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Park, E. J.

Publications and source records attributed to Park, E. J..

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Loss of SATB1 Induces a p21 Dependent CellularSenescence Phenotype in Dopaminergic Neurons

Cellular senescence is a mechanism used by mitotic cells to prevent uncontrolled cell division. As senescent cells persist in tissues, they cause local inflammation and are harmful to surrounding cells, contributing to aging. Generally, neurodegenerative diseases, such as Parkinson s, are disorders of aging. The contribution of cellular senescence to neurodegeneration is still unclear. SATB1 is a DNA binding protein associated with Parkinsons disease. We report that SATB1 prevents cellular senescence in post-mitotic dopaminergic neurons. Loss of SATB1 causes activation of a cellular senescence transcriptional program in dopamine neurons, both in human stem cell-derived dopaminergic neurons and in mice. We observed phenotypes which are central to cellular senescence in SATB1 knockout dopamine neurons in vitro and in vivo. Moreover, we found that SATB1 directly represses expression of the pro-senescence factor, p21, in dopaminergic neurons. Our data implicate senescence of dopamine neurons as a contributing factor to the pathology of Parkinsons disease.

neuroscience

Purification Of The Mammalian NgBR/hCIT cis-Prenyltransferase Complex: IdentificationOf A Conserved Carboxyterminal RxG Motif Crucial For Enzymatic Activity

Cis-Prenyltransferases (cisPTs) constitute a large family of enzymes conserved during evolution and present in all domains of life. In eukaryotes and archaea, cisPT is the first enzyme committed to the synthesis of dolichyl-phosphate (DolP). DolP is obligate lipid carrier in protein glycosylation reactions in mammals. The homodimeric bacterial enzyme, undecaprenyl diphosphate synthase (UPPS) generates 11 isoprene units and has been structurally and mechanistically characterized in great detail. Recently our group discovered that unlike UPPS, mammalian cisPT is a heteromer consisting of NgBR (NUS1) and hCIT (DHDDS) subunits and this composition has been confirmed in plants and fungal cisPTs. Here, we establish the first purification system for heteromeric cisPT and show that both NgBR and hCIT subunits function in catalysis and substrate binding. Finally, we identified a critical RxG sequence in the C-terminal tail of NgBR that is conserved and essential for enzyme activity across phyla.

biochemistry