Human metabolic incorporation of non-human sialic acid (Sia) N-glycolylneuraminic acid into endogenous glycans generates inflammation via pre-existing antibodies, likely contributing to red-meat-induced atherosclerosis acceleration. Exploring if this mechanism affects atherosclerosis in end-stage renal disease (ESRD), we instead found serum accumulation of 2-keto-3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (Kdn), a Sia prominently expressed in cold-blooded vertebrates. Levels of Kdn precursor mannose also increased but within normal range in ESRD patients. Mannose ingestion by healthy volunteers raised urinary mannose and Kdn. Kdn production pathways remain conserved in mammals but were diminished by a M42T substitution in a key biosynthetic enzyme, N-acetylneuraminate synthase. Remarkably, reversion to the ancestral methionine then occurred independently in two lineages, including humans. However, mammalian glycan databases contain no Kdn-glycans. We hypothesize that potential toxicities of excess mannose in mammals is partly buffered by conversion to free Kdn. Thus, mammals likely conserved Kdn biosynthesis and modulated it in lineage-specific manner, not for glycosylation, but to control physiological mannose intermediates/metabolites. However, human cells can be forced to express Kdn-glycans, via genetic mutations enhancing Kdn utilization, or by transfection with fish enzymes producing CMP-Kdn. Antibodies against Kdn-glycans occur in pooled human immunoglobulins. Pathological conditions that elevate Kdn levels could therefore result in antibody-mediated inflammatory pathologies.
Kunio Kawanishi, Sudeshna Saha, Sandra Diaz, Michael Vaill, Aniruddha Sasmal, Shoib S. Siddiqui, Biswa P. Choudhury, Kumar Sharma, Xi Chen, Ian C. Schoenhofen, Chihiro Sato, Ken Kitajima, Hudson H. Freeze, Anja Münster-Kühnel, Ajit Varki
Previous studies have shown that nitric oxide (NO) supplements may prevent bone loss and fractures in preclinical models of estrogen deficiency. However, the mechanisms by which NO modulates bone anabolism remain largely unclear. Argininosuccinate lyase (ASL) is the only mammalian enzyme capable of synthesizing arginine, the sole precursor for nitric oxide synthase (NOS)-dependent NO synthesis. Moreover, ASL is also required for channeling extracellular arginine to NOS for NO production. ASL deficiency (ASLD) is thus a model to study cell-autonomous, NOS-dependent NO deficiency. Here, we report that loss of ASL led to decreased NO production and impairment of osteoblast differentiation. Mechanistically, the bone phenotype was at least in part driven by the loss of NO-mediated activation of the glycolysis pathway in osteoblasts that led to decreased osteoblast differentiation and function. Heterozygous deletion of Caveolin-1, a negative regulator of NO synthesis, restored NO production, osteoblast differentiation, glycolysis, and bone mass in a hypomorphic mouse model of ASLD. The translational significance of these preclinical studies was further reiterated by studies conducted in induced pluripotent stem cells (iPSCs) from an individual with ASLD. Taken together, our findings suggest that ASLD is a unique genetic model for studying NO-dependent osteoblast function and that the NO-glycolysis pathway may be a new target to modulate bone anabolism.
Zixue Jin, Jordan Kho, Brian Dawson, Ming-Ming Jiang, Yuqing Chen-Evenson, Saima Ali, Lindsay C. Burrage, Monica Grover, Donna J. Palmer, Dustin L. Turner, Philip Ng, Sandesh C.S. Nagamani, Brendan Lee
Autosomal dominant "sterile alpha motif domain containing 9 (Samd9) and Samd9L (Samd9/9L) syndromes" are a large subgroup of currently established inherited bone marrow failure syndromes that include MIRAGE, ataxia pancytopenia, and familial monosomy 7 syndromes. Samd9/9L genes are located in tandem on chromosome 7 and have been known to be the genes responsible for myeloid malignancies associated with monosomy 7. Additionally, as interferon-inducible genes, Samd9/9L are crucial for protection against viruses. Samd9/9L syndromes are caused by gain-of-function mutations and develop into infantile myelodysplastic syndromes associated with monosomy 7 (MDS/-7) at extraordinarily high frequencies. We generated mice expressing Samd9LD764N, which mimic the MIRAGE syndrome presenting with growth retardation, a short life, bone marrow failure, and multi-organ degeneration. In hematopoietic cells, Samd9LD764N downregulates the endocytosis of transferrin and c-Kit resulting in a rare cause of anemia and a low bone marrow reconstitutive potential that ultimately causes MDS/-7. By contrast, in non-hematopoietic cells we tested, Samd9LD764N upregulated the endocytosis of EGFR by Ship2 phosphatase translocation to the cytomembrane and activated lysosomes, resulting in the reduced expression of surface receptors and signaling. Thus Samd9/9L is a downstream regulator of interferon that controls receptor metabolism, with constitutive activation leading to multi-organ dysfunction.
Akiko Nagamachi, Akinori Kanai, Megumi Nakamura, Hiroshi Okuda, Akihiko Yokoyama, Satoru Shinriki, Hirotaka Matsui, Toshiya Inaba
Chronic pancreatitis affects over 250,000 people in the US and millions worldwide. It is associated with chronic debilitating pain, pancreatic exocrine failure, high-risk of pancreatic cancer, and usually progresses to diabetes. Treatment options are limited and ineffective. We developed a new potential therapy, wherein a pancreatic ductal infusion of 1-2% acetic acid in mice and non-human primates resulted in a non-regenerative, near-complete ablation of the exocrine pancreas, with complete preservation of the islets. Pancreatic ductal infusion of acetic acid in a mouse model of chronic pancreatitis led to resolution of chronic inflammation and pancreatitis-associated pain. Furthermore, acetic acid-treated animals showed improved glucose tolerance and insulin secretion. The loss of exocrine tissue in this procedure would not typically require further management in patients with chronic pancreatitis because they usually have pancreatic exocrine failure requiring dietary enzyme supplements. Thus, this procedure, which should be readily translatable to humans through an endoscopic retrograde cholangiopancreatography (ERCP), may offer a potential innovative non-surgical therapy for chronic pancreatitis that relieves pain and prevents the progression of pancreatic diabetes.
Mohamed Saleh, Kartikeya Sharma, Ranjeet S. Kalsi, Joseph C. Fusco, Anuradha Sehrawat, Jami L. Saloman, Ping Guo, Ting Zhang, Nada Mohamed, Yan Wang, Krishna Prasadan, George Gittes
Primary membranous nephropathy (pMN) is a leading cause of the nephrotic syndrome in adults. In most cases, this autoimmune kidney disease is associated with autoantibodies against the M-type phospholipase A2 receptor (PLA2R1) expressed on kidney podocytes, but the mechanisms leading to glomerular damage remain elusive. Here, we developed a cell culture model using human podocytes and found that anti-PLA2R1 positive pMN patient sera or isolated IgG4, but not IgG4-depleted sera, induce proteolysis of the two essential podocyte proteins synaptopodin and NEPH1 in the presence of complement, resulting in perturbations of the podocyte cytoskeleton. Specific blockade of the lectin pathway prevented degradation of synaptopodin and NEPH1. Anti-PLA2R1-IgG4 directly bound mannose-binding lectin in a glycosylation-dependent manner. In a cohort of pMN patients, we identified increased levels of galactose-deficient IgG4, which correlated with anti-PLA2R1-titers and podocyte damage induced by patient sera. Assembly of the terminal C5b-9 complement complex and activation of the complement receptors C3aR1 or C5aR1 was required to induce proteolysis of synaptopodin and NEPH1 by two distinct proteolytic pathways, mediated by cysteine and aspartic proteinases, respectively. Together, these results demonstrate a mechanism by which aberrantly glycosylated IgG4 activates the lectin pathway and induces podocyte injury in primary membranous nephropathy.
George Haddad, Johan M. Lorenzen, Hong Ma, Noortje de Haan, Harald Seeger, Christelle Zaghrini, Simone Brandt, Malte Kölling, Urs Wegmann, Bence Kiss, Gábor Pál, Péter Gál, Rudolf P. Wuthrich, Manfred Wuhrer, Laurence H. Beck, David J. Salant, Gérard Lambeau, Andreas D. Kistler
To clarify the function of cyclin A2 in colon homeostasis and colorectal cancer (CRC), we generated mice deficient for cyclin A2 in colonic epithelial cells (CEC). Colons of those mice displayed architectural changes in the mucosa, and signs of inflammation as well as an increased proliferation of CEC associated with the appearance of low- and high-grade dysplasia. The main initial events triggering those alterations in cyclin A2 deficient CEC appear to be abnormal mitoses and DNA damage. Cyclin A2 deletion in CEC promoted the development of dysplasia and adenocarcinomas in the murine colitis-associated cancer model. We next explored the status of cyclin A2 expression in clinical CRC samples at the mRNA and protein level and found higher expression in tumors of stage I and II patients compared to those of stage III and IV. A meta-analysis of 11 transcriptome datasets comprising 2,239 primary CRC tumors displayed different CCNA2 (the mRNA coding for cyclin A2) expression levels among the CRC tumor subtypes with highest in CMS1 and lowest in CMS4. Moreover, high expression of CCNA2 was found to be a new independent prognosis factor for CRC tumors.
Yuchen Guo, Monica Gabola, Rossano Lattanzio, Conception Paul, Valérie Pinet, Ruizhi Tang, Hulya Turali, Julie Bremond, Ciro Longobardi, Chloé Maurizy, Quentin Da Costa, Pascal Finetti, Florence Boissière-Michot, Benjamin Rivière, Céline Lemmers, Séverine Garnier, François Bertucci, Inti Zlobec, Karim Chebli, Jamal Tazi, Rania Azar, Jean-Marie Blanchard, Peter Sicinski, Emilie Mamessier, Bénédicte Lemmers, Michael Hahne
Mutant isocitrate-dehydrogenase-1 (IDH1-R132H; mIDH1) is a hallmark of adult gliomas. Lower grade mIDH1 gliomas are classified into two molecular subgroups: (i) 1p/19q co-deletion/TERT-promoter mutations or (ii) inactivating mutations in α-thalassemia/mental retardation syndrome X-linked (ATRX) and TP53. This work, focuses on gliomas’ subtype harboring mIDH1, TP53 and ATRX inactivation. IDH1-R132H is a gain-of-function mutation that converts α-ketoglutarate into 2-hydroxyglutarate (D-2HG). The role of D-2HG within the tumor microenvironment of mIDH1/mATRX/mTP53 gliomas remains unexplored. Inhibition of D-2HG, when used as monotherapy or in combination with radiation and temozolomide (IR/TMZ), led to increased median survival (MS) of mIDH1 glioma bearing mice. Also, D-2HG inhibition elicited anti-mIDH1 glioma immunological memory. In response to D-2HG inhibition, PD-L1 expression levels on mIDH1-glioma cells increased to similar levels as observed in wild-type-IDH1 gliomas. Thus, we combined D-2HG inhibition/IR/TMZ with anti-PDL1 immune checkpoint-blockade and observed complete tumor regression in 60% of mIDH1 glioma bearing mice. This combination strategy reduced T-cell exhaustion and favored the generation of memory CD8+ T-cells. Our findings demonstrate that metabolic reprogramming elicits anti-mIDH1 glioma immunity, leading to increased MS and immunological memory. Our preclinical data supports the testing of IDH-R132H inhibitors in combination with IR/TMZ and anti-PDL1 as targeted therapy for mIDH1/mATRX/mTP53 glioma patients.
Padma Kadiyala, Stephen V. Carney, Jessica C. Gauss, Maria B. Garcia-Fabiani, Santiago Haase, Mahmoud S. Alghamri, Felipe J. Núñez, Yayuan Liu, Minzhi Yu, Ayman W. Taher, Fernando M. Nunez, Dan Li, Marta B. Edwards, Celina G. Kleer, Henry Appelman, Yilun Sun, Lili Zhao, James J. Moon, Anna Schwendeman, Pedro R. Lowenstein, Maria G. Castro
Androgen receptor (AR) nuclear localization is necessary for its activation as a transcription factor. Defining the mechanisms regulating AR nuclear localization in androgen-sensitive cells, and how these mechanisms are dysregulated in castration-resistant prostate cancer (CRPC) cells are fundamentally important and clinically relevant. According to the classical model of AR intracellular trafficking, androgens induce AR nuclear import and androgen withdrawal causes AR nuclear export. The present study led to an updated model that AR could be imported in the absence of androgens, ubiquitinated, and degraded in the nucleus. Androgen withdrawal caused nuclear AR degradation but not export. In comparison to their parental androgen-sensitive LNCaP prostate cancer cells, castration-resistant C4-2 cells exhibited reduced nuclear AR polyubiquitination and increased nuclear AR level. We previously identified 3-(4-chlorophenyl)-6,7-dihydro-5H-pyrrolo[1,2-a]imidazole (CPPI) in a high throughput screen for its inhibition of androgen-independent AR nuclear localization in CRPC cells. The current study showed that CPPI was a novel competitive AR antagonist capable of enhancing AR interaction with its E3 ligase MDM2, and degradation of AR in the nuclei of CRPC cells. Also, CPPI blocked androgen-independent AR nuclear import. Overall, these findings suggest the feasibility of targeting androgen-independent AR nuclear import and stabilization, two necessary steps leading to AR nuclear localization and activation in CRPC cells, with small molecule inhibitors.
Shidong Lv, Qiong Song, Guang Chen, Erdong Cheng, Wei Chen, Ryan Cole, Zeyu Wu, Laura E. Pascal, Ke Wang, Peter Wipf, Joel B. Nelson, Qiang Wei, Wenhua Huang, Zhou Wang
Unlike pathogens, which attack the host, commensal bacteria create a state of friendly coexistence. Here, we identified a mechanism of bacterial adaptation to the host niche, where they reside. Asymptomatic carrier strains were shown to inhibit RNA Polymerase II (Pol II) in host cells by targeting Ser2 phosphorylation; a step required for productive mRNA elongation. Assisted by a rare, spontaneous loss-of-function mutant from a human carrier, the bacterial NlpD protein was identified as a Pol II inhibitor. After internalization by host cells, NlpD was shown to target constituents of the Pol II phosphorylation complex (RPB1 and PAF1C), attenuating host gene expression. Therapeutic efficacy of the rNlpD protein was demonstrated in a urinary tract infection model, by reduced tissue pathology, accelerated bacterial clearance and attenuated Pol II-dependent gene expression. The findings suggest an intriguing, evolutionarily conserved mechanism for bacterial modulation of host gene expression, with a remarkable therapeutic potential.
Inès Ambite, Nina A. Filenko, Elisabed Zaldastanishvili, Daniel S.C. Butler, Thi Hien Tran, Arunima Chaudhuri, Parisa Esmaeili, Shahram Ahmadi, Sanchari Paul, Björn Wullt, Johannes Putze, Swaine L. Chen, Ulrich Dobrindt, Catharina Svanborg
Identification of neoepitopes that are effective in cancer therapy is a major challenge in creating cancer vaccines. Here, using an entirely unbiased approach, we queried all possible neoepitopes in a mouse cancer model and asked which of those are effective in mediating tumor rejection, and independently, in eliciting a measurable CD8 response. This analysis uncovered a large trove of effective anticancer neoepitopes which have strikingly different properties from conventional epitopes and suggested an algorithm to predict them. It also revealed that our current methods of prediction discard the overwhelming majority of true anticancer neoepitopes. These results from a single mouse model were validated in another, antigenically distinct mouse cancer model, and are consistent with data reported in human studies. Structural modeling showed how the MHC I-presented neoepitopes have an altered conformation, higher stability, or increased exposure to T cell receptors as compared to the un-mutated counterparts. T cells elicited by the active neoepitopes identified here demonstrated a stem-like early dysfunctional phenotype associated with effective responses against viruses and tumors of transgenic mice. These abundant anticancer neoepitopes, which have not been tested in human studies thus far, can be exploited for the generation of personalized human cancer vaccines.
Cory A. Brennick, Mariam M. George, Marmar R. Moussa, Adam T. Hagymasi, Sahar Al Seesi, Tatiana V. Shcheglova, Ryan P. Englander, Grant L.J. Keller, Jeremy L. Balsbaugh, Brian M. Baker, Andrea Schietinger, Ion I. Mandoiu, Pramod K. Srivastava
No posts were found with this tag.