Tumor-derived neomorphic mutations in ASXL1 impairs the BAP1-ASXL1-FOXK1/K2 transcription network

Additional sex combs-like 1 (ASXL1) interacts with BRCA1-associated protein 1 (BAP1) deubiquitinase to oppose the polycomb repressive complex 1 (PRC1)-mediated histone H2A ubiquitylation. Germline BAP1 mutations are found in a spectrum of human malignancies, while ASXL1 mutations recurrently occur in myeloid neoplasm and are associated with poor prognosis. Nearly all ASXL1 mutations are heterozygous frameshift or nonsense mutations in the middle or to a less extent the C-terminal region, resulting in the production of C-terminally truncated mutant ASXL1 proteins. How ASXL1 regulates specific target genes and how the C-terminal truncation of ASXL1 promotes leukemogenesis are unclear. Here, we report that ASXL1 interacts with forkhead transcription factors FOXK1 and FOXK2 to regulate a subset of FOXK1/K2 target genes. We show that the C-terminally truncated mutant ASXL1 proteins are expressed at much higher levels than the wild-type protein in ASXL1 heterozygous leukemia cells, and lose the ability to interact with FOXK1/K2. Specific deletion of the mutant allele eliminates the expression of C-terminally truncated ASXL1 and increases the association of wild-type ASXL1 with BAP1, thereby restoring the expression of BAP1-ASXL1-FOXK1/K2 target genes, particularly those involved in glucose metabolism, oxygen sensing, and JAK-STAT3 signaling pathways. In addition to FOXK1/K2, we also identify other DNA-binding transcription regulators including transcription factors (TFs) which interact with wild-type ASXL1, but not C-terminally truncated mutant. Our results suggest that ASXL1 mutations result in neomorphic alleles that contribute to leukemogenesis at least in part through dominantly inhibiting the wild-type ASXL1 from interacting with BAP1 and thereby impairing the function of ASXL1-BAP1-TF in regulating target genes and leukemia cell growth.

The alterations of apoptosis factor Bcl-2/Bax in the early Parkinson's disease rats and the protective effect of scorpion venom derived activity peptide / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the alterations of apoptosis factor Bcl-2/Bax in the early Parkinson's disease (PD) rats and the protective effect of scorpion venom derived bioactive peptide.</p><p><b>METHODS</b>Healthy male SD rats (180-220 g) were randomly divided into 4 groups (n = 10): early PD model group, sham operation group, scorpion venom derived bioactive peptide control group, scorpion venom derived bioactive peptide therapy group. 6-hydroxydopamine (6-OHDA) was used to prepare the early PD rat model. The immunohistochemistry was used to detect the expression of Bax and Bcl-2 and further explore the mechanism of anti-apoptosis regarding the neuroprotective effect of scorpion venom derived bioactive peptide.</p><p><b>RESULTS</b>The results indicated that compared with the control rats, the immunostaining of Bax in the brain increased significantly while that of Bcl-2 decreased significantly in the lesion side of 6-OHDA treated rats. Interestingly, scorpion venom derived bioactive peptide could attenuate the above abnormal changes.</p><p><b>CONCLUSION</b>Up-regulation of Bax and down-regulation of Bcl-2 could participate in the early stage of PD and the anti-apoptotic mechanism could be involved in the neuroprotective effect exerted by scorpion venom derived activity peptide regarding the dopaminergic neuron in the early stage.</p>

Neuroprotection by scorpion venom heat resistant peptide in 6-hydroxydopamine rat model of early-stage Parkinson's disease / 生理学报

Neuroprotective effect of scorpion venom on Parkinson's disease (PD) has already been reported. The present study was aimed to investigate whether scorpion venom heat resistant peptide (SVHRP) could attenuate ultrastructural abnormalities in mitochondria and oxidative stress in midbrain neurons of early-stage PD model. The early-stage PD model was established by injecting 6-hydroxydopamine (6-OHDA) (20 μg/3 μL normal saline with 0.1% ascorbic acid) into the striatum of Sprague Dawley (SD) rats unilaterally. The rats were intraperitoneally administered with SVHRP (0.05 mg/kg per day) or vehicle (saline) for 1 week. Two weeks after 6-OHDA treatment, the rats received behavior tests for validation of model. Three weeks after 6-OHDA injection, the immunoreactivity of dopaminergic neurons were detected by immunohistochemistry staining, and the ultrastructure of neuronal mitochondria in midbrain was observed by electron microscope. In the meantime, the activities of monoamine oxidase-B (MAO-B), superoxide dismutase (SOD) and content of malondialdehyde (MDA) in the mitochondria of the midbrain neurons, as well as the inhibitory ability of hydroxyl free radical and the antioxidant ability in the serum, were measured by corresponding kits. The results showed that 6-OHDA reduced the optical density of dopaminergic neurons, induced damage of mitochondrial ultrastructure of midbrain neurons, decreased SOD activity, increased MAO-B activity and MDA content, and reduced the antioxidant ability of the serum. SVHRP significantly reversed the previous harmful effects of 6-OHDA in early-stage PD model. These findings indicate that SVHRP may contribute to neuroprotection by preventing biochemical and ultrastructure damage changes which occur during early-stage PD.

Establishing the model of kappaB-decoy inhibiting the activity of NF-kappaB in PC12 cells / 中国应用生理学杂志

<p><b>OBJECTIVE</b>Observing the time course and establishing the model of kappaB-decoy oligodeoxynucleotides (rcB-decoy) inhibiting the activity of NF-kappaB in the PC12 cells.</p><p><b>METHODS</b>PC12 cells cultivating in the 6 wells plate were divided into 3 groups, experimental group: adding kappaB-decoy complex (6 microg DNA/well), the control group: adding scrambled-decoy complex, the normal group: adding lipid-Lipofectamine 2000, transfer and cultivate 48 h, then lipopolysaccharide (LPS, 200 ng/ml) was added in the cells for 0.5-4 h. The immunocytochemistry and Western blot were used to measure the expression or the activity of NF-kappaB in PC12 cells.</p><p><b>RESULTS</b>In PC12 cells, compared with normal group, the expression of NF-kappaB enhanced obviously with the time of the stimulation of LPS in scrambled-decoy treated control group (P < 0.01), in 2-4 h the level reached the peak; the expression of NF-kappaB showed the stable level with the time of the stimulation of LPS in kappaB-decoy treated experimental group, compared with the control group, the expression levels were obviously lower than the respective time point of control groups (P < 0.01).</p><p><b>CONCLUSION</b>kappaB-decoy could reduce the expression of NF-kappaB in the normal PC12 cells and inhibit the activity of NF-cB in the pathologic PC12 cells.</p>

Linker for activation of T cells contributes to airway inflammation in an asthmatic mouse model / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Allergic asthma is associated with airway inflammation and hyperresponsiveness caused by dysregulated production of cytokines secreted by allergen-specific helper T-type 2 (Th2) cells. The linker for activation of T cells (LAT) is a membrane-associated adaptor protein, which has been shown to take part in regulating T cell receptor (TCR) signaling and T cell homeostasis. In this study, we established an asthmatic mouse model to examine the changes in LAT levels during allergic airway disease and the effects of LAT transgenic expression on airway inflammation.</p><p><b>METHODS</b>T cells from mouse lung tissues were isolated from allergen challenged (ovalbumin (OVA)) and control mice, and the purity of these isolated T cells was examined by fluorescence-activated cell sorter (FACS). Semi-quantitative RT-PCR and Western blotting were used to detect the expression of the LAT gene and LAT protein, respectively. After an intranasally administered mixture of pCMV-HA-LAT plasmid and Lipofectamine 2000, 24 hours before and 72 hours after allergen challenge, the BALF cell count and the differential cytologies were studied. In addition, IL-4 and IFN-γ levels in the BALF were determined by ELISA, and pathological changes in lung tissues were observed.</p><p><b>RESULTS</b>LAT protein and mRNA expression were decreased in lung T cells in a mouse model of allergen-induced airway disease. After intranasal administration of pCMV-HA-LAT, histopathological examination of the lungs showed that intervention with LAT overexpression prevented mice from developing airway inflammation, and the number of total cells, eosinophils, neutrophils, and lymphocytes in the BALF was reduced significantly compared with the OVA sensitized and challenged group. In addition, the Th2 cytokine IL-4 decreased, while the Th1 cytokine IFN-γ increased compared to the OVA sensitized and challenged group or the OVA sensitized group plus pCMV-HA treatment.</p><p><b>CONCLUSION</b>This study demonstrates that LAT might effectively diminish Th2 cytokine responses, lung histopathological changes and lung inflammation to allergen challenge in a model of experimentally induced asthma.</p>

The protective effect of nicotine on dopaminergic neuron of Parkinson's disease mice / 中国应用生理学杂志

<p><b>AIM</b>To investigate the protective effect of nicotine on dopaminergic neurons and its mechanisms in mice with Parkinson's disease (PD) induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).</p><p><b>METHODS</b>C57BL/6J mice were injected with MPTP for 8 days to establish PD model. Nicotine was given for 10 days in the pretreatment group. Animals were examined behaviorally with the pole test and traction test. Tyrosine hydroxylase (TH) and gamma-aminobutyric acid (GABA) were investigated by the immunocytochemistry (ICC) method. The ultrastructural changes of caudate nucleus(CN) were observed by electron microscope.</p><p><b>RESULTS</b>The results showed that pretreatment nicotine could improve the dyskinesia of PD mice markedly. Simultaneously, TH (P < 0.01) neurons and GABA (P < 0.05) neurons were much more in the pretreatment group when compared with those in the model group. The ultrastructural injury of the pretreatment group was also ameliorated.</p><p><b>CONCLUSION</b>Nicotine has a protective effect on the dopaminergic neurons in the MPTP-treated mice.</p>

Effects of scorpion venom heat-resistant protein on kainic acid induced-damage of cultured primitive rat hippocampal neuropeptide Y-nergic neurons / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of scorpion venom heat-resistant protein (SVHRP) on kainic acid induced-damage of cultured primitive rat hippocampal neuropeptide Y-nergic neurons.</p><p><b>METHODS</b>We observed morphological changes, celluar vigor, NPY-immunoreactivity and NPY mRNA expression by means of Thionine staining, MTT assay, immunocytochemistry and RT-PCR, respectively, on the primitively cultured Sprague-Dawley rat hippocampal neuron treated with KA and SVHRP for 24 h.</p><p><b>RESULTS</b>MTT assay and morphologic analysis showed that SVHRP markedly increased neuron survival-rate, and protected them from kA-induced damage. The expression of NPY-immunoreactivity and NPY mRNA in SVHRP group increased obviously compared with other groups.</p><p><b>CONCLUSION</b>SVHRP protected the primitively cultured hippocampal neurons from KA-induced neuroexcitotoxicity and promoted the expression of NPY.</p>

Effect of no mediator on kainic acid induced behavioral seizures in rats / 中国应用生理学杂志

<p><b>AIM</b>To further explore the roles of endogenous nitric oxide (NO) or NO derivatives in complex partial seizures and generalized convulsions.</p><p><b>METHODS</b>The effect of pretreatment with L-nitroarginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), or L arginine (L-Arg), a precursor of NO on kainic acid (KA)-induced seizure in rats and the changes in the concentration of NO2 -/NO- in the hippocampus were determined.</p><p><b>RESULTS</b>The rats appeared with wet dog shakes (WDS) at 15 min and then occurred generalized convulsions during 1 h to 3 h after administration of KA (10 mg/kg i.p.). However, the pretreatment of L-NNA (50 mg/kg) so dramatically promoted and enhanced KA-induced behavioral seizures that the latency of generalized convulsion was shorten dramatically, and the mortality was greatly high. In contrast, the pretreatment with L-Arg (40 mg/kg) markedly delayed or weakened KA-induced behavioral changes, such as increasing latency of WDS and generalized convulsion, shortening time o f seizure and none of animal died during observed time. The concentration of NO2- /NO3- in the hippocampus increased immediately at 30 min and remained to 7 d after the administration of KA. Compared with control group (pretreatment with NS), the concentration of NO2- / NO3- in the hippocampus apparently increased at 3 h and 3 d after the administration of KA in the rats with L-Arg pretreatment.</p><p><b>CONCLUSION</b>The endogenous NO (NO or NO derivatives) mediators may play an important role against excitotoxin induced seizures in rats.</p>