Molecular chaperones are responsible for maintaining cellular homeostasis, and one such chaperone, GRP170, is an endoplasmic reticulum (ER) resident that oversees both protein biogenesis and quality control. We previously discovered that GRP170 regulates the degradation and assembly of the epithelial sodium channel (ENaC), which reabsorbs sodium in the distal nephron and thereby regulates salt-water homeostasis and blood pressure. To define the role of GRP170 and more generally molecular chaperones in kidney physiology, we developed an inducible, nephron-specific GRP170 knockout mouse. Here we show that GRP170 deficiency causes a dramatic phenotype: profound hypovolemia, hyperaldosteronemia, and dysregulation of ion homeostasis, all of which are associated with the loss of ENaC. Additionally, the GRP170 KO mouse exhibits hallmarks of acute kidney injury (AKI). We further demonstrate that the unfolded protein response (UPR) is activated in the GRP170 deficient mouse. Notably, the UPR is also activated in AKI when originating from various other etiologies, including ischemia, sepsis, glomerulonephritis, nephrotic syndrome, and transplant rejection. Our work establishes the central role of GRP170 in kidney homeostasis and directly links molecular chaperone function to kidney injury.
Aidan W. Porter, Diep N. Nguyen, Dennis R. Clayton, Wily G. Ruiz, Stephanie M. Mutchler, Evan C. Ray, Allison L. Marciszyn, Lubika J. Nkashama, Arohan R. Subramanya, Sebastien Gingras, Thomas R. Kleyman, Gerard Apodaca, Linda M. Hendershot, Jeffrey L. Brodsky, Teresa M. Buck
Calcific aortic valve disease (CAVD) is heritable as revealed by recent genome wide association studies. While polymorphisms linked to increased expression of CACNA1C, encoding the CaV1.2 L-type voltage-gated Ca2+ channel, and increased Ca2+ signaling are associated with CAVD, whether increased Ca2+ influx through the druggable CaV1.2 is causal for calcific aortic valve disease is unknown. With surgically removed aortic valves from patients, we confirmed the association between increased CaV1.2 expression and CAVD. We extended our studies with a transgenic mouse model that mimics increased CaV1.2 expression in within aortic valve interstitial cells (VICs). In young mice maintained on normal chow, we observed dystrophic valve lesions that mimic changes found in pre-symptomatic CAVD, and showed activation of chondrogenic and osteogenic transcriptional regulators within these valve lesions. Chronic administration of verapamil, a clinically used CaV1.2 antagonist, slowed the progression of lesion development in vivo. Exploiting VIC cultures we demonstrated that increased Ca2+ influx through CaV1.2 drives signaling programs that lead to myofibroblast activation of VICs and upregulation of genes associated with aortic valve calcification. Our data support a causal role for Ca2+ influx through CaV1.2 in CAVD and suggest that early treatment with Ca2+ channel blockers is an effective therapeutic strategy.
Maiko Matsui, Rihab Bouchareb, Mara Storto, Yasin Hussain, Andrew Gregg, Steven O. Marx, Geoffrey S. Pitt
Commensal microbes critically regulate skeletal homeostasis, yet the impact of specific microbiota communities on osteoimmune response mechanisms is unknown. To discern osteoimmunomodulatory effects imparted by the commensal oral microbiota that are distinct from the systemic microbiota, osteoimmunology studies were performed in both alveolar bone and non-oral skeletal sites of specific-pathogen-free (SPF) vs. germ-free (GF) mice, and SPF mice subjected to saline vs. chlorhexidine oral rinses. SPF vs. GF mice had reduced cortical/trabecular bone and an enhanced pro-osteoclastic phenotype in alveolar bone. Toll-like receptor signaling and TH17 cells that have known pro-osteoclastic actions were increased in alveolar, but not long-bone marrow, of SPF vs. GF mice. MHC class-II antigen presentation genes, activated dendritic cells, and activated CD4+ T-cells were elevated in alveolar, but not long-bone marrow, of SPF vs. GF mice. These findings were substantiated by in vitro allostimulation studies demonstrating increased activated dendritic cells derived from alveolar, but not long-bone marrow, of SPF vs. GF mice. Chlorhexidine antiseptic rinse depleted the oral, but not gut, bacteriome in SPF mice. Findings from saline- vs. chlorhexidine-treated SPF mice corroborated outcomes from SPF vs. GF mice, which reveals that the commensal oral microbiota imparts osteoimmunomodulatory effects separate from the systemic microbiome.
Jessica D. Hathaway-Schrader, Johannes D. Aartun, Nicole A. Poulides, Megan B. Kuhn, Blakely E. McCormick, Michael E. Chew, Emily Huang, Richard P. Darveau, Caroline Westwater, Chad M. Novince
COPD is a debilitating chronic disease and the third cause of mortality worldwide. It is characterized by airway neutrophilia, promoting tissue injury through release of toxic mediators and proteases. Recently, it has been shown that neutrophil-derived extracellular vesicles (EVs) from COPD patient lungs can cause a neutrophil elastase (NE)-dependent COPD-like disease upon transfer to mouse airways. However in vivo preclinical models elucidating the impact of EVs on disease are lacking, delaying opportunities for therapeutic testing. Here, we developed an in vivo preclinical mouse model of lung EV-induced COPD. EVs from in vivo LPS activated mouse neutrophils induced COPD-like disease in naive recipients through an alpha-1 antitrypsin resistant, NE-dependent mechanism. Together, these results show a key pathogenic and mechanistic role for neutrophil-derived EVs in a new mouse model of COPD. Broadly, the in vivo model described herein could be leveraged to develop targeted therapies for severe lung disease.
Camilla Margaroli, Matthew C. Madison, Liliana Viera, Derek W. Russell, Amit Gaggar, Kristopher R. Genschmer, J. Edwin Blalock
Currently, the most effective strategy for dealing with Alzheimer’s disease (AD) is delaying the onset of dementia. Severe hypoglycemia is strongly associated with dementia; however, the effects of recurrent moderate hypoglycemia (RH) on progression of cognitive deficits in diabetic patients with genetic susceptibility to AD remain unclear. Here, we report that insulin-controlled hyperglycemia only slightly aggravated AD-type pathologies and cognitive impairment; however, RH significantly increased neuronal hyperactivity and accelerated the progression of cognitive deficits in streptozotocin(STZ)-induced diabetic APP/PS1 mice. GLUT3-mediated neuronal glucose uptake was not significantly altered under hyperglycemia, but was markedly reduced by RH, which induced excessive mitochondrial fission in the hippocampus. Overexpression of GLUT3 specifically in DG area of hippocampus enhanced mitochondrial function and improved cognitive deficits induced by RH. Activation of TRPC6 increased GLUT3-mediated glucose uptake in brain and alleviated RH-induced cognitive deficits, and inactivation of Ca2+/AMPK pathway was responsible for TRPC6-induced GLUT3 inhibition. Taken together, RH impairs brain GLUT3-mediated glucose uptake and further provokes neuronal mitochondrial dysfunction by inhibiting TRPC6 expression, which then accelerates the progression of cognitive deficits in diabetic APP/PS1 mice. Avoiding RH is essential for glycemic control in diabetic patients, and TRPC6/GLUT3 represent potent targets for delaying the onset of dementia in diabetic patients.
Chengkang He, Qiang Li, Yuanting Cui, Peng Gao, WenTao Shu, Qing Zhou, Lijuan Wang, Li Li, Zongshi Lu, Yu Zhao, Huan Ma, Xiaowei Chen, Hongbo Jia, Hongting Zheng, Gangyi Yang, Daoyan Liu, Martin Tepel, Zhiming Zhu
Lung alveolar type 2 (AT2) cells are progenitors for alveolar type 1 (AT1) cells. Although many factors regulate AT2 cell plasticity, the role of mitochondrial calcium (mCa2+) uptake in controlling AT2 cells remains unclear. We previously identified that the microRNA family, miR-302, supports lung epithelial progenitor cell proliferation and less differentiated phenotypes during development. Here we report that a sustained elevation of miR-302 in adult AT2 cells decreases AT2-to-AT1 cell differentiation during the Streptococcus pneumoniae induced lung injury repair. We identified that miR-302 targets and represses the expression of mitochondrial Ca2+ uptake 1 (MICU1), which regulates mCa2+ uptake through the mCa2+ uniporter channel by acting as a gatekeeper at low cytosolic Ca2+ levels. Our results reveal a marked increase in MICU1 protein expression and decreased mCa2+ uptake during AT2-to-AT1 cell differentiation in the adult lung. Deletion of Micu1 in AT2 cells reduces AT2-to-AT1 cell differentiation during steady-state tissue maintenance and alveolar epithelial regeneration following bacterial pneumonia. These studies indicate that mCa2+ uptake is extensively modulated during AT2-to-AT1 cell differentiation and that MICU1-dependent mCa2+ uniporter channel gating is a prominent mechanism modulating AT2-to-AT1 cell differentiation.
Mir Ali, Xiaoying Zhang, Ryan LaCanna, Dhanendra Tomar, John W. Elrod, Ying Tian
Symmetric, progressive, necrotizing lesions in the brainstem are a defining feature of Leigh syndrome (LS). A mechanistic understanding of the pathogenesis of these lesions has been elusive. Here, we report that leukocyte proliferation is causally involved in the pathogenesis of LS. Depleting leukocytes with a colony-stimulating factor 1 receptor inhibitor disrupts disease progression, including suppression of CNS lesion formation and a substantial extension of survival. Leukocyte depletion rescues diverse symptoms including seizures, respiratory center function, hyperlactemia, and neurologic sequelae. These data reveal a mechanistic explanation for the beneficial effects of mTOR inhibition. More importantly, these findings dramatically alter our understanding of the pathogenesis of LS, demonstrating that immune involvement is causal in disease. This work has significant implications for the mechanisms of mitochondrial disease and may lead to novel therapeutic strategies.
Julia C. Stokes, Rebecca L. Bornstein, Katerina James, Kyung Yeon Park, Kira A. Spencer, Katie Vo, John C. Snell, Brittany M. Johnson, Philip G. Morgan, Margaret M. Sedensky, Nathan A. Baertsch, Simon C. Johnson
BACKGROUND. Prostate cancer is multifocal with distinct molecular subtypes. The utility of genomic subtyping has been challenged due to inter- and intra-focal heterogeneity. We sought to characterize the subtype-defining molecular alterations of primary prostate cancer across all tumor foci within radical prostatectomy (RP) specimens and determine the prevalence of collision tumors. METHODS. From the Early Detection Research Network cohort, we identified 333 prospectively collected RPs from 2010 to 2014 and assessed ERG, SPINK1, PTEN, and SPOP molecular status. We utilized dual ERG/SPINK1 immunohistochemistry, fluorescence in situ hybridization to confirm ERG rearrangements and characterize PTEN deletion, and high-resolution melting curve analysis and Sanger sequencing to determine SPOP mutation status. Analysis of biochemical recurrence-free of patients with collision tumors was conducted using Kaplan-Meier method. RESULTS. Based on index focus alone, ERG, SPINK1, PTEN, and SPOP alterations were identified in 47.5%, 10.8%, 14.3%, and 5.1% of RP specimens, respectively. In 233 multifocal RPs with ERG/SPINK1 status in all foci, 139 (59.7%) had discordant molecular alterations between foci. Collision tumors, as defined by discrepant ERG/SPINK1 status within a single focus, were identified in 29 (9.4%) RP specimens. CONCLUSION. Interfocal molecular heterogeneity was identified in ~60% of multifocal RP specimens and collision tumors were present in ~10%. We present this phenomenon as a model for the intra-focal heterogeneity observed in previous studies and propose future genomic studies screen for collision tumors to better characterize molecular heterogeneity.
Jacqueline Fontugne, Peter Y. Cai, Hussein Alnajar, Bhavneet Bhinder, Kyung Park, Huihui Ye, Shaham Beg, Verena Sailer, Javed Siddiqui, Mirjam Blattner-Johnson, Jaclyn A. Croyle, Zohal Noorzad, Carla Calagua, Theresa Y. MacDonald, Ulrika Axcrona, Mari Bogaard, Karol Axcrona, Douglas S. Scherr, Martin G. Sanda, Bjarne Johannessen, Arul M. Chinnaiyan, Olivier Elemento, Rolf I. Skotheim, Mark A. Rubin, Christopher E. Barbieri, Juan M. Mosquera
Why Multisystem Inflammatory Syndrome in Children (MIS-C) develops after SARS-CoV-2 infection in a subset of children is unknown. We hypothesized that aberrant virus52 specific T-cell responses contribute to MIS-C pathogenesis. We quantified SARS-CoV-2 reactive T-cells, serologic responses against major viral proteins, and cytokine responses from plasma and peripheral blood mononuclear cells in children with convalescent COVID-19, acute MIS-C, and healthy controls. Children with MIS-C had significantly lower virus-specific CD4+ and CD8+ T-cell responses to major SARS-CoV-2 antigens compared with children convalescing from COVID-19. Further, T-cell responses in participants with MIS-C were similar to or lower than those in healthy controls. Serologic responses against spike receptor binding domain (RBD), full-length spike, and nucleocapsid were similar among convalescent COVID-19 and MIS-C, suggesting functional B cell responses. Cytokine profiling demonstrated predominant Th1 polarization of CD4+ T-cells from children with convalescent COVID-19 and MIS-C, although cytokine production was reduced in MIS-C. Our findings support a role for constrained induction of anti-SARS-CoV-2-specific T-cells in the pathogenesis of MIS-C.
Vidisha Singh, Veronica Obregon-Perko, Stacey A. Lapp, Anna M. Horner, Alyssa Brooks, Lisa Macoy, Laila Hussaini, Austin Lu, Theda Gibson, Guido Silvestri, Alba Grifoni, Daniela Weiskopf, Alessandro Sette, Evan J. Anderson, Christina A. Rostad, Ann Chahroudi
Impaired glucose metabolism is observed in obesity and type 2 diabetes. Glucose controls gene expression through the transcription factor ChREBP in liver and adipose tissues. Mlxipl encodes two isoforms, ChREBPα, the full-length form which translocation into the nucleus is under the control of glucose and, ChREBPβ, a constitutively nuclear shorter form. ChREBPβ gene expression in white adipose tissue is strongly associated with insulin sensitivity. Here, we investigated the consequences of ChREBPβ deficiency on insulin action and energy balance. ChREBPβ-deficient male and female C57BL6/J and FVB/N mice were produced using CRISPR-Cas9-mediated gene editing. Unlike global ChREBP deficiency, lack of ChREBPβ showed modest effects on gene expression in adipose tissues and liver, with variations seen chiefly in brown adipose tissue. In mice fed chow and high fat diets, lack of ChREBPβ had moderate effects on body composition and insulin sensitivity. ChREBPβ deficiency did not prevent the whitening of brown adipose tissue reported in total ChREBP knock out mice at thermoneutrality. These findings reveal that ChREBPβ is dispensable for metabolic adaptations to nutritional and thermic challenges.
Emeline Recazens, Geneviève Tavernier, Jérémy Dufau, Camille Bergoglio, Fadila Benhamed, Stéphanie Cassant-Sourdy, Marie-Adeline Marques, Sylvie Caspar-Bauguil, Alice Brion, Laurent Monbrun, Renaud Dentin, Clara Ferrier, Mélanie Leroux, Pierre-Damien Denechaud, Cedric Moro, Jean-Paul Concordet, Catherine Postic, Etienne Mouisel, Dominique Langin
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