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JCI Insight May 2024Peripheral nerve injury-induced neuronal hyperactivity in the dorsal root ganglion (DRG) participates in neuropathic pain. The calcium-activated potassium channel...
Peripheral nerve injury-induced neuronal hyperactivity in the dorsal root ganglion (DRG) participates in neuropathic pain. The calcium-activated potassium channel subfamily N member 1 (KCNN1) mediates action potential afterhyperpolarization (AHP) and gates neuronal excitability. However, the specific contribution of DRG KCNN1 to neuropathic pain is not yet clear. We report that chronic constriction injury (CCI) of the unilateral sciatic nerve or unilateral ligation of the fourth lumbar nerve produced the downregulation of Kcnn1 mRNA and KCNN1 protein in the injured DRG. This downregulation was partially attributed to a decrease in DRG estrogen-related receptor gamma (ESRRG), a transcription factor, which led to reduced binding to the Kcnn1 promoter. Rescuing this downregulation prevented CCI-induced decreases in total potassium voltage currents and AHP currents, reduced excitability in the injured DRG neurons, and alleviated CCI-induced development and maintenance of nociceptive hypersensitivities, without affecting locomotor function and acute pain. Mimicking the CCI-induced DRG KCNN1 downregulation resulted in augmented responses to mechanical, heat, and cold stimuli in naive mice. Our findings indicate that ESRRG-controlled downregulation of DRG KCNN1 is likely essential for the development and maintenance of neuropathic pain. Thus, KCNN1 may serve as a potential target for managing this disorder.
Topics: Animals; Neuralgia; Ganglia, Spinal; Mice; Down-Regulation; Sensory Receptor Cells; Male; Peripheral Nerve Injuries; Mice, Inbred C57BL; Sciatic Nerve; Disease Models, Animal; Intermediate-Conductance Calcium-Activated Potassium Channels; Action Potentials
PubMed: 38912580
DOI: 10.1172/jci.insight.180085 -
PLoS Biology Jun 2024Breast cancer is the most prevalent malignancy and the most significant contributor to mortality in female oncology patients. Potassium Two Pore Domain Channel Subfamily...
Breast cancer is the most prevalent malignancy and the most significant contributor to mortality in female oncology patients. Potassium Two Pore Domain Channel Subfamily K Member 1 (KCNK1) is differentially expressed in a variety of tumors, but the mechanism of its function in breast cancer is unknown. In this study, we found for the first time that KCNK1 was significantly up-regulated in human breast cancer and was correlated with poor prognosis in breast cancer patients. KCNK1 promoted breast cancer proliferation, invasion, and metastasis in vitro and vivo. Further studies unexpectedly revealed that KCNK1 increased the glycolysis and lactate production in breast cancer cells by binding to and activating lactate dehydrogenase A (LDHA), which promoted histones lysine lactylation to induce the expression of a series of downstream genes and LDHA itself. Notably, increased expression of LDHA served as a vicious positive feedback to reduce tumor cell stiffness and adhesion, which eventually resulted in the proliferation, invasion, and metastasis of breast cancer. In conclusion, our results suggest that KCNK1 may serve as a potential breast cancer biomarker, and deeper insight into the cancer-promoting mechanism of KCNK1 may uncover a novel therapeutic target for breast cancer treatment.
Topics: Humans; Breast Neoplasms; Female; Cell Proliferation; Animals; Cell Line, Tumor; Histones; Mice; Gene Expression Regulation, Neoplastic; Up-Regulation; Neoplasm Metastasis; Potassium Channels, Tandem Pore Domain; Lactate Dehydrogenase 5; Mice, Nude; Neoplasm Invasiveness; Glycolysis; L-Lactate Dehydrogenase; Mice, Inbred BALB C; Prognosis; Cell Movement
PubMed: 38905316
DOI: 10.1371/journal.pbio.3002666 -
Journal of the American Heart... Jun 2024The incidental use of statins during radiation therapy has been associated with a reduced long-term risk of developing atherosclerotic cardiovascular disease. We...
BACKGROUND
The incidental use of statins during radiation therapy has been associated with a reduced long-term risk of developing atherosclerotic cardiovascular disease. We examined whether irradiation causes chronic vascular injury and whether short-term administration of statins during and after irradiation is sufficient to prevent chronic injury compared with long-term administration.
METHODS AND RESULTS
C57Bl/6 mice were pretreated with pravastatin for 72 hours and then exposed to 12 Gy X-ray head-and-neck irradiation. Pravastatin was then administered either for an additional 24 hours or for 1 year. Carotid arteries were tested for vascular reactivity, altered gene expression, and collagen deposition 1 year after irradiation. Treatment with pravastatin for 24 hours after irradiation reduced the loss of endothelium-dependent vasorelaxation and protected against enhanced vasoconstriction. Expression of markers associated with inflammation (NFκB p65 [phospho-nuclear factor kappa B p65] and TNF-α [tumor necrosis factor alpha]) and with oxidative stress (NADPH oxidases 2 and 4) were lowered and subunits of the voltage and Ca activated K BK channel (potassium calcium-activated channel subfamily M alpha 1 and potassium calcium-activated channel subfamily M regulatory beta subunit 1) in the carotid artery were modulated. Treatment with pravastatin for 1 year after irradiation completely reversed irradiation-induced changes.
CONCLUSIONS
Short-term administration of pravastatin is sufficient to reduce chronic vascular injury at 1 year after irradiation. Long-term administration eliminates the effects of irradiation. These findings suggest that a prospective treatment strategy involving statins could be effective in patients undergoing radiation therapy. The optimal duration of treatment in humans has yet to be determined.
PubMed: 38904226
DOI: 10.1161/JAHA.123.033558 -
Frontiers in Physiology 2024Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly... (Review)
Review
Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly rectifying potassium (GIRK) channels serve as key mediators of neurotransmission and cellular responses to extracellular signals. GIRK channels are members of the larger family of inwardly-rectifying potassium (Kir) channels. Typically, GIRK channels are activated via the direct binding of G-protein βγ subunits upon the activation of G-protein-coupled receptors (GPCRs). GIRK channel activation requires the presence of the lipid signaling molecule, phosphatidylinositol 4,5-bisphosphate (PIP). GIRK channels are also modulated by endogenous proteins and other molecules, including RGS proteins, cholesterol, and SNX27 as well as exogenous compounds, such as alcohol. In the last decade or so, several groups have developed novel drugs and small molecules, such as ML297, GAT1508 and GiGA1, that activate GIRK channels in a G-protein independent manner. Here, we aim to provide a comprehensive overview focusing on the direct modulation of GIRK channels by G-proteins, PIP, cholesterol, and novel modulatory compounds. These studies offer valuable insights into the underlying molecular mechanisms of channel function, and have potential implications for both basic research and therapeutic development.
PubMed: 38903913
DOI: 10.3389/fphys.2024.1386645 -
European Journal of Medical Research Jun 2024
PubMed: 38902786
DOI: 10.1186/s40001-024-01905-5 -
Nature Communications Jun 2024DNA binding transcription factors possess the ability to interact with lipid membranes to construct ion-permeable pathways. Herein, we present a thiazole-based DNA...
DNA binding transcription factors possess the ability to interact with lipid membranes to construct ion-permeable pathways. Herein, we present a thiazole-based DNA binding peptide mimic TBP2, which forms transmembrane ion channels, impacting cellular ion concentration and consequently stabilizing G-quadruplex DNA structures. TBP2 self-assembles into nanostructures, e.g., vesicles and nanofibers and facilitates the transportation of Na and K across lipid membranes with high conductance (~0.6 nS). Moreover, TBP2 exhibits increased fluorescence when incorporated into the membrane or in cellular nuclei. Monomeric TBP2 can enter the lipid membrane and localize to the nuclei of cancer cells. The coordinated process of time-dependent membrane or nuclear localization of TBP2, combined with elevated intracellular cation levels and direct G-quadruplex (G4) interaction, synergistically promotes formation and stability of G4 structures, triggering cancer cell death. This study introduces a platform to mimic and control intricate biological functions, leading to the discovery of innovative therapeutic approaches.
Topics: Humans; Peptidomimetics; DNA; G-Quadruplexes; Potassium; Cell Line, Tumor; Sodium; Cell Nucleus; Ion Channels; DNA-Binding Proteins
PubMed: 38902227
DOI: 10.1038/s41467-024-49534-0 -
Microvascular Research Jun 2024Patients with Takotsubo syndrome displayed endothelial dysfunction, but underlying mechanisms have not been fully clarified. This study aimed to explore molecular...
Patients with Takotsubo syndrome displayed endothelial dysfunction, but underlying mechanisms have not been fully clarified. This study aimed to explore molecular signalling responsible for catecholamine excess induced endothelial dysfunction. Human cardiac microvascular endothelial cells were challenged by epinephrine to mimic catecholamine excess. Patch clamp, FACS, ELISA, PCR, and immunostaining were employed for the study. Epinephrine (Epi) enhanced small conductance calcium-activated potassium channel current (I) through activating α1 adrenoceptor. Phenylephrine enhanced edothelin-1 (ET-1) and reactive oxygen species (ROS) production, and the effects involved contribution of I. HO enhanced I and ET-1 production. Enhancing I caused a hyperpolarization, which increases ROS and ET-1 production. BAPTA partially reduced phenylephrine-induced enhancement of ET-1 and ROS, suggesting that α1 receptor activation can enhance ROS/ET-1 generation in both calcium-dependent and calcium-independent ways. The study demonstrates that high concentration catecholamine can activate SK1-3 channels through α1 receptor-ROS signalling and increase ET-1 production, facilitating vasoconstriction.
PubMed: 38901735
DOI: 10.1016/j.mvr.2024.104699 -
Translational Vision Science &... Jun 2024To compare gene expression changes following branch retinal vein occlusion (BRVO) in the pig with and without bevacizumab (BEV) and triamcinolone acetonide (TA).
PURPOSE
To compare gene expression changes following branch retinal vein occlusion (BRVO) in the pig with and without bevacizumab (BEV) and triamcinolone acetonide (TA).
METHODS
Photothrombotic BRVOs were created in both eyes of four groups of nine pigs (2, 6, 10, and 20 days). In each group, six pigs received intravitreal injections of BEV in one eye and TA in the fellow eye, with three pigs serving as untreated BRVO controls. Three untreated pigs served as healthy controls. Expression of mRNA of vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), dystrophin (DMD), potassium inwardly rectifying channel subfamily J member 10 protein (Kir4.1, KCNJ10), aquaporin-4 (AQP4), stromal cell-derived factor-1α (CXCL12), interleukin-6 (IL6), interleukin-8 (IL8), monocyte chemoattractant protein-1 (CCL2), intercellular adhesion molecule 1 (ICAM1), and heat shock factor 1 (HSF1) were analyzed by quantitative reverse-transcription polymerase chain reaction. Retinal VEGF protein levels were characterized by immunohistochemistry.
RESULTS
In untreated eyes, BRVO significantly increased expression of GFAP, IL8, CCL2, ICAM1, HSF1, and AQP4. Expression of VEGF, KCNJ10, and CXCL12 was significantly reduced by 6 days post-BRVO, with expression recovering to healthy control levels by day 20. Treatment with BEV or TA significantly increased VEGF, DMD, and IL6 expression compared with untreated BRVO eyes and suppressed BRVO-induced CCL2 and AQP4 upregulation, as well as recovery of KCNJ10 expression, at 10 to 20 days post-BRVO.
CONCLUSIONS
Inflammation and cellular osmohomeostasis rather than VEGF suppression appear to play important roles in BRVO-induced retinal neurodegeneration, enhanced in both BEV- and TA-treated retinas.
TRANSLATIONAL RELEVANCE
Inner retinal neurodegeneration seen in this acute model of BRVO appears to be mediated by inflammation and alterations in osmohomeostasis rather than VEGF inhibition, which may have implications for more specific treatment modalities in the acute phase of BRVO.
Topics: Animals; Bevacizumab; Triamcinolone Acetonide; Retinal Vein Occlusion; Disease Models, Animal; Angiogenesis Inhibitors; Cytokines; Intravitreal Injections; Swine; Vascular Endothelial Growth Factor A; RNA, Messenger; Glucocorticoids; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Potassium Channels, Inwardly Rectifying
PubMed: 38899953
DOI: 10.1167/tvst.13.6.13 -
The Journal of Biological Chemistry Jun 2024The voltage-gated Kv1.5 potassium channel, conducting the ultra-rapid delayed rectifier K current (I) in human cells, plays important roles in the repolarization of...
The voltage-gated Kv1.5 potassium channel, conducting the ultra-rapid delayed rectifier K current (I) in human cells, plays important roles in the repolarization of atrial action potentials and regulation of the vascular tone. We previously reported that activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) induces endocytic degradation of cell-surface Kv1.5 channels, and a point mutation removing the phosphorylation site, T15A, in the N terminus of Kv1.5 abolished the PMA-effect. In the present study, using mutagenesis, patch clamp recording, Western blot analysis and immunocytochemical staining, we demonstrate that ubiquitination is involved in PMA-mediated degradation of mature Kv1.5 channels. Since the expression of Kv1.4 channel is unaffected by PMA treatment, we swapped the N- and/or C-termini between Kv1.5 and Kv1.4. We found that N-terminus alone did not, but both N- and C-termini of Kv1.5 did confer PMA sensitivity to mature Kv1.4 channels, suggesting the involvement of Kv1.5 C-terminus in the channel ubiquitination. Removal of each of the potential ubiquitination residue Lysine at position 536, 565, and 591 by Arginine substitution (K536R, K565R, and K591R) had little effect, but removal of all three Lysine residues with Arginine substitution (3K-R) partially reduced PMA-mediated Kv1.5 degradation. Furthermore, removing the cysteine residue at position 604 by Serine substitution (C604S) drastically reduced PMA-induced channel degradation. Removal of the three Lysines and Cys604 with a quadruple mutation (3K-R/C604S) or a truncation mutation (Δ536) completely abolished the PKC activation-mediated degradation of Kv1.5 channels. These results provide mechanistic insight into PKC activation-mediated Kv1.5 degradation.
PubMed: 38897569
DOI: 10.1016/j.jbc.2024.107483 -
BioRxiv : the Preprint Server For... Jun 2024Noise can induce hearing loss. In particularly, noise can induce cochlear synapse degeneration leading to hidden hearing loss, which is the most common type of hearing...
UNLABELLED
Noise can induce hearing loss. In particularly, noise can induce cochlear synapse degeneration leading to hidden hearing loss, which is the most common type of hearing disorders in the clinic. Currently, there is no pharmacological treatment, particularly, no post-exposure (i.e., therapeutic) treatment available in the clinic. Here, we report that systematic administration of K channel blockers before or after noise exposure could significantly attenuate NIHL and synapse degeneration. After systematic administration of a general K-channel blocker tetraethylammonium (TEA), the elevation of auditory brainstem response (ABR) thresholds after noise-exposure significantly reduced, and the active cochlear mechanics significantly improved. The therapeutic effect was further improved as the post-exposure administration time extending to 3 days. BK channel is a predominant K channel in the inner hair cells. Systematic administration of a BK channel blocker GAL-021 after noise exposure also ameliorated hearing loss and improved hearing behavioral responses tested by acoustic startle response (ASR). Finally, both TEA and GAL-021 significantly attenuated noise-induced ribbon synapse degeneration. These data demonstrate that K -channel blockers can prevent and treat NIHL and cochlear synapse degeneration. Our finding may aid in developing therapeutic strategies for post-exposure treatment of NIHL and synapse degeneration.
SIGNIFICANCE STATEMENT
Noise is a common deafness factor affecting more 100 million people in the United States. So far, there is no pharmacological treatment available. We show here that administration of K channel blockers after noise exposure could attenuate noise-induced hearing loss and synapse degeneration, and improved behavioral responses. This is the first time to real the K channel blockers that could treat noise-induced hearing loss and cochlear synaptopathy after noise exposure.
PubMed: 38895254
DOI: 10.1101/2024.06.04.597382