Renal Ischemia-Induced Cholesterol Loading : Transcription Factor Recruitment and Chromatin Remodeling along the HMG CoA Reductase Gene

Parkinson disease (PD) typically affects the cortical regions during the later stages of disease, with neuronal loss, gliosis, and formation of diffuse cortical Lewy bodies in a significant portion of patients with dementia. To identify novel proteins involved in PD progression, we prepared synaptosomal fractions from the frontal cortices of pathologically verified PD patients at different stages along with age-matched controls. Protein expression profiles were compared using a robust quantitative proteomic technique. Approximately 100 proteins displayed significant differences in their relative abundances between PD patients at various stages and controls; three of these proteins were validated using independent techniques. One of the confirmed proteins, glutathione S-transferase Pi, was further investigated in cellular models of PD, demonstrating that its level was intimately associated with several critical cellular processes that are directly related to neurodegeneration in PD. These results have, for the first time, suggested that the levels of glutathione S-transferase Pi may play an important role in modulating the progression of PD.Parkinson disease (PD), the second most common neurodegenerative disease after Alzheimer disease (AD), has been recognized recently as a disease that includes more than just nigrostriatal degeneration with motor dysfunction.^1,2 More specifically, a significant portion of PD patients suffer from non-motor symptoms, including anosmia, constipation, depression, autonomic failure, and cognitive dysfunction.^1,2,3 In fact, PD patients commonly develop reduced cognitive abilities, ranging from mild cognitive impairment to full-blown dementia, as the disease advances.^1,2The prevailing hypothesis for PD development is that the disease likely results from genetic or environmental causes, or their combinations with processes of aging, that culminate in mitochondrial and/or proteasomal dysfunction and increased oxidative stress.^1,3 Additionally, pathological observations derived from human PD cases and toxicant-based animal models suggest a dying-back mode of neurodegeneration in PD.^1,4 More specifically, loss of presynaptic terminals (for example, the axonal connections from the substantia nigra pars compacta to the striatum) precedes the loss of neuronal cell bodies. Nonetheless, the molecular pathways leading to PD progression are largely unknown. While progressive dopaminergic degeneration can be important, its link to cognitive impairment is not clear. On the other hand, most, if not all, PD patients with dementia demonstrate cortical Lewy bodies (LBs), a pathological hallmark of PD, and/or pathology related to AD.^1,2,5 Indeed, though still controversial, it appears that, at least in a subset of PD patients, progression of the disease is accompanied by spreading of LBs from the brainstem to the limbic system and, eventually, to the isocortex, including the frontal cortex.^5,6 In this study, we have elected to focus on this particular cohort of PD patients, given our ability to classify them unequivocally.Herein, using a robust shotgun proteomic approach in conjunction with an isotope labeling technique, isobaric tagging for relative and absolute quantification (iTRAQ), we quantitatively compared the protein profiles of synaptosomal fractions, the subcellular compartment likely involved in the early process of neurodegeneration, from the frontal cortex of patients with PD at different pathological stages of disease, with and without dementia, as well as with age-matched controls. The study revealed many novel proteins with quantitative expression differences as the disease progressed, and provided more detailed molecular mechanisms for one of these proteins, glutathione S-transferase Pi (GSTP1), that may modulate the progression of human PD.     

Research in retinal regenerative medicine

Although adult neurogenesis is limited in regions, accumulating evidence indicates the existence of neural regeneration even in non-neurogenic regions. In the adult retina, Müller glias generate new neurons in response to injury. Although the naively regenerated neurons were a very few in number, it could be increased by Wnt treatment. Retinal cell transplantation is another strategy for retinal regeneration. The cell source for transplantation will be prepared, for example from ES cells. There are some ways to enhance the integration of grafted cells into the host retina. We need to understand the mechanisms for integration of newly generated cells or grafted cells into existing neural networks, and to determine functional recovery in animal models of the retinal diseases.     

Oncogenic role of KIAA0101 interacting with proliferating cell nuclear antigen in pancreatic cancer

To isolate novel diagnostic markers and therapeutic targets for pancreatic cancer, we earlier did expression profile analysis of pancreatic cancer cells using a genome-wide cDNA microarray combined with microdissection. Among dozens of trans-activated genes in pancreatic cancer cells, this study focused on KIAA0101 whose overexpression in pancreatic cancer cells was validated by immunohistochemical analysis. KIAA0101 was previously identified as p15(PAF) [proliferating cell nuclear antigen (PCNA)-associated factor] to bind with PCNA; however, its function remains unknown. To investigate for the biological significance of KIAA0101 overexpression in cancer cells, we knocked down KIAA0101 by small interfering RNA (siRNA) in pancreatic cancer cells and found that the reduced expression by siRNA caused drastic attenuation of their proliferation as well as significant decrease in DNA replication rate. Concordantly, exogenous overexpression of KIAA0101 enhanced cancer cell growth, and NIH3T3 derivative cells expressing KIAA0101 revealed in vivo tumor formation, implying its growth-promoting and oncogenic property. We also showed that the expression of KIAA0101 was regulated tightly by the p53-p21 pathway. To consider the KIAA0101/PCNA interaction as a therapeutic target, we designed the cell-permeable 20-amino-acid dominant-negative peptide and found that it could effectively inhibit the KIAA0101/PCNA interaction and resulted in the significant growth suppression of cancer cells. Our results clearly implicated that suppression of the KIAA0101 and PCNA oncogenic activity, or the inhibition of KIAA0101/PCNA interaction, is likely to be a promising strategy to develop novel cancer therapeutic drugs.