Transcription Signal, Subcellular Localization,and Functional Study Of TMEM59and TMEM59L

TMEM59and TMEM59L belong to type I transmembrane protein. However,little is known about the characteristic of TMEM59and TMEM59L. Study shows thatTMEM59and TMEM59L did exist difference in transcription profiles, not only indifferent tissues but also in different subregions of the brain tissue, indicating thedifferent regulatory mechanisms between TMEM59and TMEM59L, such astranscription factors，DNA methylaton, histone acetylation, miRNA, and LncRNA，et al. We chose two histone deacetylase inhibitors nicotinamide and TSA exposure toC17.2neural stem cells (NSCs) in order to study transcription regulation of TMEM59and TMEM59L. Our results shows that nicotinamide induced TMEM59up-regulation,nicotinamide and TSA both not affect TMEM59L expression in C17.2NSCs. Becausenicotinamide and TSA have an impact on growth and proliferation of C17.2NSCs, wefurther examined the change of proliferation and apoptosis related genes and proteins.Our studies indicate that C17.2NSCs has a different sirtuin mRNA expressionprofiles compared with E14.5(embryonic day14.5) NSCs and four brain tissues ofadult mouse. sirt1, sirt5and sirt6were significant downregulated by nicotinamide.TSA treatment induced a significant downregulation in sirt1and sirt3and a significantupregulation in sirt2, sirt4, sirt6, and sirt7. Western blot analyses confirmed thatnicotinamide significantly decrease expression of bcl-2and p38. Further insight intothe molecular mechanisms shows the suppression of phosphorylation in eukaryoticinitiation factor4E-binding protein1(4EBP1) by nicotinamide, whereas, an increasedthe expression of bcl-2and p-38and phosphorylation of4EBP1by TSA. In addition,both nicotinamide and TSA significantly increase the expression of cytochrome c (cytc).To further explore the characterization and functions of TMEM59andTMEM59L. Here, our results show that TMEM59and TMEM59L can localizes thevesicular structures. Further co-localization studies illustrated that TMEM59andTMEM59L distributes in the lysosome and acidic vesicular. A novel alternative splicing of TMEM59L (vTMEM59L) and its C-terminal deletion mutant significantlychange TMEM59L expression levels and intracellular localization. TMEM59andTMEM59L movement between Golgi and cell membrane was observed in living cellsexpressing TMEM59/TMEM59L-EGFP fusion proteins. System biology analysisshowed that TMEM59coexpression with APP (amyloid precursor protein), GDI1(Rab GDP dissociation inhibitor alpha), and GDI2(Rab GDP dissociation inhibitorbeta). Cell surface transport of APP was significantly inhibited by TMEM59andTMEM59L induced increases of APP protein in HEK296T cells. However, TMEM59and TMEM59L not significantly inhibit transport of GDI1and GDI2but increasesGDI1and GDI2protein level in HEK293T cells. Moreover, TMEM59andTMEM59L not affect localization and protein level of BACE2. These results suggestthat TMEM59and TMEM59L may be involved in the packaging of acidic vesicles,modulateds transport and processing of glycoprotein, but this regulation is specific forsome glycoproteins.In an attempt to determine the transcription difference of TMEM59andTMEM59L，we demonstrated for the first time that TMEM59and TMEM59L have adifferent transcription profile in neural stem cells and adult mouse brain tissue.Moreover，we also report for the first time that TMEM59and TMEM59L cannavigate to the lysosome and acidic vesicle-like structures. The function experimentsdisplayed that TMEM59and TMEM59L specific inhibition cytoplasmic transport ofAPP protein, further increase the protein levels of intracellular APP, TMEM59andTMEM59L partial impact localization of GDI1and GDI2，no effect on localizationand protein level of BACE2. In summary，TMEM59and TMEM59L can highlyspecific inhibition transport of the APP protein, thereby reducing the production ofAβ peptide for Alzheimer’s disease pathogenesis of key protein proposed new clue oridea.