技术资料

Uridine,a pyrimidine nucleoside essential for the synthesis of RNA and bio-membranes,is a crucial element in the regulation of normal physiological processes as well as pathological states. The biological effects of uridine have been associated with the regulation of the cardio-circulatory system,at the reproduction level,with both peripheral and central nervous system modulation and with the functionality of the respiratory system. Furthermore,uridine plays a role at the clinical level in modulating the cytotoxic effects of fluoropyrimidines in both normal and neoplastic tissues. The concentration of uridine in plasma and tissues is tightly regulated by cellular transport mechanisms and by the activity of uridine phosphorylase (UPase),responsible for the reversible phosphorolysis of uridine to uracil. We have recently completed several studies designed to define the mechanisms regulating UPase expression and better characterize the multiple biological effects of uridine. Immunohistochemical analysis and co-purification studies have revealed the association of UPase with the cytoskeleton and the cellular membrane. The characterization of the promoter region of UPase has indicated a direct regulation of its expression by the tumor suppressor gene p53. The evaluation of human surgical specimens has shown elevated UPase activity in tumor tissue compared to paired normal tissue. View Publication

The production of insulin-producing $\beta$ cells from human embryonic stem cells (hESCs) in vitro represents a promising strategy for a cell-based therapy for type 1 diabetes mellitus. To explore the cellular heterogeneity and temporal progression of endocrine progenitors and their progeny,we performed single-cell qPCR on more than 500 cells across several stages of in vitro differentiation of hESCs and compared them with human islets. We reveal distinct subpopulations along the endocrine differentiation path and an early lineage bifurcation toward either polyhormonal cells or $\beta$-like cells. We uncover several similarities and differences with mouse development and reveal that cells can take multiple paths to the same differentiation state,a principle that could be relevant to other systems. Notably,activation of the key $\beta$-cell transcription factor NKX6.1 can be initiated before or after endocrine commitment. The single-cell temporal resolution we provide can be used to improve the production of functional $\beta$ cells. View Publication

In neuronal growth cones,the advancing tips of elongating axons and dendrites,specific protein substrates appear to undergo cycles of posttranslational modification by covalent attachment and removal of long-chain fatty acids. We show here that ongoing fatty acylation can be inhibited selectively by long-chain homologues of the antibiotic tunicamycin,a known inhibitor of N-linked glycosylation. Tunicamycin directly inhibits transfer of palmitate to protein in a cell-free system,indicating that tunicamycin inhibition of protein palmitoylation reflects an action of the drug separate from its previously established effects on glycosylation. Tunicamycin treatment of differentiated PC12 cells or dissociated rat sensory neurons,under conditions in which protein palmitoylation is inhibited,produces a prompt cessation of neurite elongation and induces a collapse of neuronal growth cones. These growth cone responses are rapidly reversed by washout of the antibiotic,even in the absence of protein synthesis,or by addition of serum. Two additional lines of evidence suggest that the effects of tunicamycin on growth cones arise from its ability to inhibit protein long-chain acylation,rather than its previously established effects on protein glycosylation and synthesis. (a) The abilities of different tunicamycin homologues to induce growth cone collapse very systematically with the length of the fatty acyl side-chain of tunicamycin,in a manner predicted and observed for the inhibition of protein palmitoylation. Homologues with fatty acyl moieties shorter than palmitic acid (16 hydrocarbons),including potent inhibitors of glycosylation,are poor inhibitors of growth cone function. (b) The tunicamycin-induced impairment of growth cone function can be reversed by the addition of excess exogenous fatty acid,which reverses the inhibition of protein palmitoylation but has no effect on the inhibition of protein glycosylation. These results suggest an important role for dynamic protein acylation in growth cone-mediated extension of neuronal processes. View Publication

The generation of insulin-producing pancreatic $\beta$ cells from stem cells in vitro would provide an unprecedented cell source for drug discovery and cell transplantation therapy in diabetes. However,insulin-producing cells previously generated from human pluripotent stem cells (hPSC) lack many functional characteristics of bona fide $\beta$ cells. Here,we report a scalable differentiation protocol that can generate hundreds of millions of glucose-responsive $\beta$ cells from hPSC in vitro. These stem-cell-derived $\beta$ cells (SC-$\beta$) express markers found in mature $\beta$ cells,flux Ca(2+) in response to glucose,package insulin into secretory granules,and secrete quantities of insulin comparable to adult $\beta$ cells in response to multiple sequential glucose challenges in vitro. Furthermore,these cells secrete human insulin into the serum of mice shortly after transplantation in a glucose-regulated manner,and transplantation of these cells ameliorates hyperglycemia in diabetic mice. View Publication

Antiviral strategies to inhibit Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) and the pathogenic consequences of COVID-19 are urgently required. Here,we demonstrate that the NRF2 antioxidant gene expression pathway is suppressed in biopsies obtained from COVID-19 patients. Further,we uncover that NRF2 agonists 4-octyl-itaconate (4-OI) and the clinically approved dimethyl fumarate (DMF) induce a cellular antiviral program that potently inhibits replication of SARS-CoV2 across cell lines. The inhibitory effect of 4-OI and DMF extends to the replication of several other pathogenic viruses including Herpes Simplex Virus-1 and-2,Vaccinia virus,and Zika virus through a type I interferon (IFN)-independent mechanism. In addition,4-OI and DMF limit host inflammatory responses to SARS-CoV2 infection associated with airway COVID-19 pathology. In conclusion,NRF2 agonists 4-OI and DMF induce a distinct IFN-independent antiviral program that is broadly effective in limiting virus replication and in suppressing the pro-inflammatory responses of human pathogenic viruses,including SARS-CoV2. View Publication

The protease responsible for the cleavage of poly(ADP-ribose) polymerase and necessary for apoptosis has been purified and characterized. This enzyme,named apopain,is composed of two subunits of relative molecular mass (M(r)) 17K and 12K that are derived from a common proenzyme identified as CPP32. This proenzyme is related to interleukin-1 beta-converting enzyme (ICE) and CED-3,the product of a gene required for programmed cell death in Caenorhabditis elegans. A potent peptide aldehyde inhibitor has been developed and shown to prevent apoptotic events in vitro,suggesting that apopain/CPP32 is important for the initiation of apoptotic cell death. View Publication

In situ molecular architecture analysis of organelles and protein assemblies is essential to understanding the role of individual components and their cellular function,and to engineering new molecular functionalities. Through a super-resolution-driven approach,here we characterize the organization of the ciliary basal foot,an appendage of basal bodies whose main role is to provide a point of anchoring to the microtubule cytoskeleton. Quantitative image analysis shows that the basal foot is organized into three main regions linked by elongated coiled-coil proteins,revealing a conserved modular architecture in primary and motile cilia,but showing distinct features reflecting its specialized functions. Using domain-specific BioID proximity labeling and super-resolution imaging,we identify CEP112 as a basal foot protein and other candidate components of this assembly,aiding future investigations on the role of basal foot across different cilia systems. View Publication

Mutations in nucleotide-binding oligomerization domain-containing protein 2 (NOD2) cause Blau syndrome,an inflammatory disorder characterized by uveitis. The antimicrobial functions of Nod2 are well-established,yet the cellular mechanisms by which dysregulated Nod2 causes uveitis remain unknown. Here,we report a non-conventional,T cell-intrinsic function for Nod2 in suppression of Th17 immunity and experimental uveitis. Reconstitution of lymphopenic hosts with Nod2-/- CD4+ T cells or retina-specific autoreactive CD4+ T cells lacking Nod2 reveals a T cell-autonomous,Rip2-independent mechanism for Nod2 in uveitis. In naive animals,Nod2 operates downstream of TCR ligation to suppress activation of memory CD4+ T cells that associate with an autoreactive-like profile involving IL-17 and Ccr7. Interestingly,CD4+ T cells from two Blau syndrome patients show elevated IL-17 and increased CCR7. Our data define Nod2 as a T cell-intrinsic rheostat of Th17 immunity,and open new avenues for T cell-based therapies for Nod2-associated disorders such as Blau syndrome. View Publication

Protein arginine deiminase 2 (PAD2) plays a key role in the onset and progression of multiple sclerosis,rheumatoid arthritis,and breast cancer. To date,no PAD2-selective inhibitor has been developed. Such a compound will be critical for elucidating the biological roles of this isozyme and may ultimately be useful for treating specific diseases in which PAD2 activity is dysregulated. To achieve this goal,we synthesized a series of benzimidazole-based derivatives of Cl-amidine,hypothesizing that this scaffold would allow access to a series of PAD2-selective inhibitors with enhanced cellular efficacy. Herein,we demonstrate that substitutions at both the N-terminus and C-terminus of Cl-amidine result in {\textgreater}100-fold increases in PAD2 potency and selectivity (30a,41a,and 49a) as well as cellular efficacy (30a). Notably,these compounds use the far less reactive fluoroacetamidine warhead. In total,we predict that 30a will be a critical tool for understanding cellular PAD2 function and sets the stage for treating diseases in which PAD2 activity is dysregulated. View Publication

Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. In addition,the potential adverse effects of CAR T cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a PET reporter gene for imaging of T-cell trafficking in patients with brain tumor. The HSV1-TK enzyme can act as a suicide gene of transduced cells through treatment with the prodrug ganciclovir. Here we report the molecular engineering,imaging,and ganciclovir-mediated destruction of B7H3 CAR T cells incorporating a mutated version of the HSV1-tk gene (sr39tk) with improved enzymatic activity for ganciclovir. The sr39tk gene did not affect B7H3 CAR T-cell functionality and in vitro and in vivo studies in osteosarcoma models showed no significant effect on B7H3 CAR T-cell antitumor activity. PET/CT imaging with 9-(4-[18F]-fluoro-3-[hydroxymethyl]butyl)guanine ([18F]FHBG) of B7H3-sr39tk CAR T cells in an orthotopic model of osteosarcoma revealed tumor homing and systemic immune expansion. Bioluminescence and PET imaging of B7H3-sr39tk CAR T cells confirmed complete tumor ablation with intraperitoneal ganciclovir administration. This imaging and suicide ablation system can provide insight into CAR T-cell migration and proliferation during clinical trials while serving as a suicide switch to limit potential toxicities. SIGNIFICANCE: This study showcases the only genetically engineered system capable of serving the dual role both as an effective PET imaging reporter and as a suicide switch for CAR T cells. View Publication