Inhibitory effect of gamma-secretase inhibitor on retinal neovascularization and regulative mechanism of Notch1 signal pathway / 中华实验眼科杂志

Objective:To investigate the inhibitory effect and underlying mechanism of gamma-secretase inhibitor blocking Notch1 signaling on retinal neovascularization caused by oxygen-induced retinopathy (OIR) in mice.Methods:To establish the OIR model, 7-day-old pups of C57BL/6J mice were exposed to 75% oxygen together with their mother until postnatal day (P)12.On P12, the mice were transferred to room air.All the mice were randomly divided into three groups, OIR group as control group, OIR+ DAPT group and OIR+ DMSO group receiving 1 μl intravitreal injection of gamma-secretase inhibitor (DAPT, 10 mmol/L) and 1∶20 DMSO dilution respectively.The right eye was taken as experimental eye.The mice were euthanized on P17 and the eyes were harvested to obtain retinas for further investigation.The total proteins were extracted from the retinas.The relative expression levels of Notch1 signal pathway and its downstream Hes1, the markers of M1 phenotype inducible nitric oxide synthase (iNOS) and M2 phenotype arginase-1 (Arg-1) microglia were measured by western blot.Retinal flat mounts were made and the retinal vessels were stained with isolectin B4 (IB4) to investigate the relative retinal neovascularization areas which was calculated as the ratio of neovascularization area/retinal area.The mumber of the neovascular endothelium cells beyond the inner limiting membrane was observed by hematoxylin-eosin staining.The use and care of animals complied with ARVO statement.This study protocol was approved by the Animal Ethics Committee of Guangdong Provincial People's Hospital (No.KY-Z-2021-2015-01).Results:The relative protein expression levels of Notch1 and Hes1 in OIR+ DAPT group, OIR group, and OIR+ DMSO group were 0.68±0.06 and 0.70±0.08, 1.00±0.00 and 1.00±0.00, 1.03±0.08 and 1.02±0.07, respectively, with statistically significant differences among them ( F=70.62, 53.65; both at P<0.01). Compared with the OIR group and OIR+ DMSO group, the expressions of Notch1 and Hes1 were significantly reduced in OIR+ DAPT group (all at P<0.01). The relative protein expression levels of iNOS and Arg-1 in OIR+ DAPT group, OIR group, and OIR+ DMSO group were 0.74±0.07 and 1.49±0.12, 1.00±0.00 and 1.00±0.00, 1.04±0.10 and 0.94±0.07, respectively, showing statistically significant differences ( F=31.63, 89.32; both at P<0.01). Compared with OIR group and OIR+ DMSO group, the expression of iNOS in OIR+ DAPT group was significantly reduced, and the expression of Arg-1 was significantly increased (all at P<0.01). The relative neovascularization area and the number of neovascular endothelium cells beyond the inner limiting membrane in OIR+ DAPT group, OIR group, and OIR+ DMSO group were (8.82±2.71)% and 38.17±3.29, (22.32±5.34)% and 60.83±5.11, (20.27±3.36)% and 58.67±4.75, respectively, showing statistically significant differences ( F=33.72, 39.44; both at P<0.01). The relative neovascularization area and the number of neovascular endothelium cells in OIR+ DAPT group were significantly reduced in comparison with OIR group and OIR+ DMSO group (all at P<0.01). Conclusions:Intravitreal injection of DAPT can inhibit the retinal neovascularization in OIR mice through blocking Notch1 signaling activation and promoting retinal microglia polarization from M1 to M2 phenotype.

Acne inversa in a family：a clinical survey and genetic mutation analysis / 中华皮肤科杂志

Objective To analyze γ?secretase gene mutations in a pedigree with acne inversa. Methods Clinical data were collected from a pedigree with acne inversa, which contained 30 members spanning 4 generations. Of these members, 12 were affected by acne inversa, and 9 of the affected members were alive. Peripheral blood DNA was obtained from the proband, his seven relatives (including 4 affected and 3 unaffected members), and 100 unrelatedhealthy human controls. PCR was performed to amplify all the coding exons and their flanking sequences of the NCSTN, PSEN1, PSENEN, Aph1 genes followed by DNA sequencing. Results A heterozygous insertion mutation (c.229_230insCACC)of the PSENEN gene, which led to translational frameshifting and resulted in dysfunciton of the PSENEN protein, was detected in all the 5 patients, but not in unaffected members or healthy controls. Conclusion There is a novel heterozygous insertion mutation c.229_230insCACC in the PSENEN gene, which may be the molecular basis of acne inversa in this family.

Alteration of NOTCH1 in T-cell Acute Lymphoblastic Leukemia and Development of Target Therapeutic Agent / 임상소아혈액종양

T-cell acute lymphoblastic leukemia (T-ALL) accounts for approximately 10-15% of entire ALL in children. The outcome of T-ALL has been improved through the intensified therapeutic strategy, however, it is still a more aggressive disease. In T-ALL a couple of transcription factor oncogenes are known to be relocated to the juxtaposition of T-cell receptor genes, potent promoter, by chromosome translocation. However the incidence of each chimeric gene formation in T-ALL is less than 5% and their clinical significance as a prognostic marker is lacking. A decade ago it was identified that activating mutations in NOTCH1 in about 60% of T-ALL. After then, activating NOTCH1 mutations present in T-ALL have been extensively investigated with regard to understanding its molecular pathogenesis, its prognostic significance, and developing molecularly tailored novel agents. Small molecule gamma-secretase inhibitor, blocking a proteolytic step required for creation of a fragment of NOTCH intracellular domain which actually act as a controller of its target gene expression, was tried as a target therapeutic drug for T-ALL. Although outcome of this drug was not satisfactory, challenges have been launched to develop new drugs which specifically act on the aberrant behavior of mutated NOTCH1 in T-ALL.

Alteration of NOTCH1 in T-cell Acute Lymphoblastic Leukemia and Development of Target Therapeutic Agent / 임상소아혈액종양

T-cell acute lymphoblastic leukemia (T-ALL) accounts for approximately 10-15% of entire ALL in children. The outcome of T-ALL has been improved through the intensified therapeutic strategy, however, it is still a more aggressive disease. In T-ALL a couple of transcription factor oncogenes are known to be relocated to the juxtaposition of T-cell receptor genes, potent promoter, by chromosome translocation. However the incidence of each chimeric gene formation in T-ALL is less than 5% and their clinical significance as a prognostic marker is lacking. A decade ago it was identified that activating mutations in NOTCH1 in about 60% of T-ALL. After then, activating NOTCH1 mutations present in T-ALL have been extensively investigated with regard to understanding its molecular pathogenesis, its prognostic significance, and developing molecularly tailored novel agents. Small molecule gamma-secretase inhibitor, blocking a proteolytic step required for creation of a fragment of NOTCH intracellular domain which actually act as a controller of its target gene expression, was tried as a target therapeutic drug for T-ALL. Although outcome of this drug was not satisfactory, challenges have been launched to develop new drugs which specifically act on the aberrant behavior of mutated NOTCH1 in T-ALL.

Altered expression of gamma-secretase components in animal model of major depressive disorder induced by reserpine administration / 한국실험동물학회지

Altered expression of neurotrophic factors as well as neuroinflammation is commonly associated with Major depressive disorder (MDD) and Alzheimer's disease (AD). To investigate whether or not reserpine-induced MDD affects the expression of AD-related proteins, the expression of gamma-secretase components and substrate were measured in brains of ICR mice following reserpine treatment for 15 days. In active avoidance test, total response time and peak slightly increased in the 2 mg/kg reserpine (RSP2)-treated group compared to vehicle-treated group (P<0.05). Expression and phosphorylation of MKP-1, which is a key factor in MDD pathology, were both higher in the RSP2-treated group than the vehicle- and 1 mg/kg reserpine (RSP1)-treated groups (P<0.02). Furthermore, full-length expression of amyloid precursor protein (APP) was enhanced in the RSP1 and RSP2-treated groups compared to the vehicle-treated group, whereas expression of gamma-secretase components decreased (P<0.03). Among the three components of the gamma-secretase complex, nicastrin protein underwent the largest decrease in expression, as detected by Western blotting (P<0.03). Therefore, the data presented here provide additional evidence about the pathological correlation between MDD and AD.

Effects of Red Liriope platyphylla on NGF secretion ability, NGF receptor signaling pathway and gamma-secretase components in NSE/hAPPsw transgenic mice expressing Alzheimer's Disease / 한국실험동물학회지

Liriope platyphylla (LP) has long been regarded as a curative herb for the treatment of diabetes, asthma, and neurodegenerative disorders. To examine the therapeutic effects of Red LP (RLP) manufactured by steaming process on neurodegenerative disorders, significant alteration of the key factors influencing Alzheimer's Disease (AD) was detected in NSE/hAPPsw transgenic (Tg) mice after RLP treatment. The concentration of nerve growth factor (NGF) in serum increased in RLP-treated NSE/hAPPsw Tg mice compared with vehicle-treated Tg mice. However, downstream effectors of the NGF receptor signaling pathway, including TrkA and p75NTR proteins, were suppressed in RLP-treated NSE/hAPPsw Tg mice. Especially, Tg mice showed decreased levels of TrkA, p75NTR, and RhoA expression. Production of Abeta-42 peptides was lower in RLP-treated NSE/hAPPsw Tg mice than in vehicle-treated Tg mice. Further, analysis of gamma-secretase components showed that Abeta-42 peptide expression was downregulated. Of the four components, the expression of APH-1 and Nicastrin (NCT) decreased in RLP-treated NSE/hAPPsw Tg mice, whereas expression of PS-2 and Pen-2 was maintained or increased within the same group. Overall, these results suggest that RLP can help relieve neurodegenerative diseases, especially AD, through upregulation of NGF secretion ability, activation of NGF signaling pathway, downregulation of Abeta-42 peptide deposition, and alteration of gamma-secretase components.

Peroxiredoxin I regulates the component expression of gamma-secretase complex causing the Alzheimer's disease / 한국실험동물학회지

Peroxiredoxin I (Prx I) is a member of the peroxiredoxins (Prxs) family, which are antioxidant enzymes that regulate various cellular process via intracellular oxidative signal pathways. In order to investigate the correlation between Prx I and the gamma-secretase complex, which causes Alzheimer's disease (AD), the expression level of Prx I was firstly evaluated in an animal model for AD. NSE/hPen-2 transgenic (Tg) mice, which were used as animal model in this study, showed a high level of Pen-2 expression and accumulation of Abeta-42 peptides in the hippocampus of brain. The expression level of Prx I was significantly higher on the mRNA and protein level in the brain of this model, while not change in Prx VI expression was observed. Furthermore, to verify the effect of Prx I on the gamma-secretase components in vitro, the expression level of these components was analyzed in the Prx I transfectants. Of the components of the gamma-secretase complex, the expression of PS-2 and Pen-2 was lower in the transfectants overexpressing Prx I compared to the vector transfectants. However, the expression of APP, NCT and APH-1 did not change in Prx I transfectants. Therefore, these results suggested that the expression of Prx I may be induced by the accumulation of Abeta-42 peptides and the overexpression of Prx I in neuroblastoma cells may regulate the expression of gamma-secretase components.

Effect of Ischemic Neuronal Insults on Amyloid Precursor Protein Processing

BACKGROUND: In spite of the different pathogenesis and exclusive respect in the diagnosis of Alzheimer's disease (AD) and vascular dementia (VaD), recent epidemiological and pathological studies indicates that ischemic stroke have an important role in the pathogenesis of both VaD and AD. However, the association of ischemic stroke and AD on the cellular and molecular level is still unknown. We evaluated the effect of ischemic neuronal insult on the regulation of amyloid precursor protein (APP) processing. METHODS: We used an in vitro model of cerebral ischemia (oxygen-glucose deprivation, OGD) to evaluate the effect of ischemic insult on the amyloidogenic and non-amyloidogenic pathways using human neuroblastoma cell line, SH-SY5Y, and primary cultured cells of Tg2576 APP transgenic mouse. RESULTS: Ischemic insult significantly increased the beta amyloid (A beta) production in the primary cultured cells of Tg2576 APP transgenic mice (p<0.001). A disintegrin and metalloprotease 10 (ADAM 10), a candidate of alpha-secretase, was markedly increased in the early stage of ischemic insult (up to 2 hours of OGD, p<0.001; 4 hours of OGD, p<0.05), which was followed by the decreased level of ADAM 10 expression in a later stage (p<0.001). However, the protein and mRNA expression of beta-site cleavage enzyme (BACE) and BACE activity were not significantly different between the group of ischemic insult and control. By contrast, the activity of gamma-secretase was significantly increased after 4 hours of ischemic insult, as compared to controls. CONCLUSIONS: This study demonstrates that the ischemic neuronal insults increase the production of A beta via activation of the amyloidogenic pathway, which may link the role of ischemic insults to the pathogenesis of AD.