylation status of protein phosphatase 1 and lamin A/C in oocytes in order for meiosis resumption to occur.
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| 5. |
- Černý, Viktor, et al.
(författare)
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Demographic history and admixture dynamics in African Sahelian populations
- 2021
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Ingår i: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 30:R1, s. R29-R36
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Forskningsöversikt (refereegranskat)abstract
- The Sahel/Savannah belt of Africa is a contact zone between two subsistence systems (nomadic pastoralism and sedentary farming) and of two groups of populations, namely Eurasians penetrating from northern Africa southwards and sub-Saharan Africans migrating northwards. Because pastoralism is characterized by a high degree of mobility, it leaves few significant archaeological traces. Demographic history seen through the lens of population genetic studies complements our historical and archaeological knowledge in this African region. In this review, we highlight recent advances in our understanding of demographic history in the Sahel/Savannah belt as revealed by genetic studies. We show the impact of food-producing subsistence strategies on population structure and the somewhat different migration patterns in the western and eastern part of the region. Genomic studies show that the gene pool of various groups of Sahelians consists in a complex mosaic of several ancestries. We also touch upon various signals of genetic adaptations such as lactase persistence, taste sensitivity and malaria resistance, all of which have different distribution patterns among Sahelian populations. Overall, genetic studies contribute to gain a deeper understanding about the demographic and adaptive history of human populations in this specific African region and beyond.
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| 6. |
- Choudhury, Ananyo, et al.
(författare)
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Bantu-speaker migration and admixture in southern Africa
- 2021
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Ingår i: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 30:R1, s. R56-R63
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Forskningsöversikt (refereegranskat)abstract
- The presence of Early and Middle Stone Age human remains and associated archeological artifacts from various sites scattered across southern Africa, suggests this geographic region to be one of the first abodes of anatomically modern humans. Although the presence of hunter-gatherer cultures in this region dates back to deep times, the peopling of southern Africa has largely been reshaped by three major sets of migrations over the last 2000 years. These migrations have led to a confluence of four distinct ancestries (San hunter-gatherer, East-African pastoralist, Bantu-speaker farmer and Eurasian) in populations from this region. In this review, we have summarized the recent insights into the refinement of timelines and routes of the migration of Bantu-speaking populations to southern Africa and their admixture with resident southern African Khoe-San populations. We highlight two recent studies providing evidence for the emergence of fine-scale population structure within some South-Eastern Bantu-speaker groups. We also accentuate whole genome sequencing studies (current and ancient) that have both enhanced our understanding of the peopling of southern Africa and demonstrated a huge potential for novel variant discovery in populations from this region. Finally, we identify some of the major gaps and inconsistencies in our understanding and emphasize the importance of more systematic studies of southern African populations from diverse ethnolinguistic groups and geographic locations.
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| 7. |
- Hollfelder, Nina, et al.
(författare)
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The deep population history in Africa
- 2021
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Ingår i: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 30:R1, s. R2-R10
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Forskningsöversikt (refereegranskat)abstract
- Africa is the continent with the greatest genetic diversity among humans and the level of diversity is further enhanced by incorporating non-majority groups, which are often understudied. Many of today's minority populations historically practiced foraging lifestyles, which were the only subsistence strategies prior to the rise of agriculture and pastoralism, but only a few groups practicing these strategies remain today. Genomic investigations of Holocene human remains excavated across the African continent show that the genetic landscape was vastly different compared to today's genetic landscape and that many groups that today are population isolate inhabited larger regions in the past. It is becoming clear that there are periods of isolation among groups and geographic areas, but also genetic contact over large distances throughout human history in Africa. Genomic information from minority populations and from prehistoric remains provide an invaluable source of information on the human past, in particular deep human population history, as Holocene large-scale population movements obscure past patterns of population structure. Here we revisit questions on the nature and time of the radiation of early humans in Africa, the extent of gene-flow among human populations as well as introgression from archaic and extinct lineages on the continent.
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| 8. |
- Leibiger, Christine, et al.
(författare)
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TDP-43 controls lysosomal pathways thereby determining its own clearance and cytotoxicity
- 2018
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Ingår i: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 27:9, s. 1593-1607
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Tidskriftsartikel (refereegranskat)abstract
- TDP-43 is a nuclear RNA-binding protein whose cytoplasmic accumulation is the pathological hallmark of amyotrophic lateral sclerosis (ALS). For a better understanding of this devastating disorder at the molecular level, it is important to identify cellular pathways involved in the clearance of detrimental TDP-43. Using a yeast model system, we systematically analyzed to which extent TDP-43-triggered cytotoxicity is modulated by conserved lysosomal clearance pathways. We observed that the lysosomal fusion machinery and the endolysosomal pathway, which are crucial for proper lysosomal function, were pivotal for survival of cells exposed to TDP-43. Interestingly, TDP-43 itself interfered with these critical TDP-43 clearance pathways. In contrast, autophagy played a complex role in this process. It contributed to the degradation of TDP-43 in the absence of endolysosomal pathway activity, but its induction also enhanced cell death. Thus, TDP-43 interfered with lysosomal function and its own degradation via lysosomal pathways, and triggered lethal autophagy. We propose that these effects critically contribute to cellular dysfunction in TDP-43 proteinopathies.
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| 9. |
- Peter, Bradley, et al.
(författare)
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Structural basis for adPEO-causing mutations in the mitochondrial TWINKLE helicase.
- 2019
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Ingår i: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 28:7
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Tidskriftsartikel (refereegranskat)abstract
- TWINKLE is the helicase involved in replication and maintenance of mitochondrial DNA (mtDNA) in mammalian cells. Structurally, TWINKLE is closely related to the bacteriophage T7 gp4 protein and comprises a helicase and primase domain joined by a flexible linker region. Mutations in and around this linker region are responsible for autosomal dominant progressive external ophthalmoplegia (adPEO), a neuromuscular disorder associated with deletions in mtDNA. The underlying molecular basis of adPEO-causing mutations remains unclear, but defects in TWINKLE oligomerisation are thought to play a major role. In this study, we have characterised these disease variants by single-particle electron microscopy and can link the diminished activities of the TWINKLE variants to altered oligomeric properties. Our results suggest that the mutations can be divided into those that (i) destroy the flexibility of the linker region, (ii) inhibit ring-closure, and (iii) change the number of subunits within a helicase ring. Furthermore, we demonstrate that wild-type TWINKLE undergoes large-scale conformational changes upon NTP binding and that this ability is lost in the disease-causing variants. This represents a substantial advancement in the understanding of the molecular basis of adPEO and related pathologies and may aid in the development of future therapeutic strategies.
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| 10. |
- Siibak, Triinu, et al.
(författare)
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A multi-systemic mitochondrial disorder due to a dominant p.Y955H disease variant in DNA polymerase gamma
- 2017
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 26:13, s. 2515-2525
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the mitochondrial DNA polymerase, POLG, are associated with a variety of clinical presentations, ranging from early onset fatal brain disease in Alpers syndrome to chronic progressive external ophthalmoplegia. The majority of mutations are linked with disturbances of mitochondrial DNA (mtDNA) integrity and maintenance. On a molecular level, depending on their location within the enzyme, mutations either lead to mtDNA depletion or the accumulation of multiple mtDNA deletions, and in some cases these molecular changes can be correlated to the clinical presentation. We identified a patient with a dominant p.Y955H mutation in POLG, presenting with a severe, early-onset multi-systemic mitochondrial disease with bilateral sensorineural hearing loss, cataract, myopathy, and liver failure. Using a combination of disease models of Drosophila melanogaster and in vitro biochemistry analysis, we compare the molecular consequences of the p.Y955H mutation to the well-documented p.Y955C mutation. We demonstrate that both mutations affect mtDNA replication and display a dominant negative effect, with the p.Y955H allele resulting in a more severe polymerase dysfunction.
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