CRISPR-Cas9 generated SARM1 knockout and epitope tagged mice reveal no role in transcription, despite confirmation of protein expression in macrophages
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE182091 | GEO | 2021/08/14
REPOSITORIES: GEO
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Project description:CRISPR-Cas9 generated SARM1 knockout and epitope tagged mice reveal no role in transcription, despite confirmation of protein expression in macrophages
| PRJNA754436 | ENA
Project description:Axon loss contributes to many common neurodegenerative disorders. In healthy axons, the axon survival factor NMNAT2 inhibits SARM1, the central executioner of programmed axon degeneration. We identified two rare NMNAT2 missense variants in two brothers afflicted with a progressive neuropathy syndrome. The polymorphisms result in amino acid substitutions, V98M and R232Q, which reduce NMNAT2 NAD+-synthetase activity. We generated a mouse model of the human syndrome and found that Nmnat2V98M/Nmnat2R232Q compound-heterozygous CRISPR mice survive to adulthood but develop progressive motor dysfunction, peripheral axon loss, and macrophage infiltration. These disease phenotypes are all SARM1-dependent. Remarkably, macrophage depletion therapy blocks and reverses neuropathic phenotypes in Nmnat2V98M/R232Q mice, identifying a SARM1-dependent neuroimmune mechanism as a key driver of disease pathogenesis. These findings demonstrate that SARM1 induces an inflammatory neuropathy and highlight the potential of immune therapy to treat this rare syndrome and other neurodegenerative conditions associated with NMNAT2 loss and SARM1 activation.
2022-10-25 | GSE210403 | GEO
Project description:The Toll/IL-1R domain-containing adaptor protein SARM1 is expressed primarily in the brain, where it mediates axonal degeneration. Additional roles for SARM1 in a number of other processes including TLR-signaling, viral infection, chemokine expression, and XAF1 expression have also been described. Here we report defects in the induction of Ccl3, Ccl4, and Ccl5 in Sarm1-/- macrophages, for which we were unable to find mechanistic support. We instead show that the 129 congenic locus spans both the chemokine and XAF1 loci, and SNP analysis reveals other remaining 129 genomic regions in both existing knockout strains. New knockout mouse strains generated on a pure B6 genetic background using CRISPR confirmed the role of SARM1 in axonal degeneration and susceptibility WNV infection, but not in chemokine expression or susceptibility to VSV or LACV infection. We show that XAF1 expression differences are due to sequence and isoform polymorphism between B6 and 129 strains. Given its known role in apoptosis, XAF1 polymorphism may account for some phenotypes described in Sarm1-/- mice. RNAseq in the new CRISPR strains reveals changes in transcripts of the mitochondrial electron transport chain and ribosomal proteins, suggesting possible targets of SARM1.
2020-02-23 | GSE136221 | GEO
Project description:Diabetic patients have a high risk of developing skeletal diseases accompanied by diabetic peripheral neuropathy (DPN). In this study, we isolated the role of DPN in skeletal disease with global and conditional knockout models of sterile-α and TIR-motif-containing protein-1 (Sarm1). SARM1, an NADase highly expressed in the nervous system, regulates axon degeneration upon a range of insults, including DPN. Global knockout of Sarm1 prevented DPN, but not skeletal disease, in male mice with type 1 diabetes (T1D). Female wild type mice also developed diabetic bone disease, but without DPN. Unexpectedly, global Sarm1 knockout completely protected female mice from T1D-associated bone suppression and skeletal fragility despite comparable muscle atrophy and hyperglycemia. Global Sarm1 knockout rescued bone health through sustained osteoblast function with abrogation of local oxidative stress responses. This was independent of the neural actions of SARM1, as beneficial effects on bone were lost with neural conditional Sarm1 knockout. This study demonstrates that the onset of skeletal disease occurs rapidly in both male and female mice with T1D completely independent of DPN. In addition, this reveals that clinical SARM1 inhibitors, currently being developed for treatment of neuropathy, may also have benefits for diabetic bone through actions outside of the nervous system.
2024-04-30 | GSE252292 | GEO
Project description:The Toll/IL-1R domain-containing adaptor protein SARM1 is expressed primarily in the brain, where it mediates axonal degeneration. Additional roles for SARM1 in a number of other processes including TLR-signaling, viral infection, chemokine expression, and XAF1 expression have also been described. Here we report defects in the induction of Ccl3, Ccl4, and Ccl5 in Sarm1-/- macrophages, for which we were unable to find mechanistic support. We instead show that the 129 congenic locus spans both the chemokine and XAF1 loci, and SNP analysis reveals other remaining 129 genomic regions in both existing knockout strains. New knockout mouse strains generated on a pure B6 genetic background using CRISPR confirmed the role of SARM1 in axonal degeneration and susceptibility WNV infection, but not in chemokine expression or susceptibility to VSV or LACV infection. We show that XAF1 expression differences are due to sequence and isoform polymorphism between B6 and 129 strains. Given its known role in apoptosis, XAF1 polymorphism may account for some phenotypes described in Sarm1-/- mice. RNAseq in the new CRISPR strains reveals changes in transcripts of the mitochondrial electron transport chain and ribosomal proteins, suggesting possible targets of SARM1.
2020-02-23 | GSE136284 | GEO
Project description:Upon axonal injury, Sterile alpha (SAM) and Toll/interleukin-1 receptor (TIR) motif containing 1 (SARM1) is activated by nicotinamide mononucleotide (NMN) to deplete NAD and consequently promote the process of axon degeneration (AxD). Currently, only the inactive form of SARM1 in its auto-inhibitory conformation has been resolved. The flexibility of the enzymatically active form of SARM1 has so far precluded its structural determination. To solve the problem, we generated a stabilizing nanobody, Nb-C6, that specifically recognized 30 only the NMN-activated form of SARM1. The conformation specificity was verified by immunoprecipitation and surface plasmon resonance. Fluorescently labeled Nb-C6 could immunostain only the activated SARM1 in cells stimulated with CZ-48, a permeant mimetic of NMN. Expression of Nb-C6 in live cells resulted in stabilization of the active form of the endogenous and exogenous SARM1, producing and elevating cellular levels of cyclic ADP-ribose, a calcium messenger. Cryo-EM of the NMN-activated SARM1 complexed by Nb-C6 showed an octameric structure resembling a “blooming lotus” with the ARM domains bending significantly inward and swinging out together with the TIR domains to form the “petals of the lotus”. Nb-C6 bound to the SAM domain of the activated SARM1 and stabilized its Armadillo repeat motif domain. Analyses using hydrogen-deuterium exchange mass spectrometry (HDX-MS), and cross-linking MS (XL-MS) indicate that the activated SARM1 is highly dynamic and flexible and the neighboring TIRs form dimers via the surface close to one BB loop. The Nanobody is thus a valuable tool for delineating the mechanism of activation of SARM1 in AxD and other cellular processes.
2022-11-29 | PXD033528 | Pride
Project description:To study the effect of SARM1 deficiency on brain transcriptome, we performed RNAsequencing of the brain of SARM1-/- mice and their wild type (C57BL/6J) littermates with or without prion infection. We analyzed differential gene expression.
2019-03-01 | GSE124932 | GEO
Project description:The NAD hydrolase (NADase) SARM1 acts as a central executioner of programmed axon death and is a possible therapeutic target for neurodegenerative disorders. While orthosteric inhibitors of SARM1 have been described, this multi-domain enzyme is also subject to intricate forms of autoregulation, suggesting the potential for allosteric modes of inhibition. Previous studies have identified multiple cysteine residues that support SARM1 activation and catalysis, but which of these cysteines, if any, might be selectively targetable by electrophilic small molecules remains unknown. Here we describe the chemical proteomic discovery of a series of tryptoline acrylamides that site-specifically and stereoselectively modify cysteine-311 (C311) in the non-catalytic, autoregulatory armadillo repeat (ARM) domain of SARM1. These covalent compounds inhibit the NADase activity of WT-SARM1, but not C311A or C311S SARM1 mutants, show a high degree of proteome-wide selectivity for SARM1_C311, and stereoselectively block vincristine- and vacor-induced neurite degeneration in primary rodent dorsal root ganglion neurons. Our findings describe selective, covalent inhibitors of SARM1 targeting an allosteric cysteine, pointing to a potentially attractive therapeutic strategy for axon degeneration-dependent forms of neurological disease.
2022-08-22 | PXD035400 | Pride
Project description:SARM1 is a toll/interleukin-1 receptor -domain containing protein, with roles proposed in both innate immunity and neuronal degeneration. Murine SARM1 has been reported to regulate the transcription of chemokines in both neurons and macrophages; however, the extent to which SARM1 contributes to transcription regulation remains to be fully understood. Here, we identify differential gene expression in bone-marrow-derived macrophages (BMDMs) from C57BL/6 congenic 129 ES cell-derived Sarm1-/- mice compared with wild type (WT). However, we found that passenger genes, which are derived from the 129 donor strain of mice that flank the Sarm1 locus, confound interpretation of the results, since many of the identified differentially regulated genes come from this region. To re-examine the transcriptional role of SARM1 in the absence of passenger genes, here we generated three Sarm1-/- mice using CRISPR/Cas9. Treatment of neurons from these mice with vincristine, a chemotherapeutic drug causing axonal degeneration, confirmed SARM1's function in that process; however, these mice also showed that lack of SARM1 has no impact on transcription of genes previously shown to be affected such as chemokines. To gain further insight into SARM1 function, we generated an epitope-tagged SARM1 mouse. In these mice, we observed high SARM1 protein expression in the brain and brainstem and lower but detectable levels in macrophages. Overall, the generation of these SARM1 knockout and epitope-tagged mice has clarified that SARM1 is expressed in mouse macrophages yet has no general role in macrophage transcriptional regulation and has provided important new models to further explore SARM1 function.
| S-EPMC8661062 | biostudies-literature
Project description:Intracellular signaling regulators can be concentrated into membrane-free, higher-ordered protein assemblies to initiate protective responses during stress — a process known as phase transition. Here, we show that a phase transition of the Caenorhabditis elegans Toll/interleukin-1 receptor domain protein (TIR-1), an NAD+ glycohydrolase homologous to mammalian sterile alpha and TIR motif-containing 1 (SARM1), underlies p38 PMK-1 immune pathway activation in C. elegans intestinal epithelial cells. Through visualization of fluorescently labeled TIR-1/SARM1 protein, we demonstrate for the first time that physiologic stresses, both pathogen and non-pathogen, induce multimerization of TIR-1/SARM1 into visible puncta within intestinal epithelial cells. In vitro enzyme kinetic analyses revealed that, like mammalian SARM1, the NAD+ glycohydrolase activity of C. elegans TIR-1 is dramatically potentiated by protein oligomerization and a phase transition. Accordingly, C. elegans with genetic mutations that specifically block either multimerization or the NAD+ glycohydrolase activity of TIR-1/SARM1 fail to induce p38 PMK phosphorylation, are unable to increase immune effector expression, and are dramatically susceptible to bacterial infection. Finally, we demonstrate that low cholesterol stress causes TIR-1/SARM1 to oligomerize into puncta in intestinal epithelial cells and engages its NAD+ glycohydrolase activity, which increases p38 PMK-1 phosphorylation, and primes immune effector induction in a manner that leads to reduced pathogen accumulation in the intestine during a subsequent infection. These data reveal a new adaptive response that allows a metazoan host to anticipate pathogen threats during micronutrient deprivation, a time of relative susceptibility to infection. Thus, a phase transition of TIR-1/SARM1 as a prerequisite for its NAD+ glycohydrolase activity is strongly conserved across millions of years of evolution and is essential for diverse physiological processes in multiple cell types.
2021-12-16 | GSE190585 | GEO