Variants in Miro1 Cause Alterations of ER-Mitochondria Contact Sites in Fibroblasts from Parkinson’s Disease Patients

Background: Although most cases of Parkinson´s disease (PD) are idiopathic with unknown cause, an increasing number of genes and genetic risk factors have been discovered that play a role in PD pathogenesis. Many of the PD-associated proteins are involved in mitochondrial quality control, e.g., PINK1, Parkin, and LRRK2, which were recently identified as regulators of mitochondrial-endoplasmic reticulum (ER) contact sites (MERCs) linking mitochondrial homeostasis to intracellular calcium handling. In this context, Miro1 is increasingly recognized to play a role in PD pathology. Recently, we identified the first PD patients carrying mutations in RHOT1, the gene coding for Miro1. Here, we describe two novel RHOT1 mutations identified in two PD patients and the characterization of the cellular phenotypes. Methods: Using whole exome sequencing we identified two PD patients carrying heterozygous mutations leading to the amino acid exchanges T351A and T610A in Miro1. We analyzed calcium homeostasis and MERCs in detail by live cell imaging and immunocytochemistry in patient-derived fibroblasts. Results: We show that fibroblasts expressing mutant T351A or T610A Miro1 display impaired calcium homeostasis and a reduced amount of MERCs. All fibroblast lines from patients with pathogenic variants in Miro1, revealed alterations of the structure of MERCs. Conclusion: Our data suggest that Miro1 is important for the regulation of the structure and function of MERCs. Moreover, our study supports the role of MERCs in the pathogenesis of PD and further establishes variants in RHOT1 as rare genetic risk factors for neurodegeneration.

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Metabolomic and lipidomic signatures in autosomal dominant and late-onset Alzheimer disease brains

10.1101/2021.11.04.21265941 ◽

2021 ◽

Author(s):

Brenna C Novotny ◽

Maria-Victoria Fernandez ◽

Jorge Bahena ◽

John P Budde ◽

Kristy Bergmann ◽

...

Keyword(s):

Risk Factors ◽

Alzheimer Disease ◽

Genetic Risk ◽

Autosomal Dominant ◽

Late Onset ◽

Disease Status ◽

Genetic Risk Factors ◽

Web Browser ◽

Pathogenic Variants ◽

Genetic Groups

The identification of multiple genetic risk factors for Alzheimer Disease (AD) provides evidence to support that many pathways contribute to AD onset and progression. However, the metabolomic and lipidomic profiles in carriers of distinct genetic risk factors are not fully understood. The metabolome can provide a direct image of dysregulated pathways in the brain, including information on treatment targets. In this study, we interrogate the metabolomic and lipidomic signatures in the AD brain, including carriers of pathogenic variants in APP, PSEN1, and PSEN2 (autosomal dominant AD; ADAD), APOE ϵ4 and TREM2 risk variant carriers, and non-carrier sporadic AD (sAD). We generated metabolomic and lipidomic data from parietal cortical tissue from 366 participants with AD pathology and 26 cognitively unimpaired controls using the Metabolon global metabolomics platform. We identified 133 metabolites associated with disease status (FDR q-value<0.05). In sAD brains these include tryptophan betaine (b=-0.57) and N-acetylputrescine (b=-0.14). Metabolites associated with sAD and ADAD include ergothioneine (b=-0.21 and -0.26 respectively) and serotonin (b=-0.34 and -0.58, respectively). TREM2 and ADAD showed association with α-tocopherol (b=-0.12 and -0.12) and CDP-ethanolamine (b=-0.13 and -0.10). β-citrylglutamate levels are associated with sAD, ADAD, and TREM2 compared to controls (b=-0.15; -0.22; and -0.29, respectively). Additionally, we identified a signature of 16 metabolites that is significantly altered between genetic groups (sAD vs. control p = 1.05x10-7, ADAD vs. sAD p = 3.21x10-5) and is associated with Braak tau stage and disease duration. These data are available to the scientific community through a public web browser (http://ngi.pub/Metabolomics). Our findings were replicated in an independent cohort of 327 individuals.

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Identifying sequence variants contributing to hereditary breast and ovarian cancer in BRCA1 and BRCA2 negative breast and ovarian cancer patients

Scientific Reports ◽

10.1038/s41598-019-55515-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Elisabeth Jarhelle ◽

Hilde Monica Frostad Riise Stensland ◽

Geir Åsmund Myge Hansen ◽

Siri Skarsfjord ◽

Christoffer Jonsrud ◽

...

Keyword(s):

Risk Factors ◽

Ovarian Cancer ◽

Cancer Patients ◽

Genetic Risk ◽

Genetic Risk Factors ◽

Sequence Variants ◽

Breast And Ovarian Cancer ◽

Brca1 And Brca2 ◽

Pathogenic Variants

AbstractFamilies with breast and ovarian cancer are often tested for disease associated sequence variants in BRCA1 and BRCA2. Pathogenic sequence variants (PVs) in these two genes are known to increase breast and ovarian cancer risks in females. However, in most families no PVs are detected in these two genes. Currently, several studies have identified other genes involved in hereditary breast and ovarian cancer (HBOC). To identify genetic risk factors for breast and ovarian cancer in a Norwegian HBOC cohort, 101 breast and/or ovarian cancer patients negative for PVs and variants of unknown clinical significance (VUS) in BRCA1/2 were screened for PVs in 94 genes using next-generation sequencing. Sixteen genes were closely scrutinized. Nine different deleterious germline PVs/likely pathogenic variants (LPVs) were identified in seven genes in 12 patients: three in ATM, and one in CHEK2, ERCC5, FANCM, RAD51C, TP53 and WRN. Additionally, 32 different VUSs were identified and these require further characterization. For carriers of PV/LPV in many of these genes, there are no national clinical management programs in Norway. The diversity of genetic risk factors possibly involved in cancer development show the necessity for more knowledge to improve the clinical follow-up of this genetically diverse patient group.

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The Puzzling Role of Neuron-Specific PMCA Isoforms in the Aging Process

International Journal of Molecular Sciences ◽

10.3390/ijms20246338 ◽

2019 ◽

Vol 20 (24) ◽

pp. 6338 ◽

Cited By ~ 2

Author(s):

Tomasz Boczek ◽

Tomasz Radzik ◽

Bozena Ferenc ◽

Ludmila Zylinska

Keyword(s):

Calcium Homeostasis ◽

Aging Process ◽

Ph Regulation ◽

Calcium Handling ◽

Membrane Composition ◽

Functional Studies ◽

Age Related ◽

Adaptive Processes ◽

Associated Proteins ◽

And Function

The aging process is a physiological phenomenon associated with progressive changes in metabolism, genes expression, and cellular resistance to stress. In neurons, one of the hallmarks of senescence is a disturbance of calcium homeostasis that may have far-reaching detrimental consequences on neuronal physiology and function. Among several proteins involved in calcium handling, plasma membrane Ca2+-ATPase (PMCA) is the most sensitive calcium detector controlling calcium homeostasis. PMCA exists in four main isoforms and PMCA2 and PMCA3 are highly expressed in the brain. The overall effects of impaired calcium extrusion due to age-dependent decline of PMCA function seem to accumulate with age, increasing the susceptibility to neurotoxic insults. To analyze the PMCA role in neuronal cells, we have developed stable transfected differentiated PC12 lines with down-regulated PMCA2 or PMCA3 isoforms to mimic age-related changes. The resting Ca2+ increased in both PMCA-deficient lines affecting the expression of several Ca2+-associated proteins, i.e., sarco/endoplasmic Ca2+-ATPase (SERCA), calmodulin, calcineurin, GAP43, CCR5, IP3Rs, and certain types of voltage-gated Ca2+ channels (VGCCs). Functional studies also demonstrated profound changes in intracellular pH regulation and mitochondrial metabolism. Moreover, modification of PMCAs membrane composition triggered some adaptive processes to counterbalance calcium overload, but the reduction of PMCA2 appeared to be more detrimental to the cells than PMCA3.

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