Transcriptional modulation unique to vulnerable motor neurons predict ALS across species and SOD1 gene mutations
Confirmed Presenter: Irene Mei, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, Sweden
Room: 519
Format: In Person
Moderator(s): Maria Secrier
Authors List: Show
- Irene Mei, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, Sweden
- Susanne Nichterwitz, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, Sweden
- Melanie Leboeuf, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, Sweden
- Jik Nijssen, Department of Cellular and Molecular Biology, Karolinska Institutet, Stockholm, Sweden, Sweden
- Isadora Lenoel, Institute de Cerveau (ICM), Hôpital Pitié Salpêtrière, Paris, France, France
- Dirk Repsilber, School of Medical Sciences, Örebro University, Örebro, Sweden, Sweden
- Christian S. Lobsiger, Institute de Cerveau (ICM), Hôpital Pitié Salpêtrière, Paris, France, France
- Eva Hedlund, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, Sweden
Presentation Overview: Show
Amyotrophic lateral sclerosis (ALS) is characterized by the progressive loss of somatic motor
neurons (MNs), which innervate skeletal muscles. However, certain MN groups including ocular MNs that regulate eye movement are relatively resilient to ALS. To reveal mechanisms of differential MN vulnerability, we investigate the transcriptional dynamics of two vulnerable and two resilient MN populations in SOD1G93A ALS mice. Differential gene expression analysis shows that each neuron type displays a largely unique spatial and temporal response to ALS. Resilient MNs regulate few genes in response to disease, but show clear divergence in baseline gene expression compared to vulnerable MNs, which in combination may hold the key to their resilience. EASE, fGSEA and ANUBIX enrichment analysis demonstrate that vulnerable MN groups share pathway activation, including regulation of neuronal death, ERK and MAPK cascades, inflammatory response and synaptic signaling. These pathways are largely driven by 11 upregulated genes, including Atf3, Cd44, Gadd45a, Ngfr, Ccl2, Ccl7, Gal, Timp1, Nupr1 and indicate that cell death occurs through similar mechanisms across vulnerable MNs albeit with distinct timing. Random Forest machine learning-based approach using DEGs upregulated in our SOD1G93A spinal MNs predict disease in human stem cell-derived MNs harboring the SOD1E100G mutation, and show that dysregulation of VGF, PENK, INA and NTS are strong disease-predictors across SOD1 mutations and species. A shared transcriptional vulnerability was also assessed through a meta-analysis across mouse SOD1 transcriptome datasets. In conclusion our study reveals vulnerability-specific gene regulation that may act to preserve neurons and can be used to predict disease.
Multi-dimensional Integration of PPI Network with Genetic and Molecular Data to Decipher the Genetic Underpinnings of RA Endotypes
Confirmed Presenter: Javad Rahimikollu, University of Pittsburgh, United States
Room: 519
Format: In Person
Moderator(s): Maria Secrier
Authors List: Show
- Javad Rahimikollu, University of Pittsburgh, United States
- Priyamvada Guha Roy, University of Pittsburgh, United States
- Larry Moreland, University of Colorado, United States
- Jishnu Das, University of Pittsburgh, United States
Presentation Overview: Show
Rheumatoid arthritis (RA) is a complex autoimmune disease with polyetiological genetic basis. Serum rheumatoid factor (RF) and anti-citrullinated peptide (CCP) antibodies are used to diagnose RA. However, it is unknown whether corresponding serological profiles map to distinct endotypes of RA. To address this, we first dissected differences across ~900 RA patients half of whom were serologically CCP+RF+ (i.e., double positive – DP), and half that were RF+ alone (RF). Surprisingly, there was a significant difference in heritability across these groups (~30%), suggesting fundamental differences in genetic risk of these two kinds of RA. Next, we carried out a genome wide association analysis (GWAS) and identified the HLA locus as explaining part of but not the entire difference in heritability between DP and RF RA. To delve into the missing heritability, we implemented a network-based GWAS approach. We adapt Linkage Disequilibrium Adjusted Kinships (LDAK) to aggregate the impact of multiple regulatory SNPs associated with a gene into a single score, taking into account the underlying LD structure. Using network propagation, we then identify modules that explain significant the differences in heritability across DP and RF. These modules include HLA genes, but also capture other cytokines, chemokines and immune regulators and almost completely capture the entire difference in heritability. We were also able to further validate these modules by recapitulating some of the corresponding differences at the transcriptomic and proteomic level. Together, our results suggest that DP and RF RA are different disease endotypes with distinct genetic bases and pathophysiology.