We reported that Shroom3 knockdown, via Fyn inhibition, induced albuminuria with foot process effacement (FPE) without glomerulosclerosis (FSGS) or podocytopenia. Interestingly, knockdown mice had reduced podocyte volumes. Human minimal change disease, where podocyte Fyn inactivation was reported, also showed lower glomerular volumes than FSGS. We hypothesized that lower glomerular volume prevented the progression to podocytopenia. To test this hypothesis, we utilized unilateral- and 5/6th nephrectomy models in Shroom3 knockdown mice. Knockdown mice exhibited less glomerular and podocyte hypertrophy after nephrectomy. FYN-knockdown podocytes had similar reductions in podocyte volume, implying Fyn was downstream of Shroom3. Using SHROOM3- or FYN-knockdown, we confirmed reduced podocyte protein content, along with significantly increased phosphorylated AMP-kinase, a negative regulator of anabolism. AMP-Kinase activation resulted from increased cytoplasmic redistribution of LKB1 in podocytes. Inhibition of AMP-Kinase abolished the reduction in glomerular volume and induced podocytopenia in mice with FPE, suggesting a protective role for AMP-Kinase activation. In agreement with this, treatment of glomerular injury models with AMP-Kinase activators restricted glomerular volume, podocytopenia and progression to FSGS. Glomerular transcriptomes from MCD biopsies also showed significant enrichment of Fyn-inactivation and Ampk-activation vs FSGS glomeruli. In summary, we demonstrate the important role of AMP-Kinase in glomerular volume regulation and podocyte survival. Our data suggest that AMP-Kinase activation adaptively regulates glomerular volume to prevent podocytopenia in the context of podocyte injury.
Khadija Banu, Qisheng Lin, John M. Basgen, Marina Planoutene, Chengguo Wei, Anand C. Reghuvaran, Xuefei Tian, Hongmei Shi, Felipe Garzon, Aitor Garzia, Nicholas Chun, Arun Cumpelik, Andrew D. Santeusanio, Weijia Zhang, Bhaskar Das, Fadi Salem, LI LI, Shuta Ishibe, Lloyd G. Cantley, Lewis Kaufman, Kevin V. Lemley, Zhaohui Ni, John Cijiang He, Barbara Murphy, Madhav C. Menon
MicroRNA-29 (miR-29) is a critical regulator of fibro-inflammatory processes in human diseases. In this study, we find a decrease in miR-29a in experimental and human chronic pancreatitis leading us to investigate the regulatory role of miR-29a/b1 cluster in acute pancreatitis (AP) utilizing a novel conditional miR-29a/b1 knockout (KO) mouse model. miR-29a/b1 sufficient (WT) and deficient (KO) mice were administered with supramaximal caerulein to induce AP and characterized at different timepoints, utilizing an array of immunohistochemical and biochemical analyses for AP parameters. In caerulein-induced WT mice, miR-29a remained dramatically downregulated at injury. Despite high inflammatory milieu, fibrosis and parenchymal disarray in the WT mice during early AP, the pancreata fully restored during recovery. Whereas miR-29a/b1 KO mice showed significantly greater inflammation, lymphocyte infiltration, macrophage polarization and ECM deposition, continuing until late recovery with persistent parenchymal disorganization. The increased pancreatic fibrosis was accompanied by enhanced TGFb1 coupled with persistent aSMA+ PSC activation. Additionally, these mice exhibited higher circulating IL6 and inflammation in lung parenchyma. Together, this collection of studies indicates that depletion of miR-29a/b1 cluster impacts the fibro-inflammatory mechanisms of AP resulting in (i) aggravated pathogenesis, and (ii) delayed recovery from the disease, suggesting a protective role of the molecule against AP.
Shatovisha Dey, Lata M. Udari, Primavera RiveraHernandez, Jason J. Kwon, Brandon Willis, Jeffrey J. Easler, Evan L. Fogel, Stephen Pandol, Janaiah Kota
A role for hereditary influences in the susceptibility for chronic obstructive pulmonary disease (COPD) is widely recognized. Cytotoxic lymphocytes are implicated in COPD pathogenesis, and functions of these leukocytes are modulated by interactions between their killer-cell immunoglobulin-like receptors (KIR) and human leukocyte antigen (HLA)-Class I molecules on target cells. We hypothesized HLA-Class I and KIR inheritance affect risks for COPD. HLA-Class I alleles and KIR genotypes were defined by candidate gene analyses in multiple cohorts of COPD patients (total n=392) and control smokers with normal spirometry (total n=342). Compared to controls, COPD patients had over-representations of HLA-C*07 and activating KIR2DS1, with under-representations of HLA-C*12. Particular HLA-KIR permutations were synergistic; e.g. the presence of HLA-C*07 + KIR2DS1 + HLA-C12null vs. HLAC*07null + KIR2DS1null + HLA-C12 was associated with COPD, especially among HLA-C1 allotype homozygotes (OR=18.5, 95%CI=3.7-90.9, p<0.0001). Cytotoxicity of COPD lymphocytes was more enhanced by KIR stimulation than those of controls (p=0.005) and was correlated with lung function (r=0.44, p=0.004). These data show HLA-C and KIR polymorphisms strongly influence COPD susceptibility and highlight the importance of lymphocyte-mediated cytotoxicity in COPD pathogenesis. Findings here also indicate HLA-KIR typing could stratify at-risk patients and raise possibilities HLA-KIR axis modulation may have therapeutic potential.
Takudzwa Mkorombindo, Thi Tran-Nguyen, Kaiyu Yuan, Yingze Zhang, Jianmin Xue, Gerard J. Criner, Young-il Kim, Joseph M. Pilewski, Amit Gaggar, Michael H. Cho, Frank C. Sciurba, Steven R. Duncan
The mechanisms that link visceral mechanosensation to the perception of internal organ status (i.e., interoception) remain elusive. In response to bladder filling, the urothelium releases ATP, which is hypothesized to stimulate voiding function by communicating the degree of bladder fullness to subjacent tissues including afferent nerve fibers. To determine if PIEZO channels function as mechanosensors in these events, we generated conditional urothelial Piezo1-, Piezo2-, and dual Piezo1/2-knockout (KO) mice. While functional PIEZO1 channels were expressed in all urothelial cell layers, Piezo1-KO mice had a limited phenotype. Piezo2 expression was limited to a small subset of superficial umbrella cells, yet male Piezo2-KO mice exhibited incontinence (i.e., leakage) when their voiding behavior was monitored during their active dark phase. Dual Piezo1/2-KO mice had the most significant phenotype, characterized by decreased urothelial responses to mechanical stimulation, diminished ATP release, bladder hypoactivity in anesthetized Piezo1/2-KO females, but not male ones, and urinary incontinence in both male and female Piezo1/2-KO mice during their dark phase, but not inactive light one. Our studies reveal that the urothelium functions in a sex and circadian manner to link urothelial PIEZO1/2 channel-driven mechanotransduction to normal voiding function and behavior, and in the absence of these signals, bladder dysfunction ensues.
Marianela G. Dalghi, Wily G. Ruiz, Dennis R. Clayton, Nicolas Montalbetti, Stephanie L. Daugherty, Jonathan M. Beckel, Marcelo. D. Carattino, Gerard Apodaca
Avian H7N9 influenza viruses cause sporadic outbreaks of human infections and threaten to cause a major pandemic. The breadth of B cell responses to natural infection and the dominant antigenic sites recognized during first exposure to H7 HA following infection are incompletely understood. Here, we studied the B cell response to H7 HA of two individuals who had recovered from natural H7N9 virus infection. We used competition-binding, hydrogen-deuterium mass spectrometry, and single-particle negative stain electron microscopy to identify the patterns of molecular recognition of the antibody responses to H7 hemagglutinin. We found that circulating H7-reactive B cells recognized a diverse antigenic landscape on the HA molecule, including HA head domain epitopes in antigenic Sites A, B, and the trimer interface-II region and epitopes in the stem region. Most H7 antibodies exhibited little heterosubtypic breadth, but many recognized a wide diversity of unrelated H7 strains. We tested the antibodies for functional activity and identified clones with diverse patterns of inhibition, including neutralizing, hemagglutination or egress inhibiting, or HA trimer-disrupting activities. Thus, the human B cell response to primary H7 natural infection is diverse, highly functional, and broad for recognition of diverse H7 strains.
Iuliia M. Gilchuk, Sandhya Bangaru, Nurgun Kose, Robin G. Bombardi, Andrew Trivette, Sheng Li, Hannah L. Turner, Robert H. Carnahan, Andrew B. Ward, James E. Crowe, Jr.
Myosin Binding Protein-C slow (sMyBP-C) comprises a subfamily of cytoskeletal proteins encoded by MYBPC1 that is expressed in skeletal muscles where it contributes to myosin thick filament stabilization and actomyosin cross-bridge regulation. Recently, our group described the causal association of dominant missense pathogenic variants in MYBPC1 with an early-onset myopathy characterized by generalized muscle weakness, hypotonia, dysmorphia, skeletal deformities, and myogenic tremor occurring in the absence of neuropathy. To mechanistically interrogate the etiologies of this MYBPC1-associated myopathy in vivo, we generated a knock-in mouse model carrying the E248K pathogenic variant. Using a battery of phenotypic, behavioral, and physiological measurements spanning neonatal to young adult life, we find that heterozygous E248K mice faithfully recapitulate the onset and progression of generalized myopathy, tremor occurrence, and skeletal deformities seen in human carriers. Moreover, using a combination of biochemical, ultrastructural, and contractile assessments at the level of the tissue, cell, and myofilaments, we show that the loss-of-function phenotype observed in mutant muscles is primarily driven by disordered and misaligned sarcomeres containing fragmented and out-of-register internal membranes that result in reduced force production and tremor initiation. Collectively, our findings provide mechanistic insights underscoring the E248K-disease pathogenesis and offer a relevant preclinical model for therapeutic discovery.
Janelle Geist Hauserman, Janis Stavusis, Humberto C. Joca, Joel C. Robinett, Laurin Hanft, Jack Vandermeulen, Runchen Zhao, Joseph P Stains, Konstantinos Konstantopoulos, Kerry S. McDonald, Christopher Ward, Aikaterini Kontrogianni-Konstantopoulos
Repetitive mild traumatic brain injuries (mTBI) disrupt central nervous system (CNS) barriers, the erosion of which has been linked to long-term neurodegenerative and psychiatric conditions. Although much attention has been devoted to CNS vasculature following mTBI, little is known about the glia limitans superficialis - a barrier of surface-associated astrocytes that helps protect the CNS parenchyma and maintain homeostasis. Here, we identify the glia limitans superficialis as a crucial barrier surface whose breakdown after acute repeat mTBI facilitates increased cell death and recruitment of peripheral myelomonocytic cells. Using intravital microscopy, we show that brain resident microglia fortify this structure after a single mTBI yet fail to do so following secondary injury, which triggers massive recruitment of myelomonocytic cells from the periphery that contribute to further destruction of the glia limitans superficialis but not cortical cell death. We demonstrate instead that reactive oxygen species (ROS) generated in response to repeat head injury are largely responsible for enhanced cortical cell death, and therapeutic administration of the antioxidant, glutathione, markedly reduces this cell death, preserves the glia limitans, and prevents myelomonocytic cells from entering the brain parenchyma. Collectively, our findings underscore the importance of preserving the glia limitans superficialis after brain injury and offer a therapeutic means to protect this structure and the underlying cortex.
Hannah D. Mason, Alexis M. Johnson, Nicole A. Mihelson, Panagiotis Mastorakos, Dorian B. McGavern
IgA nephropathy is caused by deposition of circulatory IgA1 in the kidney. Hypo-galactosylated IgA1 has the propensity to form poly-IgA aggregates that are prone to deposition. We purified poly-IgA from the plasma of IgA nephrology patients and showed the complex being susceptible to reducing condition, suggesting intermolecular disulfide connections between IgA units. We sought to find the cysteine residue(s) in forming intermolecular disulfide. Naturally assembled dimeric IgA, also known as secretory IgA, involves a J-chain subunit connected with two IgA1 molecules via their penultimate cysteine-471 residue on ‘tailpiece’ segment of IgA heavy chain. It is plausible that, with the absence of J-chain, the cysteine residue of mono-IgA1 might aberrantly form disulfide bond in poly-IgA formation. Mutagenesis confirmed cysteine-471 capable of promoting IgA aggregation. These discoveries prompted us to test thiol-based drugs for stabilizing cysteine. Specifically, cystine-reducing drug cysteamine used for treatment of cystinosis showed a remarkable potency in preventing IgA from self-aggregation. When administrated to rat and mouse models of IgA nephropathy, cysteamine significantly reduced glomerular IgA deposition. Collectively, our results revealed a novel molecular mechanism for aberrant formation of IgA aggregates, to which repurposed cystinosis drug cysteamine was efficacious in preventing renal IgA deposition.
Xinfang Xie, Li Gao, Pan Liu, Jicheng Lv, Wan-Hong Lu, Hong Zhang, Jing Jin
The prevalence of hypertension is increasing globally, while strategies for prevention and treatment of hypertension remain limited. FG-4592 (Roxadustat) is a novel, orally active small-molecule HIF stabilizer, and is being used clinically to treat CKD anemia. In the present study, we evaluate the effects of FG-4592 on hypertension. In an Ang II hypertension model, FG-4592 abolished hypertensive responses, prevented vascular thickening, cardiac hypertrophy, and kidney injury, downregulated AGTR1 expression, and enhanced AGTR2, eNOS, and HIF1α protein levels in the aortas of mice. Additionally, the levels of thiobarbituric acid reactive substances (TBARs) in blood and urine were diminished by FG-4592 treatment. In vascular smooth muscle cells, FG-4592 treatment reduced AGTR1 and increased AGTR2 levels, while preventing Ang II-induced oxidative stress. In vascular endothelial cells, FG-4592 upregulated total and phosphorylated eNOS. Moreover, FG-4592 treatment was hypotensive in L-NAME-induced hypertension. In summary, FG-4592 treatment remarkably ameliorated hypertension and organ injury, possibly through stabilizing HIF1α and subsequently targeting eNOS, AGTR1, AGTR2, and oxidative stress. Therefore, in addition to its role in treating CKD anemia, FG-4592 could be explored as a treatment for hypertension associated with high RAS activity or eNOS defects.
Jing Yu, Shuqin Wang, Wei Shi, Wei Zhou, Yujia Niu, Songming Huang, Yue Zhang, Aihua Zhang, Zhanjun Jia
MicroRNA-150 (miR-150) is downregulated in patients with multiple cardiovascular diseases and in diverse mouse models of heart failure (HF). MiR-150 is significantly associated with HF severity and outcome in humans. We previously reported that miR-150 is activated by β-blocker carvedilol (Carv) and plays a protective role in the heart using a systemic miR-150 knockout (KO) mouse model. However, mechanisms that regulate cell-specific miR-150 expression and function in HF are unknown. Here, we demonstrate that novel conditional cardiomyocyte (CM)-specific miR-150 knockout (miR-150 cKO) in mice worsens maladaptive cardiac remodeling after myocardial infarction (MI). Genome-wide transcriptomic analysis in miR-150 cKO mouse hearts identifies small proline-rich protein 1a (Sprr1a) as a novel target of miR-150. Our studies further reveal that Sprr1a expression is upregulated in CMs isolated from ischemic myocardium and subjected to simulated ischemia/reperfusion, while its expression is downregulated in hearts and CMs by Carv. We also show that left ventricular SPRR1A is upregulated in patients with HF and that Sprr1a knockdown in mice prevents maladaptive post-MI remodeling. Lastly, protective roles of CM miR-150 are in part attributed to the direct and functional repression of pro-apoptotic Sprr1a. Our findings suggest a crucial role for the miR-150/SPRR1A axis in regulating CM function post-MI.
Tatsuya Aonuma, Bruno Moukette, Satoshi Kawaguchi, Nipuni P. Barupala, Marisa N. Sepulveda, Christopher Corr, Yaoliang Tang, Suthat Liangpunsakul, R. Mark Payne, Monte S. Willis, Il-man Kim
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