Protein kinase Cα activation switches YAP1 from TEAD-mediated signaling to p73-mediated signaling.

Yes-associated protein 1 (YAP1) interacts with TEAD transcription factor in the nucleus and upregulates TEAD-target genes. YAP1 is phosphorylated by large tumor suppressor (LATS) kinases, the core kinases of the Hippo pathway, at 5 serine residues and is sequestered and degraded in the cytoplasm. In human cancers with the dysfunction of the Hippo pathway, YAP1 becomes hyperactive and confers malignant properties to cancer cells. We have observed that cold shock induces protein kinase C (PKC)-mediated phosphorylation of YAP1. PKC phosphorylates YAP1 at 3 serine residues among LATS-mediate phosphorylation sites. Importantly, PKC activation recruits YAP1 to the cytoplasm even in LATS-depleted cancer cells and reduces the cooperation with TEAD. PKC activation induces promyelocytic leukemia protein-mediated SUMOylation of YAP1. SUMOylated YAP1 remains in the nucleus, binds to p73, and promotes p73-target gene transcription. Bryostatin, a natural anti-neoplastic reagent that activates PKC, induces YAP1/p73-mediated apoptosis in cancer cells. Bryostatin reverses malignant transformation caused by the depletion of LATS kinases. Therefore, bryostatin and other reagents that activate PKC are expected to control cancers with the dysfunction of the Hippo pathway.

DNA Damage Triggers the Nuclear Accumulation of RASSF6 Tumor Suppressor Protein via CDK9 and BAF53 To Regulate p53 Target Gene Transcription.

RASSF6, a member of the tumor suppressor Ras-association domain family (RASSF) proteins, regulates cell cycle arrest and apoptosis via p53 and plays a tumor suppressor role. We previously reported that RASSF6 blocks MDM2-mediated p53 degradation and enhances p53 expression. In this study, we demonstrated that RASSF6 has nuclear localization and nuclear export signals and that DNA damage triggers the nuclear accumulation of RASSF6. We found that RASSF6 directly binds to BAF53, the component of SWI/SNF complex. DNA damage induces CDK9-mediated phosphorylation of BAF53, which enhances the interaction with RASSF6 and increases the amount of RASSF6 in the nucleus. Subsequently, RASSF6 augments the interaction between BAF53 and BAF60a, another component of the SWI/SNF complex, and further promotes the interaction of BAF53 and BAF60a with p53. BAF53 silencing or BAF60a silencing attenuates RASSF6-mediated p53 target gene transcription and apoptosis. Thus, RASSF6 is involved in the regulation of DNA damage-induced complex formation, including BAF53, BAF60a, and p53.

Imbalance of antioxidant enzymes activities and trace elements levels in Ghanaian HIV-infected patients.

Human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) have been associated with high oxidative stress in HIV patients. The disparity in antioxidant-oxidant levels in HIV patients favours viral replication and disease progression. This study aimed at determining the effect of ART on antioxidant enzymes activities and trace elements levels in Ghanaian HIV patients. A total of 242 participants; comprising of 105 HIV-infected patients on ART, 77 HIV-infected ART-naïve, and 60 HIV seronegative controls were recruited for the study. Whole blood was collected and used for haematological profiling, and the determination of CD4+ counts, superoxide dismutase (SOD) activity and trace element levels. Serum was used for liver function tests and the determination of glutathione reductase (GR) activity, and plasma was used to estimate reduced glutathione (GSH) levels. Low levels of haemoglobin (HB), hematocrit, mean cell volume (MCV) and mean cell hemoglobin (MCH), and trace elements were found in ART-naïve patients compared to those on ART and the seronegative controls. In the ART-naïve patients, glutathione reductase (GR) activity and reduced glutathione (GSH) level were significantly low compared to patients on ART and seronegative controls. Activity of SOD was significantly reduced in ART-naïve patients compared to those on ART and the control group, and manganese is the only trace element that showed a strong negative correlation with SOD activity and a positive and significant correlation with CD4+ count, and therefore needs to be investigated further. The study suggests that assessing antioxidant levels or enzymes activities of patients infected with HIV should be considered during therapy.

Haptoglobin phenotypes with weak antioxidant capacity increase risk factors of cardiovascular disease in Ghanaian HIV-infected patients on highly active antiretroviral therapy.

OBJECTIVE: Highly active antiretroviral therapy (HAART) has considerably reduced HIV/AIDS-related morbidity and mortality; however, the therapy has been associated with the development of cardiovascular disease (CVD), and genetic predisposition factors may aggravate disease outcome. This study was aimed at investigating the relationship between haptoglobin phenotypes and risk factors of CVD in HIV patients. METHODS: A total of 105 HIV sero-positive patients on HAART and 75 HIV-infected HAART-naïve individuals were enrolled in the study. Socio-demographics and clinical characteristics of the participants were obtained using a well-structured questionnaire. Lipid profile, lactate dehydrogenase (LDH) and haptoglobin (Hp) phenotypes were analysed from serum whiles haemoglobin (Hb) level, CD4+ cell count and HIV viral RNA load were determined using whole blood. RESULTS: Atherogenic index of plasma (AIP) was significantly higher in patients on HAART than the naïve group (P < 0.05). Age, BMI, visceral fat, systolic blood pressure LDH and lipid variables strongly and positively correlated with AIP (P < 0.05), with the exception of HDL-c (P < 0.001) which showed a negative correlation. HAART was associated with hypertension (χ2  = 4.33, P = 0.037), hypercholesterolaemia (χ2  = 10.99, P < 0.001), elevated LDL-c (χ2 = 10.30, P < 0.001) and decreased HDL-c (χ2  = 3.87, P = 0.09). Hp2-2 and Hp0 collectively was strongly associated with hypertension (OR = 2.54, P = 0.011), obesity (OR = 5.97, P < 0.001) and hypercholesterolaemia (OR = 2.99, P < 0.001). CONCLUSION: HIV/AIDS patients on HAART expressing Hp phenotypes with weak antioxidant capacity have an increased risk of developing CVD.

OBJECTIF: La thérapie antirétrovirale hautement active (HAART) a considérablement réduit la morbidité et la mortalité liées au VIH/SIDA; cependant, le traitement a été associé au développement de maladie cardiovasculaire (MCV) et des facteurs de prédisposition génétique pourraient aggraver l'évolution de la maladie. Cette étude visait à étudier la relation entre les phénotypes de l'haptoglobine et les facteurs de risque de MCV chez les patients VIH. MÉTHODES: Un total de 105 patients VIH positifs sous HAART et 75 personnes infectés par le VIH mais naïfs au HAART ont été recrutés pour l'étude. Les caractéristiques sociodémographiques et cliniques des participants ont été obtenues à l'aide d'un questionnaire bien structuré. Le profil lipidique, les phénotypes de la lactate déshydrogénase (LDH) et de l' haptoglobine (Hp) ont été analysés à partir du sérum tandis que le taux d'hémoglobine (Hb), la numération des cellules CD4+ et la charge d'ARN viral du VIH ont été déterminés en utilisant du sang total. RÉSULTATS: L'indice athérogène du plasma (IAP) était significativement plus élevé chez les patients sous HAART que chez le groupe naïf (p <0,05). Les variables âge, IMC, graisse viscérale, tension artérielle systolique, LDH et lipides étaient fortement et positivement corrélées à l'IAP (p < 0,05), à l'exception du HDL-c (p < 0,001) qui présentait une corrélation négative. L'HAART a été associée à l'hypertension (χ2 = 4,33; p = 0,037), l'hypercholestérolémie (χ2 = 10,99; p <0,001), une LDL-c élevée (χ2 = 10,30; p <0,001) et une diminution de HDL-c (χ2 = 3,87; p = 0,09). Ensemble, Hp2-2 et Hp0 étaient fortement associés à l'hypertension (OR = 2,54; p = 0,011), à l'obésité (OR = 5,97; p <0,001) et à l'hypercholestérolémie (OR = 2,99; p <0,001). CONCLUSION: Les patients VIH/SIDA sous HAART exprimant des phénotypes Hp à faible capacité antioxydante ont un risque accru de développer une maladie cardiovasculaire.

Homozygous deletion of both GSTM1 and GSTT1 genes is associated with higher CD4+ T cell counts in Ghanaian HIV patients.

Glutathione S-transferase (GST) family of enzymes are involved in a two-stage detoxification process of a wide range of environmental toxins, carcinogens and xenobiotics. The GST enzymes play important roles in oxidative stress pathways, and polymorphisms in the GSTM1 and GSTT1 genes mediate susceptibility and outcome in different diseases. Human immunodeficiency virus (HIV) infection is associated with oxidative stress, but there is limited data on the frequency of deleted GSTM1 and GSTT1 genes in HIV/AIDS patients and their effect on progression among Ghanaians. This study sought to investigate the association between homozygous deletion of GSTM1 and GSTT1 genes (both null deletion) with HIV/AIDS disease progression in Ghanaian patients. HIV-infected individuals on antiretroviral therapy (ART), ART-naïve HIV patients, and HIV seronegative individuals were recruited for the study. HIV/AIDS disease progression was assessed by measuring CD4+ cell count and viral load of the patients, and GST polymorphism was determined by amplifying the GSTT1 and GSTM1 genes using multiplex PCR, with CYP1A1 gene as an internal control. The mean CD4+ count of patients that were naïve to ART (298 ± 243 cells/mm3) was significantly lower than that of patients on ART (604 ± 294 cells/mm3), and viral load was significantly lower in the ART-experienced group (30379 ± 15073 copies/mm3) compared to the ART-naïve group (209882 ± 75045 copies/mm3). Frequencies of GSTM1 and GSTT1 deletions were shown to be 21.9% and 19.8%, respectively, in the HIV patients, and patients with homozygous deletion of both GSTM1 and GSTT1 were more likely to have their CD4+ count rising above 350 cells/mm3 (OR = 6.44, 95% CI = 0.81-51.49, p = 0.039) suggesting that patients with homozygous deletion of GSTM1 and GSTT1 genes have slower disease progression. The findings of this study show that double deletion of glutathione S-transferases M1 and T1 is statistically associated with normal CD4+ count in patients diagnosed with HIV/AIDS. Further study is required to investigate the clinical importance of the both null deletion in HIV patients.