GluD1 is a signal transduction device disguised as an ionotropic receptor
Dai, J;Patzke, C;Liakath-Ali, K;Seigneur, E;Südhof, TC;
PMID: 34135511 | DOI: 10.1038/s41586-021-03661-6
Ionotropic glutamate delta receptors 1 (GluD1) and 2 (GluD2) exhibit the molecular architecture of postsynaptic ionotropic glutamate receptors, but assemble into trans-synaptic adhesion complexes by binding to secreted cerebellins that in turn interact with presynaptic neurexins1-4. It is unclear whether neurexin-cerebellin-GluD1/2 assemblies serve an adhesive synapse-formation function or mediate trans-synaptic signalling. Here we show in hippocampal synapses, that binding of presynaptic neurexin-cerebellin complexes to postsynaptic GluD1 controls glutamate receptor activity without affecting synapse numbers. Specifically, neurexin-1-cerebellin-2 and neurexin-3-cerebellin-2 complexes differentially regulate NMDA (N-methyl-D-aspartate) receptors and AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors by activating distinct postsynaptic GluD1 effector signals. Of note, minimal GluD1 and GluD2 constructs containing only their N-terminal cerebellin-binding and C-terminal cytoplasmic domains, joined by an unrelated transmembrane region, fully control the levels of NMDA and AMPA receptors. The distinct signalling specificity of presynaptic neurexin-1 and neurexin-35,6 is encoded by their alternatively spliced splice site 4 sequences, whereas the regulatory functions of postsynaptic GluD1 are mediated by conserved cytoplasmic sequence motifs spanning 5-13 residues. Thus, GluDs are signalling molecules that regulate NMDA and AMPA receptors by an unexpected transduction mechanism that bypasses their ionotropic receptor architecture and directly converts extracellular neurexin-cerebellin signals into postsynaptic receptor responses.
Massive Perivillous Fibrin Deposition and Chronic Histiocytic Intervillositis a Complication of SARS-CoV-2 Infection
Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society
Marton, T;Hargitai, B;Hunter, K;Pugh, M;Murray, P;
PMID: 34082613 | DOI: 10.1177/10935266211020723
An emerging complication of COVID-19 (SARS-CoV-2) infection is reported. A 23-year-old patient presented with high temperature and reduced fetal movements at 25 + 5/40 weeks of gestation. RT-PCR proved maternal COVID-19 infection. Ultrasound examination confirmed intrauterine death. Placenta histology showed necrosis of the villous trophoblast, associated with Chronic Histiocytic Intervillositis (CHI) and Massive Perivillous Fibrin Deposition (MPFD) with up to 90% - of the intervillous spaces being involved. Immunohistochemistry showed CD68 positive histiocytes in the intervillous spaces and the villous trophoblast was positive for the COVID-19 spike protein. RNA scope signal was indicative of the presence of the viral genome and active viral replication in the villous trophoblastic cells, respectively. MPFD is a gradually developing end-stage disease with various etiology, including autoimmune and alloimmune maternal response to antigens expressed at the feto-maternal interface and frequently accompanies chronic alloimmune villitis or histiocytic intervillositis. Covid-19 infection is associated with similar pattern of histological changes of the placenta leading to placental insufficiency and fetal death. This case report supports maternal- fetal vertical transmission of SARS-CoV-2 virus leading to placental insufficiency and fetal demise. MPFD and CHI appear to be the typical placental histology for SARS-CoV-2 virus infection associated fetal demise.
Rejection of benign melanocytic nevi by nevus-resident CD4+ T cells
Schiferle, EB;Cheon, SY;Ham, S;Son, HG;Messerschmidt, JL;Lawrence, DP;Cohen, JV;Flaherty, KT;Moon, JJ;Lian, CG;Sullivan, RJ;Demehri, S;
PMID: 34162549 | DOI: 10.1126/sciadv.abg4498
Melanoma and melanocytic nevi harbor shared lineage-specific antigens and oncogenic mutations. Yet, the relationship between the immune system and melanocytic nevi is unclear. Using a patient-derived xenograft (PDX) model, we found that 81.8% of the transplanted nevi underwent spontaneous regression, while peripheral skin remained intact. Nevus-resident CD4+ T helper 1 cells, which exhibited a massive clonal expansion to melanocyte-specific antigens, were responsible for nevus rejection. Boosting regulatory T cell suppressive function with low-dose exogenous human interleukin-2 injection or treatment with a human leukocyte antigen (HLA) class II-blocking antibody prevented nevus rejection. Notably, mice with rejected nevus PDXs were protected from melanoma tumor growth. We detected a parallel CD4+ T cell-dominant immunity in clinically regressing melanocytic nevi. These findings reveal a mechanistic explanation for spontaneous nevus regression in humans and posit the activation of nevus-resident CD4+ effector T cells as a novel strategy for melanoma immunoprevention and treatment.
Thyroid-Like Cholangiocarcinoma: Histopathological, Immunohistochemical, In-Situ Hybridization and Molecular Studies on an Uncommon Emerging Entity
International journal of surgical pathology
Hissong, E;Chiu, K;Park, H;Solomon, J;Song, W;Jessurun, J;
PMID: 33939475 | DOI: 10.1177/10668969211013906
Thyroid-like cholangiocarcinoma is a very uncommon variant of peripheral-type cholangiocarcinoma. To date, only 4 prior cases have been reported. The molecular features of this tumor have not been described. We report a case of a 60-year-old woman with a tumor that evolved over a period of 10 years. A left hepatectomy specimen showed an 11 cm tumor that on histology exhibited areas reminiscent of a thyroid tumor with follicular and insular features which were positive on immunohistochemistry for cytokeratin 7 and in-situ hybridization for albumin. A detailed molecular analysis failed to show mutations common to cholangiocarcinomas but revealed frameshift mutations in 2 chromatin-remodeling genes, CREBBP and KMNT2A. This case confirms that thyroid-like cholangiocarcinoma is a histologic variant of this tumor that is associated with relatively low growth. As most cholangiocarcinomas, it is diffusely positive for cytokeratin 7 and albumin by in-situ hybridization. Given its rarity, the molecular alterations in this specific histologic subtype remain to be fully elucidated.
Single-cell RNA sequencing to study vascular diversity and function
Current opinion in hematology
Ma, F;Hernandez, GE;Romay, M;Iruela-Arispe, ML;
PMID: 33714967 | DOI: 10.1097/MOH.0000000000000651
Single-cell RNA sequencing (scRNA-seq) can capture the transcriptional profile of thousands of individual cells concurrently from complex tissues and with remarkable resolution. Either with the goal of seeking information about distinct cell subtypes or responses to a stimulus, the approach has provided robust information and promoted impressive advances in cardiovascular research. The goal of this review is to highlight strategies and approaches to leverage this technology and bypass potential caveats related to evaluation of the vascular cells. As the most recent technological development, details associated with experimental strategies, analysis, and interpretation of scRNA-seq data are still being discussed and scrutinized by investigators across the vascular field. Compilation of this information is valuable for those using the technology but particularly important to those about to start utilizing scRNA-seq to seek transcriptome information of vascular cells. As our field progresses to catalog transcriptomes from distinct vascular beds, it is undeniable that scRNA-seq technology is here to stay. Sharing approaches to improve the quality of cell dissociation procedures, analysis, and a consensus of best practices is critical as information from this powerful experimental platform continues to emerge.
Molecular Analysis of the Kidney From a Patient With COVID-19-Associated Collapsing Glomerulopathy
Meliambro, K;Li, X;Salem, F;Yi, Z;Sun, Z;Chan, L;Chung, M;Chancay, J;Vy, HMT;Nadkarni, G;Wong, JS;Fu, J;Lee, K;Zhang, W;He, JC;Campbell, KN;
PMID: 33942030 | DOI: 10.1016/j.xkme.2021.02.012
Recent Case reports suggest COVID-19 is associated with collapsing glomerulopathy in African Americans with APOL1 risk alleles, however, it is unclear if disease pathogenesis is similar to HIVAN. Here RNA sequencing analysis of a kidney biopsy specimen from a patient with COVID-19-associated collapsing glomerulopathy and APOL1 risk alleles (G1/G1) revealed similar levels of APOL1 and ACE2 mRNA transcripts as compared to 12 control kidney samples downloaded from the GTEx Portal. Whole genome sequencing of the COVID-19-associated collapsing glomerulopathy kidney sample identified four indel gene variants, three of which are of unknown significance with respect to chronic kidney disease and/or FSGS. Molecular profiling of the kidney demonstrated activation of COVID-19-associated cell injury pathways such as inflammation and coagulation. Evidence for direct SARS-CoV-2 infection of kidney cells was lacking, which is consistent with the findings of several recent studies. Interestingly, immunostaining of kidney biopsy sections revealed increased expression of phospho-STAT3 in both COVID-19-associated collapsing glomerulopathy and HIVAN as compared to control kidney tissue. Importantly, IL-6-induced activation of STAT3 may be a targetable mechanism driving COVID-19-associated acute kidney injury.
Epigenomic landscape of human colorectal cancer unveils an aberrant core of pan-cancer enhancers orchestrated by YAP/TAZ
Della Chiara, G;Gervasoni, F;Fakiola, M;Godano, C;D'Oria, C;Azzolin, L;Bonnal, RJP;Moreni, G;Drufuca, L;Rossetti, G;Ranzani, V;Bason, R;De Simone, M;Panariello, F;Ferrari, I;Fabbris, T;Zanconato, F;Forcato, M;Romano, O;Caroli, J;Gruarin, P;Sarnicola, ML;Cordenonsi, M;Bardelli, A;Zucchini, N;Ceretti, AP;Mariani, NM;Cassingena, A;Sartore-Bianchi, A;Testa, G;Gianotti, L;Opocher, E;Pisati, F;Tripodo, C;Macino, G;Siena, S;Bicciato, S;Piccolo, S;Pagani, M;
PMID: 33879786 | DOI: 10.1038/s41467-021-22544-y
Cancer is characterized by pervasive epigenetic alterations with enhancer dysfunction orchestrating the aberrant cancer transcriptional programs and transcriptional dependencies. Here, we epigenetically characterize human colorectal cancer (CRC) using de novo chromatin state discovery on a library of different patient-derived organoids. By exploring this resource, we unveil a tumor-specific deregulated enhancerome that is cancer cell-intrinsic and independent of interpatient heterogeneity. We show that the transcriptional coactivators YAP/TAZ act as key regulators of the conserved CRC gained enhancers. The same YAP/TAZ-bound enhancers display active chromatin profiles across diverse human tumors, highlighting a pan-cancer epigenetic rewiring which at single-cell level distinguishes malignant from normal cell populations. YAP/TAZ inhibition in established tumor organoids causes extensive cell death unveiling their essential role in tumor maintenance. This work indicates a common layer of YAP/TAZ-fueled enhancer reprogramming that is key for the cancer cell state and can be exploited for the development of improved therapeutic avenues.
Distinct uptake, amplification, and release of SARS-CoV-2 by M1 and M2 alveolar macrophages
Lv, J;Wang, Z;Qu, Y;Zhu, H;Zhu, Q;Tong, W;Bao, L;Lv, Q;Cong, J;Li, D;Deng, W;Yu, P;Song, J;Tong, WM;Liu, J;Liu, Y;Qin, C;Huang, B;
PMID: 33850112 | DOI: 10.1038/s41421-021-00258-1
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invades the alveoli, where abundant alveolar macrophages (AMs) reside. How AMs respond to SARS-CoV-2 invasion remains elusive. Here, we show that classically activated M1 AMs facilitate viral spread; however, alternatively activated M2 AMs limit the spread. M1 AMs utilize cellular softness to efficiently take up SARS-CoV-2. Subsequently, the invaded viruses take over the endo-lysosomal system to escape. M1 AMs have a lower endosomal pH, favoring membrane fusion and allowing the entry of viral RNA from the endosomes into the cytoplasm, where the virus achieves replication and is packaged to be released. In contrast, M2 AMs have a higher endosomal pH but a lower lysosomal pH, thus delivering the virus to lysosomes for degradation. In hACE2 transgenic mouse model, M1 AMs are found to facilitate SARS-CoV-2 infection of the lungs. These findings provide insights into the complex roles of AMs during SARS-CoV-2 infection, along with potential therapeutic targets.
Single-cell transcriptomics of human embryos identifies multiple sympathoblast lineages with potential implications for neuroblastoma origin
Kameneva, P;Artemov, AV;Kastriti, ME;Faure, L;Olsen, TK;Otte, J;Erickson, A;Semsch, B;Andersson, ER;Ratz, M;Frisén, J;Tischler, AS;de Krijger, RR;Bouderlique, T;Akkuratova, N;Vorontsova, M;Gusev, O;Fried, K;Sundström, E;Mei, S;Kogner, P;Baryawno, N;Kharchenko, PV;Adameyko, I;
PMID: 33833454 | DOI: 10.1038/s41588-021-00818-x
Characterization of the progression of cellular states during human embryogenesis can provide insights into the origin of pediatric diseases. We examined the transcriptional states of neural crest- and mesoderm-derived lineages differentiating into adrenal glands, kidneys, endothelium and hematopoietic tissue between post-conception weeks 6 and 14 of human development. Our results reveal transitions connecting the intermediate mesoderm and progenitors of organ primordia, the hematopoietic system and endothelial subtypes. Unexpectedly, by using a combination of single-cell transcriptomics and lineage tracing, we found that intra-adrenal sympathoblasts at that stage are directly derived from nerve-associated Schwann cell precursors, similarly to local chromaffin cells, whereas the majority of extra-adrenal sympathoblasts arise from the migratory neural crest. In humans, this process persists during several weeks of development within the large intra-adrenal ganglia-like structures, which may also serve as reservoirs of originating cells in neuroblastoma.
Immune-regulated IDO1-dependent tryptophan metabolism is source of one-carbon units for pancreatic cancer and stellate cells
Newman, AC;Falcone, M;Huerta Uribe, A;Zhang, T;Athineos, D;Pietzke, M;Vazquez, A;Blyth, K;Maddocks, ODK;
PMID: 33831358 | DOI: 10.1016/j.molcel.2021.03.019
Cancer cells adapt their metabolism to support elevated energetic and anabolic demands of proliferation. Folate-dependent one-carbon metabolism is a critical metabolic process underpinning cellular proliferation supplying carbons for the synthesis of nucleotides incorporated into DNA and RNA. Recent research has focused on the nutrients that supply one-carbons to the folate cycle, particularly serine. Tryptophan is a theoretical source of one-carbon units through metabolism by IDO1, an enzyme intensively investigated in the context of tumor immune evasion. Using in vitro and in vivo pancreatic cancer models, we show that IDO1 expression is highly context dependent, influenced by attachment-independent growth and the canonical activator IFNγ. In IDO1-expressing cancer cells, tryptophan is a bona fide one-carbon donor for purine nucleotide synthesis in vitro and in vivo. Furthermore, we show that cancer cells release tryptophan-derived formate, which can be used by pancreatic stellate cells to support purine nucleotide synthesis.
Specific populations of basal ganglia output neurons target distinct brain stem areas while collateralizing throughout the diencephalon
McElvain, LE;Chen, Y;Moore, JD;Brigidi, GS;Bloodgood, BL;Lim, BK;Costa, RM;Kleinfeld, D;
PMID: 33823137 | DOI: 10.1016/j.neuron.2021.03.017
Basal ganglia play a central role in regulating behavior, but the organization of their outputs to other brain areas is incompletely understood. We investigate the largest output nucleus, the substantia nigra pars reticulata (SNr), and delineate the organization and physiology of its projection populations in mice. Using genetically targeted viral tracing and whole-brain anatomical analysis, we identify over 40 SNr targets that encompass a roughly 50-fold range of axonal densities. Retrograde tracing from the volumetrically largest targets indicates that the SNr contains segregated subpopulations that differentially project to functionally distinct brain stem regions. These subpopulations are electrophysiologically specialized and topographically organized and collateralize to common diencephalon targets, including the motor and intralaminar thalamus as well as the pedunculopontine nucleus and the midbrain reticular formation. These findings establish that SNr signaling is organized as dense, parallel outputs to specific brain stem targets concurrent with extensive collateral branches that encompass the majority of SNr axonal boutons.
Thymosin β4 protects against aortic aneurysm via endocytic regulation of growth factor signaling
The Journal of clinical investigation
Munshaw, S;Bruche, S;Redpath, AN;Jones, A;Patel, J;Dubé, KN;Lee, R;Hester, SS;Davies, R;Neal, G;Handa, A;Sattler, M;Fischer, R;Channon, KM;Smart, N;
PMID: 33784254 | DOI: 10.1172/JCI127884
Vascular stability and tone are maintained by contractile smooth muscle cells (VSMCs). However, injury-induced growth factors stimulate a contractile-synthetic phenotypic modulation which increases susceptibility to abdominal aortic aneurysm (AAA). As a regulator of embryonic VSMC differentiation, we hypothesised that Thymosin β4 (Tβ4) may function to maintain healthy vasculature throughout postnatal life. This was supported by the identification of an interaction with Low density lipoprotein receptor related protein 1 (LRP1), an endocytic regulator of PDGF-BB signalling and VSMC proliferation. LRP1 variants have been implicated by genome-wide association studies with risk of AAA and other arterial diseases. Tβ4-null mice displayed aortic VSMC and elastin defects, phenocopying LRP1 mutants, and their compromised vascular integrity predisposed to Angiotensin II-induced aneurysm formation. Aneurysmal vessels were characterised by enhanced VSMC phenotypic modulation and augmented platelet-derived growth factor (PDGF) receptor (PDGFR)β signalling. In vitro, enhanced sensitivity to PDGF-BB, upon loss of Tβ4, associated with dysregulated endocytosis, with increased recycling and reduced lysosomal targeting of LRP1-PDGFRβ. Accordingly, the exacerbated aneurysmal phenotype in Tβ4-null mice was rescued upon treatment with the PDGFRβ antagonist, Imatinib. Our study identifies Tβ4 as a key regulator of LRP1 for maintaining vascular health and provides insights into the mechanisms of growth factor-controlled VSMC phenotypic modulation underlying aortic disease progression.