Center for Molecular Chaperone/Radiobiology & Cancer Virology: Faculty Research and Presentations
Behavioral Defects in Chaperone-Deficient Alzheimer's Disease Model MiceMolecular chaperones protect cells from the deleterious effects of protein misfolding and aggregation. Neurotoxicity of amyloid-beta (Ab) aggregates and their deposition in senile plaques are hallmarks of Alzheimer's disease (AD). We observed that the overall content of aB-crystallin, a small heat shock protein molecular chaperone, decreased in AD model mice in an age-dependent manner. We hypothesized that aB-crystallin protects cells against Ab toxicity. To test this, we crossed aB-crystallin/HspB2 deficient (CRYAB-/-HSPB2-/-) mice with AD model transgenic mice expressing mutant human amyloid precursor protein. Transgenic and non-transgenic mice in chaperone-sufficient or deficient backgrounds were examined for representative behavioral paradigms for locomotion and memory network functions: (i) spatial orientation and locomotion was monitored by open field test; (ii) sequential organization and associative learning was monitored by fear conditioning; and (iii) evoked behavioral response was tested by hot plate method. Interestingly, aB-crystallin/HspB2 deficient transgenic mice were severely impaired in locomotion compared to each genetic model separately. Our results highlight a synergistic effect of combining chaperone deficiency in a transgenic mouse model for AD underscoring an important role for chaperones in protein misfolding diseases.
Parkinson's disease-related protein, alpha-synuclein, in malignant melanoma.BACKGROUND: Melanoma is the major cause of skin cancer death worldwide. Parkinson's disease is a neurodegenerative disorder that is caused by mutation of alpha-synuclein or other genes. Importantly, epidemiological studies have reported co-occurrence of melanoma and Parkinson's disease, suggesting that these two diseases could share common genetic components. METHODOLOGY/PRINCIPAL FINDINGS: Recently, we found that human melanoma cell lines highly express alpha-synuclein, whereas the protein is undetectable in the non-melanoma cancer cell lines tested. To investigate the expression of alpha-synuclein in human melanoma tissues, we immunostained sections of melanoma, nevus, non-melanocytic cutaneous carcinoma, and normal skin. alpha-Synuclein was positively detected in 86% of the primary and 85% of the metastatic melanoma sections, as well as in 89% of nevus sections. However, alpha-synuclein was undetectable in non-melanocytic cutaneous carcinoma and normal skin. CONCLUSIONS/SIGNIFICANCE: The Parkinson's disease-related protein, alpha-synuclein, is expressed in both malignant and benign melanocytic lesions, such as melanomas and nevi. Although alpha-synuclein cannot be used to distinguish between malignant and benign melanocytic skin lesions, it might be a useful biomarker for the diagnosis of metastatic melanoma.
NUB1, an interferon-inducible protein, mediates anti-proliferative actions and apoptosis in renal cell carcinoma cells through cell-cycle regulation.BACKGROUND: NEDD8 ultimate buster 1 (NUB1) is an interferon (IFN)-inducible protein that downregulates NEDD8 expression and its conjugation system. Although overexpression of NUB1 induces a growth-inhibitory effect in cells, the mechanisms underlying the anti-mitogenic actions of NUB1 in cancer cells remain uncertain. We investigated the anti-cancer effects of NUB1 in human renal cell carcinoma (RCC) cells. METHODS: Nine human RCC cells were used for this study. The proliferation of RCC cells exposed to IFN-alpha was measured by water-soluble tetrazolium salt assay. The expression level of NUB1 in cells was measured by quantitative reverse transcriptase PCR or western blot analysis. Apoptosis and cell-cycle analysis were performed by flow cytometry. Silencing of NUB1 was performed using a small interfering RNA. RESULTS: Both NUB1 messenger RNA and protein were significantly induced by IFN-alpha in seven out of nine selected RCC cell lines, and the NUB1 expressions induced by IFN-alpha correlated positively with cell growth inhibition. Overexpression of NUB1 remarkably induced S-phase transition during cell cycle and apoptosis in IFN-alpha-resistant A498 cells, in which NUB1 is not induced by IFN-alpha. The expression levels of two cell-cycle regulator proteins, cyclin E and p27, were increased under the aforementioned conditions. The knockdown of NUB1 enhanced cell proliferation of IFN-alpha-resistant A498 cells and suppressed IFN-alpha-induced growth inhibition in IFN-alpha-sensitive 4TUHR cells. CONCLUSION: NUB1 may be a key factor involved not only in cell growth inhibition by IFN-alpha in RCC cells but also in the anti-cancer effect against IFN-alpha-resistant RCC cells.