Conti et al. report that mTORC1 hyperactivation is a diagnostic marker and therapeutic target in a highly malignant subset of medulloblastomas characterized by p53 mutation and sonic hedgehog activation as well as large cell/anaplastic histology. The cover image shows tumor cells from a murine medulloblastoma visualized using bright-field microscopy to detect pS6 (brown) as a marker for mTORC1 pathway hyperactivation.
We performed next generation sequencing in patients with familial steroid sensitive nephrotic syndrome (SSNS) and identified a homozygous segregating variant (p.H310Y) in the gene encoding clavesin-1 (CLVS1) in a consanguineous family with three affected individuals. Knockdown of the clavesin gene in zebrafish (clvs2) produced edema phenotypes due to disruption of podocyte structure and loss of glomerular filtration barrier integrity that can be rescued by WT CLVS1 but not the p.H310Y variant. Analysis of cultured human podocytes with CRISPR-Cas9 mediated CLVS1 knockout or homozygous H310Y knockin revealed deficits in clathrin-mediated endocytosis and increased susceptibility to apoptosis that could be rescued with corticosteroid treatment, mimicking the steroid-responsiveness observed in SSNS patients. The p.H310Y variant also disrupts binding of clavesin-1 to alpha-tocopherol transfer protein, resulting in increased reactive oxygen species (ROS) accumulation in CLVS1-deficient podocytes. Treatment of CLVS1 knockout or homozygous H310Y knockin podocytes with pharmacological ROS inhibitors restored viability to control levels. Taken together, this data identifies CLVS1 as a candidate gene for SSNS, provides insight into therapeutic effects of corticosteroids on podocyte cellular dynamics and adds to the growing evidence on the importance of endocytosis and oxidative stress regulation to podocyte function.
Brandon M. Lane, Megan Chryst-Stangl, Guanghong Wu, Mohamed Shalaby, Sherif El Desoky, Claire C. Middleton, Kinsie Huggins, Amika Sood, Alejandro Ochoa, Andrew F. Malone, Ricardo Vancini, Sara E. Miller, Gentzon Hall, So Young Kim, David N. Howell, Jameela A. Kari, Rasheed Gbadegesin
Approximately 80% of pancreatic cancer patients suffer from cachexia and one-third die due to cachexia-related complications such as respiratory failure and cardiac arrest. Although there has been considerable research into cachexia mechanisms and interventions, there are, to date, no FDA-approved therapies. A major contributing factor could be the failure of animal models to accurately recapitulate the human condition. In this study, we generated an aged model of pancreatic cancer cachexia to compare cachexia progression in young versus aged tumor-bearing mice. Comparative skeletal muscle transcriptome analyses identified 3-methyladenine (3-MA) as a candidate anti-wasting compound. In vitro analyses confirmed anti-wasting capacity while in vivo analysis revealed potent anti-tumor effects. Transcriptome analyses of 3-MA-treated tumor cells implicated Perp as a 3-MA target gene. We subsequently 1) observed significantly higher expression of Perp in cancer cell lines compared to control cells, 2) noted a survival disadvantage associated with elevated Perp, and 3) found that 3-MA-associated Perp reduction inhibited tumor cell growth. Finally, we provide in vivo evidence that survival benefits conferred by 3-MA administration are independent of its effect on tumor progression. Taken together, we report a novel mechanism linking 3-MA to Perp inhibition, and further implicate PERP as a novel tumor promoting factor in pancreatic cancer.
Aneesha Dasgupta, Paige C. Arneson-Wissink, Rebecca E. Schmitt, Dong Seong Cho, Alexandra M. Ducharme, Tara L. Hogenson, Eugene W. Krueger, William R. Bamlet, Lizhi Zhang, Gina L. Razidlo, Martin E. Fernandez-Zapico, Jason D. Doles
BACKGROUND. >1,500 variants in the ABCA4 locus underlie a heterogeneous spectrum of retinal disorders ranging from aggressive childhood-onset chorioretinopathy to milder, late-onset macular disease. Genotype-phenotype correlation studies have been limited in clinical applicability as patient cohorts are typically small and seldom capture the full natural history of individual genotypes. To overcome these limitations, we constructed a genotype-phenotype correlation matrix that provides quantifiable probabilities of long-term disease outcomes associated with specific ABCA4 genotypes from a large, age-restricted patient cohort. METHODS. The study included 112 unrelated patients ≥50 years of age in whom 2 pathogenic variants were identified after sequencing of the ABCA4 locus. Clinical characterization was performed using the results of best-corrected visual acuity, retinal imaging and full-field electroretinogram testing. RESULTS. Four distinct prognostic groups were defined according to the spatial severity of disease features across the fundus. Recurring genotypes were observed in milder prognoses including those associated with a newly defined class of rare hypomorphic alleles. PVS1 (predicted null) variants were enriched in the most severe prognoses; however, missense variants comprised a larger than expected fraction of these patients. Analysis of allele combinations and their respective prognostic severity, showed that certain variants such as p.(Gly1961Glu), and both rare and frequent hypomorphic alleles, are “clinically dominant” with respect to patient phenotypes irrespective of the allele in trans. CONCLUSION. These results provide much needed structure to the complex genetic and clinical landscape of ABCA4 disease and adds a tool to the clinical repertoire to quantitatively assess individual genotype-specific prognoses in patients.
Winston Lee, Jana Zernant, Pei-Yin Su, Takayuki Nagasaki, Stephen H. Tsang, Rando Allikmets
Nonphlogistic migration of macrophages contributes to the clearance of pathogens and apoptotic cells: critical steps for the resolution of inflammation and return to homeostasis. Angiotensin-(1-7) [Ang-(1-7)] is an heptapeptide of the Renin-Angiotensin system that acts through Mas receptor (MasR). Ang-(1-7) has recently emerged as a novel pro-resolving mediator, yet Ang-(1-7) resolution mechanisms are not fully determined. Herein, Ang-(1-7) stimulated migration of human and murine monocytes/macrophages in a MasR, CCR2 and MEK/ERK1/2-dependent manner. Pleural injection of Ang-(1-7) promoted nonphlogistic mononuclear cell influx alongside increased levels of CCL2, IL-10 and macrophage polarization towards a regulatory phenotype. Ang-(1-7) induction of CCL2 and mononuclear cell migration was also dependent on MasR and MEK/ERK. Noteworthy, MasR was upregulated during resolution phase of inflammation and their pharmacological inhibition or genetic deficiency impaired mononuclear cell recruitment during self-resolving models of LPS pleurisy and E. coli peritonitis. Inhibition/absence of MasR was associated with reduced CCL2 levels, impaired phagocytosis of bacteria, efferocytosis and delayed resolution of inflammation. In summary, we have uncovered a novel pro-resolving feature of Ang-(1-7), namely the recruitment of mononuclear cells favoring efferocytosis, phagocytosis and resolution of inflammation. Mechanistically, cell migration was dependent on MasR, CCR2 and the MEK/ERK pathway.
Isabella Zaidan, Luciana P. Tavares, Michelle A. Sugimoto, Kátia M. Lima, Graziele L. Negreiros-Lima, Lívia C.R. Teixeira, Thais C. Miranda, Bruno V.S. Valiate, Allysson Cramer, Juliana Priscila Vago, Gabriel H. Campolina-Silva, Jéssica A.M. Souza, Laís C. Grossi, Vanessa Pinho, Maria Jose Campagnole-Santos, Robson A .S. Santos, Mauro M. Teixeira, Izabela Galvão, Lirlândia P. Sousa
Immune checkpoint therapy targeting the PD-1/PD-L1 axis is a novel development in anticancer therapy and has been applied to clinical medicine. However, there are still some problems, including a relatively low response rate, innate mechanisms of resistance against immune checkpoint blockades, and the absence of reliable biomarkers to predict responsiveness. In this study of in vitro and in vivo models, we demonstrate that PD-L1-vInt4, a splicing variant of PD-L1, plays a role as a decoy in anti-PD-L1 antibody treatment. First, we showed that PD-L1-vInt4 was detectable in clinical samples and that it was possible to visualize the secreting variants with IHC. By overexpressing the PD-L1-secreted splicing variant on MC38 cells, we observed that an immune-suppressing effect was not induced by their secretion alone. We then demonstrated that PD-L1-vInt4 secretion resisted anti-PD-L1 antibody treatment, compared with wild type PD-L1, which was explicable by the PD-L1-vInt4’s decoying of the anti-PD-L1 antibody. The decoying function of PD-L1 splicing variants may be one of the reasons for cancers being resistant to anti-PD-L1 therapy. Measuring serum PD-L1 levels might be helpful in deciding the therapeutic strategy.
Ray Sagawa, Seiji Sakata, Bo Gong, Yosuke Seto, Ai Takemoto, Satoshi Takagi, Hironori Ninomiya, Noriko Yanagitani, Masayuki Nakao, Mingyon Mun, Ken Uchibori, Makoto Nishio, Yasunari Miyazaki, Yuichi Shiraishi, Seishi Ogawa, Keisuke Kataoka, Naoya Fujita, Kengo Takeuchi, Ryohei Katayama
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