Common genetic variation at the Klotho gene locus and its relationship to age-related phenotypes

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe proportion of older adults in Western populations is increasing and there is, therefore, a need to define factors affecting the maintenance of physical and cognitive health in old age. Klotho, an FGF-23 co-receptor, has been shown to increase the lifespan in mice and there are numerous reports of common variants at the Klotho gene locus, particularly those that make up the KL-VS haplotype, being associated with age-related phenotypes. However, these reports are based on small sample sizes and are consequently under-powered. The work described in this thesis uses a candidate gene association approach to evaluate the previously reported associations between common genetic variants at the Klotho gene locus and age-related phenotypes in the UK Biobank, a large prospective cohort study of half a million participants. There was preliminary evidence for the following associations: rs2283368 and rs9536338 with longevity; rs495392 with HbA1c; rs141113969, rs2227122 and rs676046 with memory; and rs71436501 and rs78425544 with melanoma survival. However, none of these associations could be adequately replicated and are likely to be unreliable. These results show that the previous reports of associations between Klotho variants and longevity, cognitive function, cardiometabolic disease and cancer are likely to be false positives, which leads to two overall conclusions: one, there is insufficient evidence that common variation at the Klotho gene locus is associated with age-related phenotypes; and two, there is a need for well-powered replication studies

Repo-Man/protein phosphatase 1 SUMOylation mediates binding to lamin A and serine 22 dephosphorylation

© 2022 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License. http://creativecommons.org/licenses/by/4.0/Lamin A phosphorylation/de-phosphorylation is an important process during cells division as it allows for nuclear envelope (NE) disassembly at mitotic entry and its re-assembly during mitotic exit. Several kinases have been identified as responsible for these phosphorylations, but no protein phosphatase has been implicated in their reversal. One of the mitotic phosphosites in lamin A responsible for its dynamic behaviour is serine 22 (S22) which is de-phosphorylated during mitotic exit. Recent evidence has also linked the nuclear pool of lamin A S22ph in interphase to gene expression regulation. Previous work suggested that the phosphatase responsible for lamin A S22 de-phosphorylation is chromatin bound and interacts with lamin A via SUMO-SIM motives. We have previously reported that Repo-Man/protein phosphatase 1 (PP1) is a chromatin-associated phosphatase that regulates NE reformation. Here we propose that Repo-Man/PP1 phosphatase mediates lamin A S22 de-phosphorylation. We indeed show that depletion of Repo-Man leads to NE defects, causes hyperphosphorylation of lamin A S22 that can be rescued by a wild-type but not a SUMOylation-deficient mutant. Lamin A and Repo-Man interact in vivo and in vitro, and the interaction is mediated by SUMOylation. Moreover, the localization of Repo-Man/PP1 to the chromatin is essential for lamin A S22 de-phosphorylation.Peer reviewedFinal Published versio

Using genetics to investigate the association between lanosterol and cataract

Background: Cataract is one of the most prevalent causes of blindness worldwide. Whilst surgery is the primary treatment for cataracts, it is not always an available option, particularly in developing countries. Non-surgical methods of treatment would increase treatment availability for more patients. Several studies have investigated how topical application of oxysterols, such as lanosterol, may break down aggregated proteins and restore lens transparency. However, the results are conflicting and inconclusive.Aim: In this study, we focus on combining genetic evidence for associations between lanosterol related genetic variation and cataract to explore whether lanosterol is a potentially suitable drug treatment option.Method: Using data from 45,449 available cataract cases from the UK Biobank, with participant ages ranging from 40–69, we conducted a genetic association study (GWAS) to assess the risk of cataract. Cataract cases were defined using diagnostic and operation codes. We focused on genetic variants in the lanosterol synthase gene region. We also compared our results with previously published genetic associations of phytosterol-to-lanosterol ratios. Finally, we performed a genetic risk score analysis to test the association between lanosterol within the cholesterol synthesis pathway and the risk of cataract.Results: No statistically significant single nucleotide polymorphisms (SNPs) associations with cataract were observed in the gene region of lanosterol synthase at a multiple testing adjusted significance threshold of p < 0.05/13. The comparison between cataract risk and genetic association of 8 phytosterol-to-lanosterol GWAS results also showed no evidence to support lanosterol’s protective properties for cataract risk. No statistically significant association was found between the lanosterol within the cholesterol synthesis pathway genetic risk score and cataract outcomes (OR = 1.002 p = 0.568).Conclusion: There was no evidence observed for genetic associations between lanosterol and cataract risk. Our results do not support lanosterol’s potential role in treating cataracts. Further research may be needed to address the effect of lanosterol on specific cataract subtypes

DOI: 10.3329/bmrcb.v35i1.2313 Neurological findings and outcome in adult cerebral malaria

The neurological findings of 100 patients of adult cerebral malaria were studied. The commonest neurological feature was symmetrical upper motor neuron lesion as evidenced by exaggerated tendon reflexes and bilateral planter extensor (61%). Twenty two percent had features of meningeal irritation and/or meningism. Abnormal posturing occurred decerebrate rigidity (6%) and decorticate rigidity (4%) with or without opisthotonus, focal neurological deficit was noted in 5 % cases. Pupillary size and reaction were normal in 86%, poor in 14%. Corneal reflexes were absent in 4 % cases. Fundoscopy showed retinal hemorrhage in 16%, papilloedema is 3 % and exudates in 1%. Majority of the patients recovered (80%) without any persistent neurological sequelae at the time of discharge from hospital and death rate was 20%. Patients having focal neurological deficit, disconjugate gaze, poor pupillary reaction, absent corneal reflex and papilloedema were more susceptible to death. Delay in hospitalization and deep coma were also associated with increased mortality, whereas early hospitalization and proper nursing care could reduce mortality

Table1_Using genetics to investigate the association between lanosterol and cataract.docx

Background: Cataract is one of the most prevalent causes of blindness worldwide. Whilst surgery is the primary treatment for cataracts, it is not always an available option, particularly in developing countries. Non-surgical methods of treatment would increase treatment availability for more patients. Several studies have investigated how topical application of oxysterols, such as lanosterol, may break down aggregated proteins and restore lens transparency. However, the results are conflicting and inconclusive.Aim: In this study, we focus on combining genetic evidence for associations between lanosterol related genetic variation and cataract to explore whether lanosterol is a potentially suitable drug treatment option.Method: Using data from 45,449 available cataract cases from the UK Biobank, with participant ages ranging from 40–69, we conducted a genetic association study (GWAS) to assess the risk of cataract. Cataract cases were defined using diagnostic and operation codes. We focused on genetic variants in the lanosterol synthase gene region. We also compared our results with previously published genetic associations of phytosterol-to-lanosterol ratios. Finally, we performed a genetic risk score analysis to test the association between lanosterol within the cholesterol synthesis pathway and the risk of cataract.Results: No statistically significant single nucleotide polymorphisms (SNPs) associations with cataract were observed in the gene region of lanosterol synthase at a multiple testing adjusted significance threshold of p Conclusion: There was no evidence observed for genetic associations between lanosterol and cataract risk. Our results do not support lanosterol’s potential role in treating cataracts. Further research may be needed to address the effect of lanosterol on specific cataract subtypes.</p

Table2_Using genetics to investigate the association between lanosterol and cataract.docx

Background: Cataract is one of the most prevalent causes of blindness worldwide. Whilst surgery is the primary treatment for cataracts, it is not always an available option, particularly in developing countries. Non-surgical methods of treatment would increase treatment availability for more patients. Several studies have investigated how topical application of oxysterols, such as lanosterol, may break down aggregated proteins and restore lens transparency. However, the results are conflicting and inconclusive.Aim: In this study, we focus on combining genetic evidence for associations between lanosterol related genetic variation and cataract to explore whether lanosterol is a potentially suitable drug treatment option.Method: Using data from 45,449 available cataract cases from the UK Biobank, with participant ages ranging from 40–69, we conducted a genetic association study (GWAS) to assess the risk of cataract. Cataract cases were defined using diagnostic and operation codes. We focused on genetic variants in the lanosterol synthase gene region. We also compared our results with previously published genetic associations of phytosterol-to-lanosterol ratios. Finally, we performed a genetic risk score analysis to test the association between lanosterol within the cholesterol synthesis pathway and the risk of cataract.Results: No statistically significant single nucleotide polymorphisms (SNPs) associations with cataract were observed in the gene region of lanosterol synthase at a multiple testing adjusted significance threshold of p Conclusion: There was no evidence observed for genetic associations between lanosterol and cataract risk. Our results do not support lanosterol’s potential role in treating cataracts. Further research may be needed to address the effect of lanosterol on specific cataract subtypes.</p

Continuous glucose monitoring-guided insulin adjustment in children and adolescents on near-physiological insulin regimens: a randomized controlled trial

This randomized controlled trial assesses the effect on glycemic control of continuous glucose monitoring system (CGMS)-guided insulin therapy adjustment in young people with type 1 diabetes on intensive diabetes treatment regimens with continuous subcutaneous insulin infusion (CSII) or glargine. Pediatric subjects were recruited if they had an HbA^sub 1c^ (A1C) < 10% and had been on CSII or glargine for at least 3 months. Thirty-six subjects were randomized to insulin adjustment on the basis of 72 h of CGMS every 3 weeks or intermittent self-monitoring of blood glucose (SMBG) for 3 months. A1C and fructosamine were measured at baseline and 6 and 12 weeks. Follow-up A1C was measured at 6 months. Mean baseline A1C was 8.2% (n = 19) in the CGMS group and 7.9% (n = 17) in the control group. There was a significant improvement in A1C from baseline values in both groups, but there was no difference in the degree of improvement in A1C at 12 weeks between the CGMS (-0.4% [95% CI -0.7 to -0.1]) and the control group (-0.4% [-0.8 to 0.2]). In the CGMS group, improved A1C was at the cost of increased duration of hypoglycemia. CGMS is no more useful than intermittent fingerstick SMBG and frequent review in improving diabetes control in reasonably well-controlled patients on near-physiological insulin regimens when used in an outpatient clinic setting