Session TOG. There are 4 abstracts in this session.

Session: Aging and Neurological Diseases, time: 4:30 - 4:55 pm

Integrating MS-Based Proteomics and Lipidomcs Studies in the Cerebellar Degeneration Disorder, Niemann-Pick Type C1

Stephanie Cologna
Univ of Illinois at Chicago, Chicago, IL

Advances in mass spectrometry technology have enabled large-scale differential analysis of proteins and lipids to investigate altered pathways in human diseases. Our laboratory studies Niemann-Pick Disease, Type C1 (NPC1) a lysosomal storage disorder with visceral involvement and progressive cerebellar neurodegeneration. Using a combination of differential proteomics, lipidomics and mass spectrometry imaging, we have identified new candidate biomarkers in a mouse model of NPC1. These alterations now provide a basis for evaluation in NPC1 patients and also can be used for therapeutic development. Several examples will be presented.

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Session: Aging and Neurological Diseases, time: 4:55 - 5:20 pm

The Role of Senescence in Aging and Age-related Diseases – Proteomics as Tool to Decipher Mechanisms

Nathan Basisty1; Abhijit Kale1; Okhee Jeon1; Christopher D. Wiley1; Su Liu1; Chisaka Kuehnemann1; Anja Holtz1; Julie Anderson1; Pankaj Kapahi1; Luigi Ferrucci2; Judith Campisi1; Birgit Schilling1
1Buck Institute for Research on Aging, Novato, CA; 2National Institute on Aging, NIH, Rockville, MD

Cellular senescence is a striking example of a prime driver of aging phenotypes and pathologies across multiple tissues. This complex stress response causes an essentially irreversible arrest of cell proliferation and the development of a multi-component senescence-associated secretory phenotype (SASP). We hypothesize that, via the SASP, senescent cells exert cell non-autonomous effects that can disrupt cells and tissues locally and at a distance and contribute to neurodegeneration, thrombosis, and multiple age-related pathologies. Using modern proteomic technologies has allowed us to start to better understand the role of secreted proteins and SASP. Using proteomic technologies and quantitative SILAC as well as more comprehensive data-independent acquisitions approaches, we have assessed the composition and functions of the SASP in aging and disease contexts. As anticipated, the human SASP is incredibly diverse and heterogeneous, depending on different cell types, tissue source and cause of senescence burden. Recently, our proteomic screens have identified a novel role for senescent cells and SASP in hemostasis and blood coagulation. Since senescent cells accumulate with age, it is tempting to speculate that the SASP is at least partly responsible for thrombotic events that increase with age. The general role of senescent cells as driver of age-related diseases has moved forward potential strategies and therapeutics (senolytics) to remove senescent cells to improve health span. Overall, it will be of key importance to identify senescence markers, both as biomarkers for aging and age-related diseases, in order to monitor therapeutic interventions to eliminate senescent cells, such as by using senolytics in human trials.  

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Session: Aging and Neurological Diseases, time: 5:20 - 5:35 pm

A quantitative perspective of the dynamics of huntingtin protein interactions provides insight into Huntington’s Disease pathogenesis

Todd Greco; Joel Federspiel; Ileana Cristea
Princeton University, Princeton, NJ

Huntington’s disease is a monogenic disorder, with only one known causative gene, huntingtin (Htt). Expansion of a trinucleotide (CAG) repeat within the Htt gene results in the Htt protein containing polyglutamine (polyQ) stretches, which through yet uncharacterized mechanisms, is the main driver of neuronal degeneration in the brain, predominantly in the striatum and cortex. To understand the role of polyQ in disease pathogenesis, the protein interactions of wild-type and mutant Htt have been an active area of investigation. While numerous putative interactions have been proposed and a subset found altered under pathological conditions, there are still open questions about which interactions are the most proximal to disease progression. To identify these interactions, we studied the dynamics of Htt protein interactions in the striatum of mice with wild-type (Q20) and mutant (Q140) Htt at pre- and post-symptomatic ages using complementary IP-MS approaches. Label-free IP-MS was used to determine the specificity and abundance of the interactions. Isotope-labeled IP-MS using the I-DIRT approach was employed to identify stable versus transient interactions. We found that Htt interaction abundances were predominantly increased and driven by polyQ length, but in different subset of interactions at 2 and 10 months. Functional analysis suggested these early interaction changes involve proteins that function in synaptic transmission and phagocytosis, while later interactions mediate changes in synapse morphogenesis and impact the actin cytoskeletal network. Combining these abundance changes with I-DIRT IP-MS, we found that interaction stability was increased in a polyQ-dependent manner at both 2 and 10 months, largely represented by proteins that regulate actin filament polymerization. We also observed a subset of proteins with decreased stability at 10 versus 2 months, which included components of phosphatase and kinase signaling networks. Overall, these experiments have identified the most dynamic components of interaction networks driven by mutant Htt at different disease stages.

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Session: Aging and Neurological Diseases, time: 5:35 - 5:50 pm

Mapping the Brain Proteome of HIV-associated Neurocognitive Decline

Saima Ahmed1, 2; Amanda Guise1, 2; Hendrik Wesseling1, 2; Judith Steen1, 2; Hanno Steen1, 2
1Boston Children's Hospital, Boston, MA; 2Harvard Medical School, Boston, MA

The advancement of antiretroviral therapies has significantly improved health outcomes for HIV (Human Immunodeficiency Virus) infected patients. Despite these improvements, the problem of HIV infection-associated neurological complications remains unresolved. A spectrum of neurocognitive impairment associated with HIV infection known as HAND (HIV associated neurocognitive decline) include asymptomatic neurocognitive decline (ANI), minor cognitive and motor disorder (MCMD), and HIV-associated dementia (HAD). Here, we present a proteomic investigation of human post mortem brain specimens from HIV-infected patients with various stages of HAND and HIV positive neurocognitive normals. Using sarkosyl fractionation approach coupled with our house developed high throughput MStern blotting strategy (Berger et al. Mol Cell Proteomics. 2015; 14:2814), our analysis revealed many significantly changed proteins and pathways differentiating various stages of HAND. Apart from several pathways known to be dysregulated in HAND, this first of its kind neuroproteomic study also revealed several proteins associated with HAND that hasn't been described before. The pathway analysis is reflective of the well described dysregulation of small molecule metabolic processes and small GTPase mediated signal transduction (both: GO-BP), as well as downregulation of glucose metabolism in ANI and MCMD compared the neurocognitive normals. In addition, we observed inflammation-related dysregulation of the protein folding, proteasomal and ubiquitination machinery proteins accompanying changes in proteins associated with T cell activation, antiviral signaling, and neuronal injury proteins.

In addition to the mapping the proteomes, we also investigated Tau, a signature protein of dementia. The observed striking differences in the composition of the proteoforms and modifications of Tau in both soluble and insoluble fractions of various brain regions in HAND vs. other tauopathies were confirmed using antibody-based methods.

In summary, our results can be used to further elucidate the underlying pathogenesis of HIV infection induced neurological complications to facilitate the development of definitive markers and a better approach to treatment.

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