Alzheimer Disease: Song S

Sanchez-Ramos J, Song S, Cao C, Arendash G. · Department of Neurology, University of South Florida, Tampa, FL 33612, USA. · BMC Neurosci. · Pubmed #19090991 links to  free full text

Abstract: There are no effective interventions that significantly forestall or reverse neurodegeneration and cognitive decline in Alzheimer's disease. In the past decade, the generation of new neurons has been recognized to continue throughout adult life in the brain's neurogenic zones. A major challenge has been to find ways to harness the potential of the brain's own neural stem cells to repair or replace injured and dying neurons. The administration of hematopoietic growth factors or cytokines has been shown to promote brain repair by a number of mechanisms, including increased neurogenesis, anti-apoptosis and increased mobilization of bone marrow-derived microglia into brain. In this light, cytokine treatments may provide a new therapeutic approach for many brain disorders, including neurodegenerative diseases like Alzheimer's disease. In addition, neuronal hematopoietic growth factor receptors provide novel targets for the discovery of peptide-mimetic drugs that can forestall or reverse the pathological progression of Alzheimer's disease.

Song S, Jung YK. · Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea. · Trends Mol Med. · Pubmed #15519283 No free full text.

Abstract: Ubiquitin-positive deposits are histopathologically found in patients with Alzheimer's disease (AD). It is not understood why ubiquitin is accumulated in intra- and extra-cellular deposits or how it is involved in AD pathogenesis. Interestingly, recent evidence, including studies of E2-25K/Hip-2, has elucidated the molecular mechanism of the ubiquitin-proteasome system (UPS) malfunction in AD. The neurotoxicity and proteasome inhibition by Abeta, a main cause of AD pathogenesis, are mediated by increased E2-25K/Hip-2 in the brains of patients with AD. Furthermore, E2-25K/Hip-2 is required for the neurotoxicity that is mediated by a ubiquitin B mutant (UBB+1), which is a potent inhibitor of proteasomes that is found in patients with AD. Intensive research is required to identify the components of the UPS that are involved in AD pathogenesis.

Song W, Su H, Song S, Paudel HK, Schipper HM. · Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada. · J Cell Physiol. · Pubmed #16222706 No free full text.

Abstract: Glial heme oxygenase-1 is over-expressed in the CNS of subjects with Alzheimer disease (AD), Parkinson disease (PD) and multiple sclerosis (MS). Up-regulation of HO-1 in rat astroglia has been shown to facilitate iron sequestration by the mitochondrial compartment. To determine whether HO-1 induction promotes mitochondrial oxidative stress, assays for 8-epiPGF(2alpha) (ELISA), protein carbonyls (ELISA) and 8-OHdG (HPLC-EC) were used to quantify oxidative damage to lipids, proteins, and nucleic acids, respectively, in mitochondrial fractions and whole-cell compartments derived from cultured rat astroglia engineered to over-express human (h) HO-1 by transient transfection. Cell viability was assessed by trypan blue exclusion and the MTT assay, and cell proliferation was determined by [3H] thymidine incorporation and total cell counts. In rat astrocytes, hHO-1 over-expression (x 3 days) resulted in significant oxidative damage to mitochondrial lipids, proteins, and nucleic acids, partial growth arrest, and increased cell death. These effects were attenuated by incubation with 1 microM tin mesoporphyrin, a competitive HO inhibitor, or the iron chelator, deferoxamine. Up-regulation of HO-1 engenders oxidative mitochondrial injury in cultured rat astroglia. Heme-derived ferrous iron and carbon monoxide (CO) may mediate the oxidative modification of mitochondrial lipids, proteins and nucleic acids in these cells. Glial HO-1 hyperactivity may contribute to cellular oxidative stress, pathological iron deposition, and bioenergetic failure characteristic of degenerating and inflamed neural tissues and may constitute a rational target for therapeutic intervention in these conditions.

Jo DG, Lee JY, Hong YM, Song S, Mook-Jung I, Koh JY, Jung YK. · Department of Life Science, Kwangju Institute of Science and Technology, Kwangju, Korea. · J Neurochem. · Pubmed #14720210 No free full text.

Abstract: Calsenilin/DREAM/KChIP3 was identified as a calcium-binding protein that interacts with presenilins, serves as a transcription repressor, and binds to the A-type potassium channel. In this study, we hypothesized that calsenilin might be involved in the neurodegeneration of Alzheimer's disease and examined calsenilin expression in Alzheimer's disease. Calsenilin levels were elevated in the cortex region of Alzheimer's patient brains and in the neocortex and the hippocampus of Swedish mutant beta-amyloid precursor protein transgenic mice brains. Induction of calsenilin was also observed in the activated astroglia as well as in the neurons surrounding beta-amyloid (Abeta)- and Congo red-positive plaques. Exposing cultured cortical and hippocampal neurons to Abeta42, an amyloid-beta peptide whose deposition in the brain is a characteristic of Alzheimer's disease, induced both calsenilin protein and mRNA expression, and cell death. Moreover, blocking the calsenilin expression protected the neuronal cells from Abeta toxicity. These findings suggest that chronic up-regulation of calsenilin may be a risk factor for developing Alzheimer's disease, perhaps by facilitating calsenilin-mediated neurodegeneration.

Song S, Kim SY, Hong YM, Jo DG, Lee JY, Shim SM, Chung CW, Seo SJ, Yoo YJ, Koh JY, Lee MC, Yates AJ, Ichijo H, Jung YK. · Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, South Korea. · Mol Cell. · Pubmed #14527403 No free full text.

Abstract: The ubiquitin/proteasome system has been proposed to play an important role in Alzheimer's disease (AD) pathogenesis. However, the critical factor(s) modulating both amyloid-beta peptide (Abeta) neurotoxicity and ubiquitin/proteasome system in AD are not known. We report the isolation of an unusual ubiquitin-conjugating enzyme, E2-25K/Hip-2, as a mediator of Abeta toxicity. The expression of E2-25K/Hip-2 was upregulated in the neurons exposed to Abeta(1-42) in vivo and in culture. Enzymatic activity of E2-25K/Hip-2 was required for both Abeta(1-42) neurotoxicity and inhibition of proteasome activity. E2-25K/Hip-2 functioned upstream of apoptosis signal-regulating kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK) in Abeta(1-42) toxicity. Further, the ubiquitin mutant, UBB+1, a potent inhibitor of the proteasome which is found in Alzheimer's brains, was colocalized and functionally interacted with E2-25K/Hip-2 in mediating neurotoxicity. These results suggest that E2-25K/Hip-2 is a crucial factor in regulating Abeta neurotoxicity and could play a role in the pathogenesis of Alzheimer's disease.

Tan J, Town T, Suo Z, Wu Y, Song S, Kundtz A, Kroeger J, Humphrey J, Crawford F, Mullan M. · The Roskamp Institute, University of South Florida, Tampa 33612, USA. · Brain Res Bull. · Pubmed #10535333 No free full text.

Abstract: Growing evidence suggests that beta-amyloid (Abeta) peptides play a central role in mediating vascular endothelium dysfunction, but the extent to which immune mechanisms are involved in this process remains unclear. To explore such mechanisms, we incubated cultured human aortic endothelial cells (HAEC) with freshly solublized Abeta and examined expression of a central immunoregulatory molecule, CD40, in these cells using reverse transcriptase-polymerase chain reaction, Western immunoblotting, and Flow cytometry. Our results show that treatment of endothelial cells with Abeta1-40, Abeta1-42 or gamma interferon (IFN-gamma) results in a dose-dependent induction of endothelial CD40 expression. Furthermore, ligation of endothelial CD40 and simultaneous treatment of human endothelial cells with IFN-gamma or Abeta peptides leads to a significant release of interleukin-1beta (IL-1beta), a marker for endothelial cell activation. Since IL-1beta is an important inflammatory response mediator, these findings suggest that the functional role of Abeta-induced endothelial CD40 may be promotion of the inflammatory cascade in vascular endothelial cells.

Takahashi H, Mercken M, Honda T, Saito Y, Murayama M, Song S, Takashima A. · Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan. · Neurosci Lett. · Pubmed #10025714 No free full text.

Abstract: Many cases of early-onset familial Alzheimer's disease (FAD) are caused by mutations in the presenilin 1 (PS1) and PS2 genes. PS1 protein is generated as a 47 kDa protein and is endoproteolytically cleaved into N-terminal 28 kDa and C-terminal 19 kDa fragments in vivo. To examine whether mutated PS1 protein is abnormally metabolized, we performed immunoblot analysis of lymphoblasts from familial Alzheimer's disease patients and controls. More full-length PS1 was apparently detected in samples from PS1 mutants than those from PS2 mutant and controls. This result suggests that impaired proteolysis of PS1 may be associated with the pathogenesis of FAD. Moreover, our simple test using lymphocytes from FAD patients might be useful from a diagnostic point of view.