Concomitant inactivation of foxo3a and fancc or fancd2 reveals a two-tier protection from oxidative stress-induced hydrocephalus

Novel therapeutic modulators of astrocytes for hydrocephalus

Hydrocephalus is mainly characterized by excessive production or impaired absorption of cerebrospinal fluid that causes ventricular dilation and intracranial hypertension. Astrocytes are the key response cells to inflammation in the central nervous system. In hydrocephalus, astrocytes are activated and show dual characteristics depending on the period of development of the disease. They can suppress the disease in the early stage and may aggravate it in the late stage. More evidence suggests that therapeutics targeting astrocytes may be promising for hydrocephalus. In this review, based on previous studies, we summarize different forms of hydrocephalus-induced astrocyte reactivity and the corresponding function of these responses in hydrocephalus. We also discuss the therapeutic effects of astrocyte regulation on hydrocephalus in experimental studies.

The AICD fragment of APP initiates a FoxO3a mediated response via FANCD2

The amyloid precursor protein (APP) is a cell surface protein of uncertain function that is notable for being the parent protein of beta-amyloid. Research around this protein has focussed heavily on the link to Alzheimer's disease and neurodegeneration. However, there is increasing evidence that APP may be linked to neuronal loss through mechanisms independent of beta-amyloid. FoxO3a is a transcription factor associated with neuronal longevity and apoptosis. In neurons, FoxO3a is associated with cell death through pathways that include BIM, a BCL-2 family member. In this study we have shown that APP overexpression increased the cellular levels and activity of FoxO3a. This increased expression and activity is not a result of decreased phosphorylation but is more likely a result of increased nuclear stability due to increased levels of FANCD2, a binding partner of FoxO3a. The changes caused by APP overexpression were shown to be due to the AICD fragment of APP possibly directly inducing transcription increase in FANCD2. These findings strengthen the link between APP metabolism and FoxO3a neuronal activity. This link may be crucial in better understanding the cellular role of APP and its link to neurodegeneration and aging.

Identification of metabolic changes leading to cancer susceptibility in Fanconi anemia cells

Fanconi anemia (FA) is a chromosomal instability disorder of bone marrow associated with aplastic anemia, congenital abnormalities and a high risk of malignancies. The identification of more than two dozen FA genes has revealed a plethora of interacting proteins that are mainly involved in repair of DNA interstrand crosslinks (ICLs). Other important findings associated with FA are inflammation, oxidative stress response, mitochondrial dysfunction and mitophagy. In this work, we performed quantitative proteomic and metabolomic analyses on defective FA cells and identified a number of metabolic abnormalities associated with cancer. In particular, an increased de novo purine biosynthesis, a high concentration of fumarate, and an accumulation of purinosomal clusters were found. This was in parallel with decreased OXPHOS and altered glycolysis. On the whole, our results indicate an association between the need for nitrogenous bases upon impaired DDR in FA cells with a subsequent increase in purine metabolism and a potential role in oncogenesis.

In Vivo RNAi Screen Unveils PPARγ as a Regulator of Hematopoietic Stem Cell Homeostasis

Hematopoietic stem cell (HSC) defects can cause repopulating impairment leading to hematologic diseases. To target HSC deficiency in a disease setting, we exploited the repopulating defect of Fanconi anemia (FA) HSCs to conduct an in vivo short hairpin RNA (shRNA) screen. We exposed Fancd2^−/− HSCs to a lentiviral shRNA library targeting 947 genes. We found enrichment of shRNAs targeting genes involved in the PPARγ pathway that has not been linked to HSC homeostasis. PPARγ inhibition by shRNA or chemical compounds significantly improves the repopulating ability of Fancd2^−/− HSCs. Conversely, activation of PPARγ in wild-type HSCs impaired hematopoietic repopulation. In mouse HSCs and patient-derived lymphoblasts, PPARγ activation is manifested in upregulating the p53 target p21. PPARγ and co-activators are upregulated in total bone marrow and stem/progenitor cells from FA patients. Collectively, this work illustrates the utility of RNAi technology coupled with HSC transplantation for the discovery of novel genes and pathways involved in stress hematopoiesis.

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In vivo screening identifies of deleterious Pparγ effect on HSCs

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Pharmacological activation of Pparγ impaired normal HSC repopulation

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Inhibition of Pparγ improves Fancd2-deficient HSC repopulation ability

Edaravone reduces astrogliosis and apoptosis in young rats with kaolin-induced hydrocephalus

PURPOSE

We investigated the possible neuroprotective effects of the free radical scavenger edaravone in experimental hydrocephalus.

METHODS

Seven-day-old Wistar rats were divided into three groups: control group (C), untreated hydrocephalic (H), and hydrocephalic treated with edaravone (EH). The H and EH groups were subjected to hydrocephalus induction by 20% kaolin intracisternal injection. The edaravone (20 mg/kg) was administered daily for 14 days from the induction of hydrocephalus. All animals were daily weighed and submitted to behavioral test and assessment by magnetic resonance imaging. After 14 days, the animals were sacrificed and the brain was removed for histological, immunohistochemical, and biochemical studies.

RESULTS

The gain weight was similar between groups from the ninth post-induction day. The open field test performance of EH group was better (p < 0.05) as compared to untreated hydrocephalic animals. Hydrocephalic animals (H and EH) showed ventricular ratio values were higher (p < 0.05), whereas magnetization transfer values were lower (p < 0.05), as compared to control animals. Astrocyte activity (glial fibrillary acidic protein) and apoptotic cells (caspase-3) of EH group were decreased on the corpus callosum (p > 0.01), germinal matrix (p > 0.05), and cerebral cortex (p > 0.05), as compared to H group.

CONCLUSIONS

We have demonstrated that administration of edaravone for 14 consecutive days after induction of hydrocephalus reduced astrocyte activity and that it has some beneficial effects over apoptotic cell death.