Perilipin 2 downregulation in β cells impairs insulin secretion under nutritional stress and damages mitochondria

Perilipin 2 (PLIN2) is a lipid droplet (LD) protein in β cells that increases under nutritional stress. Downregulation of PLIN2 is often sufficient to reduce LD accumulation. To determine whether PLIN2 positively or negatively affects β cell function under nutritional stress, PLIN2 was downregulated in mouse β cells, INS1 cells, and human islet cells. β Cell-specific deletion of PLIN2 in mice on a high-fat diet reduced glucose-stimulated insulin secretion (GSIS) in vivo and in vitro. Downregulation of PLIN2 in INS1 cells blunted GSIS after 24-hour incubation with 0.2 mM palmitic acid. Downregulation of PLIN2 in human pseudoislets cultured at 5.6 mM glucose impaired both phases of GSIS, indicating that PLIN2 is critical for GSIS. Downregulation of PLIN2 decreased specific OXPHOS proteins in all 3 models and reduced oxygen consumption rates in INS1 cells and mouse islets. Moreover, we found that PLIN2-deficient INS1 cells increased the distribution of a fluorescent oleic acid analog to mitochondria and showed signs of mitochondrial stress, as indicated by susceptibility to fragmentation and alterations of acyl-carnitines and glucose metabolites. Collectively, PLIN2 in β cells has an important role in preserving insulin secretion, β cell metabolism, and mitochondrial function under nutritional stress

Effect of zinc and boron on the performance of rainy season local potato variety “Sete” (Solanum tuberosum L.) at Rukumkot, Rukum East, Nepal

A field experiment was carried out at Rukumkot, Rukum East, Nepal during the rainy season of 2021 to study the effect of boron and zinc on vegetative growth and yield parameters of the local “Sete” variety of potato. The experiment was laid out in a randomized complete block design (RCBD) with 4 replications, and 7 treatments i.e., control, boron @2kg/ha soil application, zinc @4.5kg/ha soil application, boron @2kg/ha + zinc @4.5kg/ha soil application, 0.1% boron spray, 0.1% zinc spray and 0.1% boron+ 0.1% zinc spray. The highest tuber yield per hill and productivity was reported in boron @2kg/ha + zinc @4.5kg/ha soil application i.e., 2888.52 grams and 27.51 ton/ha, respectively. A similar result was shown by zinc @4.5kg/ha soil application. Plant height (26.33cm, 46.57cm), number of branches (4.85, 12.02) and number of leaves per plant (30.05, 73.70) were significantly high in boron @2kg/ha + zinc @4.5kg/ha soil application at both 45 DAP (days after planting) and 60DAP. Soil application of only boron, only zinc and boron + zinc increased the total yield of tubers by 10.23%, 24.66% and 25.66%, respectively over the control. The foliar application of only boron, only zinc and boron + zinc increased the total yield of tubers by 4.22%, 2.07% and 12.37%, respectively over the control. Hence, research suggested combined soil application of zinc and boron at the rate of 4.5kg/ha and 2kg/ha, respectively over the foliar cum solitary application of micronutrients for increasing number of medium and large sized tubers and get an overall high yield of potato

Regulation of the volume-regulated anion channel pore-forming subunit LRRC8A in the intrahippocampal kainic acid model of mesial temporal lobe epilepsy

Volume-regulated anion channels (VRACs) are a group of ubiquitously expressed outwardly-rectifying anion channels that sense increases in cell volume and act to return cells to baseline volume through an efflux of anions and organic osmolytes, including glutamate. Because cell swelling, increased extracellular glutamate levels, and reduction of the brain extracellular space (ECS) all occur during seizure generation, we set out to determine whether VRACs are dysregulated throughout mesial temporal lobe epilepsy (MTLE), the most common form of adult epilepsy. To accomplish this, we employed the IHKA experimental model of MTLE, and probed for the expression of LRRC8A, the essential pore-forming VRAC subunit, at acute, early-, mid-, and late-epileptogenic time points (1-, 7-, 14-, and 30-days post-IHKA, respectively). Western blot analysis revealed the upregulation of total dorsal hippocampal LRRC8A 14-days post-IHKA in both the ipsilateral and contralateral hippocampus. Immunohistochemical analyses showed an increased LRRC8A signal 7-days post-IHKA in both the ipsilateral and contralateral hippocampus, along with layer-specific changes 1-, 7-, and 30-days post-IHKA bilaterally. LRRC8A upregulation 1 day post-IHKA was observed primarily in astrocytes; however, some upregulation was also observed in neurons. Glutamate-GABA/glutamine cycle enzymes glutamic acid decarboxylase, glutaminase, and glutamine synthetase were also dysregulated at the 7-day timepoint post status epilepticus. The timepoint-dependent upregulation of total hippocampal LRRC8A and the possible subsequent increased efflux of glutamate in the epileptic hippocampus suggest that the dysregulation of astrocytic VRAC may play an important role in the development of epilepsy

Adipose-targeted SWELL1 deletion exacerbates obesity- and age-related nonalcoholic fatty liver disease

Healthy expansion of adipose tissue is critical for the maintenance of metabolic health, providing an optimized reservoir for energy storage in the form of triacylglycerol-rich lipoproteins. Dysfunctional adipocytes that are unable to efficiently store lipid can result in lipodystrophy and contribute to nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome. Leucine-rich repeat containing protein 8a/SWELL1 functionally encodes the volume-regulated anion channel complex in adipocytes, is induced in early obesity, and is required for normal adipocyte expansion during high-fat feeding. Adipose-specific SWELL1 ablation (Adipo KO) leads to insulin resistance and hyperglycemia during caloric excess, both of which are associated with NAFLD. Here, we show that Adipo-KO mice exhibited impaired adipose depot expansion and excess lipolysis when raised on a variety of high-fat diets, resulting in increased diacylglycerides and hepatic steatosis, thereby driving liver injury. Liver lipidomic analysis revealed increases in oleic acid-containing hepatic triacylglycerides and injurious hepatic diacylglyceride species, with reductions in hepatocyte-protective phospholipids and antiinflammatory free fatty acids. Aged Adipo-KO mice developed hepatic steatosis on a regular chow diet, and Adipo-KO male mice developed spontaneous, aggressive hepatocellular carcinomas (HCCs). These data highlight the importance of adipocyte SWELL1 for healthy adipocyte expansion to protect against NAFLD and HCC in the setting of overnutrition and with aging

Conditional deletion of LRRC8A in the brain reduces stroke damage independently of swelling-activated glutamate release

The ubiquitous volume-regulated anion channels (VRACs) facilitate cell volume control and contribute to many other physiological processes. Treatment with non-specific VRAC blockers or brain-specific deletion of the essential VRAC subunit LRRC8A is highly protective in rodent models of stroke. Here, we tested the widely accepted idea that the harmful effects of VRACs are mediated by release of the excitatory neurotransmitter glutamate. We produced conditional LRRC8A knockout either exclusively in astrocytes or in the majority of brain cells. Genetically modified mice were subjected to an experimental stroke (middle cerebral artery occlusion). The astrocytic LRRC8A knockout yielded no protection. Conversely, the brain-wide LRRC8A deletion strongly reduced cerebral infarction in both heterozygous (Het) and full KO mice. Yet, despite identical protection, Het mice had full swelling-activated glutamate release, whereas KO animals showed its virtual absence. These findings suggest that LRRC8A contributes to ischemic brain injury via a mechanism other than VRAC-mediated glutamate release

Correlation of Anthropometric Measurements with Hamstring Graft Size in Anterior Cruciate Ligament Reconstruction in Nepalese Population: A Prospective Observational Study

Background: The use of autologous hamstring tendon for arthroscopic Anterior Cruciate ligament (ACL) reconstruction is very common. The size of hamstring tendons varies significantly between individuals, and graft diameter is unpredictable. Anthropometric measurements may be a simple way to estimate hamstring tendon length and diameter. This study aims to determine the correlation between anthropometric measurements of patients with length and diameter of harvested hamstring autograft during ACL reconstruction. Methods: A prospective observational study was carried out after ethical approval. All patients who underwent arthroscopic ACL reconstruction from 1 March 2022 to 30 April 2023 in Birat Medical College Teaching Hospital were included. Fourty seven patients’ age, sex, height, weight and thigh length were recorded preoperatively. Hamstring tendons were harvested and length of the semitendinosus tendon and diameter of the quadrupled graft (doubled semitendinosus and doubled gracilis) was measured intraoperatively. We used Pearson’s correlation coefficient to observe the relationship between anthropometric measurements and graft variables. Results: Mean length of harvested semitendinosus tendon was 27.4 ± 1.8 cm and mean quadrupled hamstring autograft diameter was 7.4 ± 0.8 mm. A significant positive correlation between graft variables (semitendinosus tendon length and quadrupled hamstring autograft diameter) and patients’ height and thigh length was found.Regression equations for predicting Semitendinosus tendon length and quadrupled hamstring autograft diameter from thigh length in males and females are also derived. Conclusion: Height and thigh length of patients are useful parameters for predicting semitendinosus tendon length and quadrupled hamstring graft diameter before ACL reconstruction

Cardiac-Specific Elevations in Thyroid Hormone Enhance Contractility and Prevent Pressure Overload-Induced Cardiac Dysfunction

Thyroid hormone (TH) is critical for cardiac development and heart function. In heart disease, TH metabolism is abnormal, and many biochemical and functional alterations mirror hypothyroidism. Although TH therapy has been advocated for treating heart disease, a clear benefit of TH has yet to be established, possibly because of peripheral actions of TH. To assess the potential efficacy of TH in treating heart disease, type 2 deiodinase (D2), which converts the prohormone thyroxine to active triiodothyronine (T3), was expressed transiently in mouse hearts by using the tetracycline transactivator system. Increased cardiac D2 activity led to elevated cardiac T3 levels and to enhanced myocardial contractility, accompanied by increased Ca(2+) transients and sarcoplasmic reticulum (SR) Ca(2+) uptake. These phenotypic changes were associated with up-regulation of sarco(endo)plasmic reticulum calcium ATPase (SERCA) 2a expression as well as decreased Na(+)/Ca(2+) exchanger, beta-myosin heavy chain, and sarcolipin (SLN) expression. In pressure overload, targeted increases in D2 activity could not block hypertrophy but could completely prevent impaired contractility and SR Ca(2+) cycling as well as altered expression patterns of SERCA2a, SLN, and other markers of pathological hypertrophy. Our results establish that elevated D2 activity in the heart increases T3 levels and enhances cardiac contractile function while preventing deterioration of cardiac function and altered gene expression after pressure overload

The SWELL1-LRRC8 complex regulates endothelial AKT-eNOS signaling and vascular function

The endothelium responds to numerous chemical and mechanical factors in regulating vascular tone, blood pressure, and blood flow. The endothelial volume-regulated anion channel (VRAC) has been proposed to be mechanosensitive and thereby sense fluid flow and hydrostatic pressure to regulate vascular function. Here, we show that the leucine-rich repeat-containing protein 8a, LRRC8A (SWELL1), is required for VRAC in human umbilical vein endothelial cells (HUVECs). Endothelial LRRC8A regulates AKT-endothelial nitric oxide synthase (eNOS) signaling under basal, stretch, and shear-flow stimulation, forms a GRB2-Cav1-eNOS signaling complex, and is required for endothelial cell alignment to laminar shear flow. Endothelium-restricte

Small molecule SWELL1 complex induction improves glycemic control and nonalcoholic fatty liver disease in murine Type 2 diabetes

Type 2 diabetes is associated with insulin resistance, impaired pancreatic β-cell insulin secretion, and nonalcoholic fatty liver disease. Tissue-specific SWELL1 ablation impairs insulin signaling in adipose, skeletal muscle, and endothelium, and impairs β-cell insulin secretion and glycemic control. Here, we show that