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  • Brain Endothelial Cells Are Exquisite Sensors of Age-Related Circulatory Cues. Cell reports Chen, M. B., Yang, A. C., Yousef, H., Lee, D., Chen, W., Schaum, N., Lehallier, B., Quake, S. R., Wyss-Coray, T. 2020; 30 (13): 4418

    Abstract

    Brain endothelial cells (BECs) are key constituents of the blood-brain barrier (BBB), protecting the brain from pathogens and restricting access of circulatory factors. Yet, because circulatory proteins have prominent age-related effects on adult neurogenesis, neuroinflammation, and cognitive function in mice, we wondered whether BECs receive and potentially relay signals between the blood and brain. Using single-cell RNA sequencing of hippocampal BECs, we discover that capillary BECs-compared with arterial and venous BECs-undergo the greatest transcriptional changes in normal aging, upregulating innate immunity and oxidative stress response pathways. Short-term infusions of aged plasma into young mice recapitulate key aspects of this aging transcriptome, and remarkably, infusions of young plasma into aged mice exert rejuvenation effects on the capillary transcriptome. Together, these findings suggest that the transcriptional age of BECs is exquisitely sensitive to age-related circulatory cues and pinpoint the BBB itself as a promising therapeutic target to treat brain disease.

    View details for DOI 10.1016/j.celrep.2020.03.012

    View details for PubMedID 32234477

  • A single-cell transcriptomic atlas characterizes ageing tissues in the mouse. Nature 2020

    Abstract

    Ageing is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death1. Despite rapid advances over recent years, many of the molecular and cellular processes that underlie the progressive loss of healthy physiology are poorly understood2. To gain a better insight into these processes, here we generate a single-cell transcriptomic atlas across the lifespan of Mus musculus that includes data from 23 tissues and organs. We found cell-specific changes occurring across multiple cell types and organs, as well as age-related changes in the cellular composition of different organs. Using single-cell transcriptomic data, we assessed cell-type-specific manifestations of different hallmarks of ageing-such as senescence3, genomic instability4 and changes in the immune system2. This transcriptomic atlas-which we denote Tabula Muris Senis, or 'Mouse Ageing Cell Atlas'-provides molecular information about how the most important hallmarks of ageing are reflected in a broad range of tissues and cell types.

    View details for DOI 10.1038/s41586-020-2496-1

    View details for PubMedID 32669714

  • Common diseases alter the physiological age-related blood microRNA profile. Nature communications Fehlmann, T., Lehallier, B., Schaum, N., Hahn, O., Kahraman, M., Li, Y., Grammes, N., Geffers, L., Backes, C., Balling, R., Kern, F., Kruger, R., Lammert, F., Ludwig, N., Meder, B., Fromm, B., Maetzler, W., Berg, D., Brockmann, K., Deuschle, C., von Thaler, A., Eschweiler, G. W., Milman, S., Barziliai, N., Reichert, M., Wyss-Coray, T., Meese, E., Keller, A. 2020; 11 (1): 5958

    Abstract

    Aging is a key risk factor for chronic diseases of the elderly. MicroRNAs regulate post-transcriptional gene silencing through base-pair binding on their target mRNAs. We identified nonlinear changes in age-related microRNAs by analyzing whole blood from 1334 healthy individuals. We observed a larger influence of the age as compared to the sex and provide evidence for a shift to the 5' mature form of miRNAs in healthy aging. The addition of 3059 diseased patients uncovered pan-disease and disease-specific alterations in aging profiles. Disease biomarker sets for all diseases were different between young and old patients. Computational deconvolution of whole-blood miRNAs into blood cell types suggests that cell intrinsic gene expression changes may impart greater significance than cell abundance changes to the whole blood miRNA profile. Altogether, these data provide a foundation for understanding the relationship between healthy aging and disease, and for the development of age-specific disease biomarkers.

    View details for DOI 10.1038/s41467-020-19665-1

    View details for PubMedID 33235214

  • Ageing hallmarks exhibit organ-specific temporal signatures. Nature Schaum, N. n., Lehallier, B. n., Hahn, O. n., Pálovics, R. n., Hosseinzadeh, S. n., Lee, S. E., Sit, R. n., Lee, D. P., Losada, P. M., Zardeneta, M. E., Fehlmann, T. n., Webber, J. T., McGeever, A. n., Calcuttawala, K. n., Zhang, H. n., Berdnik, D. n., Mathur, V. n., Tan, W. n., Zee, A. n., Tan, M. n., Pisco, A. O., Karkanias, J. n., Neff, N. F., Keller, A. n., Darmanis, S. n., Quake, S. R., Wyss-Coray, T. n. 2020

    Abstract

    Ageing is the single greatest cause of disease and death worldwide, and understanding the associated processes could vastly improve quality of life. Although major categories of ageing damage have been identified-such as altered intercellular communication, loss of proteostasis and eroded mitochondrial function1-these deleterious processes interact with extraordinary complexity within and between organs, and a comprehensive, whole-organism analysis of ageing dynamics has been lacking. Here we performed bulk RNA sequencing of 17 organs and plasma proteomics at 10 ages across the lifespan of Mus musculus, and integrated these findings with data from the accompanying Tabula Muris Senis2-or 'Mouse Ageing Cell Atlas'-which follows on from the original Tabula Muris3. We reveal linear and nonlinear shifts in gene expression during ageing, with the associated genes clustered in consistent trajectory groups with coherent biological functions-including extracellular matrix regulation, unfolded protein binding, mitochondrial function, and inflammatory and immune response. Notably, these gene sets show similar expression across tissues, differing only in the amplitude and the age of onset of expression. Widespread activation of immune cells is especially pronounced, and is first detectable in white adipose depots during middle age. Single-cell RNA sequencing confirms the accumulation of T cells and B cells in adipose tissue-including plasma cells that express immunoglobulin J-which also accrue concurrently across diverse organs. Finally, we show how gene expression shifts in distinct tissues are highly correlated with corresponding protein levels in plasma, thus potentially contributing to the ageing of the systemic circulation. Together, these data demonstrate a similar yet asynchronous inter- and intra-organ progression of ageing, providing a foundation from which to track systemic sources of declining health at old age.

    View details for DOI 10.1038/s41586-020-2499-y

    View details for PubMedID 32669715

  • Undulating changes in human plasma proteome profiles across the lifespan. Nature medicine Lehallier, B. n., Gate, D. n., Schaum, N. n., Nanasi, T. n., Lee, S. E., Yousef, H. n., Moran Losada, P. n., Berdnik, D. n., Keller, A. n., Verghese, J. n., Sathyan, S. n., Franceschi, C. n., Milman, S. n., Barzilai, N. n., Wyss-Coray, T. n. 2019; 25 (12): 1843–50

    Abstract

    Aging is a predominant risk factor for several chronic diseases that limit healthspan1. Mechanisms of aging are thus increasingly recognized as potential therapeutic targets. Blood from young mice reverses aspects of aging and disease across multiple tissues2-10, which supports a hypothesis that age-related molecular changes in blood could provide new insights into age-related disease biology. We measured 2,925 plasma proteins from 4,263 young adults to nonagenarians (18-95 years old) and developed a new bioinformatics approach that uncovered marked non-linear alterations in the human plasma proteome with age. Waves of changes in the proteome in the fourth, seventh and eighth decades of life reflected distinct biological pathways and revealed differential associations with the genome and proteome of age-related diseases and phenotypic traits. This new approach to the study of aging led to the identification of unexpected signatures and pathways that might offer potential targets for age-related diseases.

    View details for DOI 10.1038/s41591-019-0673-2

    View details for PubMedID 31806903

  • Small-molecule MDM2 antagonists attenuate the senescence-associated secretory phenotype Schaum, N., Wiley, C., Almirah, F., Lopez-Dominguez, J. A., Scott, G., Benz, C., Campisi, J., Davalos, A. R. AMER ASSOC CANCER RESEARCH. 2018
  • Small-molecule MDM2 antagonists attenuate the senescence-associated secretory phenotype SCIENTIFIC REPORTS Wiley, C. D., Schaum, N., Alimirah, F., Lopez-Dominguez, J., Orjalo, A. V., Scott, G., Desprez, P., Benz, C., Davalos, A. R., Campisi, J. 2018; 8: 2410

    Abstract

    Processes that have been linked to aging and cancer include an inflammatory milieu driven by senescent cells. Senescent cells lose the ability to divide, essentially irreversibly, and secrete numerous proteases, cytokines and growth factors, termed the senescence-associated secretory phenotype (SASP). Senescent cells that lack p53 tumor suppressor function show an exaggerated SASP, suggesting the SASP is negatively controlled by p53. Here, we show that increased p53 activity caused by small molecule inhibitors of MDM2, which promotes p53 degradation, reduces inflammatory cytokine production by senescent cells. Upon treatment with the MDM2 inhibitors nutlin-3a or MI-63, human cells acquired a senescence-like growth arrest, but the arrest was reversible. Importantly, the inhibitors reduced expression of the signature SASP factors IL-6 and IL-1α by cells made senescent by genotoxic stimuli, and suppressed the ability of senescent fibroblasts to stimulate breast cancer cell aggressiveness. Our findings suggest that MDM2 inhibitors could reduce cancer progression in part by reducing the pro-inflammatory environment created by senescent cells.

    View details for DOI 10.1038/s41598-018-20000-4

    View details for Web of Science ID 000424087700082

    View details for PubMedID 29402901

    View details for PubMedCentralID PMC5799282

  • Single-cell transcriptomics of 20 mouse organs creates a Tabula Muris. Nature 2018; 562 (7727): 367–72

    Abstract

    Here we present a compendium of single-cell transcriptomic data from the model organism Mus musculus that comprises more than 100,000 cells from 20 organs and tissues. These data represent a new resource for cell biology, reveal gene expression in poorly characterized cell populations and enable the direct and controlled comparison of gene expression in cell types that are shared between tissues, such as T lymphocytes and endothelial cells from different anatomical locations. Two distinct technical approaches were used for most organs: one approach, microfluidic droplet-based 3'-end counting, enabled the survey of thousands of cells at relatively low coverage, whereas the other, full-length transcript analysis based on fluorescence-activated cell sorting, enabled the characterization of cell types with high sensitivity and coverage. The cumulative data provide the foundation for an atlas of transcriptomic cell biology.

    View details for DOI 10.1038/s41586-018-0590-4

    View details for PubMedID 30283141

  • MDM2 small molecule inhibitors synergize with chemotherapeutics to attenuate senescence-driven inflammatory secretion Schaum, N., Almirah, F., Scott, G., Benz, C., Campisi, J., Davalos, A. R. AMER ASSOC CANCER RESEARCH. 2015
  • Simulations of monomeric amyloid beta-peptide (1-40) with varying solution conditions and oxidation state of Met35: Implications for aggregation ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS Brown, A. M., Lemkul, J. A., Schaum, N., Bevan, D. R. 2014; 545: 44–52

    Abstract

    The amyloid β-peptide (Aβ) is a 40-42 residue peptide that is the principal toxic species in Alzheimer's disease (AD). The oxidation of methionine-35 (Met35) to the sulfoxide form (Met35(ox)) has been identified as potential modulator of Aβ aggregation. The role Met35(ox) plays in Aβ neurotoxicity differs among experimental studies, which may be due to inconsistent solution conditions (pH, buffer, temperature). We applied atomistic molecular dynamics (MD) simulations as a means to probe the dynamics of the monomeric 40-residue alloform of Aβ (Aβ40) containing Met35 or Met35(ox) in an effort to resolve the conflicting experimental results. We found that Met35 oxidation decreases the β-strand content of the C-terminal hydrophobic region (residues 29-40), with a specific effect on the secondary structure of residues 33-35, thus potentially impeding aggregation. Further, there is an important interplay between oxidation state and solution conditions, with pH and salt concentration augmenting the effects of oxidation. The results presented here serve to rationalize the conflicting results seen in experimental studies and provide a fundamental biophysical characterization of monomeric Aβ40 dynamics in both reduced and oxidized forms, providing insight into the biochemical mechanism of Aβ40 and oxidative stress related to AD.

    View details for DOI 10.1016/j.abb.2014.01.002

    View details for Web of Science ID 000332751700005

    View details for PubMedID 24418316

  • p53-dependent release of Alarmin HMGB1 is a central mediator of senescent phenotypes JOURNAL OF CELL BIOLOGY Davalos, A. R., Kawahara, M., Malhotra, G. K., Schaum, N., Huang, J., Ved, U., Beausejour, C. M., Coppe, J., Rodier, F., Campisi, J. 2013; 201 (4): 613–29

    Abstract

    Cellular senescence irreversibly arrests proliferation in response to potentially oncogenic stress. Senescent cells also secrete inflammatory cytokines such as IL-6, which promote age-associated inflammation and pathology. HMGB1 (high mobility group box 1) modulates gene expression in the nucleus, but certain immune cells secrete HMGB1 as an extracellular Alarmin to signal tissue damage. We show that nuclear HMGB1 relocalized to the extracellular milieu in senescent human and mouse cells in culture and in vivo. In contrast to cytokine secretion, HMGB1 redistribution required the p53 tumor suppressor, but not its activator ATM. Moreover, altered HMGB1 expression induced a p53-dependent senescent growth arrest. Senescent fibroblasts secreted oxidized HMGB1, which stimulated cytokine secretion through TLR-4 signaling. HMGB1 depletion, HMGB1 blocking antibody, or TLR-4 inhibition attenuated senescence-associated IL-6 secretion, and exogenous HMGB1 stimulated NF-κB activity and restored IL-6 secretion to HMGB1-depleted cells. Our findings identify senescence as a novel biological setting in which HMGB1 functions and link HMGB1 redistribution to p53 activity and senescence-associated inflammation.

    View details for DOI 10.1083/jcb.201206006

    View details for Web of Science ID 000318909500012

    View details for PubMedID 23649808

    View details for PubMedCentralID PMC3653366