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1.
Brain ; 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38917025

RESUMEN

Dominant missense mutations of the calcium-permeable cation channel TRPV4 cause Charcot-Marie-Tooth disease (CMT) type 2C and two forms of distal spinal muscular atrophy. These conditions are collectively referred to as TRPV4-related neuromuscular disease and share features of motor greater than sensory dysfunction and frequent vocal fold weakness. Pathogenic variants lead to gain of ion channel function that can be rescued by TRPV4 antagonists in cellular and animal models. As small molecule TRPV4 antagonists have proven safe in trials for other disease indications, channel inhibition is a promising therapeutic strategy for TRPV4 patients. However, the current knowledge of the clinical features and natural history of TRPV4-related neuromuscular disease is insufficient to enable rational clinical trial design. To address these issues, we developed a TRPV4 patient database and administered a TRPV4-specific patient questionnaire. Here, we report demographic and clinical information, including CMT examination scores (CMTES), from 68 patients with known pathogenic TRPV4 variants, 40 of whom also completed the TRPV4 patient questionnaire. TRPV4 patients showed a bimodal age of onset, with the largest peak occurring in the first 2 years of life. Compared to CMT1A patients, TRPV4 patients showed distinct symptoms and signs, manifesting more ambulatory difficulties and more frequent involvement of proximal arm and leg muscles. Although patients reported fewer sensory symptoms, sensory dysfunction was often detected clinically. Many patients were affected by vocal fold weakness (55%) and shortness of breath (55%), and 11% required ventilatory support. Skeletal abnormalities were common, including scoliosis (64%), arthrogryposis (33%), and foot deformities. Strikingly, patients with infantile onset of disease showed less sensory involvement and less progression of symptoms. These results highlight distinctive clinical features in TRPV4 patients, including motor-predominant disease, proximal arm and leg weakness, severe ambulatory difficulties, vocal fold weakness, respiratory dysfunction, and skeletal involvement. In addition, patients with infantile onset of disease appeared to have a distinct phenotype with less apparent disease progression based on CMTES. These collective observations indicate that clinical trial design for TRPV4-related neuromuscular disease should include outcome measures that reliably capture non-length dependent motor dysfunction, vocal fold weakness, and respiratory disease.

2.
J Hand Surg Glob Online ; 6(2): 183-187, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38903831

RESUMEN

Purpose: This review aimed to compare the postoperative outcomes of open reduction internal fixation (ORIF) versus excision in the surgical treatment of hook of hamate fractures. Methods: A systematic review of PubMed and EMBASE databases from 1954 to 2023 was performed using the search term "hook of hamate fracture" to identify all publications regarding the use of ORIF or excision in the treatment of hook of hamate fractures. Outcomes included a return to sport, pain, ulnar nerve dysfunction, flexor tendon dysfunction, union rate, wrist range of motion (ROM; % of contralateral hand), grip strength (% of contralateral hand), and quick disabilities of arm, shoulder, and hand scores. Results: Twenty-seven of the 705 total screened articles were included. Excision of the hook of hamate (n = 779) resulted in a shorter return to sport time (6 vs 7.8 weeks), lower rates of postoperative pain (6.1% vs 33.3%), higher rates of ulnar nerve sensory dysfunction (4.2% vs 0%), and higher rates of ulnar nerve motor dysfunction (1.5% vs 0%) relative to ORIF (n = 51). Chronic fractures had a longer return to sport time (7.2 vs 5.7 weeks) relative to nonchronic injuries. Conclusions: Both surgical procedures appear to yield acceptable outcomes in the treatment of hook of hamate fractures. However, based on the sparsity of available data, we are unable to determine a consistent difference between hook of hamate excision and ORIF. Clinical relevance: To our knowledge, no current consensus on the optimal surgical treatment for hook of hamate fractures exists. Our findings emphasize the need for a large prospective cohort study using standardized outcomes to provide strong evidence as to whether surgical excision or ORIF yields greater outcomes in the treatment of hook of hamate fractures.

3.
Trauma Surg Acute Care Open ; 9(1): e001465, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38933603

RESUMEN

Background: The reporting of adverse events (AEs) is required and well defined in the execution of clinical trials, but is poorly characterized particularly in prehospital trials focusing on traumatic injury. In the setting of prehospital traumatic injury trials, no literature currently exists analyzing the clinical implications of AEs and their associations with mortality and morbidity. We sought to analyze AEs from three prehospital hemorrhagic shock trials and characterize their time course, incidence, severity, associated clinical outcomes, and relatedness. Methods: We performed a secondary analysis of three prehospital randomized clinical trials. We analyzed AEs at both the patient level as well as the individual AE level. We categorized patients who had no AEs, a single documented AE and those with multiple events (>1 AE). We characterized AE timing, severity, relatedness and attributable mortality outcomes. Results: We included 1490 patients from the three harmonized clinical trials, with 299 (20.1%) individual patients having at least a single AE documented with 529 AEs documented overall as a proportion of patients had multiple events. Over 44% of patients had a death-related misclassified AE. Patients with at least a single documented AE had a significantly higher 28-day mortality (log-rank χ2=81.27, p<0.001) compared with those without an AE documented. Patients with a single AE had a significant higher mortality than those with multiple AEs, potentially due to survival bias (log-rank χ2=11.80, p=0.006). When relatedness of each individual AE was characterized, over 97% of AEs were classified as 'definitely not related' or 'probably not related' to the intervention. Conclusions: AEs in hemorrhagic shock trials are common, occur early and are associated with mortality and survival bias. The potential for inaccurate reporting exists, and education and training remain essential for appropriate treatment arm comparison. The current results have important relevance to injury-related clinical trials. Trial registration numbers: NCT01818427, NCT02086500 and NCT03477006. Level of evidence: II.

4.
Artículo en Inglés | MEDLINE | ID: mdl-38523128

RESUMEN

INTRODUCTION: Recent randomized clinical trials have demonstrated that prehospital tranexamic acid (TXA) administration following injury is safe and improves survival. However, the effect of prehospital TXA on adverse events, transfusion requirements and any dose response relationships require further elucidation. METHODS: A secondary analysis was performed using harmonized data from two large, double-blinded, randomized prehospital TXA trials. Outcomes, including 28-day mortality, pertinent adverse events and 24-hour red cell transfusion requirements were compared between TXA and placebo groups. Regression analyses were utilized to determine the independent associations of TXA after adjusting for study enrollment, injury characteristics and shock severity across a broad spectrum of injured patients. Dose response relationships were similarly characterized based upon grams of prehospital TXA administered. RESULTS: A total of 1744 patients had data available for secondary analysis and were included in the current harmonized secondary analysis. The study cohort had an overall mortality of 11.2% and a median injury severity score of 16 (IQR: 5-26). TXA was independently associated with a lower risk of 28-day mortality (HR: 0.72, 95% CI 0.54, 0.96, p = 0.03). Prehospital TXA also demonstrated an independent 22% lower risk of mortality for every gram of prehospital TXA administered (HR: 0.78, 95% CI 0.63, 0.96, p = 0.02). Multivariable linear regression verified that patients who received TXA were independently associated with lower 24-hour red cell transfusion requirements (ß: -0.31, 95% CI -0.61, -0.01, p = 0.04) with a dose-response relationship (ß: -0.24, 95% CI -0.45, -0.02, p = 0.03). There was no independent association of prehospital TXA administration on VTE, seizure, or stroke. CONCLUSIONS: In this secondary analysis of harmonized data from two large randomized interventional trials, prehospital TXA administration across a broad spectrum of injured patients is safe. Prehospital TXA is associated with a significant 28-day survival benefit, lower red cell transfusion requirements at 24 hours and demonstrates a dose-response relationship. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

5.
Sci Rep ; 14(1): 2747, 2024 02 02.
Artículo en Inglés | MEDLINE | ID: mdl-38302619

RESUMEN

Injury mechanism is an important consideration when conducting clinical trials in trauma. Mechanisms of injury may be associated with differences in mortality risk and immune response to injury, impacting the potential success of the trial. We sought to characterize clinical and endothelial cell damage marker differences across blunt and penetrating injured patients enrolled in three large, prehospital randomized trials which focused on hemorrhagic shock. In this secondary analysis, patients with systolic blood pressure < 70 or systolic blood pressure < 90 and heart rate > 108 were included. In addition, patients with both blunt and penetrating injuries were excluded. The primary outcome was 30-day mortality. Mortality was characterized using Kaplan-Meier and Cox proportional-hazards models. Generalized linear models were used to compare biomarkers. Chi squared tests and Wilcoxon rank-sum were used to compare secondary outcomes. We characterized data of 696 enrolled patients that met all secondary analysis inclusion criteria. Blunt injured patients had significantly greater 24-h (18.6% vs. 10.7%, log rank p = 0.048) and 30-day mortality rates (29.7% vs. 14.0%, log rank p = 0.001) relative to penetrating injured patients with a different time course. After adjusting for confounders, blunt mechanism of injury was independently predictive of mortality at 30-days (HR 1.84, 95% CI 1.06-3.20, p = 0.029), but not 24-h (HR 1.65, 95% CI 0.86-3.18, p = 0.133). Elevated admission levels of endothelial cell damage markers, VEGF, syndecan-1, TM, S100A10, suPAR and HcDNA were associated with blunt mechanism of injury. Although there was no difference in multiple organ failure (MOF) rates across injury mechanism (48.4% vs. 42.98%, p = 0.275), blunt injured patients had higher Denver MOF score (p < 0.01). The significant increase in 30-day mortality and endothelial cell damage markers in blunt injury relative to penetrating injured patients highlights the importance of considering mechanism of injury within the inclusion and exclusion criteria of future clinical trials.


Asunto(s)
Servicios Médicos de Urgencia , Heridas no Penetrantes , Heridas Penetrantes , Humanos , Heridas Penetrantes/complicaciones , Heridas no Penetrantes/complicaciones , Modelos de Riesgos Proporcionales , Células Endoteliales , Estudios Retrospectivos
6.
Trauma Surg Acute Care Open ; 9(1): e001346, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38375027

RESUMEN

Background: Tranexamic acid (TXA) has been hypothesized to mitigate coagulopathy in patients after traumatic injury. Despite previous prehospital clinical trials demonstrating a TXA survival benefit, none have demonstrated correlated changes in thromboelastography (TEG) parameters. We sought to analyze if missing TEG data contributed to this paucity of findings. Methods: We performed a secondary analysis of the Study of Tranexamic Acid During Air Medical and Ground Prehospital Transport Trial. We compared patients that received TEG (YES-TEG) and patients unable to be sampled (NO-TEG) to analyze subgroups in which to investigate TEG differences. TEG parameter differences across TXA intervention arms were assessed within subgroups disproportionately present in the NO-TEG relative to the YES-TEG cohort. Generalized linear models controlling for potential confounders were applied to findings with p<0.10 on univariate analysis. Results: NO-TEG patients had lower prehospital systolic blood pressure (SBP) (100 (78, 140) vs 125 (88, 147), p<0.01), lower prehospital Glascow Coma Score (14 (3, 15) vs 15 (12, 15), p<0.01), greater rates of prehospital intubation (39.4% vs 24.4%, p<0.01) and greater mortality at 30 days (36.4% vs 6.8%, p<0.01). NO-TEG patients had a greater international normalized ratio relative to the YES-TEG subgroup (1.2 (1.1, 1.5) vs 1.1 (1.0, 1.2), p=0.04). Within a severe prehospital shock cohort (SBP<70), TXA was associated with a significant decrease in clot lysis at 30 min on multivariate analysis (ß=-27.6, 95% CI (-51.3 to -3.9), p=0.02). Conclusions: Missing data, due to the logistical challenges of sampling certain severely injured patients, may be associated with a lack of TEG parameter changes on TXA administration in the primary analysis. Previous demonstration of TXA's survival benefit in patients with severe prehospital shock in tandem with the current findings supports the notion that TXA acts at least partially by improving clot integrity. Level of evidence: Level II.

7.
World Neurosurg ; 184: e784-e793, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38360207

RESUMEN

OBJECTIVE: Clear cell meningiomas (CCM) are an uncommon meningioma subtype marked by aggressive growth and high rates of recurrence despite initial resection. The present study evaluates the adjuvant benefit of stereotactic radiosurgery (SRS) for residual or recurrent tumors. METHODS: After review of our prospectively maintained database, we identified 6 patients (3 female) with histologically confirmed Grade 2 CCMs. The median age of the patients at the time of SRS was 45 years. Five patients had undergone prior gross total surgical resection and 1 patient had subtotal resection before SRS. The median SRS treatment volume was 4.7 cc and the median radiosurgical margin dose was 13 Gy (range: 10-15 Gy). RESULTS: The median follow-up time was 35.5 months (range 6-168 months). Three patients achieved tumor control after the first SRS procedure. Three patients experienced tumor progression at 4, 22, and 32 months after initial SRS. Tumor control was obtained in 2 of these patients after additional SRS. One patient with multiple SRS procedures had suspected adverse radiation effect that was successfully treated with corticosteroids followed by bevacizumab. CONCLUSIONS: Tumor control was maintained in 5 of 6 patients after one or more SRS procedures. SRS should be considered for early intervention after surgical resection of CCM. To maximize the tumor control rate, patients with diagnosed CCM should be treated more generously and higher margin dose should be prescribed. Patients with CCM should be counselled that more than one SRS may be necessary to provide sustained tumor control.


Asunto(s)
Neoplasias Meníngeas , Meningioma , Radiocirugia , Humanos , Femenino , Persona de Mediana Edad , Meningioma/radioterapia , Meningioma/cirugía , Meningioma/etiología , Radiocirugia/métodos , Resultado del Tratamiento , Recurrencia Local de Neoplasia/cirugía , Recurrencia Local de Neoplasia/etiología , Neoplasias Meníngeas/radioterapia , Neoplasias Meníngeas/cirugía , Neoplasias Meníngeas/etiología , Estudios Retrospectivos , Estudios de Seguimiento
8.
Clin Transplant ; 38(1): e15246, 2024 01.
Artículo en Inglés | MEDLINE | ID: mdl-38289885

RESUMEN

BACKGROUND: Experience with lung transplantation (LT) in patients with human immunodeficiency virus (HIV) is limited. Many studies have demonstrated the success of kidney and liver transplantation in HIV-seropositive (HIV+) patients. Our objective was to conduct a national registry analysis comparing LT outcomes in HIV+ to HIV-seronegative (HIV-) recipients. METHODS: The United Network for Organ Sharing database was queried to identify LTs performed in adult HIV+ patients between 2016 and 2023. Patients with unknown HIV status, multiorgan transplants, and redo transplants were excluded. The primary endpoints were mortality and graft rejection. Survival time was analyzed using Kaplan-Meier analysis. RESULTS: The study included 17 487 patients, 67 of whom were HIV+. HIV+ recipients were younger (59 vs. 62 years, p = .02), had higher pulmonary arterial pressure (28 vs. 25 mm Hg, p = .04), and higher lung allocation scores (47 vs. 41, p = .01) relative to HIV- recipients. There were no differences in graft/recipient survival time between groups. HIV+ recipients had higher rates of post-transplant dialysis (18% vs. 8.4%, p = .01), but otherwise had similar post-transplant outcomes to HIV-recipients. CONCLUSIONS: This national registry analysis suggests LT outcomes in HIV+ patients are not inferior to outcomes in HIV- patients and that well-selected HIV+ recipients can achieve comparable patient and graft survival rates relative to HIV- recipients.


Asunto(s)
Infecciones por VIH , Trasplante de Pulmón , Adulto , Humanos , VIH , Supervivencia de Injerto , Sistema de Registros , Rechazo de Injerto/epidemiología , Rechazo de Injerto/etiología , Infecciones por VIH/complicaciones , Infecciones por VIH/cirugía
9.
J Vasc Surg ; 79(4): 904-910, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38092308

RESUMEN

OBJECTIVE: Supervised exercise therapy (SET) for patients with intermittent claudication (IC) can lower the risk of progression to chronic limb-threatening ischemia and amputation, while preserving and restoring functional status. Despite supporting evidence, it remains underutilized, and among those who initiate programs, attrition rates are extremely high. We hypothesize that socioeconomic factors may represent significant barriers to SET completion. METHODS: Patients with IC referred to SET at a multi-hospital, single-institution health care system (2018-2022) from a prospectively maintained database were retrospectively analyzed. Our primary endpoint was SET program completion and graduation, defined as completion of 36 sessions. Our secondary endpoints were vascular intervention within 1 year of referral and change in ankle-brachial index (ABI). Baseline demographics were assessed using standard statistical methods. Predictors of SET graduation were analyzed using multivariable logistic regression generating adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Change in ABI was analyzed using t-test between subgroups. Reasons for attrition were tabulated. Patient Health Questionnaire-9 (PHQ-9), metabolic equivalent level, Vascular QOL, Duke Activity Status, and ABI were analyzed using paired t-tests across the entire cohort. RESULTS: Fifty-two patients met inclusion criteria: mean age 67.85 ± 10.69 years, 19 females (36.54%), mean baseline ABI of 0.77 ± 0.16. The co-pays for 100% of patients were fully covered by primary and secondary insurance plans. Twenty-one patients (40.38%) completed SET. On multivariable analysis, residence in a ZIP code with median household income <$47,000 (aOR, 0.10; 95% CI, 0.01-0.76; P = .03) and higher body mass index (aOR, 0.81; 95% CI, 0.67-0.99; P = .04) were significant barriers to SET graduation. There were no differences in ABI change or vascular intervention within 1 year between graduates and non-graduates. Non-graduates reported transportation challenges (25.00%), lack of motivation (20.83%), and illness/functional limitation (20.83%) as primary reasons for SET attrition. Metabolic Equivalent Level (P ≤ .01) and Duke Activity Status scores (P = .04) were significantly greater after participating in a SET program. CONCLUSIONS: Although SET participation improves lower extremity and functionality outcomes, only 40% of referred patients completed therapy in our cohort. Our findings suggest that both socioeconomic and functional factors influence the odds of completing SET programs, indicating a need for holistic pre-referral assessment to facilitate enhanced program accessibility for these populations.


Asunto(s)
Enfermedad Arterial Periférica , Calidad de Vida , Femenino , Humanos , Persona de Mediana Edad , Anciano , Estudios Retrospectivos , Claudicación Intermitente/diagnóstico , Claudicación Intermitente/terapia , Terapia por Ejercicio/métodos , Factores Socioeconómicos , Enfermedad Arterial Periférica/diagnóstico , Enfermedad Arterial Periférica/terapia , Caminata
10.
J Clin Med ; 12(22)2023 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-38002643

RESUMEN

BACKGROUND: With new variants challenging the effectiveness of preventive measures, we are beginning to recognize the reality that COVID-19 will continue to pose an endemic threat. The manifestations of COVID-19 in lung transplant recipients during index admission are poorly understood with very few cases reported in recent lung transplant recipients. Optimal management of immunosuppression and antiviral therapy in recent transplant recipients is challenging. METHODS: We performed a retrospective analysis identifying lung transplant recipients at our institution who contracted COVID-19 in the immediate postoperative period (within index admission). In addition, we performed a systematic review from January 2020 to August 2023 identifying all publications on the PUBMED database regarding COVID-19 infection in lung transplant recipients during index admission. RESULTS: We report four cases of COVID-19 pneumonia in lung transplant recipients in the immediate postoperative period and we describe the clinical course, treatment options, and immunosuppression changes to manage this unique clinical problem. All patients made a full recovery and were eventually discharged home. Within our review of the literature, the most prevalent presenting symptoms were cough, dyspnea, and fatigue. Six (75%) patients decreased or held their antimetabolite. The two most common treatments were monoclonal antibodies (38%) and remdesivir (63%). CONCLUSION: Although previous literature demonstrates that COVID-19 can be deadly in recent lung transplant recipients, rapid treatment with anti-viral therapy/immunotherapy, deescalating immunosuppression, and treatment of respiratory decompensation with Decadron was effective in our patients.

11.
Hematology ; 28(1): 2250647, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37639579

RESUMEN

BACKGROUND: The introduction of low titer group O whole blood (LTOWB) that contains potentially ABO-incompatible plasma and the increasing use of group A plasma, due to shortages of AB plasma, in trauma patients whose ABO group is unknown could put the recipients of incompatible plasma at risk of increased morbidity and mortality. This study evaluated civilian trauma patient outcomes following receipt of incompatible plasma. METHODS: One trauma center's patient contributions to three multicenter studies of different trauma resuscitation strategies was analyzed; these patients were separated into two groups based on receipt of only compatible plasma versus receipt of any quantity of incompatible plasma. Multivariate analysis was performed to determine if receipt of incompatible plasma was associated with 24-hour or 30-day mortality. RESULTS: There were 347 patients eligible for this secondary analysis with 167 recipients of only compatible plasma and 180 recipients of incompatible plasma. The two groups were well matched demographically and on both prehospital and hospital arrival vital signs. The median (IQR) volume of incompatible plasma received by these patients was 684 ml (342, 1229). There was not a significant difference between the groups in 24-hour and 30-day mortality, nor in in-hospital or intensive care unit lengths of stay. In the Cox proportional-hazards regression model for both 24-hour and 30-day survival, receipt of incompatible plasma was not independently predictive of either mortality endpoint. CONCLUSION: Receipt of incompatible plasma was not independently associated with increased mortality in trauma patients. Prospective studies are needed to confirm these findings.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Reacción a la Transfusión , Humanos , Transfusión de Componentes Sanguíneos , Plasma , Transfusión Sanguínea , Sistema del Grupo Sanguíneo ABO
12.
Br J Neurosurg ; : 1-3, 2023 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-37424102

RESUMEN

Background: Malignant pleural mesothelioma (MPM) is a rare cancer of the respiratory system that rarely metastasizes to the brain. We report a case of sarcomatoid MPM (SMPM) managed with Stereotactic radiosurgery (SRS) to achieve intracranial tumor control and improve neurological symptoms.Illustrative case: This 67-year-old female patient underwent SRS twice in order to treat a total of 15 brain metastases. One-month follow-up imaging after the first SRS demonstrated local tumor response and seven tumors with symptomatic vasogenic edema that responded to initial corticosteroids followed by bevacizumab. At a three-month follow-up after the first procedure, eight new tumors were detected and required repeat SRS. Although sustained tumor control resulted in improved neurological function, the patient subsequently expired from systemic disease progression 12 months after initial diagnosis and six months after initial SRS for brain metastases despite the concurrent use of systemic immunotherapy and systemic chemotherapy.Conclusions: Although SRS provided overall tumor control of metastatic brain disease, further advances in systemic therapies will be needed to improve survival in this aggressive rare cancer.

13.
Nat Commun ; 14(1): 4165, 2023 07 13.
Artículo en Inglés | MEDLINE | ID: mdl-37443299

RESUMEN

Intrinsically disordered regions (IDRs) are essential for membrane receptor regulation but often remain unresolved in structural studies. TRPV4, a member of the TRP vanilloid channel family involved in thermo- and osmosensation, has a large N-terminal IDR of approximately 150 amino acids. With an integrated structural biology approach, we analyze the structural ensemble of the TRPV4 IDR and the network of antagonistic regulatory elements it encodes. These modulate channel activity in a hierarchical lipid-dependent manner through transient long-range interactions. A highly conserved autoinhibitory patch acts as a master regulator by competing with PIP2 binding to attenuate channel activity. Molecular dynamics simulations show that loss of the interaction between the PIP2-binding site and the membrane reduces the force exerted by the IDR on the structured core of TRPV4. This work demonstrates that IDR structural dynamics are coupled to TRPV4 activity and highlights the importance of IDRs for TRP channel function and regulation.


Asunto(s)
Fenómenos Fisiológicos Celulares , Canales Catiónicos TRPV , Canales Catiónicos TRPV/metabolismo , Dominios Proteicos , Secuencias Reguladoras de Ácidos Nucleicos , Lípidos
14.
J Biol Chem ; 298(4): 101826, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35300980

RESUMEN

Ubiquitin (Ub)-mediated regulation of plasmalemmal ion channel activity canonically occurs via stimulation of endocytosis. Whether ubiquitination can modulate channel activity by alternative mechanisms remains unknown. Here, we show that the transient receptor potential vanilloid 4 (TRPV4) cation channel is multiubiquitinated within its cytosolic N-terminal and C-terminal intrinsically disordered regions (IDRs). Mutagenizing select lysine residues to block ubiquitination of the N-terminal but not C-terminal IDR resulted in a marked elevation of TRPV4-mediated intracellular calcium influx, without increasing cell surface expression levels. Conversely, enhancing TRPV4 ubiquitination via expression of an E3 Ub ligase reduced TRPV4 channel activity but did not decrease plasma membrane abundance. These results demonstrate Ub-dependent regulation of TRPV4 channel function independent of effects on plasma membrane localization. Consistent with ubiquitination playing a key negative modulatory role of the channel, gain-of-function neuropathy-causing mutations in the TRPV4 gene led to reduced channel ubiquitination in both cellular and Drosophila models of TRPV4 neuropathy, whereas increasing mutant TRPV4 ubiquitination partially suppressed channel overactivity. Together, these data reveal a novel mechanism via which ubiquitination of an intracellular flexible IDR domain modulates ion channel function independently of endocytic trafficking and identify a contributory role for this pathway in the dysregulation of TRPV4 channel activity by neuropathy-causing mutations.


Asunto(s)
Canales Catiónicos TRPV , Ubiquitinación , Animales , Calcio/metabolismo , Membrana Celular/metabolismo , Drosophila/genética , Drosophila/metabolismo , Humanos , Ratones , Mutación , Canales Catiónicos TRPV/genética , Canales Catiónicos TRPV/metabolismo , Ubiquitina/metabolismo
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