Antibody recognition and RNA binding of a neuronal nuclear autoantigen associated with paraneoplastic neurological syndromes and small cell lung carcinoma

Brain insulin-like growth factor and neurotrophin resistance in Parkinson's disease and dementia with Lewy bodies: potential role of manganese neurotoxicity

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) frequently overlap with Alzheimer's disease, which is linked to brain impairments in insulin, insulin-like growth factor (IGF), and neurotrophin signaling. We explored whether similar abnormalities occur in PD or DLB, and examined the role of manganese toxicity in PD/DLB pathogenesis. Quantitative RT-PCR demonstrated reduced expression of insulin, IGF-II, and insulin, IGF-I, and IGF-II receptors (R) in PD and/or DLB frontal white matter and amygdala, and reduced IGF-IR and IGF-IIR mRNA in DLB frontal cortex. IGF-I and IGF-II resistance was present in DLB but not PD frontal cortex, and associated with reduced expression of Hu, nerve growth factor, and Trk neurotrophin receptors, and increased levels of glial fibrillary acidic protein, alpha-synuclein, dopamine-beta-hydroxylase, 4-hydroxy-2-nonenal (HNE), and ubiquitin immunoreactivity. MnCl2 treatment reduced survival, ATP, and insulin, IGF-I and IGF-II receptor expression, and increased alpha-synuclein, HNE, and ubiquitin immunoreactivity in cultured neurons. The results suggest that: 1) IGF-I, IGF-II, and neurotrophin signaling are more impaired in DLB than PD, corresponding with DLB's more pronounced neurodegeneration, oxidative stress, and alpha-synuclein accumulation; 2) MnCl2 exposure causes PD/DLB associated abnormalities in central nervous system neurons, and therefore may contribute to their molecular pathogenesis; and 3) molecular abnormalities in PD/DLB overlap with but are distinguishable from Alzheimer's disease.

Insulin and insulin-like growth factor resistance in alcoholic neurodegeneration

BACKGROUND

Chronic alcohol feeding of adult Long Evans rats causes major central nervous system abnormalities that link neuronal loss and impaired acetylcholine homeostasis to ethanol inhibition of insulin and insulin-like growth factor (IGF) signaling and increased oxidative stress.

OBJECTIVES

We now characterize the integrity of insulin and IGF signaling mechanisms and assess molecular indices of neurodegeneration in the cerebellar vermis and anterior cingulate gyrus of human alcoholics.

RESULTS

Alcoholic cerebella had increased neuronal loss, gliosis, lipid peroxidation, and DNA damage relative to control. Quantitative RT-PCR studies demonstrated reduced expression of insulin, insulin receptor and IGF-II receptor in the anterior cingulate, and reduced expression of insulin, IGF-I, and their corresponding receptors in the vermis. Competitive equilibrium binding assays revealed significantly reduced specific binding to the insulin, IGF-I, and IGF-II receptors in both the anterior cingulate and vermis of alcoholic brains. These effects of chronic alcohol abuse were associated with significantly reduced expression of choline acetyltransferase, which is needed for acetylcholine biosynthesis.

CONCLUSIONS

The results suggest that alcoholic neurodegeneration in humans is associated with insulin and IGF resistance with attendant impairment of neuronal survival mechanisms and acetylcholine homeostasis.

Insulin and Insulin-Like Growth Factor Resistance With Neurodegeneration in an Adult Chronic Ethanol Exposure Model

BACKGROUND

Previous studies linked cerebellar hypoplasia, neuronal loss, and impaired acetylcholine homeostasis to ethanol inhibition of insulin and insulin-like growth factor signaling mechanisms in experimental models of fetal alcohol syndrome (FAS).

METHODS

To determine the extent to which similar abnormalities occur in mature brains, gene expression, ligand binding, and histopathological studies were performed with temporal lobe, hypothalamus, and cerebellar cortex from adult male Long Evans rats that were pair-fed for 6 weeks with liquid diets containing 0% or 37% ethanol by caloric content.

RESULTS

Real time quantitative RT-PCR analysis demonstrated that the chronic ethanol-fed rats had significantly reduced insulin-like growth factors (IGF)-II receptor expression in all 3 regions and reduced insulin receptor expression in the temporal lobe. However, equilibrium binding assays revealed ethanol-associated impairments in insulin and IGF-I receptor binding in all 3 regions and reduced IGF-II receptor binding in the cerebellum. These abnormalities were associated with decreased expression of Hu (neuronal loss) in the temporal lobe and cerebellum, and choline acetyltransferase (ChAT) in the hypothalamus and cerebellum, and increased expression of NADPH oxidase 3 in all 3 regions examined. Ethanol-associated neuronal loss with increased indices of lipid peroxidation and DNA damage were demonstrated by histopathological, immunohistochemical, and enzyme linked immunosorbant assay studies.

CONCLUSIONS

These results suggest that ethanol-induced neurodegeneration in adults is mediated by insulin/IGF resistance, persistent oxidative stress, and impaired acetylcholine biosynthesis, similar to the findings in FAS. The reductions in ChAT gene expression most likely contribute to the cognitive and motor deficits that occur with chronic alcohol abuse.

Effects of antineuronal antibodies from patients with paraneoplastic neurological syndrome on primary-cultured neurons

Some patients with paraneoplastic neurological syndrome (PNS) produce autoantibodies against tumor and neuronal tissues of symptom-relevant areas. These characteristic antibodies are detected at early stages of the neurological disorder and are reliable markers for the diagnosis of PNS and underlying cancers. These antibodies are thought to be related directly to neuronal damage. However, the passive transfer of antibodies to rodents has been succeeded only in those in which the target antigens were expressed on the cell surface, like Lambert-Eaton myasthenic syndrome. The serum IgGs from patients with PNS and anti-Yo or anti-Hu antibody were not shown to induce the disease by passive transfer or active immunization with these antigen proteins to date. Instead, cytotoxic T lymphocytes (CTLs) against these antigen peptides-presenting targets could be induced in the peripheral blood of PNS patients. However, there is no direct proof of CTLs killing neurons. In this study, we examined the effects of the anti-Yo or anti-Hu antibody on mouse-brain-derived neurons in a primary culture system and found that these antibodies did not kill neurons, but induced the expression of cell adhesion molecules and accelerated neuronal differentiation. These effects of serum IgG fractions containing the anti-Yo or the anti-Hu antibody on the cultured neurons were the same, suggesting that their effects were not through the binding of the antibody to specific antigens, but to some other factors contained in IgG fractions.