Myricetin Protects Against High Glucose-Induced β-Cell Apoptosis by Attenuating Endoplasmic Reticulum Stress via Inactivation of Cyclin-Dependent Kinase 5

BACKGROUND: Chronic hyperglycemia has deleterious effects on pancreatic β-cell function and turnover. Recent studies support the view that cyclin-dependent kinase 5 (CDK5) plays a role in β-cell failure under hyperglycemic conditions. However, little is known about how CDK5 impair β-cell function. Myricetin, a natural flavonoid, has therapeutic potential for the treatment of type 2 diabetes mellitus. In this study, we examined the effect of myricetin on high glucose (HG)-induced β-cell apoptosis and explored the relationship between myricetin and CDK5. METHODS: To address this question, we subjected INS-1 cells and isolated rat islets to HG conditions (30 mM) in the presence or absence of myricetin. Docking studies were conducted to validate the interaction between myricetin and CDK5. Gene expression and protein levels of endoplasmic reticulum (ER) stress markers were measured by real-time reverse transcription polymerase chain reaction and Western blot analysis. RESULTS: Activation of CDK5 in response to HG coupled with the induction of ER stress via the down regulation of sarcoendoplasmic reticulum calcium ATPase 2b (SERCA2b) gene expression and reduced the nuclear accumulation of pancreatic duodenal homeobox 1 (PDX1) leads to β-cell apoptosis. Docking study predicts that myricetin inhibit CDK5 activation by direct binding in the ATP-binding pocket. Myricetin counteracted the decrease in the levels of PDX1 and SERCA2b by HG. Moreover, myricetin attenuated HG-induced apoptosis in INS-1 cells and rat islets and reduce the mitochondrial dysfunction by decreasing reactive oxygen species production and mitochondrial membrane potential (Δψm) loss. CONCLUSION: Myricetin protects the β-cells against HG-induced apoptosis by inhibiting ER stress, possibly through inactivation of CDK5 and consequent upregulation of PDX1 and SERCA2b.

Small molecules that allosterically inhibit p21-activated kinase activity by binding to the regulatory p21-binding domain

p21-activated kinases (PAKs) are key regulators of actin dynamics, cell proliferation and cell survival. Deregulation of PAK activity contributes to the pathogenesis of various human diseases, including cancer and neurological disorders. Using an ELISA-based screening protocol, we identified naphtho(hydro)quinone-based small molecules that allosterically inhibit PAK activity. These molecules interfere with the interactions between the p21-binding domain (PBD) of PAK1 and Rho GTPases by binding to the PBD. Importantly, they inhibit the activity of full-length PAKs and are selective for PAK1 and PAK3 in vitro and in living cells. These compounds may potentially be useful for determining the details of the PAK signaling pathway and may also be used as lead molecules in the development of more selective and potent PAK inhibitors.

Small molecules that allosterically inhibit p21-activated kinase activity by binding to the regulatory p21-binding domain

p21-activated kinases (PAKs) are key regulators of actin dynamics, cell proliferation and cell survival. Deregulation of PAK activity contributes to the pathogenesis of various human diseases, including cancer and neurological disorders. Using an ELISA-based screening protocol, we identified naphtho(hydro)quinone-based small molecules that allosterically inhibit PAK activity. These molecules interfere with the interactions between the p21-binding domain (PBD) of PAK1 and Rho GTPases by binding to the PBD. Importantly, they inhibit the activity of full-length PAKs and are selective for PAK1 and PAK3 in vitro and in living cells. These compounds may potentially be useful for determining the details of the PAK signaling pathway and may also be used as lead molecules in the development of more selective and potent PAK inhibitors.

Mutation analysis of PAH gene and characterization of a recurrent deletion mutation in Korean patients with phenylketonuria

Phenylketonuria (PKU; MIM 261600) is an autosomal recessive metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH; EC 1.14.16.1). Point mutations in the PAH gene are known to cause PKU in various ethnic groups, and large deletions or duplications account for up to 3% of the PAH mutations in some ethnic groups. However, a previous study could not identify ~14% of the mutant alleles by sequence analysis in Korean patients with PKU, which suggests that large deletions or duplication might be frequent causes of PKU in Koreans. To test this hypothesis, we performed multiplex ligation-dependent probe amplification (MLPA) for the identification of uncharacterized mutant alleles after PAH sequence analysis of 33 unrelated Korean patients with PKU. Bi-directional sequencing of the PAH exons and flanking intronic regions revealed 27 different mutations, including four novel mutations (two missense and two deletion mutations), comprising 57/66 (86%) mutant alleles. MLPA identified a large deletion that encompassed exons 5 and 6 in four patients, another large deletion that extended from exon 4 to exon 7 in one patient, and a duplication of exon 4 in one patient. Chromosomal walking characterized the deletion breakpoint of the most common large deletion that involved exons 5 and 6 (c.456_706+138del). The present study shows that the allelic frequency of exon deletion or duplication is 9% (6/66) in Korean PKU patients, which suggests that these mutations may be frequent causes of PKU in Korean subjects.

Testis Biopsy in Infertile Men with Azospermia / 대한비뇨기과학회지

Concepts regarding the evaluation and management of the infertile male have evolved during the past decade primarily because of the development of new methodology. Nevertheless, the causes of male infertility is often obscure, and the clearly defined causes are infrequent or rare. Testicular biopsy findings are basic and very important in evaluating the causes of infertility. The testis biopsy findings of 30 azoospermic patients were evaluated and it was observed in aspect of testicular size and past history. Following results were obtained. 1. Among the 91 patients who underwent semenalysis, 30 cases (33%)were azospermia. 2. In testicular biopsy findings hypospermatogenesis was the most frequent finding and the more severe hypospermatogenesis was the more atrophic the seminiferous tubule is and showed frequent Leydig cell hyperplasia. 3. Testicular biopsy findings revealed no specific correlation between small testis and normal testis patients. 4. In aspect of past history 2 epididymal tubercu1osis patients showed normal biopsy findings which suggest obstruction of sperm route and one cryptorchism and one varicocele patients showed hypospermatogenesis. 5. By testicular biopsy most of the cause of infertility was testicular and 3 cases were posttesticular.

Suprapubic Ultrasonographic Findings of the Prostatic Diseases / 대한비뇨기과학회지

There have been much limitations and errors in evaluating prostatic conditions by traditional radiologic methods due to its location and anatomical structure. However recent introduction and improvement of the ultrasonography have been enabled us to visualize boundary of the prostate clearly and differentiate the variable findings within the prostate. Transrectal or transurethral ultrasonography of the prostate is popular nowadays, however we performed suprapubic ultrasonography of which merits are traumatic to the patients, easy to perform and it requires no adjustments or additions to basic ultrasound equipment. In order to evaluate ultrasonogram of the prostate in patients with prostatic diseases and normal adults and compare preoperative volume of the prostate on ultrasonographic estimation with postoperative volume, 31 patients with prostatic diseases and 40 normal adults under the age 60 were studied with suprapubic ultrasonography. The results obtained were as follows. 1. On ultrasonographic picture of the prostate, normal adults showed symmetrical or triangular or elliptical appearance and there were numerous fine homogenous spots within the prostate. BPH patients showed symmetric, round or oval shapes and its margin was smooth and numerous fine spots were seen within the prostate as normal adults. The prostatic size enlarged and elevated to the bladder base. Advanced prostatic cancer patients showed dyssymmetric irregular appearance. The prostate of acute prostatitis patients resembled normal prostate but prostatic size enlarged. 2. The mean prostatic volume of normal adults on ultrasonographic estimation was 21.30+/-24.80 cm3 and there were no differences of the prostatic volume between ages. 3. The mean prostatic volume of 21 BPH patients on ultrasonographic estimation was 46.2+/-17.2 cm3 and majority patients were in 33.49-61.56 cm3. 4. Comparisonal studies between preoperative ultrasonographic prostatic volume and resected prostatic volume showed correlation coefficient 0.98 (P<0.005) and mean error rate 17.58+/-8.1%. Most cases showed preoperative prostatic volume was larger than the postoperative volume which was probably due to inadequate removal of tissue and surgical capsule. As results of the above, the suprapubic ultrasonography was helpful in differential diagnosis of the prostatic diseases and estimation of the prostatic size.