Geniposide accelerates proteasome degradation of Txnip to inhibit insulin secretion in pancreatic β-cells

PURPOSE

To analyze the role of geniposide in the protein degradation of Txnip and to determine the impact of Txnip on geniposide-regulated GSIS in pancreatic INS-1 cells.

METHODS

The content of Txnip protein was measured by western blot; insulin content and glucose uptake were determined by ELISA; and knockdown of Txnip was the method of RNA interference.

RESULTS

Glucose induces a rapid increase in Txnip protein, and geniposide accelerates the degradation of Txnip via proteasome pathway in the presence of high glucose (25 mM) in INS-1 pancreatic β-cells. And MG132, a proteasomal inhibitor, potentiates glucose uptake, metabolism (ATP production) and glucose-stimulated insulin secretion (GSIS) in high-glucose (25 mM)-treated INS-1 cells, but geniposide significantly prevents these effects. Furthermore, the combination of geniposide and Txnip knockdown shows substantial synergistic effects to reduce glucose uptake, metabolism and GSIS in high-glucose (25 mM)-treated INS-1 cells.

CONCLUSIONS

Txnip protein played an essential role in glucose uptake, metabolism and GSIS, and geniposide could accelerate the degradation via proteasome pathway in high-glucose-treated pancreatic INS-1 cells.

[A childhood-onset rapid-onset dystonia parkinsonism family with ATP1A3 gene mutation and literatures review]

Objective: To explore clinical characteristics, treatment, and prognosis of a family with childhood-onset rapid-onset dystonia parkinsonism (RDP) caused by ATP1A3 gene mutation and review literatures. Method: The clinical data of a RDP child, his brother and mother had been analyzed retrospectively. This family was admitted to Xiangya Hospital in January 2016. DNA samples were analyzed by the next-generation sequencing and confirmed by Sanger sequencing. Related literature from PubMed, Online Mendelian Inheritance in Man (OMIM), CNKI and Wanfang databases to date (up to October 2016) with"Rapid-onset dystonia-parkinsonism""RDP""DYT12" as key words was reviewed. Result: The proband boy was three years and four months old (April 2015) when he had the first attack of the disease. After a febricity, he suddenly acquired acute aphasia and limb movement disorder. Rehabilitation therapy and supportive treatment made his speech gradually recovered but still slurred. However, his abnormal walking posture still existed. Nine months later (January 2016, 4 years and one months old), symptoms including aphasia, dysphagia, and weakness with rostrocaudal gradient reoccured after fever. The disease progressed to the critical condition within 24 hours. He"seizured" four times with tonic spasms of limbs but without loss of consciousness. Family history showed his grandparents were consanguineous marriage. His mother and brother also developed abnormal gait and dysarthria after an infection before primary school age. Their symptoms improved gradually without relapsing. However, they did not recover entirely with mild intellectual disability. His mother had a healthy brother and sister. This proband had no other siblings but the brother. Heterozygous missense mutation p. R756H in ATP1A3 gene was detected in this proband, his mother and his brother. This mutation had been reported pathogenically related to RDP, and it located in highly conserved gene region. Benzodiazepine was used for the proband and his brother, with the proband being improved better although not completely. Meanwhile, benzodiazepine had no significant effect on his mother because of poor compliance. This is the first case report of RDP in China. The mutations of ATP1A3 have been previously reported in 51 patients including 6 large families and 16 other unrelated patients. A total of 14 different mutations in ATP1A3 gene with RDP have been reported to date, including 12 missense mutations, a 3-bp in-frame deletion, and a 3-bp in-frame insertion. The sporadic cases all had the typical clinical phenotypes of RDP, such as the abrupt onset of dysarthria, dysphagia, limb dystonia with bradykinesia, and postural instability. The symptoms of bulbar and arms were much more obvious. It was hard to diagnose RDP in a family because some patients had typical symptoms of RDP, while the others might experience from mild symptoms to no symptoms, which might be related to incomplete penetrance of RDP. Two cases carrying the same mutation as our patients also presented some overlapping phenotypes. Conclusion: The p. R756H heterozygous mutation in ATP1A3 gene is the pathogenic mutation of RDP, analysis of genotype-phenotype correlations of RDP will be very important and meaningful.

[A novel mutation in KCNB1 gene in a child with neuropsychiatric comorbidities with both intellectual disability and epilepsy and review of literature]

Objective: To explore the association between the phenotype and KCNB1 gene mutation. Method: Clinical information including physical features, laboratory and genetic data of one patient of mental retardation with refractory epilepsy from Department of Pediatrics, Xiangya Hospital in January 2016 was analyzed. This patient was discovered to have KCNB1 gene mutations through whole exome sequencing. Relevant information about KCNB1 gene mutation was searched and collected from Pubmed, CNKI, Human Gene Mutation Database(HGMD) and Online Mendelian Inheritance in Man(OMIM). Searching was done using "KCNB1" as a keyword. Result: A 3.5 years old boy who visited our hospital firstly at the age of 2 years because of development delay came for follow up as he developed seizures.The forms included tonic, clonic seizures and spasm. The condition became more severe 10 months later. Electroencephalogram(EEG) showed high frequency discharge (>85%). He had poor response to multiple anti-epileptic drugs, methylprednisolone and ketogenic diet. At the age of 3, he started to have mental regression. Whole exome-sequencing study (trios) identified a novel heterozygous mutation c. G1136T (p.G379V) in KCNB1, which is not available in the databases mentioned above. This is the first case report of KCNB1 gene mutation in China. Eight cases have been reported so far worldwide and all of them were diagnosed with refractory epilepsy. Those 8 reported cases of encephalopathy were all due to de novo mutation. Conclusion: The main clinical features of patients with KCNB1 mutations include severe to profound intellectual disability, intractable seizures, hypotonia and regression of cognition and motor activity which lead to poor prognosis.

Corrosion resistance and biological properties of a micro–nano structured Ti surface consisting of TiO2 and hydroxyapatite

A micro–nanostructured Ti surface consisting of TiO₂ and HA was prepared by MAO, and showed improved corrosion resistance and biological properties.

Role of autophagy in cadmium-induced testicular injury

The testis is sensitive to cadmium, but studies investigating cadmium-induced testicular injury have not yet clearly revealed the underlying mechanisms. This study aimed to investigate the injurious effects of cadmium on rat testes and the role that autophagy plays in this process. Wistar rats were randomly divided into four groups and intraperitoneally injected with 0.2 (low), 0.4 (middle), and 0.8 mg/kg·body weight (high) cadmium chloride for 5 weeks, while the control rats were injected with equal volume of saline. Rats exposed to cadmium appeared inactive and had reduced body weights and increased testicular organ coefficients at the end of treatment compared with control rats. Atomic absorption results showed that cadmium levels increased with increased cadmium exposure. Hematoxylin and eosin staining of testicular sections showed seminiferous tubular atrophy, decreased pipe diameter, spermatogonial stem cells falling off the inner lining, and reduced germ cell layers of disorderly arrangements in cadmium-treated rats. Immunohistochemical and western blot results both showed that levels of the autophagy-related proteins Beclin1 and microtubule-associated protein 1 light chain 3B (LC3B) increased with increased cadmium exposure. We also found that LC3B-II and calcium-sensing receptor (CSR) levels in cadmium-exposed rats significantly increased. By immunofluorescence, we found that the percentage of cells that expressed the CSR was significantly higher in LC3B-positive than LC3B-negative cells. Together, our results showed that cadmium accumulates in the testes causing testicular injury, which may be related to increased autophagy levels. Furthermore, calcium disorders associated with the CSR may reveal a potential way to activate autophagy.

Effect of WC/Co coherency phase boundaries on Fracture toughness of the nanocrystalline cemented carbides

The effect of coherency WC/Co phase boundaries on the fracture toughness of the nanocrystalline WC-Co cemented carbides is studied by MD simulation method. The simulation results show that the nanocrystalline WC-Co cemented carbides with coherency WC/Co phase boundaries has higher fracture toughness than that without coherency WC/Co phase boundaries. Moreover, the mechanism of why coherency WC/Co phase boundaries can improve the fracture toughness of the nanocrystalline cemented carbides is also investigated. It is found the fact that the separation energy of the coherent WC/Co phase boundary is larger than that of the incoherent WC/Co phase boundaries is the main reason for this excellent mechanical property.