Genetic dissection of glutathione S-transferase omega-1:identification of novel downstream targets and Alzheimer's disease pathways

Alzheimer's disease(AD)is affected by genetic factors.Polymorphisms in the glutathione S-transfe rase omega-1(Gsto1)gene have been shown by genetic correlation analyses performed in different ethnic populations to be genetic risk factors for AD.Gene expression profile data from BXD recombinant inbred mice were used in combination with genetic and bioinformatic analyses to chara cterize the mechanisms underlying regulation of Gstol variation regulation and to identify network membe rs that may contribute to AD risk or progression.Allele-specific assays confirmed that variation in Gstol expression is controlled by cis-expression quantitative trait loci.We found that Gstol mRNA levels were related to several central nervous system traits,such as glial acidic fibrillary protein levels in the caudate putamen,co rtical gray matter volume,and hippocampus mossy fiber pathway volume.We identified 2168 genes whose expression was highly correlated with that of Gsto1.Some genes were enriched for the most common neurodegenerative diseases.Some Gsto1-related genes identified in this study had previously been identified as susceptibility genes for AD,such as APP,Grin2 b,Ide,and Psenen.To evaluate the relationships between Gstol and candidate network members,we transfected astrocytes with Gstol siRNA and assessed the effect on putative downstream effecto rs.We confirmed that knockdown of Gstol had a significant influence on Pa2g4 expression,suggesting that Pa2g4 may be a downstream effector of Gstol,and that both genes intera ct with other genes in a network during AD pathogenesis.

High SIPA-1 Expression in Proximal Tubules of Human Kidneys under Pathological Conditions

Systemic lupus erythematosus（SLE） and clear cell renal cell carcinoma（CC-RCC） are serious disorders and usually fatal, and always accompanied with pathological changes in the kidney. Signal-induced proliferation-associated protein 1（SIPA-1） is a Rap1 GTPase activating protein（Rap1GAP） expressed in the normal distal and collecting tubules of the murine kidney. Lupus-like autoimmune disease and leukemia have been observed in SIPA-1 deficient mice, suggesting a pathological relevance of SIPA-1 to SLE and carcinoma in human being. The expression pattern of SIPA-1 is as yet undefined and the pathogenesis of these diseases in humans remains elusive. In this study, we used both immunohistochemistry and quantum dot（QD）-based immunofluorescence staining to investigate the expression of SIPA-1 in renal specimens from SLE and CC-RCC patients. MTT assay and Western blotting were employed to evaluate the effects of SIPA-1 overexpression on the proliferation and apoptosis of renal cell lines. Semi-quantitative reverse transcriptase-PCR（RT-PCR） was applied to examine the changes of hypoxia-inducible factor-1α（HIF-1α） mR NA level. Results showed that SIPA-1 was highly expressed in the proximal and collecting tubules of nephrons in SLE patients compared to normal ones, and similar results were obtained in the specimens of CC-RCC patients. Although SIPA-1 overexpression did not affect cellular proliferation and apoptosis of both human 786-O renal cell carcinoma cells and rat NRK-52 E renal epithelial cell lines, RT-PCR results showed that HIF-1α mR NA level was down-regulated by SIPA-1 overexpression in 786-O cells. These findings suggest that SIPA-1 may play critical roles in the pathological changes in kidney, and might provide a new biomarker to aid in the diagnosis of SLE and CC-RCC.