Co-Silencing of the Voltage-Gated Calcium Channel β Subunit and High-Voltage Activated α1 Subunit by dsRNA Soaking Resulted in Enhanced Defects in Locomotion, Stylet Thrusting, Chemotaxis, Protein Secretion, and Reproduction in Ditylenchus destructor

The voltage-gated calcium channel (VGCC) β subunit (Cavβ) protein is a kind of cytosolic auxiliary subunit that plays an important role in regulating the surface expression and gating characteristics of high-voltage-activated (HVA) calcium channels. Ditylenchus destructor is an important plant-parasitic nematode. In the present study, the putative Cavβ subunit gene of D. destructor, namely, DdCavβ, was subjected to molecular characterization. In situ hybridization assays showed that DdCavβ was expressed in all nematode tissues. Transcriptional analyses showed that DdCavβ was expressed during each developmental stage of D. destructor, and the highest expression level was recorded in the third-stage juveniles. The crucial role of DdCavβ was verified by dsRNA soaking-mediated RNA interference (RNAi). Silencing of DdCavβ or HVA Cavα1 alone and co-silencing of the DdCavβ and HVA Cavα1 genes resulted in defective locomotion, stylet thrusting, chemotaxis, protein secretion and reproduction in D. destructor. Co-silencing of the HVA Cavα1 and Cavβ subunits showed stronger interference effects than single-gene silencing. This study provides insights for further study of VGCCs in plant-parasitic nematodes.

Evaluation of Serum voltage gated calcium channel α2δ1 as a novel Marker for diagnosis of Hepatocellular Carcinoma in Cirrhotic Egyptian Patient

Background Hepatocellular carcinoma (HCC) is the most common primary liver tumor and represents the third-leading cause of cancer-related death in the world. The incidence of HCC continues to increase worldwide, with a unique geographic, age, and sex distribution. The most important risk factor associated with HCC is liver cirrhosis, with the majority of cases caused by chronic infection with hepatitis B (HBV) and C (HCV) viruses and alcohol abuse, although nonalcoholic fatty liver disease is emerging as an increasingly important cause. Primary prevention in the form of HBV vaccination has led to a significant decrease in HBV-related HCC, and initiation of antiviral therapy appears to reduce the incidence of HCC in patients with chronic HBV or HCV infection. Additionally, the use of ultrasonography enables the early detection of small liver tumors and forms the backbone of recommended surveillance programs for patients at high risk for the development of HCC. Cross-sectional imaging studies, including computed tomography and magnetic resonance imaging, represent further noninvasive techniques that are increasingly employed to diagnose HCC in patients with cirrhosis. The mainstay of potentially curative therapy includes surgery – either resection or liver transplantation. However, most patients are ineligible for surgery, because of either advanced disease or underlying liver dysfunction, and are managed with locoregional and/or systemic therapies. Randomized controlled trials have demonstrated a survival benefit with both local therapies, either ablation or embolization, and systemic therapy in the form of the multikinase inhibitor sorafenib. Despite this, median survival remains poor and recurrence rates significant. Further advances in our understanding of the molecular pathogenesis of HCC hold promise in improving the diagnosis and treatment of this highly lethal cancer. Objectives Evaluation of Serum voltage gated calcium channel α2δ1 as a novel Marker for diagnosis of Hepatocellular Carcinoma in Cirrhotic Egyptian Patients. Patients and Methods This study had been carried out on 90 subjects, age range 21-73 year selected from Internal medicine and Hepatology outpatient clinics and inpatient wards at Ain shams university hospitals. Subjects were divided as follow: Group A(Case): 40 patients with liver cirrhosis without Hepatocellular carcinoma and group B (Control): 40 patients with liver cirrhosis and Hepatocellular carcinoma and group C: 10 normal population for detecting normal value of the marker with exclusion criteria including age < 18 years old and Patients diagnosed with malignancy other than HCC. Results The study subjects are classified into three groups: Group A cirrhotic patients without HCC, Group B cirrhotic patients with HCC and Group C normal individual subjects. Conclusion Serum voltage gated calcium channel levels were significantly higher in patients with HCC and mildly elevated in patients with liver cirrhosis compared to the control group. Thus it can be used as a tumor marker for HCC.

Abstract 15494: Physiological Investigation of the C57bl6 Mouse Aorta Reveals a Critical Role for Voltage Gated Calcium Channel Activity in Spontaneous Arterial Ageing

Introduction: Arterial stiffness (AS) has gained much recognition as a hallmark and independent predictor of cardiovascular (CV) events. Although generally assumed to be an adaptive response to increased blood pressure (BP), AS precedes hypertension in at least two experimental mouse models, thus revealing an incomplete understanding of AS pathophysiology. Methods: The current study presents the longitudinal CV characterization of spontaneously ageing C57Bl6 mice (2, 4, 6, 9, 12 and 24-month old) (male, n>8). In vivo analysis of peripheral BP (Coda), aortic pulse wave velocity (aPWV, Vevo2100), and echocardiography (Vevo2100) was combined with ex vivo aortic studies of isometric reactivity (organ baths) and AS measurements in the Rodent Oscillatory Tension set-up for Arterial Compliance (ROTSAC). (Data are presented as mean ± SEM.) Results: In vivo and ex vivo characterisation confirms that aortic stiffness precedes peripheral BP alterations in spontaneously ageing C57Bl6 mice, with significantly and gradually increasing aPWV (Fig.A) and isobaric Peterson modulus (Ep) (Fig.B) from 6-month of age onward. Thereafter, cardiac hypertrophy was observed at 9-months of age (Fig.C), and peripheral BP measurement reveals elevated pulse pressure at 24-months (30% increase vs. all other ages) (Fig.D). Ex vivo investigation of the thoracic aorta shows increased contractions to phenylephrine (PE) in old (6-24 month) vs. young (2-4 month) mice (Fig.E,F) with an increased contribution of voltage-gated calcium channel (VGCC) (Fig.G,H) with age. Remarkably, no differences were observed on endothelial function, meaning that all changes occur on the level of the vascular smooth muscle cell (VSMC). Conclusions: Physiological ageing of VSMC results in high PE contractions, increased VGCC activity, and the development of significant arterial stiffening by 6-months of age. AS thereby precedes the development of peripheral BP alterations by 18 months.

TWIST1 Preserves Hematopoietic Stem Cell Function Via Repression of Cacna1b Expression

The mitochondria of hematopoietic stem cell (HSC) play crucial roles in regulating cell fate and in preserving HSC functionality and survival. However, the mechanism underlying its regulation remain poorly understood. Here, we identify transcription factor TWIST1 as a novel regulator of HSC maintenance through modulating mitochondrial function. We demonstrate that Twist1 deletion results in a significantly decreased long-term HSC (LT-HSC) frequency, markedly reduced dormancy and self-renewal capacities and skewed myeloid differentiation in steady-state hematopoiesis. Twist1-deficient LT-HSC are more compromised in tolerance of irradiation and 5 fluorouracil-induced stresses, and exhibit typical phenotypes of senescence and higher levels of DNA damage and apoptosis. Mechanistically, Twist1 deficiency upregulates the expression of voltage-gated calcium channel Cacna1b in HSC, leading to noticeable increases in mitochondrial calcium levels, biogenesis, metabolic activity and reactive oxygen species production. Suppression of voltage-gated calcium channel by a calcium channel blocker largely rescues the phenotypic and functional defects in Twist1-deleted HSCs under both steady-state and stress conditions. Collectively, our data, for the first time, characterize TWIST1 as a critical regulator of HSC function acting through CACNA1B/Ca2+/mitochondria axis, and highlight the importance of Ca2+ in HSC maintenance. These observations provide new insights into the mechanisms for the control of HSC fate. Disclosures No relevant conflicts of interest to declare.