Search

Two coding variants of apolipoprotein L1 (APOL1), called G1 and G2, explain much of the excess risk of kidney disease in African Americans. While various cytotoxic phenotypes have been reported in experimental models, the proximal mechanism by which G1 and G2 cause kidney disease is poorly understood. Here, we leveraged 3 experimental models and a recently reported small molecule blocker of APOL1 protein, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. In HEK293 cells, we demonstrated that G1-mediated [Na.sup.+] import/[K.sup.+] efflux triggered activation of GPCR/IP3- mediated calcium release from the ER, impaired mitochondrial ATP production, and impaired translation, which were all reversed by VX- 147. In human urine-derived podocyte-like epithelial cells (HUPECs), we demonstrated that G1 caused cytotoxicity that was again reversible by VX-147. Finally, in podocytes isolated from APOL1G1 transgenic mice, we showed that IFN-[gamma]- mediated induction of G1 caused [K.sup.+] efflux, activation of GPCR/IP3 signaling, and inhibition of translation, podocyte injury, and proteinuria, all reversed by VX-147. Together, these results establish APOL1-mediated [Na.sup.+]/[K.sup.+] transport as the proximal driver of APOL1-mediated kidney disease., Introduction Two African apolipoprotein L1 (APOL1) variants, named G1 (p.S342G and p.I384M) and G2 (deletion of p.N388/Y389), appear to have evolved to confer protection against the African sleeping sickness parasite [...]

Background: Perfluorohexane sulfonate (PFHxS) is a frequently detected per- and polyfluoroalkyl substance in most populations, including in individuals who are pregnant, a period critical for early life development. Despite epidemiological evidence of exposure, developmental toxicity, particularly at realistic human exposures, remains understudied. Objectives: We evaluated the effect of gestational exposure to human-relevant body burden of PFHxS on fetal and placental development and explored mechanisms of action combining alternative splicing (AS) and gene expression (GE) analyses. Methods: Pregnant ICR mice were exposed to 0, 0.03, and 0.3 [micro]g/kg/day from gestational day 7 to day 17 via oral gavage. Upon euthanasia, PFHxS distribution was measured using liquid chromatography-tandem mass spectrometry. Maternal and fetal phenotypes were recorded, and histopathology was examined for placenta impairment. Multiomics was adopted by combining AS and GE analyses to unveil disruptions in mRNA quality and quantity. The key metabolite transporters were validated by quantitative real-time PCR (qRT-PCR) for quantification and three-dimensional (3D) structural simulation by AlphaFold2. Targeted metabolomics based on liquid chromatography-tandem mass spectrometry was used to detect amino acid and amides levels in the placenta. Results: Pups developmentally exposed to PFHxS exhibited signs of intrauterine growth restriction (IUGR), characterized by smaller fetal weight and body length (p Discussion: The findings from this study suggest that exposure to human-relevant very-low-dose PFHxS during pregnancy in mice caused IUGR, likely via downregulating of placental amino acid transporters, thereby impairing placental amino acid transportation, resulting in impairment of placental development. Our findings confirm epidemiological findings and call for future attention on the health risk of this persistent yet ubiquitous chemical in the early developmental stage and provide a new approach for understanding gene expression from both quantitative and qualitative omics approaches in toxicological studies. https://doi.org/10.1289/EHP13217, Introduction Per- and polyfluoroalkyl substances (PFAS) are a large group of fluorine-containing chemicals commonly applied in industrial and commercial products, resulting in ubiquitous presence in the environment (1,2) and attracting [...]

Byline: A. Q. Rao, K. S. Bajwa, M. A. Ali, A. Bakhsh, A. Iqbal, A. Latif, T. Husnain, I. A. Nasir and A. A. Shahid Keywords: Herbicides, transgenic cotton, weed [...]

The tight junction protein claudin-2 is upregulated in disease. Although many studies have linked intestinal barrier loss to local and systemic disease, these have relied on macromolecular probes. In vitro analyses show, however, that these probes cannot be accommodated by size- and charge-selective claudin-2 channels. We sought to define the impact of claudin-2 channels on disease. Transgenic claudin-2 overexpression or IL-13-induced claudin-2 upregulation increased intestinal small cation permeability in vivo. IL-13 did not, however, affect permeability in claudin-2-knockout mice. Claudin-2 is therefore necessary and sufficient to effect size- and charge-selective permeability increases in vivo. In chronic disease, T cell transfer colitis severity was augmented or diminished in claudin-2-transgenic or -knockout mice, respectively. We translated the in vitro observation that casein kinase-2 (CK2) inhibition blocks claudin-2 channel function to prevent acute, IL-13-induced, claudin-2-mediated permeability increases in vivo. In chronic immune-mediated colitis, CK2 inhibition attenuated progression in claudin-2-sufficient, but not claudin-2-knockout, mice, i.e., the effect was claudin-2 dependent. Paracellular flux mediated by claudin-2 channels can therefore promote immune-mediated colitis progression. Although the mechanisms by which claudin-2 channels intensify disease remain to be defined, these data suggest that claudin-2 may be an accessible target in immune-mediated disorders, including inflammatory bowel disease., Introduction Barriers that define distinct tissue compartments and separate self from non-self are necessary for survival of multicellular organisms. In some organs, for example the integument and bladder, the barrier [...]

Essential tremor is a common brain disorder affecting millions of people, yet the neuronal mechanisms underlying this prevalent disease remain elusive. Here, we showed that conditional deletion of synaptotagmin-2, the fastest [Ca.sup.2+] sensor for synaptic neurotransmitter release, from parvalbumin neurons in mice caused an action tremor syndrome resembling the core symptom of essential tremor patients. Combining brain region-specific and cell type-specific genetic manipulation methods, we found that deletion of synaptotagmin-2 from excitatory parvalbumin-positive neurons in cerebellar nuclei was sufficient to generate an action tremor. The synaptotagmin-2 deletion converted synchronous into asynchronous neurotransmitter release in projections from cerebellar nuclei neurons onto gigantocellular reticular nucleus neurons, which might produce an action tremor by causing signal oscillations during movement. The tremor was rescued by completely blocking synaptic transmission with tetanus toxin in cerebellar nuclei, which also reversed the tremor phenotype in the traditional harmaline-induced essential tremor model. Using a promising animal model for action tremor, our results thus characterized a synaptic circuit mechanism that may underlie the prevalent essential tremor disorder., Introduction Essential tremor is the most common movement disorder of human patients (1). Clinically, essential tremor is characterized by a 4-Hz to 12-Hz action tremor (2) that affects different body [...]

Allergic asthma is mediated by Th2 responses to inhaled allergens. Although previous experiments indicated that Notch signaling activates expression of the key Th2 transcription factor Gata3, it remains controversial how Notch promotes allergic airway inflammation. Here we show that T cell-specific Notch deficiency in mice prevented house dust mite-driven eosinophilic airway inflammation and significantly reduced Th2 cytokine production, serum IgE levels, and airway hyperreactivity. However, transgenic Gata3 overexpression in Notch-deficient T cells only partially rescued this phenotype. We found that Notch signaling was not required for T cell proliferation or Th2 polarization. Instead, Notch-deficient in vitro-polarized Th2 cells showed reduced accumulation in the lungs upon in vivo transfer and allergen challenge, as Notch-deficient Th2 cells were retained in the lung-draining lymph nodes. Transcriptome analyses and sequential adoptive transfer experiments revealed that while Notch-deficient lymph node Th2 cells established competence for lung migration, they failed to upregulate sphingosine-1-phosphate receptor 1 (S1PR1) and its critical upstream transcriptional activator Kruppel-like factor 2 (KLF2). As this KLF2/S1PR1 axis represents the essential cell-intrinsic regulator of T cell lymph node egress, we conclude that the druggable Notch signaling pathway licenses the Th2 response in allergic airway inflammation via promoting lymph node egress., Introduction Allergic asthma is a common but heterogeneous chronic inflammatory lung disease characterized by type 2 airway inflammation and bronchial hyperreactivity (1). Asthma patients experience symptoms such as wheezing, shortness [...]

As there is growing evidence for the tumor microenvironment's role in tumorigenesis, we investigated the role of fibroblast-expressed kinases in triple-negative breast cancer (TNBC). Using a high-throughput kinome screen combined with 3D invasion assays, we identified fibroblast-expressed PIK3C[delta] (f- PIK3C[delta]) as a key regulator of cancer progression. Although PIK3C[delta] was expressed in primary fibroblasts derived from TNBC patients, it was barely detectable in breast cancer (BC) cell lines. Genetic and pharmacological gain- and loss-of-function experiments verified the contribution of f-PIK3C[delta] in TNBC cell invasion. Integrated secretomics and transcriptomics analyses revealed a paracrine mechanism via which f-PIK3C[delta] confers its protumorigenic effects. Inhibition of f-PIK3C[delta] promoted the secretion of factors, including PLGF and BDNF, that led to upregulation of NR4A1 in TNBC cells, where it acts as a tumor suppressor. Inhibition of PIK3C[delta] in an orthotopic BC mouse model reduced tumor growth only after inoculation with fibroblasts, indicating a role of f-PIK3C[delta] in cancer progression. Similar results were observed in the MMTV-PyMT transgenic BC mouse model, along with a decrease in tumor metastasis, emphasizing the potential immune-independent effects of PIK3C[delta] inhibition. Finally, analysis of BC patient cohorts and TCGA data sets identified f-PIK3C[delta] (protein and mRNA levels) as an independent prognostic factor for overall and disease-free survival, highlighting it as a therapeutic target for TNBC., Introduction Triple-negative breast cancer (TNBC; [ER.sup.-], [PR.sup.-], [HER2.sup.-]) represents a molecularly diverse and highly heterogeneous subtype of breast cancer (BC) (15%-20%) with a poor prognosis and high rates of recurrence [...]