Interaction of cochlin and mechanosensitive channel TREK-1 in trabecular meshwork cells influences the regulation of intraocular pressure.

This work was funded by National Institute of Health Grants R01 EY016112, EY015266, and EY014801 and an unrestricted grant to the University of Miami's Bascom Palmer Eye Institute from Research to Prevent Blindness. Financial support from Fight for Sight is gratefully acknowledged. Funding to XG was provided by Instituto de Salud Carlos III, Spain (FIS PI14/00141 and RETIC RD12/0034/0003) and Generalitat de Catalunya (2014SGR1165). In the eye, intraocular pressure (IOP) is tightly regulated and its persistent increase leads to ocular hypertension and glaucoma. We have previously shown that trabecular meshwork (TM) cells might detect aqueous humor fluid shear stress via interaction of the extracellular matrix (ECM) protein cochlin with the cell surface bound and stretch-activated channel TREK-1. We provide evidence here that interaction between both proteins are involved in IOP regulation. Silencing of TREK-1 in mice prevents the previously demonstrated cochlin-overexpression mediated increase in IOP. Biochemical and electrophysiological experiments demonstrate that high shear stress-induced multimeric cochlin produces a qualitatively different interaction with TREK-1 compared to monomeric cochlin. Physiological concentrations of multimeric but not monomeric cochlin reduce TREK-1 current. Results presented here indicate that the interaction of TREK-1 and cochlin play an important role for maintaining IOP homeostasis

Anionic Phospholipids Bind to and Modulate the Activity of Human TRESK Background K+ Channel

The background K+ channel TRESK regulates sensory neuron excitability and changes in its function/expression contribute to neuronal hyperexcitability after injury/inflammation, making it an attractive therapeutic target for pain-related disorders. Factors that change the plasma membrane bilayer composition/properties (including volatile anesthetics, chloroform, chlorpromazine, shear stress and cell swelling/shrinkage) modify TRESK current but despite the importance of anionic phospholipids (e.g. PIP2) in the regulation of many ion channels, it remains unknown if membrane lipids affect TRESK function. We describe that both human and rat TRESK contain potential anionic phospholipid binding sites (apbs) in the large cytoplasmic loop, but only the human channel is able to bind to multilamellar vesicles (MLVs), enriched with anionic phospholipids, suggesting an electrostatically-mediated interaction. We mapped the apbs to a short stretch of 14 amino acids in the loop, located at the membrane-cytosol interface. Disruption of electrostatic lipid-TRESK interactions inhibited hTRESK currents, whilst subsequent application of Folch Fraction MLVs or a PIP2 analog activated hTRESK, an effect that was absent in the rat ortholog. Strikingly, channel activation by anionic phospholipids was conferred to rTRESK by replacing the equivalent rat sequence with the human apbs. Finally, stimulation of a Gq/11-linked GPCR reduced hTRESK current when Ca2+/calcineurin is blocked, while in physiological conditions, the Ca2+-mediated stimulation is prominent. This novel regulation of hTRESK by anionic phospholipids is a characteristic of the human channel that is not present in rodent orthologs. This must be considered when extrapolating results from animal models and may open the door to the development of novel channel modulators as analgesics

The LRRC8-mediated volume-regulated anion channel is altered in glaucoma

LRRC8; Anion channel; GlaucomaLRRC8; Canal Aniònic; GlaucomaLRRC8; Canal Aniónico; GlaucomaRegulation of cellular volume is an essential process to balance volume changes during cell proliferation and migration or when intracellular osmolality increases due to transepithelial transport. We previously characterized the key role of volume-regulated anion channels (VRAC) in the modulation of the volume of trabecular meshwork (TM) cells and, in turn, the aqueous humour (AH) outflow from the eye. The balance between the secretion and the drainage of AH determines the intraocular pressure (IOP) that is the major casual risk factor for glaucoma. Glaucoma is an ocular disease that causes irreversible blindness due to the degeneration of retinal ganglion cells. The recent identification of Leucine-Rich Repeat-Containing 8 (LRRC8A-E) proteins as the molecular components of VRAC opens the field to elucidate their function in the physiology of TM and glaucoma. Human TM cells derived from non-glaucomatous donors and from open-angle glaucoma patients were used to determine the expression and the functional activity of LRRC8-mediated channels. Expression levels of LRRC8A-E subunits were decreased in HTM glaucomatous cells compared to normotensive HTM cells. Consequently, the activity of VRAC currents and volume regulation of TM cells were significantly affected. Impaired cell volume regulation will likely contribute to altered aqueous outflow and intraocular pressure

The background K+ channel TRESK in sensory physiology and pain

TRESK belongs to the K2P family of potassium channels, also known as background or leak potassium channels due to their biophysical properties and their role regulating membrane potential of cells. Several studies to date have highlighted the role of TRESK in regulating the excitability of specific subtypes of sensory neurons. These findings suggest TRESK could be involved in pain sensitivity. Here, we review the different evidence available that involves the channel in pain and sensory perception, from studies knocking out the channel or overexpressing it to identified mutations that link the channel to migraine pain. In addition, the therapeutic possibilities are discussed, as targeting the channel seems an interesting therapeutic approach to reduce nociceptor activation and to decrease pain

Direccionamiento estratégico de sectores industriales en colombia a partir de sistemas de inteligencia tecnológica.

La publicación “Direccionamiento estratégico para sectores productivos desde el enfoque de la inteligencia tecnológica”, reúne los resultados de cuatro estudios de previsión tecnológica e industrial realizados bajo el liderazgo del Ministerio de Comercio

The LRRC8-mediated volume-regulated anion channel is altered in glaucoma.

Regulation of cellular volume is an essential process to balance volume changes during cell proliferation and migration or when intracellular osmolality increases due to transepithelial transport. We previously characterized the key role of volume-regulated anion channels (VRAC) in the modulation of the volume of trabecular meshwork (TM) cells and, in turn, the aqueous humour (AH) outflow from the eye. The balance between the secretion and the drainage of AH determines the intraocular pressure (IOP) that is the major casual risk factor for glaucoma. Glaucoma is an ocular disease that causes irreversible blindness due to the degeneration of retinal ganglion cells. The recent identification of Leucine-Rich Repeat-Containing 8 (LRRC8A-E) proteins as the molecular components of VRAC opens the field to elucidate their function in the physiology of TM and glaucoma. Human TM cells derived from non-glaucomatous donors and from open-angle glaucoma patients were used to determine the expression and the functional activity of LRRC8-mediated channels. Expression levels of LRRC8A-E subunits were decreased in HTM glaucomatous cells compared to normotensive HTM cells. Consequently, the activity of VRAC currents and volume regulation of TM cells were significantly affected. Impaired cell volume regulation will likely contribute to altered aqueous outflow and intraocular pressure

Pyrethroids inhibit K2P channels and activate sensory neurons: basis of insecticide-induced paraesthesias

Pyrethroid insecticides are widely used for pest control in agriculture or in human public health commonly as a topical treatment for scabies and head lice. Exposure to pyrethroids such as permethrin or tetramethrin (TM) causes sensory alterations such as transient pain, burning, stinging sensations, and paraesthesias. Despite the well-known effects of pyrethroids on sodium channels, actions on other channels that control sensory neuron excitability are less studied. Given the role of 2-pore domain potassium (K2P) channels in modulating sensory neuron excitability and firing, both in physiological and pathological conditions, we examined the effect of pyrethroids on K2P channels mainly expressed in sensory neurons. Through electrophysiological and calcium imaging experiments, we show that a high percentage of TM-responding neurons were nociceptors, which were also activated by TRPA1 and/or TRPV1 agonists. This pyrethroid also activated and enhanced the excitability of peripheral saphenous nerve fibers. Pyrethroids produced a significant inhibition of native TRESK, TRAAK, TREK-1, and TREK-2 currents. Similar effects were found in transfected HEK293 cells. At the behavioral level, intradermal TM injection in the mouse paw produced nocifensive responses and caused mechanical allodynia, demonstrating that the effects seen on nociceptors in culture lead to pain-associated behaviors in vivo. In TRESK knockout mice, pain-associated behaviors elicited by TM were enhanced, providing further evidence for a role of this channel in preventing excessive neuronal activation. Our results indicate that inhibition of K2P channels facilitates sensory neuron activation and increases their excitability. These effects contribute to the generation of paraesthesias and pain after pyrethroid exposure

Evolution of oral cancer treatment in an andalusian population sample : rehabilitation with prosthetic obturation and removable partial prosthesis

Radical surgical resection as a treatment modality for oral cancer often leads to an extensive deficit in both the maxillary and mandibular levels, where the use of a palatal obturator prosthesis (POP) or removable partial denture (RPP). The aim of this study was to evaluate the treatment with POP and RPP in patients treated for oral cancer in the Unit of Prosthetic Rehabilitation of the University Hospital Virgen del Rocío in a period of 20 years. Retrospective descriptive study during the years 1991 and 2011 analyzing oral cancer type, characteristics, treatment and follow-up. The sample consisted of patients whose tumor had previously been removed and who had been referred to the Oncological Rehabilitation Unit of the Oral and Maxillofacial Surgery Unit of the ?Virgen del Rocío? University Hospital for rehabilitation. The inclusion criteria were patients whose underlying pathology was any type of neoplasia, which after its treatment had been referred to the aforementioned Oncological Prosthetic Rehabilitation unit. Of the 45 patients included in our study, 15 patients were rehabilitated with palatal obturator (33.3%) and 5 patients with removable partial denture (11.1%). The mean age of the sample of patients with POP was 57.3 ± 9.23, while the mean age of the sample of patients with RPP was 58 ± 13.5. The most common underlying pathology in patients with POP was squamous cell carcinoma (60%), whereas in patients with RPP it was 100%. The most frequent location found among POP patients was the upper jaw, while in the PRP patients there was no predominant location. The univariate and multivariate logistic regressions did not show any statistically significant association between the independent variables age, sex, smoking habit and alcoholic habit with the dependent variable type of rehabilitating prosthesis. Based on our data, we can conclude that RPP is used in few cases of oncological rehabilitation. The POP has a greater use, as long as the defect in the bones of the facial middle third is limited

TRESK background K+ channel deletion selectively uncovers enhanced mechanical and cold sensitivity

Background potassium-permeable ion channels play a critical role in tuning the excitability of nociceptors, yet the precise role played by different subsets of channels is not fully understood. Decreases in TRESK (TWIK-related spinal cord K+ channel) expression/function enhance sensory neurons excitability, but its role in somatosensory perception and nociception is poorly understood. Here, we used a TRESK knockout (KO) mouse to address these questions. We show that TRESK regulates the sensitivity of sensory neurons in a modality-specific manner, contributing to mechanical and cold sensitivity but without any effect on heat sensitivity. Nociceptive neurons isolated from TRESK KO mice show a decreased threshold for activation and skin nociceptive C-fibers show an enhanced activation by cold and mechanical stimulation that was also observed in behavioral tests in vivo. TRESK is also involved in osmotic pain and in early phases of formalin-induced inflammatory pain, but not in the development of mechanical and heat hyperalgesia during chronic pain. In contrast, mice lacking TRESK present cold allodynia that is not further enhanced by oxaliplatin. In summary, genetic removal of TRESK uncovers enhanced mechanical and cold sensitivity, indicating that the channel regulates the excitability of specific neuronal subpopulations involved in mechanosensitivity and cold-sensing, acting as a brake to prevent activation by innocuous stimuli

Evolution of oral neoplasm in an andalusian population (Spain)

Head and neck cancer are one of the most common neoplasm pathologies in humans. The aim of this study was to analyze the type, characteristics, treatment and evolution of oral neoplasm or precancerous lesion in a sample of Andalusian population (Spain) derived from the Oncology Rehabilitation Hospital Unit during a period of 20 years. A retrospective descriptive study was carried out during the years 1991 and 2011 analyzing the type, characteristics, treatment and follow-up of oral neoplasm in the Oral and Maxillofacial Surgery Unit of the Universitary Hospital ?Virgen del Rocío?. The inclusion criteria were patients whose underlying pathology was any type of benign or malignant neoplasm or presence of precancerous lesion that, after treatment, had been referred to the Prosthetic Rehabilitation Unit. Of the initial analyzed sample of 60 patients, only 45 patients met the inclusion criteria. Of the final sample analyzed, 31 subjects were men (68.9%) and 14 women (31.1%) (p = 0.0169). The mean age of the sample was 57 years ± 13.83, been more frequently in older people with more than 50 years (73.3%) (p = 0.0169). The most common type of neoplasm was epidermoid carcinoma (64.4%). The site most frequently found in squamous cell carcinoma was the floor of the mouth (31%). The most frequent treatment modality was surgery with postoperative radiotherapy (42.2%). All patients had a minimum follow-up of 5 years, and a recurrence in this period was identified in 11.1% of the sample. Multivariate logistic regression showed a statistically significant association for the variables age (p = 0.0063) and smoking (p = 0.0434). Epidermoid carcinoma is the most frequent tumor in the oral cavity, where increase age and smoking are confirmed as associated risk factors