OBJECTIVE: Synaptic vesicle mobilization and neurite outgrowth regulation molecules were examined in modulation of effects of methylphenidate (MPH) in Spontaneous Hypertensive Rats (SHRs), a model for attention-deficit hyperactivity disorder (ADHD). METHODS: We compared the changes in the protein expression level of Cyclin dependent kinase 5 (Cdk5) and molecular substrates of Cdk5; tropomyosin receptor kinase B (TrkB), syntaxin 1A (STX1A) and synaptosomal-associated protein 25 (SNAP25). Comparisons were made in prefrontal cortex of vehicle (distilled water i.p. for 7 days)-treated SHRs, vehicle-treated Wistar Kyoto Rats (WKYs) and MPH (2 mg/kg i.p. for 7 days) treated SHRs. RESULTS: The Cdk5 level of vehicle-treated SHRs was significantly decreased compared to the Cdk5 level of vehicle-treated WKY rats, but was restored to the expression level of vehicle-treated WKYs in MPH-treated SHR. The ratio of p25/p35 was significantly decreased in MPH-treated SHR compared to vehicle-treated SHR. Moreover, TrkB, STX1A and SNAP25 of vehicle-treated SHRs were significantly decreased compared to vehicle-treated WKY rats, but were restored to the expression level of vehicle-treated WKYs in MPH-treated SHR. CONCLUSION: The results show that Cdk5, TrkB, STX1A, and SNAP25 were involved in the modulation of MPH effects in prefrontal cortex of SHRs and play important role in treatment of ADHD.
Animals ; Cyclin-Dependent Kinase 5 ; Methylphenidate ; Neurites ; Phosphotransferases ; Prefrontal Cortex ; Rats ; Rats, Inbred WKY ; Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins ; Synaptic Vesicles ; Synaptosomal-Associated Protein 25 ; Syntaxin 1 ; Tropomyosin ; Water

Mitochondria continuously fuse and divide to maintain homeostasis. An impairment in the balance between the fusion and fission processes can trigger mitochondrial dysfunction. Accumulating evidence suggests that mitochondrial dysfunction is related to neurodegenerative diseases such as Parkinson's disease (PD), with excessive mitochondrial fission in dopaminergic neurons being one of the pathological mechanisms of PD. Here, we investigated the balance between mitochondrial fusion and fission in the substantia nigra of a non-human primate model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. We found that MPTP induced shorter and abnormally distributed mitochondria. This phenomenon was accompanied by the activation of dynamin-related protein 1 (Drp1), a mitochondrial fission protein, through increased phosphorylation at S616. Thereafter, we assessed for activation of the components of the cyclin-dependent kinase 5 (CDK5) and extracellular signal-regulated kinase (ERK) signaling cascades, which are known regulators of Drp1(S616) phosphorylation. MPTP induced an increase in p25 and p35, which are required for CDK5 activation. Together, these findings suggest that the phosphorylation of Drp1(S616) by CDK5 is involved in mitochondrial fission in the substantia nigra of a non-human primate model of MPTP-induced PD.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine ; Cyclin-Dependent Kinase 5 ; Cyclin-Dependent Kinases ; Dopaminergic Neurons ; Homeostasis ; Mitochondria ; Mitochondrial Dynamics ; Neurodegenerative Diseases ; Parkinson Disease ; Phosphorylation ; Phosphotransferases ; Primates ; Substantia Nigra

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.
Animals ; Apoptosis ; Blotting, Western ; Calcium-Transporting ATPases ; Cyclin-Dependent Kinase 5 ; Diabetes Mellitus, Type 2 ; Down-Regulation ; Endoplasmic Reticulum Stress ; Endoplasmic Reticulum ; Gene Expression ; Genes, Homeobox ; Glucose ; Hyperglycemia ; Insulin-Secreting Cells ; Membrane Potential, Mitochondrial ; Polymerase Chain Reaction ; Rats ; Reactive Oxygen Species ; Reticulum ; Reverse Transcription ; Up-Regulation

OBJECTIVESTo explore the protective effects of Tongmai Yizhi Decoction (, TYD), a Chinese herb complex prescription against the impairment of cognitive functions and memory loss in amyloid beta 1-40 (Aβ) peptide and ibotenic (IBO)-induced Alzheimer's disease (AD) model rats.

METHODSThe in vivo model was established by injecting Aβand IBO into left hippocampal CA1 area of Sprague-Dawley (SD) rat to mimic AD. Totally 32 SD rats were divided into 4 groups, including sham operation group, AD model group, TYD group [AD rats treated with TYD at the dosage of 19.44 g/(kg•d) for 4 weeks] and huperzine A group [AD rats treated with huperzine A at the dosage of 40.5 μg/(kg•d) for 4 weeks]. Spatial learning and memory level was detected by Morris Water Maze test. Histological morphology in the hippocampus was tested by hematoxylin-eosin (HE) staining. Cyclin-dependent kinase-5 (Cdk5) protein and gene expression level were investigated by Western blot analysis and real-time quantitative polymerase chain reaction (RT-qPCR), respectively.

RESULTSAβ1-40 and IBO treatment induced longer escape latency of rats, compared with sham operation group from day 25 (P<0.01). However, TYD and huperzine A obviously shortened the escape latency from day 26 (P<0.01). Moreover, the effect of TYD was similar to huperzine A (P>0.05). Furthermore, HE staining also showed that TYD and huperzine A reversed the neuropathological changes in the hippocampus triggered by Aβ1-40 and IBO. TYD and huperzine A effectively reduced the expression levels of Cdk5 protein and gene located in rat hippocampus, compared with the AD model group (P<0.01).

CONCLUSIONTYD could be a promising neuroprotective agent for protecting neuron from AD injury through inhibiting Cdk5 expression.

Alzheimer Disease ; drug therapy ; pathology ; Animals ; Cognition ; drug effects ; Cyclin-Dependent Kinase 5 ; metabolism ; Disease Models, Animal ; Down-Regulation ; drug effects ; Drugs, Chinese Herbal ; therapeutic use ; Female ; Hippocampus ; drug effects ; Male ; Maze Learning ; drug effects ; Memory ; drug effects ; Neuroprotective Agents ; therapeutic use ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effect of monoamine oxidase inhibitor phenelzine on proliferation, apoptosis and histone modulation in acute lymphoblastic leukemia cell line Molt-4 cells.

METHODSThe effect of Phenelzine on cell proliferation was detected by MTT. Apoptotic rate was measured by flow cytometry. The variation of apoptosis associated proteins Caspase-3, Bcl-2 and Bax, cyclin-dependent kinase inhibitor p21, tumor suppressor protein p15, and the expression level of histone methylation of H3K4, H3K9 and histone acetylation of H3, DNMT1 were detected by Western Blot.

RESULTS① Molt-4 cell proliferation rates were (87.68±3.54)%, (67.84±3.24)%, (51.48±3.37)%, (28.72±2.56)% respectively after exposured to phenelzine at 5, 10, 15, 20 μmol/L for 24 h, P<0.05. ② After 10 μmol/L of phenelzine exposure for 24, 48, 72 h, cell proliferation rates were (67.84±3.24)%, (50.24±2.01)%, (40.31±2.25)%, P<0.05. ③ The apoptotic rates were (13.64±2.58)%, (31.24±3.42)%, (56.37±4.26)% after phenelzine treatment at 5, 10, 20 μmol/L for 24 h, which was concentration dependent. ④ Phenelzine could upregulate the expression of Bax, caspase-3, p21, and downregulate Bcl-2 expression. Phenelzine upregulated the methylation level of histone H3K4me1, H3K4me2 and histone acetylated H3, while it didn't change the level of histone H3K4me3, H3K9me1, H3K9me2. ⑤ Phenelzine inhibited DNMT1 expression and promoted p15 expression.

CONCLUSIONSPhenelzine increased the methylation of histone H3K4me1, H3K4me2, acetylation of histone H3 and p21, and decreased the expression of DNMT1 and p15, and ultimately inhibited the proliferation and apoptosis of Molt-4 cells.

Acetylation ; Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor p15 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; metabolism ; Histones ; metabolism ; Humans ; Methylation ; Phenelzine ; pharmacology

OBJECTIVETo investigate the expression of p16INK4a protein in breast cancer and analyze its clinical significance.

METHODSA total of 132 surgical specimens of primary breast cancer obtained between 2014 and 2015 were examined for expressions of ER, PR, CK5/6, Her-2 and p16INK4a proteins using immunohistochemistry.

RESULTSThe breast cancer samples were classified into 5 molecular subtypes, namely Luminal A (58 cases), Luminal B (32 cases), Her-2-positive (21 cases), basal-like (12 cases) and normal-like (9 cases) types. p16INK4a expression was negative in 7/132 (5.30%) cases, weakly positive in 15/132 (11.36%) cases, positive in 40/132 (30.30%) cases, and strongly positive in 70/132 (53.03%) cases. When categorizing negative and weakly positive cases into negative group and the positive and strongly positive cases into positive group, the total negative and positive expression rates of p16INK4a were 16.67% (22/132) and 83.33% (110/132) in the carcinoma tissues. Statistical analysis showed the expression intensity of p16INK4a differed significantly between the age groups (P<0.05) but was not significantly correlated with ER, PR, Her-2, molecular subtypes or metastasis of the tumors.

CONCLUSIONThe compensatory high expression of p16INK4a is the main mechanism of cell cycle deregulation in invasive breast cancer and can be an important specific molecular marker for invasive breast cancer.

Biomarkers, Tumor ; metabolism ; Breast Neoplasms ; classification ; diagnosis ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Female ; Humans ; Keratin-5 ; metabolism ; Keratin-6 ; metabolism ; Receptor, ErbB-2 ; metabolism ; Receptors, Estrogen ; metabolism ; Receptors, Progesterone ; metabolism

Cyclin-dependent kinase 5 (CDK5) is a member of cyclin-dependent kinase family, which does not directly regulate cell cycle. Through phosphorylation of target protein, CDK5 plays an irreplaceable role in the development, reparation and degeneration of neurons. Brain injury refers to the organic injury of brain tissue caused by external force hit on the head. Owing to the stress and repair system activated by our body itself after injury, various proteins and enzymes of the brain tissues are changed quantitatively, which can be used as indicators for estimating the time of injury. This review summarizes the progress on the distribution, the activity mechanism and the physiological effects of CDK5 after brain injury and its corresponding potential served as a marker for brain injury determination.
Brain/physiopathology* ; Brain Injuries/physiopathology* ; Cyclin-Dependent Kinase 5/metabolism* ; Nerve Tissue Proteins/metabolism* ; Neurons ; Neuroprotective Agents/pharmacology* ; Phosphorylation/drug effects* ; Time Factors

BACKGROUNDFetal insulin hypothesis was proposed that the association between low birth weight and type 2 diabetes is principally genetically mediated. The aim of this study was to investigate whether common variants in genes CDKAL1, HHEX, ADCY5, SRR, PTPRD that predisposed to type 2 diabetes were also associated with reduced birthweight in Chinese Han population.

METHODSTwelve single nucleotide polymorphisms (rs7756992/rs10946398 in CDKAL1, rs1111875 in HHEX, rs391300 in SRR, rs17584499 in PTPRD, rs1170806/rs9883204/rs4678017/rs9881942/rs7641344/rs6777397/rs6226243 in ADCY5) were genotyped in 1174 unrelated individuals born in Peking Union Medical College Hospital from 1921 to 1954 by TaqMan allelic discrimination assays, of which 645 had normal glucose tolerance, 181 had developed type 2 diabetes and 348 impaired glucose regulation. Associations of these 12 genetic variants with birthweight and glucose metabolism in later life were analyzed.

RESULTSBirthweight was inversely associated with CDKAL1-rs10946398 (β = -41 g [95% confidence interval [CI]: -80, -3], P = 0.034), common variants both associated with increased risk of impaired glucose metabolism and decreased insulin secretion index later in life. After adjusting for sex, gestational weeks, parity and maternal age, the risk allele of CDKAL1-rs7756992 was associated with reduced birthweight (β = -36 g [95% CI: -72, -0.2], P = 0.048). The risk allele in SRR showed a trend toward a reduction of birthweight (P = 0.085).

CONCLUSIONSThis study identified the association between type 2 diabetes risk variants in CDKAL1 and birthweight in Chinese Han individuals, and the carrier of risk allele within SRR had the trend of reduced birthweight. This demonstrates that there is a clear overlap between the genetics of type 2 diabetes and fetal growth, which proposes that lower birth weight and type 2 diabetes may be two phenotypes of one genotype.

Adenylyl Cyclases ; genetics ; Aged ; Alleles ; Asian Continental Ancestry Group ; genetics ; Birth Weight ; genetics ; Cyclin-Dependent Kinase 5 ; genetics ; Diabetes Mellitus, Type 2 ; genetics ; Female ; Genetic Predisposition to Disease ; genetics ; Homeodomain Proteins ; genetics ; Humans ; Infant, Low Birth Weight ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; genetics ; Receptor-Like Protein Tyrosine Phosphatases, Class 2 ; genetics ; Transcription Factors ; genetics ; tRNA Methyltransferases

OBJECTIVETo observe the effects of polydatin on learning and memory and cyclin-dependent kinase 5 (Cdk5) kinase activity in the hippocampus of rats with chronic alcoholism.

METHODSForty rats were randomly divided into 4 groups: control group, chronic alcoholism group, low and high polydatin group. The rat chronic alcoholism model was established by ethanol 3.0 g/(kg · d) (intragastric administration). The abstinence scoring was used to evaluate the rats withdrawal symptoms; cognitive function was measured by Morris water maze experiment; Cdk5 protein expression in the hippocampus was detected by immunofluorescence; Cdk5 kinase activity in the hippocampus was detected by liquid scintillation counting method.

RESULTSThe abstinence score, escape latency, Cdk5 kinase activity in chronic alcoholism group rats were significantly higher than those of control group (P < 0.05). The abstinence score, escape latency in high polydatin group rats were significantly lower than those of chronic alcoholism group (P < 0.05); Cdk5 kinase activity in high and low polydatin group rats was significantly lower than that of chronic alcoholism group( P < 0.05); immunofluorescence showed that the Cdk5 positive cells of chronic alcoholism group were significantly increased compared with control group (P < 0.05), and the Cdk5 positive cells of polydatin groups were significantly decreased compared with chronic alcoholism group ( P < 0.05).

CONCLUSIONPolydatin-reduced the chronic alcoholism damage may interrelate with regulation of Cdk5 kinase activity.

Alcoholism ; physiopathology ; Animals ; Cyclin-Dependent Kinase 5 ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Glucosides ; pharmacology ; Hippocampus ; drug effects ; enzymology ; Learning ; drug effects ; Memory ; drug effects ; Rats ; Stilbenes ; pharmacology

OBJECTIVETo study the effect of arsenic on neuronal cell apoptosis and the mRNA and protein expression of calpain 1, calpain 2, and cyclin-dependent kinases 5 (cdk5)/p25 and to provide a scientific basis for the research on neurotoxic mechanism of arsenic trioxide (As2O3).

METHODSPrimary cultured rat neurons were divided into untreated control group, dimethyl sulfoxide (DMSO) solvent control group, and 1, 5, and 10 µmol/L As2O3 treated groups. Eight hours after being treated with As2O3, cell apoptosis rate was determined by flow cytometry, the mRNA expression of calpain 1, calpain 2, cdk5, and p35 was measured by real-time fluorescence quantitative PCR, and the protein expression of calpain 1, calpain 2, cdk5, p35, and p25 was measured by Western blot.

RESULTSCompared with those in the untreated control group and DMSO solvent control group, the cell apoptosis rates in the 5 and 10 µmol/L As2O3 treated groups were significantly increased (P < 0.05). The mRNA expression levels of calpain 1 were 6.36±3.26, 7.11±5.13, and 7.47±2.59 in the 1, 5, and 10 µmol/L As2O3 treated groups, respectively, and the mRNA expression levels of cdk5 were 1.27±0.19, 1.54±0.04, and 1.79±0.21 in the 1, 5, and 10 µmol/L As2O3 treated groups, respectively, which were significantly higher than those in the untreated group (0.72±0.15 and 1.77±0.87) and those in the DMSO solvent control group (0.96±1.23 and 1.18±0.09) (P < 0.05). The mRNA expression levels of p35 in the 1 and 5 µmol/L As2O3 treated groups were 2.17±0.59 and 2.51±0.51, respectively, which were significantly higher than that in the untreated control group (1.26±0.37) (P < 0.05). The protein expression levels of calpain 1 were 0.37±0.10, 0.42±0.13, and 0.51±0.18 in the 1, 5, and 10 µmol/L As2O3 treated groups, respectively, which were significantly higher than those in the untreated control group (0.11±0.08) and DMSO solvent control group (0.13±0.07) (P < 0.05). In the 5 and 10 µmol/L As2O3 treated groups, the protein expression levels of cdk5 were 0.34±0.12 and 0.37±0.21, while the protein expression levels of p25 were 0.31±0.23 and 0.55±0.16, all of which were significantly higher than those in the untreated control group and DMSO solvent control group (P < 0.05). The protein expression levels of p35 were reduced in the 5 µmol/L As2O3 treated group (0.31±0.23) and 10 µmol/L As2O3 treated group (0.26±0.16), as compared with those in the untreated control group and DMSO solvent control group (P < 0.05). The mRNA and protein expression of calpain 2 showed no significant differences between all groups (P > 0.05).

CONCLUSIONThe calpain 1-cdk5/p25 pathway may be involved in the process of As2O3-induced neuronal cell apoptosis.

Animals ; Apoptosis ; drug effects ; Arsenic Poisoning ; Arsenicals ; Calpain ; metabolism ; Cells, Cultured ; Cyclin-Dependent Kinase 5 ; metabolism ; Neurons ; drug effects ; metabolism ; Oxides ; toxicity ; Rats