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1.
Genes Dev ; 2022 Aug 25.
Article in English | MEDLINE | ID: mdl-36008138

ABSTRACT

Stem cells are fundamental units of tissue remodeling whose functions are dictated by lineage-specific transcription factors. Home to epidermal stem cells and their upward-stratifying progenies, skin relies on its secretory functions to form the outermost protective barrier, of which a transcriptional orchestrator has been elusive. KLF5 is a Krüppel-like transcription factor broadly involved in development and regeneration whose lineage specificity, if any, remains unclear. Here we report KLF5 specifically marks the epidermis, and its deletion leads to skin barrier dysfunction in vivo. Lipid envelopes and secretory lamellar bodies are defective in KLF5-deficient skin, accompanied by preferential loss of complex sphingolipids. KLF5 binds to and transcriptionally regulates genes encoding rate-limiting sphingolipid metabolism enzymes. Remarkably, skin barrier defects elicited by KLF5 ablation can be rescued by dietary interventions. Finally, we found that KLF5 is widely suppressed in human diseases with disrupted epidermal secretion, and its regulation of sphingolipid metabolism is conserved in human skin. Altogether, we established KLF5 as a disease-relevant transcription factor governing sphingolipid metabolism and barrier function in the skin, likely representing a long-sought secretory lineage-defining factor across tissue types.

2.
Epilepsy Res ; 159: 106255, 2020 01.
Article in English | MEDLINE | ID: mdl-31855828

ABSTRACT

In recent years there has been increasing interest in applying network science tools to EEG data. At the 2018 American Epilepsy Society conference in New Orleans, LA, the yearly session of the Engineering and Neurostimulation Special Interest Group focused on emerging, translational technologies to analyze seizure networks. Each speaker demonstrated practical examples of how network tools can be utilized in clinical care and provide additional data to help care for patients with intractable epilepsy. The groups presented advances using tools from functional connectivity, control theory, and graph theory to analyze human EEG data. These tools have great potential to augment clinical interpretation of EEG signals.


Subject(s)
Brain/physiopathology , Epilepsy/physiopathology , Nerve Net/physiopathology , Brain Mapping , Electroencephalography , Humans
3.
Arterioscler Thromb Vasc Biol ; 33(8): 1861-71, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23702660

ABSTRACT

OBJECTIVE: Mice genetically deficient in endothelial nitric oxide synthase (eNOS(-/-)) are hypertensive with lower circulating nitrite levels, indicating the importance of constitutively produced nitric oxide (NO•) to blood pressure regulation and vascular homeostasis. Although the current paradigm holds that this bioactivity derives specifically from the expression of eNOS in endothelium, circulating blood cells also express eNOS protein. A functional red cell eNOS that modulates vascular NO• signaling has been proposed. APPROACH AND RESULTS: To test the hypothesis that blood cells contribute to mammalian blood pressure regulation via eNOS-dependent NO• generation, we cross-transplanted wild-type and eNOS(-/-) mice, producing chimeras competent or deficient for eNOS expression in circulating blood cells. Surprisingly, we observed a significant contribution of both endothelial and circulating blood cell eNOS to blood pressure and systemic nitrite levels, the latter being a major component of the circulating NO• reservoir. These effects were abolished by the NOS inhibitor L-NG-nitroarginine methyl ester and repristinated by the NOS substrate L-arginine and were independent of platelet or leukocyte depletion. Mouse erythrocytes were also found to carry an eNOS protein and convert (14)C-arginine into (14)C-citrulline in NOS-dependent fashion. CONCLUSIONS: These are the first studies to definitively establish a role for a blood-borne eNOS, using cross-transplant chimera models, that contributes to the regulation of blood pressure and nitrite homeostasis. This work provides evidence suggesting that erythrocyte eNOS may mediate this effect.


Subject(s)
Blood Pressure/physiology , Homeostasis/physiology , Hypertension/metabolism , Nitric Oxide Synthase Type III/genetics , Nitric Oxide Synthase Type III/metabolism , Nitrites/blood , Animals , Arginine/blood , Arginine/pharmacokinetics , Carbon Radioisotopes , Citrulline/blood , Citrulline/pharmacokinetics , Endothelium, Vascular/enzymology , Enzyme Inhibitors/pharmacology , Erythrocytes/enzymology , Hypertension/genetics , Mice , Mice, Knockout , NG-Nitroarginine Methyl Ester/pharmacology , Nitric Oxide/blood , Nitric Oxide Synthase Type III/antagonists & inhibitors , Signal Transduction/physiology
4.
PLoS One ; 7(4): e35090, 2012.
Article in English | MEDLINE | ID: mdl-22563377

ABSTRACT

The impact of synthetic amyloid ß (1-42) (Aß(1-42)) oligomers on biophysical properties of voltage-gated potassium channels Kv 1.3 and lipid bilayer membranes (BLMs) was quantified for protocols using hexafluoroisopropanol (HFIP) or sodium hydroxide (NaOH) as solvents prior to initiating the oligomer formation. Regardless of the solvent used Aß(1-42) samples contained oligomers that reacted with the conformation-specific antibodies A11 and OC and had similar size distributions as determined by dynamic light scattering. Patch-clamp recordings of the potassium currents showed that synthetic Aß(1-42) oligomers accelerate the activation and inactivation kinetics of Kv 1.3 current with no significant effect on current amplitude. In contrast to oligomeric samples, freshly prepared, presumably monomeric, Aß(1-42) solutions had no effect on Kv 1.3 channel properties. Aß(1-42) oligomers had no effect on the steady-state current (at -80 mV) recorded from Kv 1.3-expressing cells but increased the conductance of artificial BLMs in a dose-dependent fashion. Formation of amyloid channels, however, was not observed due to conditions of the experiments. To exclude the effects of HFIP (used to dissolve lyophilized Aß(1-42) peptide), and trifluoroacetic acid (TFA) (used during Aß(1-42) synthesis), we determined concentrations of these fluorinated compounds in the stock Aß(1-42) solutions by (19)F NMR. After extensive evaporation, the concentration of HFIP in the 100× stock Aß(1-42) solutions was ∼1.7 µM. The concentration of residual TFA in the 70× stock Aß(1-42) solutions was ∼20 µM. Even at the stock concentrations neither HFIP nor TFA alone had any effect on potassium currents or BLMs. The Aß(1-42) oligomers prepared with HFIP as solvent, however, were more potent in the electrophysiological tests, suggesting that fluorinated compounds, such as HFIP or structurally-related inhalational anesthetics, may affect Aß(1-42) aggregation and potentially enhance ability of oligomers to modulate voltage-gated ion channels and biological membrane properties.


Subject(s)
Amyloid beta-Peptides/pharmacology , Electric Conductivity , Kv1.3 Potassium Channel/metabolism , Lipid Bilayers/metabolism , Peptide Fragments/pharmacology , Solvents/chemistry , Amyloid beta-Peptides/chemical synthesis , Halogenation , Kinetics , Light , Membranes, Artificial , Patch-Clamp Techniques , Peptide Fragments/chemical synthesis , Propanols/chemistry , Scattering, Radiation , Sodium Hydroxide/chemistry
5.
Free Radic Biol Med ; 47(5): 510-7, 2009 Sep 01.
Article in English | MEDLINE | ID: mdl-19464364

ABSTRACT

Dietary nitrate, found in abundance in green vegetables, can be converted to the cytoprotective molecule nitrite by oral bacteria, suggesting that nitrate and nitrite may represent active cardioprotective constituents of the Mediterranean diet. We therefore tested the hypothesis that dietary nitrate and nitrite levels modulate tissue damage and ischemic gene expression in a mouse liver ischemia-reperfusion model. We found that stomach content, plasma, heart, and liver nitrite levels were significantly reduced after dietary nitrate and nitrite depletion and could be restored to normal levels with nitrite supplementation in water. Remarkably, we confirmed that basal nitrite levels significantly reduced liver injury after ischemia-reperfusion. Consistent with an effect of nitrite on the posttranslational modification of complex I of the mitochondrial electron transport chain, the severity of liver infarction was inversely proportional to complex I activity after nitrite repletion in the diet. The transcriptional response of dietary nitrite after ischemia was more robust than after normoxia, suggesting a hypoxic potentiation of nitrite-dependent transcriptional signaling. Our studies indicate that normal dietary nitrate and nitrite levels modulate ischemic stress responses and hypoxic gene expression programs, supporting the hypothesis that dietary nitrate and nitrite are cytoprotective components of the diet.


Subject(s)
Animal Structures/metabolism , Diet , Ischemia/metabolism , Nitrates/pharmacology , Nitrites/blood , Nitrites/pharmacology , Animal Structures/drug effects , Animals , Cytoprotection/drug effects , Cytoprotection/genetics , Gastric Mucosa/metabolism , Gene Expression Profiling , Heart/drug effects , Ischemia/blood , Ischemia/genetics , Liver/drug effects , Liver/metabolism , Mice , Mice, Inbred C57BL , Myocardium/metabolism , Nitrates/blood , Nitrates/metabolism , Nitrites/metabolism , Oligonucleotide Array Sequence Analysis , Reperfusion Injury/blood , Reperfusion Injury/genetics , Reperfusion Injury/metabolism
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