engleski

Ganglioside deficiency alters Kras gene expression in murine hippocampus

Gangliosides are sialic acid-bearing membrane lipids found in high abundance in the mammalian central nervous system (CNS), which stabilize the mature CNS by promoting the axon-glia interactions. In this study we firstly examined the differences in transcriptomes between GD3 synthase (Siat8a) knockout (KO) and wild type (WT) mice. Siat8a KO mice lack b-series gangliosides, normally enriched in the cerebellum. Their phenotype upon aging includes dysmyelination and impaired nerve regeneration. RNA was isolated from brain samples of 3 WT and 3 KO animals. After quality analysis, cerebellar samples were labeled for two color microarray experiments performed on Agilent's 1x22K Whole Mouse Genome Oligo Microarrays and analyzed with GenePix Pro and BRB-Assay Tools. Gene annotation was performed using publicly available annotation tools. After analysis a list of differentially expressed genes was retrieved. The gene found to be most upregulated was Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) involved in Ras signalling pathway. Because Ras signalling has been linked to a wide range of neuronal functions including synaptic plasticity and is thought to underlie higher brain processes such as learning and memory we also examined changes in gene expression for Kras in hippocampal tissue using quantitative real-time PCR (qRT-PCR) in two models: Siat8a KO mice and GM2/GD2 synthase deficient mice (Galgt1) who fail to express complex brain gangliosides. The results of qRT-PCR experiments show significant increase in relative mRNA expression for Kras in hippocampi of both Siat8a and Galgt1 mice when compared to WT controls. Considerable reported evidence points to an essential role of Ras signalling in a variety of neuronal functions. Our results show that these complex signalling pathways may be altered as a consequence of deficient ganglioside synthesis and changed membrane lipid profile.

Brain; gangliosides; Kras; hippocampus

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