Li S, Uno Y, Rudolph U, Cobb J, Liu J, Anderson T, Levy D, Balu DT, Coyle JT.
PMID: 29305854 | DOI: 10.1016/j.bcp.2017.12.023
D-Serine is a co-agonist at forebrain N-methyl-D-aspartate receptors (NMDAR) and is synthesized by serine racemase (SR). Although D-serine and SR were originally reported to be localized to glia, recent studies have provided compelling evidence that under healthy physiologic conditions both are localized primarily in neurons. However, in pathologic conditions, reactive astrocytes can also express SR and synthesize D-serine. Since cultured astrocytes exhibit features of reactive astrocytes, we have characterized D-serine synthesis and the expression of enzymes involved in its disposition in primary glial cultures. The levels of SR were quite low early in culture and increased markedly in all astrocytes with the duration in vitro. The concentration of D-serine in the culture medium increased in parallel with SR expression in the astrocytes. Microglia, identified by robust expression of Iba1, did not express SR. While the levels of glial fibrillary acidic protein (GFAP), glycine decarboxylase (GLDC) and phosphoglycerate dehydrogenase (PHGDH), the initial enzyme in the pathway converting glycine to L-serine, remained constant in culture, the expression of lipocalin-2, a marker for pan-reactive astrocytes, increased several-fold. The cultured astrocytes also expressed Complement-3a, a marker for a subpopulation of reactive astrocytes (A1). Astrocytes grown from mice with a copy number variant associated with psychosis, which have four copies of the GLDC gene, showed a more rapid production of D-serine and a reduction of glycine in the culture medium. These results substantiate the conclusion that A1 reactive astrocytes express SR and release D-serine under pathologic conditions, which may contribute to their neurotoxic effects by activating extra-synaptic NMDARs.
Lin, YF;Schang, G;Buddle, ERS;Schultz, H;Willis, TL;Ruf-Zamojski, F;Zamojski, M;Mendelev, N;Boehm, U;Sealfon, SC;Andoniadou, CL;Bernard, DJ;
PMID: 35957608 | DOI: 10.1210/endocr/bqac131
The inhibins control reproduction by suppressing follicle-stimulating hormone synthesis in pituitary gonadotrope cells. The newly discovered inhibin B co-receptor, TGFBR3L, is selectively and highly expressed in gonadotropes in both mice and humans. Here, we describe our initial characterization of mechanisms controlling cell-specific Tgfbr3l/TGFBR3L transcription. We identified two steroidogenic factor 1 (SF-1 or NR5A1) cis-elements in the proximal Tgfbr3l promoter in mice. SF-1 induction of murine Tgfbr3l promoter-reporter activity was inhibited by mutations in one or both sites in heterologous cells. In homologous cells, mutation of these cis-elements or depletion of endogenous SF-1 similarly decreased reporter activity. We observed nearly identical results when using a human TGFBR3L promoter-reporter. The Tgfbr3l gene was tightly compacted and Tgfbr3l mRNA expression was essentially absent in gonadotropes of SF-1 (Nr5a1) conditional knockout mice. During murine embryonic development, Tgfbr3l precedes Nr5a1 expression, though the two transcripts are fully co-localized by embryonic day 18.5 and thereafter. Collectively, these data indicate that SF-1 directly regulates Tgfbr3l/TGFBR3L transcription and is required for post-natal expression of the gene in gonadotropes.
Elkjaer ML, Frisch T, Reynolds R, Kacprowski T, Burton M, Kruse TA, Thomassen M, Baumbach J, Illes Z.
PMID: 31023379 | DOI: 10.1186/s40478-019-0709-3
The heterogeneity of multiple sclerosis is reflected by dynamic changes of different lesion types in the brain white matter (WM). To identify potential drivers of this process, we RNA-sequenced 73 WM areas from patients with progressive MS (PMS) and 25 control WM. Lesion endophenotypes were described by a computational systems medicine analysis combined with RNAscope, immunohistochemistry, and immunofluorescence. The signature of the normal-appearing WM (NAWM) was more similar to control WM than to lesions: one of the six upregulated genes in NAWM was CD26/DPP4 expressed by microglia. Chronic active lesions that become prominent in PMS had a signature that were different from all other lesion types, and were differentiated from them by two clusters of 62 differentially expressed genes (DEGs). An upcoming MS biomarker, CHI3L1 was among the top ten upregulated genes in chronic active lesions expressed by astrocytes in the rim. TGFβ-R2 was the central hub in a remyelination-related protein interaction network, and was expressed there by astrocytes. We used de novo networks enriched by unique DEGs to determine lesion-specific pathway regulation, i.e. cellular trafficking and activation in active lesions; healing and immune responses in remyelinating lesions characterized by the most heterogeneous immunoglobulin gene expression; coagulation and ion balance in inactive lesions; and metabolic changes in chronic active lesions. Because we found inverse differential regulation of particular genes among different lesion types, our data emphasize that omics related to MS lesions should be interpreted in the context of lesion pathology. Our data indicate that the impact of molecular pathways is substantially changing as different lesions develop. This was also reflected by the high number of unique DEGs that were more common than shared signatures. A special microglia subset characterized by CD26 may play a role in early lesion development, while astrocyte-derived TGFβ-R2 and TGFβ pathways may be drivers of repair in contrast to chronic tissue damage. The highly specific mechanistic signature of chronic active lesions indicates that as these lesions develop in PMS, the molecular changes are substantially skewed: the unique mitochondrial/metabolic changes and specific downregulation of molecules involved in tissue repair may reflect a stage of exhaustion.
The journal of headache and pain
Zhang, L;Lu, C;Kang, L;Li, Y;Tang, W;Zhao, D;Yu, S;Liu, R;
PMID: 35033010 | DOI: 10.1186/s10194-021-01382-9
Astrocytic activation might play a significant role in the central sensitization of chronic migraine (CM). However, the temporal characteristics of the astrocytic activation in the trigeminal nucleus caudalis (TNC) and the molecular mechanism under the process remain not fully understood. Therefore, this study aims to investigate the duration and levels change of astrocytic activation and to explore the correlation between astrocytic activation and the levels change of cytokines release.We used a mice model induced by recurrent dural infusion of inflammatory soup (IS). The variation with time of IS-induced mechanical thresholds in the periorbital and hind paw plantar regions were evaluated using the von Frey filaments test. We detected the expression profile of glial fibrillary acidic protein (GFAP) in the TNC through immunofluorescence staining and western blot assay. We also investigated the variation with time of the transcriptional levels of GFAP and ionized calcium binding adapter molecule 1 (Iba1) through RNAscope in situ hybridization analysis. Then, we detected the variation with time of cytokines levels in the TNC tissue extraction and serum, including c-c motif chemokine ligand 2 (CCL2), c-c motif chemokine ligand 5 (CCL5), c-c motif chemokine ligand 7 (CCL7), c-c motif chemokine ligand 12 (CCL12), c-x-c motif chemokine ligand 1 (CXCL1), c-x-c motif chemokine ligand 13 (CXCL13), interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), macrophage colony-stimulating factor (M-CSF), interleukin 1beta (IL-1β), interleukin 6 (IL-6), interleukin 10 (IL-10), interleukin 17A (IL-17A).Recurrent IS infusion resulted in cutaneous allodynia in both the periorbital region and hind paw plantar, ranging from 5 d (after the second IS infusion) to 47 d (28 d after the last infusion) and 5 d to 26 d (7 d after the last infusion), respectively. The protein levels of GFAP and messenger ribonucleic acid (mRNA) levels of GFAP and Iba1 significantly increased and sustained from 20 d to 47 d (1 d to 28 d after the last infusion), which was associated with the temporal characteristics of astrocytic activation in the TNC. The CCL7 levels in the TNC decreased from 20 d to 47 d. But the CCL7 levels in serum only decreased on 20 d (1 d after the last infusion). The CCL12 levels in the TNC decreased on 22 d (3 d after the last infusion) and 33 d (14 d after the last infusion). In serum, the CCL12 levels only decreased on 22 d. The IL-10 levels in the TNC increased on 20 d.Our results indicate that the astrocytic activation generated and sustained in the IS-induced mice model from 1 d to 28 d after the last infusion and may contribute to the pathology through modulating CCL7, CCL12, and IL-10 release.
Le, MT;Shon, HK;Nguyen, HP;Lee, CH;Kim, KS;Na, HK;Lee, TG;
PMID: 35696262 | DOI: 10.1021/acs.analchem.2c00676
The importance of multi-omic-based approaches to better understand diverse pathological mechanisms including neurodegenerative diseases has emerged. Spatial information can be of great help in understanding how biomolecules interact pathologically and in elucidating target biomarkers for developing therapeutics. While various analytical methods have been attempted for imaging-based biomolecule analysis, a multi-omic approach to imaging remains challenging due to the different characteristics of biomolecules. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful tool due to its sensitivity, chemical specificity, and high spatial resolution in visualizing chemical information in cells and tissues. In this paper, we suggest a new strategy to simultaneously obtain the spatial information of various kinds of biomolecules that includes both labeled and label-free approaches using ToF-SIMS. The enzyme-assisted labeling strategy for the targets of interest enables the sensitive and specific imaging of large molecules such as peptides, proteins, and mRNA, a task that has been, to date, difficult for any MS analysis. Together with the strength of the analytical performance of ToF-SIMS in the label-free tissue imaging of small biomolecules, the proposed strategy allows one to simultaneously obtain integrated information of spatial distribution of metabolites, lipids, peptides, proteins, and mRNA at a high resolution in a single measurement. As part of the suggested strategy, we present a sample preparation method suitable for MS imaging. Because a comprehensive method to examine the spatial distribution of multiple biomolecules in tissues has remained elusive, our strategy can be a useful tool to support the understanding of the interactions of biomolecules in tissues as well as pathological mechanisms.
Jiwaji, Z;Tiwari, SS;Avilés-Reyes, RX;Hooley, M;Hampton, D;Torvell, M;Johnson, DA;McQueen, J;Baxter, P;Sabari-Sankar, K;Qiu, J;He, X;Fowler, J;Febery, J;Gregory, J;Rose, J;Tulloch, J;Loan, J;Story, D;McDade, K;Smith, AM;Greer, P;Ball, M;Kind, PC;Matthews, PM;Smith, C;Dando, O;Spires-Jones, TL;Johnson, JA;Chandran, S;Hardingham, GE;
PMID: 35013236 | DOI: 10.1038/s41467-021-27702-w
Alzheimer's disease (AD) alters astrocytes, but the effect of Aß and Tau pathology is poorly understood. TRAP-seq translatome analysis of astrocytes in APP/PS1 ß-amyloidopathy and MAPTP301S tauopathy mice revealed that only Aß influenced expression of AD risk genes, but both pathologies precociously induced age-dependent changes, and had distinct but overlapping signatures found in human post-mortem AD astrocytes. Both Aß and Tau pathology induced an astrocyte signature involving repression of bioenergetic and translation machinery, and induction of inflammation pathways plus protein degradation/proteostasis genes, the latter enriched in targets of inflammatory mediator Spi1 and stress-activated cytoprotective Nrf2. Astrocyte-specific Nrf2 expression induced a reactive phenotype which recapitulated elements of this proteostasis signature, reduced Aß deposition and phospho-tau accumulation in their respective models, and rescued brain-wide transcriptional deregulation, cellular pathology, neurodegeneration and behavioural/cognitive deficits. Thus, Aß and Tau induce overlapping astrocyte profiles associated with both deleterious and adaptive-protective signals, the latter of which can slow patho-progression.
Ichiki, T;Wang, T;Kennedy, A;Pool, AH;Ebisu, H;Anderson, DJ;Oka, Y;
PMID: 35082448 | DOI: 10.1038/s41586-021-04359-5
Ingested food and water stimulate sensory systems in the oropharyngeal and gastrointestinal areas before absorption1,2. These sensory signals modulate brain appetite circuits in a feed-forward manner3-5. Emerging evidence suggests that osmolality sensing in the gut rapidly inhibits thirst neurons upon water intake. Nevertheless, it remains unclear how peripheral sensory neurons detect visceral osmolality changes, and how they modulate thirst. Here we use optical and electrical recording combined with genetic approaches to visualize osmolality responses from sensory ganglion neurons. Gut hypotonic stimuli activate a dedicated vagal population distinct from mechanical-, hypertonic- or nutrient-sensitive neurons. We demonstrate that hypotonic responses are mediated by vagal afferents innervating the hepatic portal area (HPA), through which most water and nutrients are absorbed. Eliminating sensory inputs from this area selectively abolished hypotonic but not mechanical responses in vagal neurons. Recording from forebrain thirst neurons and behavioural analyses show that HPA-derived osmolality signals are required for feed-forward thirst satiation and drinking termination. Notably, HPA-innervating vagal afferents do not sense osmolality itself. Instead, these responses are mediated partly by vasoactive intestinal peptide secreted after water ingestion. Together, our results reveal visceral hypoosmolality as an important vagal sensory modality, and that intestinal osmolality change is translated into hormonal signals to regulate thirst circuit activity through the HPA pathway.
Arteriosclerosis, thrombosis, and vascular biology
Chou, EL;Chaffin, M;Simonson, B;Pirruccello, JP;Akkad, AD;Nekoui, M;Lino Cardenas, CL;Bedi, KC;Nash, C;Juric, D;Stone, JR;Isselbacher, EM;Margulies, KB;Klattenhoff, C;Ellinor, PT;Lindsay, ME;
PMID: 36172868 | DOI: 10.1161/ATVBAHA.122.317953
Mural cells in ascending aortic aneurysms undergo phenotypic changes that promote extracellular matrix destruction and structural weakening. To explore this biology, we analyzed the transcriptional features of thoracic aortic tissue.Single-nuclear RNA sequencing was performed on 13 samples from human donors, 6 with thoracic aortic aneurysm, and 7 without aneurysm. Individual transcriptomes were then clustered based on transcriptional profiles. Clusters were used for between-disease differential gene expression analyses, subcluster analysis, and analyzed for intersection with genetic aortic trait data.We sequenced 71 689 nuclei from human thoracic aortas and identified 14 clusters, aligning with 11 cell types, predominantly vascular smooth muscle cells (VSMCs) consistent with aortic histology. With unbiased methodology, we found 7 vascular smooth muscle cell and 6 fibroblast subclusters. Differentially expressed genes analysis revealed a vascular smooth muscle cell group accounting for the majority of differential gene expression. Fibroblast populations in aneurysm exhibit distinct behavior with almost complete disappearance of quiescent fibroblasts. Differentially expressed genes were used to prioritize genes at aortic diameter and distensibility genome-wide association study loci highlighting the genes JUN, LTBP4 (latent transforming growth factor beta-binding protein 1), and IL34 (interleukin 34) in fibroblasts, ENTPD1, PDLIM5 (PDZ and LIM domain 5), ACTN4 (alpha-actinin-4), and GLRX in vascular smooth muscle cells, as well as LRP1 in macrophage populations.Using nuclear RNA sequencing, we describe the cellular diversity of healthy and aneurysmal human ascending aorta. Sporadic aortic aneurysm is characterized by differential gene expression within known cellular classes rather than by the appearance of novel cellular forms. Single-nuclear RNA sequencing of aortic tissue can be used to prioritize genes at aortic trait loci.
Morrow, MR;Batchuluun, B;Wu, J;Ahmadi, E;Leroux, JM;Mohammadi-Shemirani, P;Desjardins, EM;Wang, Z;Tsakiridis, EE;Lavoie, DCT;Reihani, A;Smith, BK;Kwiecien, JM;Lally, JSV;Nero, TL;Parker, MW;Ask, K;Scott, JW;Jiang, L;Paré, G;Pinkosky, SL;Steinberg, GR;
PMID: 35675800 | DOI: 10.1016/j.cmet.2022.05.004
Elevated liver de novo lipogenesis contributes to non-alcoholic steatohepatitis (NASH) and can be inhibited by targeting acetyl-CoA carboxylase (ACC). However, hypertriglyceridemia limits the use of pharmacological ACC inhibitors as a monotherapy. ATP-citrate lyase (ACLY) generates acetyl-CoA and oxaloacetate from citrate, but whether inhibition is effective for treating NASH is unknown. Here, we characterize a new mouse model that replicates many of the pathological and molecular drivers of NASH and find that genetically inhibiting ACLY in hepatocytes reduces liver malonyl-CoA, oxaloacetate, steatosis, and ballooning as well as blood glucose, triglycerides, and cholesterol. Pharmacological inhibition of ACLY mirrors genetic inhibition but has additional positive effects on hepatic stellate cells, liver inflammation, and fibrosis. Mendelian randomization of human variants that mimic reductions in ACLY also associate with lower circulating triglycerides and biomarkers of NASH. These data indicate that inhibiting liver ACLY may be an effective approach for treatment of NASH and dyslipidemia.
