We report that tumor cells without mitochondrial DNA (mtDNA) show delayed tumor growth, and that tumor formation is associated with acquisition of mtDNA from host cells. This leads to partial ...recovery of mitochondrial function in cells derived from primary tumors grown from cells without mtDNA and a shorter lag in tumor growth. Cell lines from circulating tumor cells showed further recovery of mitochondrial respiration and an intermediate lag to tumor growth, while cells from lung metastases exhibited full restoration of respiratory function and no lag in tumor growth. Stepwise assembly of mitochondrial respiratory (super)complexes was correlated with acquisition of respiratory function. Our findings indicate horizontal transfer of mtDNA from host cells in the tumor microenvironment to tumor cells with compromised respiratory function to re-establish respiration and tumor-initiating efficacy. These results suggest pathophysiological processes for overcoming mtDNA damage and support the notion of high plasticity of malignant cells.
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•Tumor cells lacking mtDNA form tumors only after acquiring host mtDNA•Tumor microenvironment instructs stepwise recovery of respiration•Recovery of mitochondrial function aligns with efficient tumor formation•Functional respirasome and complex II assembly occur in metastatic cells
Mitochondrial genome acquisition from cells in the tumor microenvironment restores tumorigenicity and respiration in cells lacking mtDNA. Cell lines derived from primary and circulating tumor cells and lung metastases that grew from these cells showed stepwise recovery of tumorigenicity and respiration that was associated with respirasome and complex II assembly.
It is thought that despite highly variable phenotypic expression, 70—80% of all epileptic cases are caused by one or more genetic mutations. Next generation sequencing technologies, such as whole ...exome sequencing (WES), can be used in a diagnostic or research setting to identify genetic mutations which may have significant prognostic implications for patients and their families. In this study, 398 genes associated with epilepsy or recurrent seizures were stratified into tiers based on genotype–phenotype concordance, tissue gene expression, frequency of affected individuals with mutations and evidence from functional and family studies. WES was completed on 14 DNA samples (2 with known mutations in
SCN1A
and 12 with no known mutations) from individuals diagnosed with epilepsy using an Ion AmpliSeq approach. WES confirmed positive
SCN1A
mutations in two samples. In
n
= 5/12 samples (S-3 to -14) we identified potentially causative mutations across five different genes. S-5 was identified to have a novel missense mutation in
CCM2;
S-6 a novel frameshift mutation identified in
ADGRV1
; S-10 had a previously reported pathogenic mutation in
PCDH19,
whilst a novel missense mutation in
PCDH19
was shown in S-12; and S-13 identified to have separate missense mutations in
KCNA2
and
NPRL3.
The application of WES followed by a targeted variant prioritization approach allowed for the discovery of potentially causative mutations in our cohort of previously undiagnosed epilepsy patients.
Migraine is a common neurological disorder and is characterized by debilitating head pain and an assortment of additional symptoms which can include nausea, emesis, photophobia, phonophobia, and ...occasionally, visual sensory disturbances. A number of genes have been implicated in the pathogenesis of this disease, including genes involved in regulating the vascular system. Of particular importance are the methylenetetrahydrofolate reductase (MTHFR) gene and the role it plays in migraine with aura. Migraine with aura has previously been shown to have a significant comorbidity with stroke, making the vascular class of genes a priority for migraine studies. In this report, we outline the importance of the MTHFR gene in migraine and also discuss the use of a genetic isolate to investigate MTHFR genetic variants. From this study, 3 MTHFR single nucleotide polymorphisms showing association with migraine in the Norfolk Island population have been identified, thus reinforcing the potential role of MTHFR in migraine susceptibility. Further studies will continue to build a gene profile of variants involved in the complex disease migraine and improve understanding of the underlying genetic causes of this disorder.
Background
Migraine is a common neurological disorder which affects a large proportion of the population. The Norfolk Island population is a genetically isolated population and is an ideal discovery ...cohort for genetic variants involved in complex disease susceptibility given the reduced genetic and environmental heterogeneity. Given that the majority of proteins responsible for mitochondrial function are nuclear encoded, this study aimed to investigate the role of Nuclear Encoded Mitochondrial Protein (NEMP) genes in relation to migraine susceptibility.
Methods
A gene‐centric association analysis of NEMP genes was undertaken in the most related individuals (n = 315) within the genetically isolated Norfolk Island population. The discovery phase included genes with three or more SNP associations (P < 0.005), which were investigated further in a replication phase using an unrelated migraine case–control cohort (544 patients and 584 controls).
Results
The discovery phase of the study implicated SNPs in 5 NEMP genes to be associated with migraine susceptibility (P < 0.005). Replication analysis validated some of these implicated genes with SNPs in three NEMP genes shown to be associated with migraine in the replication cohort. These were CSNK1G3 (P = 0.00037), ELOVL6 (P = 0.00035) and SARDH (P = 0.00081), which are involved in phosphorylation, fatty acid metabolism, and oxidative demethylation, respectively.
Conclusion
Here we provide evidence that variation in NEMP genes is associated with migraine susceptibility. This study provides evidence for a link between mitochondrial function and migraine susceptibility.
This is the first molecular genetic study to comprehensively investigate the role of NEMPs in migraine susceptibility in both a genetically isolated population, as well as an outbred Australian Caucasian population. Three new key candidate genes were identified in this study, showing a novel relationship between metabolic pathways and migraine susceptibility.
The Pacific Oceania region was one of the last regions of the world to be settled via human migration. Here we outline a settlement of this region that has given rise to a uniquely admixed ...population. The current Norfolk Island population has arisen from a small number of founders with mixed Caucasian and Polynesian ancestry, descendants of a famous historical event. The 'Mutiny on the Bounty' has been told in history books, songs and the big screen, but recently this story can be portrayed through comprehensive molecular genetics. Written history details betrayal and murder leading to the founding of Pitcairn Island by European mutineers and the Polynesian women who left Tahiti with them. Investigation of detailed genealogical records supports historical accounts.
Using genetics, we show distinct maternal Polynesian mitochondrial lineages in the present day population, as well as a European centric Y-chromosome phylogeny. These results comprehensively characterise the unique gender-biased admixture of this genetic isolate and further support the historical records relating to Norfolk Island.
Our results significantly refine previous population genetic studies investigating Polynesian versus Caucasian diversity in the Norfolk Island population and add information that is beneficial to future disease and gene mapping studies.
Familial hemiplegic migraine (FHM) is a rare autosomal dominant subtype of migraine with aura. It is divided into three subtypes FHM1, FHM2 and FHM3, which are caused by mutations in the CACNA1A, ...ATP1A2 and SCN1A genes respectively. As part of a regular diagnostic service, we investigated 168 patients with FHM symptoms. Samples were tested for mutations contained within the CACNA1A gene. Some tested samples (4.43%) showed an FHM1 mutation, with five of the mutations found in exon 5, one mutation in exon 16 and one in exon 17. Four polymorphisms were also detected, one of which occurred in a large percentage of samples (14.88%). The exon 16 2094G>A polymorphism, however, has been found to occur in healthy Caucasian control populations up to a frequency of 16% and is not considered to be significantly associated with FHM. A finding of significance, found in a single patient, was the detection of a novel mutation in exon 5 that results in a P225H change. The affected individual was an 8-year-old female. The exact phenotypic effect of this mutation is unknown, and further studies are needed to understand the pathophysiology of this mutation in FHM1. New information will allow for diagnostic procedures to be constantly updated, thus improving accuracy of diagnosis. It is possible that new information will also aid the development of new therapeutic agents for the treatment of FHM.
Ion channelopathies and migraine pathogenesis Albury, Cassie L.; Stuart, Shani; Haupt, Larisa M. ...
Molecular genetics and genomics,
08/2017, Letnik:
292, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Migraine is a common neurological disorder that affects approximately 12–20% of the general adult population. Migraine pathogenesis is complex and not wholly understood. Molecular genetic ...investigations, imaging and biochemical studies, have unveiled a number of interconnected neurological pathways which seem to have a cause and effect component integral to its cause. Much weight of migraine attack initiation can be placed on the initial trigger and the pathways involved in its neuronal counter reaction. Ion channels play a large role in the generation, portrayal and mitigation of the brains response to external triggers. Several genetic studies have identified and implicated a number of ion channelopathy genes which may contribute to this generalised process. This review will focus on the genetics of migraine with particular emphasis placed on the potentially important role genes
HEPH
(responsible for iron transport and homeostasis) and
KCNK18
(important for the transport and homeostasis of potassium) play in migraine cause.
Migraine is a common, disabling headache disorder, which is influenced by multiple genes and environmental triggers. After puberty, the prevalence of migraine in women is three times higher than in ...men and >50% of females suffering from migraine report a menstrual association, suggesting hormonal fluctuations can influence the risk of migraine attacks. It has been hypothesized that the drop in estrogen during menses is an important trigger for menstrual migraine. Catechol-O-methyltransferase (COMT) and Cytochrome P450 (CYP) enzymes are involved in estrogen synthesis and metabolism. Functional polymorphisms in these genes can influence estrogen levels and therefore may be associated with risk of menstrual migraine. In this study we investigated four single nucleotide polymorphisms in three genes involved in estrogen metabolism that have been reported to impact enzyme levels or function, in a specific menstrual migraine cohort. 268 menstrual migraine cases and 142 controls were genotyped for rs4680 in COMT (Val158Met), rs4646903 and rs1048943 in CYP1A1 (T3801C and Ile462Val) and rs700519 in CYP19A1 (Cys264Arg). Neither genotype nor allele frequencies for the COMT and CYP SNPs genotyped were found to be significantly different between menstrual migraineurs and controls by chi-square analysis (P>0.05). Therefore we did not find association of functional polymorphisms in the estrogen metabolism genes COMT, CYP1A1 or CYP19A1 with menstrual migraine. Further studies are required to assess whether menstrual migraine is genetically distinct from the common migraine subtypes and identify genes that influence risk.
•Polymorphisms in estrogen metabolism genes were investigated in menstrual migraine.•Polymorphisms were genotyped in a specific menstrual migraine case-control cohort.•COMT Val158Met, CYP1A1 Ile462Val and 3798T>C, and CYP19A1 Cys264Arg were studied.•None of the polymorphisms were significantly associated with menstrual migraine.
Migraine is a common neurological disorder classified by the World Health Organisation (WHO) as one of the top twenty most debilitating diseases in the developed world. Current therapies are only ...effective for a proportion of sufferers and new therapeutic targets are desperately needed to alleviate this burden. Recently the role of epigenetics in the development of many complex diseases including migraine has become an emerging topic. By understanding the importance of acetylation, methylation and other epigenetic modifications, it then follows that this modification process is a potential target to manipulate epigenetic status with the goal of treating disease. Bisulphite sequencing and methylated DNA immunoprecipitation have been used to demonstrate the presence of methylated cytosines in the human D-loop of mitochondrial DNA (mtDNA), proving that the mitochondrial genome is methylated. For the first time, it has been shown that there is a difference in mtDNA epigenetic status between healthy controls and those with disease, especially for neurodegenerative and age related conditions. Given co-morbidities with migraine and the suggestive link between mitochondrial dysfunction and the lowered threshold for triggering a migraine attack, mitochondrial methylation may be a new avenue to pursue. Creative thinking and new approaches are needed to solve complex problems and a systems biology approach, where multiple layers of information are integrated is becoming more important in complex disease modelling.
Therapeutically actionable ROS1 rearrangements have been described in 1–3% of non-small cell lung cancer (NSCLC). Screening for ROS1 rearrangements is recommended to be by immunohistochemistry (IHC), ...followed by confirmation with fluorescence in situ hybridisation (FISH) or sequencing. However, in practise ROS1 IHC presents difficulties due to conflicting scoring systems, multiple clones and expression in tumours that are wild-type for ROS1. We assessed ROS1 IHC in 285 consecutive cases of NSCLC with non-squamous histology over a nearly 2-year period. IHC was scored with ROS1 clone D4D6 (n=270), clone SP384 (n=275) or both clones (n=260). Results were correlated with ROS1 break-apart FISH (n=67), ALK status (n=194), and sequence data of EGFR (n=178) and other drivers, where possible. ROS1 expression was detected in 161/285 cases (56.5%), including 13/14 ROS1 FISH-positive cases. There was no ROS1 expression in one ROS1 FISH-positive case in which sequencing detected an ALK-EML4 fusion, but not a ROS1 fusion. The other 13 ROS1 FISH-positive cases showed moderate to strong staining with both IHC clones. However, one case with a TPM3-ROS1 fusion would have been scored as negative with SP384 and D4D6 clones by some previous criteria. ROS1 expression was also detected in 58/285 cases (20.4%) that had driver mutations in genes other than ROS1. A sensitivity of 100% for detecting a ROS1 rearrangement by FISH was achieved by omitting intensity from the IHC scoring criteria and expression in >0% cells with D4D6 or in ≥50% cells with SP384. Excluding cases with driver events in any MAPK pathway gene (e.g., in ALK, EGFR, KRAS, BRAF, ERBB2 and MET) substantially reduced the number of cases proceeding to ROS1 FISH. Only 15.9% of MAPK-negative NSCLC would proceed to FISH for an IHC threshold of >0% cells with D4D6, with a specificity of 42.4%. For a threshold of ≥50% cells with SP384, only 18.5% of MAPK-negative cases would proceed to FISH, with a specificity of 31.4%. Based on our data we suggest an algorithm for screening for ROS1 rearrangements in NSCLC in which ROS1 FISH is only performed in cases that have been demonstrated to lack activating mutations in any MAPK pathway gene by comprehensive sequencing and ALK IHC, and show staining at any intensity in ≥50% of cells with clone SP384, or >0% cells with D4D6.
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