Phosphorylation Modulates Aspartyl-(Asparaginyl)-β Hydroxylase Protein Expression, Catalytic Activity and Migration in Human Immature Neuronal Cerebellar Cells

Association between dietary soy prevention of fetal alcohol spectrum disorder and normalization of placental insulin and insulin-like growth factor signaling networks and downstream effector molecule expression

Chronic prenatal alcohol exposure causes fetal alcohol spectrum disorder (FASD), often associated with impaired placentation and intrauterine growth restriction. Ethanol's inhibition of insulin and insulin-like growth factor Type 1 (IGF-1) signaling compromises trophoblastic cell motility and maternal vascular transformation at the implantation site. Previous studies have demonstrated that dietary soy effectively normalizes placentation and fetal growth in an experimental model of FASD. The studies were extended to better understand the mechanisms underlying soy's beneficial effects. Pregnant Long Evans rats were pair-fed with isocaloric liquid diets containing either 0% or 36% caloric ethanol from gestation day (GD) 6. The protein source in the diets consisted of either casein (standard and control) or soy isolate. On GD19, placentas were harvested to measure mRNA levels corresponding to major components of the insulin/IGF-1 pathway, as well as aspartyl-asparaginyl-β-hydroxylase (ASPH), Notch, and HES, which play critical roles in placentation. Chronic gestational ethanol exposure in rats fed diets containing casein significantly reduced the expression of insulin, insulin receptor, Igf1, IGF-1 receptor (Igf1r), insulin receptor substrate Type 1 (Irs1), Irs2, Asph, and Hes1. In addition, ethanol significantly decreased ASPH protein expression. Dietary soy mitigated most of these effects and further enhanced signaling by upregulating Igf2, Igf2r, Irs1, Irs2, Irs4, Notch, and Hes1 in rats chronically exposed to ethanol relative to corresponding control samples. The protective effects of dietary soy in FASD act at the mRNA level and positively impact pathways imperative for normal placentation and fetal development. Gestational dietary soy may provide an effective means of preventing FASD in vulnerable populations.

Differential rescue effects of choline chloride and soy isolate on metabolic dysfunction in immature central nervous system neurons: Relevance to fetal alcohol spectrum disorder

Background

Central Nervous System (CNS) abnormalities with insulin resistance and mediated by developmental exposures to ethanol can be avoided or remediated by consumption of dietary soy, which has insulin-sensitizing as well as antioxidant effects. However, choline supplementation has been shown to diminish Fetal Alcohol Spectrum Disorder (FASD) pathologies, and dietary soy contains abundant choline. This study was designed to determine if the therapeutic effects of soy were mediated by or independent of choline.

Methods

Human PNET2 cells exposed to 0 mM or 100 mM ethanol for 48 hours were seeded into 96-well or 12-well plates and treated with vehicle, choline chloride (75 μM), or 1 μM Daidzein+1 μM Genistein (D+G) for 24 h. The cells were then analyzed for viability (Hoechst 33342), mitochondrial function (MTT), and GAPDH, Tau, Acetyl Cholinesterase (AChE), Choline Acetyl Transferase (ChAT), and Aspartyl-Asparaginyl-β-Hydroxylase (ASPH) immunoreactivity.

Results

Choline and D+G significantly increased MTT activity (mitochondrial function) corrected for cell number relative to vehicle in control and ethanol-exposed cultures. Both choline and D+G prevented the ethanol-induced inhibition of GAPDH and ChAT and increased cellular accumulations of Tau. However, D+G significantly increased ASPH expression relative to vehicle and Choline.

Conclusion

Choline and D+G differentially modulated the expression of neuronal proteins, mitochondrial function, and ASPH. Importantly, the prominently increased expression of ASPH by D+G corresponds with the insulin-sensitizer actions of soy isoflavones since ASPH is an insulin-responsive molecule. The findings further suggest that dietary soy may be more effective than choline for reducing ethanol-impaired neuronal migration linked to ASPH inhibition in FASD.

Aspartate β-hydroxylase as a target for cancer therapy

As metastasis is a major cause of death in cancer patients, new anti-metastatic strategies are needed to improve cancer therapy outcomes. Numerous pathways have been shown to contribute to migration and invasion of malignant tumors. Aspartate β-hydroxylase (ASPH) is a key player in the malignant transformation of solid tumors by enhancing cell proliferation, migration, and invasion. ASPH also promotes tumor growth by stimulation of angiogenesis and immunosuppression. These effects are mainly achieved via the activation of Notch and SRC signaling pathways. ASPH expression is upregulated by growth factors and hypoxia in different human tumors and its inactivation may have broad clinical impact. Therefore, small molecule inhibitors of ASPH enzymatic activity have been developed and their anti-metastatic effect confirmed in preclinical mouse models. ASPH can also be targeted by monoclonal antibodies and has also been used as a tumor-associated antigen to induce both cluster of differentiation (CD) 8+ and CD4+ T cells in mice. The PAN-301-1 vaccine against ASPH has already been tested in a phase 1 clinical trial in patients with prostate cancer. In summary, ASPH is a promising target for anti-tumor and anti-metastatic therapy based on inactivation of catalytic activity and/or immunotherapy.