Dulaglutide Ameliorates Palmitic Acid-Induced Hepatic Steatosis by Activating FAM3A Signaling Pathway

Background@#Dulaglutide, a long-acting glucagon-like peptide-1 receptor agonist (GLP-1RA), has been shown to reduce body weight and liver fat content in patients with type 2 diabetes. Family with sequence similarity 3 member A (FAM3A) plays a vital role in regulating glucose and lipid metabolism. The aim of this study was to determine the mechanisms by which dulaglutide protects against hepatic steatosis in HepG2 cells treated with palmitic acid (PA). @*Methods@#HepG2 cells were pretreated with 400 μM PA for 24 hours, followed by treatment with or without 100 nM dulaglutide for 24 hours. Hepatic lipid accumulation was determined using Oil red O staining and triglyceride (TG) assay, and the expression of lipid metabolism-associated factor was analyzed using quantitative real time polymerase chain reaction and Western blotting. @*Results@#Dulaglutide significantly decreased hepatic lipid accumulation and reduced the expression of genes associated with lipid droplet binding proteins, de novo lipogenesis, and TG synthesis in PA-treated HepG2 cells. Dulaglutide also increased the expression of proteins associated with lipolysis and fatty acid oxidation and FAM3A in PA-treated cells. However, exendin-(9-39), a GLP-1R antagonist, reversed the expression of FAM3A, and fatty acid oxidation-associated factors increased due to dulaglutide. In addition, inhibition of FAM3A by siRNA attenuated the reducing effect of dulaglutide on TG content and its increasing effect on regulation of fatty acid oxidation. @*Conclusion@#These results suggest that dulaglutide could be used therapeutically for improving nonalcoholic fatty liver disease, and its effect could be mediated in part via upregulation of FAM3A expression through a GLP-1R-dependent pathway.

Cervical Myelopathy with Retro-Odontoid Pseudotumor without Atlanto-Axial Instability / 대한정형외과학회잡지

An 82-year-old male patient was admitted for neck pain, motor weakness in both upper extremities, and gait disorder. The patient had no history of rheumatoid arthritis or other specific histories, and the findings of cervical myelopathy with retro-odontoid pseudotumor were confirmed by cervical magnetic resonance imaging. On cervical radiography, there was no evidence of atlantoaxial instability or subluxation. Therefore, posterior fusion was not performed; only a C1 laminectomy was performed. Immediately after surgery, the pain decreased, and neurological symptoms were also improved. In the case of a retro-odontoid pseudotumor without atlantoaxial instability, it is believed that the symptoms can be improved only with C1 laminectomy.

Schmorl’s Node Accompanying Multiple Osteonecroses / 대한정형외과학회잡지

A Schmorl’s node is defined as intervertebral disc herniation from the endplate to the adjacent vertebral body. This can cause pain and osteonecrosis in the vertebral body. The authors encountered a 59-year-old female patient with a Schmorl’s node accompanying multiple osteonecroses. To the best of the author’s knowledge, a Schmorl’s node accompanying multiple osteonecroses has not been reported in Korea. The authors report this case with a literature review.

Clusterin Protects Lipotoxicity-Induced Apoptosis via Upregulation of Autophagy in Insulin-Secreting Cells

Background@#There is a great need to discover factors that could protect pancreatic β-cells from apoptosis and thus prevent diabetes mellitus. Clusterin (CLU), a chaperone protein, plays an important role in cell protection in numerous cells and is involved in various cellular mechanisms, including autophagy. In the present study, we investigated the protective role of CLU through autophagy regulation in pancreatic β-cells. @*Methods@#To identify the protective role of CLU, mouse insulinoma 6 (MIN6) cells were incubated with CLU and/or free fatty acid (FFA) palmitate, and cellular apoptosis and autophagy were examined. @*Results@#Treatment with CLU remarkably upregulated microtubule-associated protein 1-light chain 3 (LC3)-II conversion in a doseand time-dependent manner with a significant increase in the autophagy-related 3 (Atg3) gene expression level, which is a mediator of LC3-II conversion. Moreover, co-immunoprecipitation and fluorescence microscopy experiments showed that the molecular interaction of LC3 with Atg3 and p62 was markedly increased by CLU. Stimulation of LC3-II conversion by CLU persisted in lipotoxic conditions, and FFA-induced apoptosis and dysfunction were simultaneously improved by CLU treatment. Finally, inhibition of LC3-II conversion by Atg3 gene knockdown markedly attenuated the cytoprotective effect of CLU. @*Conclusion@#Taken together, these findings suggest that CLU protects pancreatic β-cells against lipotoxicity-induced apoptosis via autophagy stimulation mediated by facilitating LC3-II conversion. Thus, CLU has therapeutic effects on FFA-induced pancreatic β-cell dysfunction.

Clusterin Protects Lipotoxicity-Induced Apoptosis via Upregulation of Autophagy in Insulin-Secreting Cells

Background@#There is a great need to discover factors that could protect pancreatic β-cells from apoptosis and thus prevent diabetes mellitus. Clusterin (CLU), a chaperone protein, plays an important role in cell protection in numerous cells and is involved in various cellular mechanisms, including autophagy. In the present study, we investigated the protective role of CLU through autophagy regulation in pancreatic β-cells. @*Methods@#To identify the protective role of CLU, mouse insulinoma 6 (MIN6) cells were incubated with CLU and/or free fatty acid (FFA) palmitate, and cellular apoptosis and autophagy were examined. @*Results@#Treatment with CLU remarkably upregulated microtubule-associated protein 1-light chain 3 (LC3)-II conversion in a doseand time-dependent manner with a significant increase in the autophagy-related 3 (Atg3) gene expression level, which is a mediator of LC3-II conversion. Moreover, co-immunoprecipitation and fluorescence microscopy experiments showed that the molecular interaction of LC3 with Atg3 and p62 was markedly increased by CLU. Stimulation of LC3-II conversion by CLU persisted in lipotoxic conditions, and FFA-induced apoptosis and dysfunction were simultaneously improved by CLU treatment. Finally, inhibition of LC3-II conversion by Atg3 gene knockdown markedly attenuated the cytoprotective effect of CLU. @*Conclusion@#Taken together, these findings suggest that CLU protects pancreatic β-cells against lipotoxicity-induced apoptosis via autophagy stimulation mediated by facilitating LC3-II conversion. Thus, CLU has therapeutic effects on FFA-induced pancreatic β-cell dysfunction.

Validity, Reliability and Responsiveness of the Korean Version of Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire in Patients with Carpal Tunnel Syndrome

BACKGROUND: The Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH) is one of the most widely used questionnaires for assessing functional ability of the patients with upper extremity diseases. Carpal tunnel syndrome (CTS) is the most common neuropathic disease in the upper extremities. The aim of this study was to verify the validity, reliability, and responsiveness of Korean version of QuickDASH questionnaire (K-QuickDASH) in the patients with CTS. METHODS: In total, 83 subjects who underwent open carpal tunnel release (CTR) operation were selected. They fulfilled Korean version of Disabilities of the Arm, Shoulder and Hand questionnaire (K-DASH) and K-QuickDASH at two different time points: before and six months after the surgery. Both criterion-related and construct validities were evaluated using Pearson's correlation coefficient and factor analysis. Internal consistency was estimated using Cronbach's alpha, and test-retest reliability was assessed to verify the reliability of K-QuickDASH using intraclass correlation coefficient (ICC). The standardized response mean and the effect size were analyzed to confirm the responsiveness of the K-QuickDASH in CTS patients. RESULTS: Significant positive correlation was found between K-QuickDASH and K-DASH. All the questionnaire items were categorized into three factors. Acceptable internal consistency was confirmed in three categories of K-QuickDASH. A high test-retest reliability and responsiveness of K-QuickDASH were detected. CONCLUSION: K-QuickDASH in Korean patients with CTS was confirmed to have high degree of validity and reliability, and responsiveness after CTR. Therefore, the K-QuickDASH would be a good evaluation tool for evaluating clinical symptoms and determination of treatment outcomes in the patients with CTS.

Deficiency of Sphingosine-1-Phosphate Reduces the Expression of Prohibitin and Causes β-Cell Impairment via Mitochondrial Dysregulation

BACKGROUND: Emerging evidence suggests that sphingolipids may be involved in type 2 diabetes. However, the exact signaling defect through which disordered sphingolipid metabolism induces β-cell dysfunction remains unknown. The current study demonstrated that sphingosine-1-phosphate (S1P), the product of sphingosine kinase (SphK), is an essential factor for maintaining β-cell function and survival via regulation of mitochondrial action, as mediated by prohibitin (PHB). METHODS: We examined β-cell function and viability, as measured by mitochondrial function, in mouse insulinoma 6 (MIN6) cells in response to manipulation of cellular S1P and PHB levels. RESULTS: Lack of S1P induced by sphingosine kinase inhibitor (SphKi) treatment caused β-cell dysfunction and apoptosis, with repression of mitochondrial function shown by decreases in cellular adenosine triphosphate content, the oxygen consumption rate, the expression of oxidative phosphorylation complexes, the mitochondrial membrane potential, and the expression of key regulators of mitochondrial dynamics (mitochondrial dynamin-like GTPase [OPA1] and mitofusin 1 [MFN1]). Supplementation of S1P led to the recovery of mitochondrial function and greatly improved β-cell function and viability. Knockdown of SphK2 using small interfering RNA induced mitochondrial dysfunction, decreased glucose-stimulated insulin secretion (GSIS), and reduced the expression of PHB, an essential regulator of mitochondrial metabolism. PHB deficiency significantly reduced GSIS and induced mitochondrial dysfunction, and co-treatment with S1P did not reverse these trends. CONCLUSION: Altogether, these data suggest that S1P is an essential factor in the maintenance of β-cell function and survival through its regulation of mitochondrial action and PHB expression.

Pioglitazone Attenuates Palmitate-Induced Inflammation and Endoplasmic Reticulum Stress in Pancreatic β-Cells

BACKGROUND: The nuclear receptor peroxisome proliferator-activator gamma (PPARγ) is a useful therapeutic target for obesity and diabetes, but its role in protecting β-cell function and viability is unclear. METHODS: To identify the potential functions of PPARγ in β-cells, we treated mouse insulinoma 6 (MIN6) cells with the PPARγ agonist pioglitazone in conditions of lipotoxicity, endoplasmic reticulum (ER) stress, and inflammation. RESULTS: Palmitate-treated cells incubated with pioglitazone exhibited significant improvements in glucose-stimulated insulin secretion and the repression of apoptosis, as shown by decreased caspase-3 cleavage and poly (adenosine diphosphate [ADP]-ribose) polymerase activity. Pioglitazone also reversed the palmitate-induced expression of inflammatory cytokines (tumor necrosis factor α, interleukin 6 [IL-6], and IL-1β) and ER stress markers (phosphor-eukaryotic translation initiation factor 2α, glucose-regulated protein 78 [GRP78], cleaved-activating transcription factor 6 [ATF6], and C/EBP homologous protein [CHOP]), and pioglitazone significantly attenuated inflammation and ER stress in lipopolysaccharide- or tunicamycin-treated MIN6 cells. The protective effect of pioglitazone was also tested in pancreatic islets from high-fat-fed KK-Ay mice administered 0.02% (wt/wt) pioglitazone or vehicle for 6 weeks. Pioglitazone remarkably reduced the expression of ATF6α, GRP78, and monocyte chemoattractant protein-1, prevented α-cell infiltration into the pancreatic islets, and upregulated glucose transporter 2 (Glut2) expression in β-cells. Moreover, the preservation of β-cells by pioglitazone was accompanied by a significant reduction of blood glucose levels. CONCLUSION: Altogether, these results support the proposal that PPARγ agonists not only suppress insulin resistance, but also prevent β-cell impairment via protection against ER stress and inflammation. The activation of PPARγ might be a new therapeutic approach for improving β-cell survival and insulin secretion in patients with diabetes mellitus

Median nerve neuropathy

The median nerve is the most important nerve in the upper extremity, as it is responsible for most of the sensation of the hand, the fine motor functions of the thumb, and finger grasping. Median neuropathies most commonly occur as compressive neuropathy or entrapment neuropathy, but sometimes as neuritis without any compressive lesion. Carpal tunnel syndrome (CTS), anterior interosseous nerve syndrome, and pronator teres syndrome are the subtypes of median nerve neuropathies, of which CTS is the most common. Median neuropathies can be diagnosed clinically by careful history-taking and a physical examination. Typical symptoms of CTS include night pain (crying), a tingling sensation of the radial digits, numbness or paresthesia, clumsiness, and atrophy of the thenar muscles. Electrophysiologic testing can be used for confirmation of the diagnosis and for documentation before surgical treatment. Imaging modalities including ultrasonography or magnetic resonance imaging can be used to ensure diagnostic accuracy and to detect unusual causes of compression. Conservative treatments include rest, bracing, nerve stretching, non-steroidal anti-inflammatory drugs, and steroid injections. If nonsurgical approaches are unsatisfactory or the nerve damage is severe, surgical treatment should be considered. Carpal tunnel release for CTS is a relatively simple procedure that involves division of the transverse carpal ligament and decompression of the median nerve. Early diagnosis and proper management are important, as muscle atrophy and sensory loss may persist when surgical release is delayed in patients with advanced disease.

Exendin-4 Inhibits the Expression of SEPP1 and Fetuin-A via Improvement of Palmitic Acid-Induced Endoplasmic Reticulum Stress by AMPK

BACKGROUND: Selenoprotein P (SEPP1) and fetuin-A, both circulating liver-derived glycoproteins, are novel biomarkers for insulin resistance and nonalcoholic fatty liver disease. However, the effect of exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, on the expression of hepatokines, SEPP1, and fetuin-A, is unknown. METHODS: The human hepatoma cell line HepG2 was treated with palmitic acid (PA; 0.4 mM) and tunicamycin (tuni; 2ug/ml) with or without exendin-4 (100 nM) for 24 hours. The change in expression of PA-induced SEPP1, fetuin-A, and endoplasmic reticulum (ER) stress markers by exendin-4 treatment were evaluated using quantitative real-time reverse transcription polymerase chain reaction and Western blotting. Transfection of cells with AMP-activated protein kinase (AMPK) small interfering RNA (siRNA) was performed to establish the effect of exendin-4-mediated AMPK in the regulation of SEPP1 and fetuin-A expression. RESULTS: Exendin-4 reduced the expression of SEPP1, fetuin-A, and ER stress markers including PKR-like ER kinase, inositol-requiring kinase 1alpha, activating transcription factor 6, and C/EBP homologous protein in HepG2 cells. Exendin-4 also reduced the expression of SEPP1 and fetuin-A in cells treated with tunicamycin, an ER stress inducer. In cells treated with the AMPK activator 5-aminoidazole-4-carboxamide ribonucleotide (AICAR), the expression of hepatic SEPP1 and fetuin-A were negatively related by AMPK, which is the target of exendin-4. In addition, exendin-4 treatment did not decrease SEPP1 and fetuin-A expression in cells transfected with AMPK siRNA. CONCLUSION: These data suggest that exendin-4 can attenuate the expression of hepatic SEPP1 and fetuin-A via improvement of PA-induced ER stress by AMPK.

Activation of AMP-Activated Protein Kinase Attenuates Tumor Necrosis Factor-alpha-Induced Lipolysis via Protection of Perilipin in 3T3-L1 Adipocytes

BACKGROUND: Tumor necrosis factor (TNF)-alpha and AMP-activated protein kinase (AMPK) are known to stimulate and repress lipolysis in adipocytes, respectively; however, the mechanisms regulating these processes have not been completely elucidated. METHODS: The key factors and mechanism of action of TNF-alpha and AMPK in lipolysis were investigated by evaluating perilipin expression and activity of protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2 alpha (eIF2alpha) by Western blot and an immunofluorescence assay in 24-hour TNF-alpha-treated 3T3-L1 adipocytes with artificial manipulation of AMPK activation. RESULTS: Enhancement of AMPK activity by the addition of activator minoimidazole carboxamide ribonucleotide (AICAR) suppressed TNF-alpha-induced lipolysis, whereas the addition of compound C, an inhibitor of AMPK phosphorylation, enhanced lipolysis. Perilipin, a lipid droplet-associated protein, was decreased by TNF-alpha and recovered following treatment with AICAR, showing a correlation with the antilipolytic effect of AICAR. Significant activation of PERK/eIF2alpha, a component of the unfolded protein response signaling pathway, was observed in TNF-alpha or vesicle-treated 3T3-L1 adipocytes. The antilipolytic effect and recovery of perilipin expression by AICAR in TNF-alpha-treated 3T3-L1 adipocytes were significantly diminished by treatment with 2-aminopurine, a specific inhibitor of eIF2alpha. CONCLUSION: These data indicated that AICAR-induced AMPK activation attenuates TNF-alpha-induced lipolysis via preservation of perilipin in 3T3-L1 adipocytes. In addition, PERK/eIF2alpha activity is a novel mechanism of the anti-lipolytic effect of AICAR.

National Utilization of Calcium Supplements in Patients with Osteoporotic Hip Fracture in Korea

BACKGROUND: Calcium is prescribed worldwide for patients diagnosed with osteoporosis. However, the national utilization of calcium and compliance with calcium is unclear in Korea. Our purpose is to evaluate Korea's national utilization of calcium and compliance with calcium in patients with osteoporotic hip fracture from 2007 to 2010 using data from the Health Insurance Review and Assessment (HIRA) Service. METHODS: From 2007 to 2011, osteoporotic hip fractures were identified using the International Classification of Diseases, 10th revision (ICD-10) and procedure code form from the nationwide database of the Health Insurance Review and Assessment Service. Compliant users of calcium were defined as the patients' medication possession ratio of 80 or more. We analyzed the compliance of calcium according to age and gender. RESULTS: Among 85,228 patients with hip fracture, 20,800 patients (24.4%) received a prescription of a calcium supplement. Among them, only 1,692 patients (8.1%) were identified as compliant users of calcium. The proportion of compliant users was higher in women than men in all age groups. The proportion of compliant users decreased with age in women. CONCLUSIONS: In Korea, the national utilization of calcium was low and compliance with calcium was unsatisfactory even in patients with osteoporotic hip fracture.

GLP-1 Receptor Agonist and Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), one of the most common liver diseases, is caused by the disruption of hepatic lipid homeostasis. It is associated with insulin resistance as seen in type 2 diabetes mellitus. Glucagon-like peptide-1 (GLP-1) is an incretin that increases insulin sensitivity and aids glucose metabolism. In recent in vivo and in vitro studies, GLP-1 presents a novel therapeutic approach against NAFLD by increasing fatty acid oxidation, decreasing lipogenesis, and improving hepatic glucose metabolism. In this report, we provide an overview of the role and mechanism of GLP-1 in relieving NAFLD.

The Pancreatic Tissue Regeneration and Molecular Regulators / 대한해부학회지

Pancreas is a unique organ that produces and secretes digestive enzymes to alimentary tube and supplies endocrine hormones regulating metabolic homeostasis. In the postnatal stage, pancreatic tissue is maintained by a simple proliferation of the preexisting cells. It has been known that tissue regeneration rarely occurs in the normal adult pancreas, particularly in the human pancreas. However regeneration of pancreatic tissue can be induced experimentally following pancreatic injuries in animal models. Regeneration occurs at the site of tissue injury by forming new lobules, so called 'neogenic lobule', that consist of the immature pancreatic tissues of both exocrine and endocrine components. We postulate that regeneration is instigated from the small tubular structures with elongated epithelial cells (neogenic ductules) which grow to ducts and acini for exocrine neogenesis, as well as to islet cells for endocrine tissue formation. As a sequential process of neogenic regeneration, the regenerating tissue becomes heterogeneous in tissue composition. Neogenic lobules in earlier regenerating stage were mainly composed of neogenic ductules which are substituted with developing acini in later stages. The endocrine cells, including insulin secreting beta cells, are also derived from the stem/precursor cells in neogenic ductules. After budding off from the neogenic ductules, the primitive endocrine cells continue to proliferate and differentiate, forming a large cell cluster or primitive islet. Such neogenic regeneration differs, but not completely, from pancreas development during fetal organogenesis. We found that the pancreatic regeneration is regulated by the several biological factors including nestin, clusterin and INGAP which are not involved in embryonic pancreas development. We suggest that the stem/precursor cells are recapitulated and regenerated to functional cells, and stem cell-derived pancreatic regeneration could provide a source of the pancreatic cells, particularly insulin secreting beta cells for cell replacement therapy of diabetes.

Pancreatic Exocrine and Endocrine Cell Differentiation during Pancreatic Regeneration / 한양의대학술지

Pancreatic tissue is maintained by a simple proliferation of the preexisting cells in adulthood, whereas, they are dynamically derived from precursor/ stem cells from ductal epithelia during prenatal life. It has been known that tissue regeneration rarely occurs in the normal adult pancreas, particularly in the human pancreas. However, regeneration can be experimentally induced in the adult pancreas in response to various tissue injuries such as partial resection, pancreatitis by obstruction of the duct, and chemical insults. Regenerating pancreatic tissue shares a common morphogenic feature of "neogenic regeneration" in all regenerating animal models. Neogenic regeneration occurs at the site of tissue injury by forming small tubular structures with elongated epithelial cells (ductules) which grow to form pancreatic ducts and acini. The endocrine cells, including insulin secreting beta cells, are also derived from these ductules. As a sequential process of neogenesis, the regenerating tissue becomes heterogeneous in composition. Some areas were composed by tubules and ductules in surrounding loose connective tissue while others were denser with differentiating acini derived from tubules or ductules. Such neogenic regeneration mimics tissue development during fetal pancreatic organogenesis. In the process of pancreatic neogenesis, we found unique expressions of bioactive proteins such as nestin and clusterin as morphogenic factors. It is likely that the stem/precursor cells could be recapitulated and regenerated to functional cells, including endocrine and exocrine pancreatic cells with acinar and ductal cells during neogenic regeneration of the pancreas.