Two Endoplasmic Reticulum (ER)/ER Golgi Intermediate Compartment-based Lysine Acetyltransferases Post-translationally Regulate BACE1 Levels

Abstract

We have recently identified a novel form of post-translational regulation of BACE1 (β-site amyloid precursor protein-cleaving enzyme 1), a membrane protein that acts as the rate-limiting enzyme in the generation of the Alzheimer disease amyloid β-peptide. Specifically, nascent BACE1 is transiently acetylated in seven lysine residues clustered in a highly disordered region of the protein that faces the lumen of the endoplasmic reticulum (ER)/ER Golgi intermediate compartment (ER/ERGIC). The acetylation protects the nascent protein from degradation by PCSK9/NARC-1 in the ERGIC and allows it to reach the Golgi apparatus. Here we report the identification of two ER/ERGIC-based acetyltransferases, ATase1 and ATase2. Both proteins display acetyl-CoA:lysine acetyltransferase activity, can interact with and acetylate BACE1, and display an ER/ERGIC localization with the catalytic site facing the lumen of the organelle. Both ATase1 and ATase2 regulate the steady-state levels of BACE1 and the rate of amyloid β-peptide generation. Finally, their transcripts are up-regulated by ceramide treatment. In conclusion, our studies have identified two new enzymes that may be involved in the pathogenesis of late-onset Alzheimer disease. The biochemical characterization of the above events could lead to the identification of novel pharmacological strategies for the prevention of this form of dementia. We have recently identified a novel form of post-translational regulation of BACE1 (β-site amyloid precursor protein-cleaving enzyme 1), a membrane protein that acts as the rate-limiting enzyme in the generation of the Alzheimer disease amyloid β-peptide. Specifically, nascent BACE1 is transiently acetylated in seven lysine residues clustered in a highly disordered region of the protein that faces the lumen of the endoplasmic reticulum (ER)/ER Golgi intermediate compartment (ER/ERGIC). The acetylation protects the nascent protein from degradation by PCSK9/NARC-1 in the ERGIC and allows it to reach the Golgi apparatus. Here we report the identification of two ER/ERGIC-based acetyltransferases, ATase1 and ATase2. Both proteins display acetyl-CoA:lysine acetyltransferase activity, can interact with and acetylate BACE1, and display an ER/ERGIC localization with the catalytic site facing the lumen of the organelle. Both ATase1 and ATase2 regulate the steady-state levels of BACE1 and the rate of amyloid β-peptide generation. Finally, their transcripts are up-regulated by ceramide treatment. In conclusion, our studies have identified two new enzymes that may be involved in the pathogenesis of late-onset Alzheimer disease. The biochemical characterization of the above events could lead to the identification of novel pharmacological strategies for the prevention of this form of dementia. The efficiency of folding, conformational maturation, and molecular stability of nascent membrane and secretory proteins is greatly affected in the endoplasmic reticulum (ER) 2The abbreviations used are: ER, endoplasmic reticulum; ERGIC, ER Golgi intermediate compartment; APP, amyloid precursor protein; BACE1, β-site APP-cleaving enzyme 1; AD, Alzheimer disease; Aβ, amyloid β-peptide; siRNA, short interfering RNA; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; BisTris, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol; CHO, Chinese hamster ovary; HAT, histone acetyltransferase. by post-translational events that modify, either temporally or definitively, the protein (1Trombetta E.S. Parodi A.J. Annu. Rev. Cell Dev. Biol.. 2003; 19: 649-676Google Scholar). One of the best characterized forms of transient modification is the attachment of a glucose residue to improperly folded nascent glycoproteins by the UDP-glucose:glycoprotein glucosyltransferase (2Dempski Jr., R.E. Imperiali B. Curr. Opin. Chem. Biol.. 2002; 6: 844-850Google Scholar, 3Kleizen B. Braakman I. Curr. Opin. Cell Biol.. 2004; 16: 343-349Google Scholar). This transient event regulates the interaction of the nascent protein with the chaperone calnexin and its ability to leave the early secretory pathway. The mechanism works in such a way that successfully folded proteins dissociate from the calnexin/calreticulin cycle and advance toward the Golgi apparatus, whereas misfolded intermediates are directed toward the ER-associated degradation system (1Trombetta E.S. Parodi A.J. Annu. Rev. Cell Dev. Biol.. 2003; 19: 649-676Google Scholar, 4Meusser B. Hirsch C. Jarosch E. Sommer T. Nat. Cell Biol.. 2005; 7: 766-772Google Scholar). We have recently reported the identification of a novel form of post-translational regulation of BACE1 (β-site APP-cleaving enzyme 1) (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar), a membrane protein that acts as the rate-limiting enzyme in the generation of the Alzheimer disease amyloid β-peptide (Aβ) from the amyloid precursor protein (APP). Specifically, nascent BACE1 is transiently acetylated in seven lysine residues clustered in a highly disordered region of the protein that faces the lumen of the ER and ER Golgi intermediate compartment (ERGIC). The lysine acetylation of nascent BACE1 regulates its ability to advance toward the Golgi apparatus, where a Golgi-based deacetylase removes the acetyl groups. Nonacetylated intermediates of the nascent protein are retained in the early secretory pathway and degraded by a mechanism that involves the serine protease PCSK9/NARC-1 (proprotein convertase subtilisin kexin-type 9/neural apoptosis-regulated convertase-1) (6Jonas M.C. Costantini C. Puglielli L. EMBO Rep.. 2008; 9: 916-922Google Scholar). The acetylation of nascent BACE1 in the lumen of the ER and/or ERGIC requires a membrane transporter that translocates acetyl-CoA, the donor of the acetyl group, from the cytoplasm to the lumen of the ER, and one or more ER/ERGIC-based acetyl-CoA:lysine acetyltransferases (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). The acetylation/deacetylation process is tightly regulated by the lipid second messenger ceramide (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, 7Puglielli L. Ellis B.C. Saunders A.J. Kovacs D.M. J. Biol. Chem.. 2003; 278: 19777-19783Google Scholar, 8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar) and is under the control of the general aging program mediated by the insulin-like growth factor 1 receptor (IGF-1R) (9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar, 10Puglielli L. Neurobiol. Aging.. 2008; 29: 795-811Google Scholar). Ceramide, the last output of the above pathway, regulates both efficiency of acetylation in the lumen of the ER/ERGIC and rate of deacetylation in the Golgi apparatus (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). As a result, the hyperactivation of ceramide signaling that occurs during normal aging (8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar) or in progeroid-like animal models (9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar) leads to increased acetylation and steady-state levels of BACE1 and to increased production of Aβ (8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar, 9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar). The relevance of the above events for AD neuropathology is stressed by the fact that aging is the single most important risk factor for late-onset AD and that AD patients have very high levels of ceramide in the brain, when compared with age-matched controls (reviewed in Ref. 10Puglielli L. Neurobiol. Aging.. 2008; 29: 795-811Google Scholar). Here we report the identification of two ER/ERGIC-based acetyltransferases, which we named ATase1 and ATase2. Both proteins display acetyl-CoA:lysine acetyltransferase activity in vitro and under native conditions can interact with and acetylate BACE1 in vitro and in vivo, and show an ER/ERGIC localization. They both regulate the steady-state levels of BACE1 and the generation of Aβ, and are up-regulated by ceramide treatment of cultured cells. The following experimental procedures, which have been extensively described in our previous work, are in the supplemental Methods: cell cultures and cell treatment; cell extraction, immunoprecipitation, and affinity purification; subcellular fractionation; Aβ and treatment. and for ATase1 and ATase2 from and a system as described (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, 7Puglielli L. Ellis B.C. Saunders A.J. Kovacs D.M. J. Biol. Chem.. 2003; 278: 19777-19783Google Scholar, 8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar, 9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar, L. G. E. R.E. Kovacs D.M. Nat. Cell Biol.. Scholar, M.H. Puglielli L. J. Biol. Chem.. 2007; Scholar). The following used in this lysine Cell Cell and Cell used a by In the to BACE1 with the from J. B. T. E. R. L. R. J. 2007; of with with the and and the and used of to the of the acetyltransferase activity, we BACE1 as of the acetyl and as donor of the acetyl The acetyl-CoA:lysine acetyltransferases and/or either as enzymes following affinity with the supplemental or as membrane of cells. The in of acetylation 1 and for 1 The by an of and in BACE1 with an BACE1 and a The experimental controls are described in the the acetyltransferase activity of ATase1 and ATase2 with and The as by the from and and the the system and used for as GAPDH, and by in a system and by of for and and 25: Scholar) with from the of and as The with and with an of the are as of the of The by of and of ATase1 and ATase2 as studies the of acetyl-CoA:lysine acetyltransferase activity in the They that the catalytic site of the ER/ERGIC-based the lumen of the (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). the we in the for proteins to the histone acetyltransferase catalytic The of which to in the The biochemical and named and 1 They to have in L. Dev. Biol.. Scholar) in or The biochemical activity of both proteins and the reported acetyltransferase 1 and to their biochemical the Both ATase1 and ATase2 have a high of proteins the of the of and T. H. 2007; Scholar, Biochem. Scholar). of the of ATase1 and ATase2 an the two proteins the the of one single to the In both the catalytic site is in the and is to the lumen of the ATase1 an ER/ERGIC which and a a the to subcellular localization and affinity for the in vitro in ATase1 from control and in vitro for acetyl-CoA:lysine acetyltransferase The in the of BACE1, which as of the acetyl group, and acetyl-CoA, which as donor of the acetyl that the of ATase1 increased the acetyltransferase activity from membrane by activity when the in the of of the or in the of that been to the studies a ERGIC localization that to ER, to which is with our previous localization of the ER/ERGIC-based acetyl-CoA:lysine acetyltransferase activity (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). The subcellular localization of ATase1 with the where the acetylation of nascent BACE1 occurs and the of BACE1 are retained (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). In we have that the and the forms of BACE1 be acetylated in and in are retained in the ER/ERGIC and degraded by a system (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, M.C. Costantini C. Puglielli L. EMBO Rep.. 2008; 9: 916-922Google Scholar). we the acetyl-CoA:lysine acetyltransferase activity of the from the in and that the of ATase1 with the acetyl-CoA:lysine acetyltransferase activity Finally, when compared with control ERGIC from increased acetyltransferase activity The above that ATase1 is in the where the acetylation of nascent BACE1 They that the of ATase1 in increased acetyl-CoA:lysine acetyltransferase the that ATase1 is a in the of lysine this we used ATase1 of membrane for the in vitro acetylation of As we used which as of the acetyl in vitro or in (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). that ATase1 to acetylate that it is an acetyl-CoA:lysine acetyltransferase. The with are important that ATase1 can acetylate the lysine residues that are acetylated under conditions (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). we ATase1 with BACE1 in the of Both BACE1 and ATase1 by affinity to the BACE1 the of the and by In the of ATase1 the form of BACE1 could be with an lysine by with ATase1 of two to the and a intermediate form of BACE1 by and with and that ATase1 can acetylate The normal of the and intermediate forms of BACE1 is in the of and in supplemental The lysine a with the molecular of the of BACE1 by The could be with an the of BACE1 with the of BACE1 or the and by The of BACE1 and the for the in vitro acetylation that it to the of BACE1 and most from in vitro as described L. C. J. Biol. Chem.. Scholar). the lysine a of which to ATase1 In the could be with with the or of that ATase1 can interact with BACE1 in vitro and can acetylation in one or more lysine most an mechanism ATase2 an ER/ERGIC ATase2 a a the This used to ATase2 and ATase1 ATase2 to the of ATase2 increased the acetyl-CoA:lysine acetyltransferase activity from membrane In the subcellular of ATase2 to with ATase1 and with the normal of the acetyl-CoA:lysine acetyltransferase activity Finally, ER/ERGIC from increased acetyltransferase activity, when compared with from control As with activity in to the Golgi apparatus Ref. C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). ATase2 with BACE1 and acetyl-CoA, we a in the acetylation of both intermediates of BACE1 the acetylation by ATase2 from the one with ATase1 to in of the two to the of BACE1 in the of in vitro in to we could a to ATase2 with an lysine This ATase2 could be identified with an in the biochemical and regulation of ATase1 and ATase2 Finally, of ATase2 with BACE1 and in acetylation of that ATase2 can acetylate the lysine residues that are acetylated under conditions (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). We used a that a to the of the histone as of the acetyl group, and a highly histone acetyltransferase as The to our of HAT, as of the that both ATase1 and ATase2 acetyl-CoA:lysine acetyltransferase activity, which in the of that with Finally, when ATase1 and ATase2 in the we a that the two enzymes can of in to be the is by their ability to lysine residues of the or by the of in the The ability of ATase1 and ATase2 to acetylate an by a that the histone as and as donor of ATase1 and ATase2 the of the ER/ERGIC have that the transient acetylation of the and of nascent BACE1 occurs in the lumen of the ER/ERGIC system (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). We that the acetyltransferase activity for the lysine acetylation of the nascent protein in the of the secretory compartment (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). The with the the E. of ATase1 and ATase2 the which the acetyl-CoA:lysine acetyltransferase to the lumen of the ER/ERGIC We to this the by in vitro the acetyl-CoA:lysine acetyltransferase activity from ERGIC of or under two experimental conditions as in the or of of are and of the membrane as in (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, J. Biol. Chem.. Scholar, L. J. Biol. Chem.. Scholar, L. D.M. J. Biol. Chem.. Scholar). under normal conditions the acetylation of BACE1 can the catalytic site of the enzyme or is facing the of the the catalytic site of the enzyme in the of the the in the of of which of both the and donor to ATase1 or ATase2 that the acetyltransferase activity of native ATase1 and ATase2 could be in the of that the catalytic site is facing the lumen of the in its native The activity in the of in the normal of with the and supplemental we of the fact that both ATase1 and ATase2 have a the which is to the lumen of the ER/ERGIC the above with an to for The under both the and conditions to the of the that ATase1 and ATase2 could be when the used under the which the to interact with the when the above that both ATase1 and ATase2 have the with the catalytic facing the lumen of the ER/ERGIC where the lysine acetylation of nascent BACE1 ATase1 and ATase2 the of BACE1 and the of in and that both ATase1 and ATase2 can be with BACE1 this of and BACE1 in we to the interaction the enzyme and the in this we used cell that been with or with that we could the interaction with ATase1 and ATase2 with the in and by with an that BACE1 in the that both acetyltransferases interact with BACE1 in the two to intermediates of BACE1 the with the normal of BACE1 a in and could be with ATase1 and ATase2 supplemental are with the fact that ATase1 and ATase2 are in the ER and ERGIC and where both intermediates of BACE1 can be Ref. C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). are we that the In the is the one that can be with lysine of BACE1 from cell (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar) This could be by the levels and of the intermediate that In fact the of this is by subcellular supplemental or affinity and this we the acetylation of BACE1 of ATase1 and ATase2. that both BACE1 intermediates are when that ATase1 and ATase2 interact with nascent BACE1 in the ER/ERGIC system supplemental for a We that the lysine acetylation of nascent BACE1 in molecular and increased steady-state levels of the (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). we the of ATase1 and ATase2 affected the levels of BACE1 and/or the production of The in that both ATase1 and ATase2 an in the steady-state levels of BACE1, with ATase2 an which could be to the more acetyl-CoA:lysine acetyltransferase activity in vitro with for membrane and with for the by the increased levels of Aβ in the by the increased levels of and by the in the lysine acetylation of BACE1 in and cells. is the of that from of and the for the generation of The of the acetylated intermediates of nascent BACE1 from cell is by the deacetylation that occurs in the Golgi apparatus (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). this we to BACE1 from ER/ERGIC to with an lysine that under the above conditions the of intermediates is and the by the of ATase1 and ATase2 is more In both acetyltransferases a in the acetylation of the form of we to ATase1 and ATase2 and the the steady-state levels of that two ATase1 successfully the steady-state levels of the the levels of BACE1 to the of ATase1 by the The fact that the of ATase1 in a of BACE1 that ATase2 the activity of ATase1 in is that the ATase1 the of ATase2 This is with the in which that ATase1 and ATase2 as enzymes in The of ATase2 in a of BACE1 levels it is important to that the of ATase2 by cell which with the of BACE1 an of the and following of ATase1 or we this as of an important of ATase2 in the The of ATase1 or ATase2 by of Aβ the and by levels of and the above that ATase1 and ATase2 the levels of BACE1 and the rate of Aβ generation. The with ATase1 and ATase2 are important that biochemical of ATase1 and ATase2 be for pharmacological the prevention of late-onset the of ATase1 and that ceramide treatment of cell in increased acetylation and of BACE1 (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, 7Puglielli L. Ellis B.C. Saunders A.J. Kovacs D.M. J. Biol. Chem.. 2003; 278: 19777-19783Google Scholar, 8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar). We that the increased of ceramide in the by either normal aging in or by the hyperactivation of signaling in a of aging B. B. T. T. Scrable H. 2004; Scholar), in increased acetylation and of BACE1 (8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar, 9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar). we to the by ceramide the levels of ATase1 and ATase2 in and cells. conditions the levels of both in in when with both cell a of of ATase1 and as by The could be as early as treatment and which is with the that we described L. Ellis B.C. Saunders A.J. Kovacs D.M. J. Biol. Chem.. 2003; 278: 19777-19783Google Scholar, 8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar). In conclusion, the above that ATase1 and ATase2 are up-regulated by ceramide treatment and a in AD In AD patients have increased levels of ceramide when compared with age-matched in the D.M. Jr., J. J. 2002; Scholar, J. 2004; Scholar). We have recently described a novel form of post-translational regulation of nascent BACE1 that involves transient acetylation of seven lysine residues in the lumen of the ER/ERGIC system by deacetylation of the protein in the lumen of the Golgi apparatus (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). The acetylated protein is to the secretory pathway and conformational whereas the intermediates are retained and in the ERGIC (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). a novel form of post-translational the biochemical for events is Here we report the identification of two ER/ERGIC-based acetyl-CoA:lysine acetyltransferases that are involved in the lysine acetylation of nascent The named 1 and for their have identified biochemical activity and named ATase1 and ATase2 to their Both ATase1 and ATase2 to have acetyl-CoA:lysine acetyltransferase activity in vitro and under native and to be to acetylate BACE1 in the lysine residues that we identified (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). Both enzymes to in the where the lysine acetylation of BACE1 a with the ER/ERGIC acetyl-CoA:lysine acetyltransferase activity, and to have the with the catalytic site facing the lumen of the as by our previous (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). Finally, to interact with BACE1 in vitro and in and to the steady-state levels of their are the and biochemical ATase1 and ATase2 to display two important ATase1 could and acetylate the form of BACE1, in whereas ATase2 could ATase1 could be with an lysine whereas ATase2 could The in of the two whereas the catalytic important when to biochemical for pharmacological R. 2007; Scholar). In this it is important to that an that and as an that regulates its acetyltransferase when it and when it the activity of the enzyme L. J. Nat. Biol.. 2004; Scholar, B. L. L. J. Biol. Chem.. 2006; Scholar). it is that ATase1 can and that this event as an mechanism to control its biochemical that the of ATase1 in a in the levels of BACE1 in the of cell this could to biochemical The transient acetylation of the of a lysine residue been with histone where it to control and and proteins where it to regulate activity, and Biochem. Scholar, T. EMBO J.. 19: Scholar, C. 2007; Scholar, EMBO Rep.. 2007; Scholar). recently reported B. J. E. 2006; Scholar) that a event regulates the activity of a whereas we reported (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar) that a transient form of lysine acetylation regulates the maturation, the secretory pathway, and molecular stability of a nascent membrane this new form of post-translational modification to in is that we recently identified a second membrane protein that transient acetylation in the early secretory pathway, the receptor (6Jonas M.C. Costantini C. Puglielli L. EMBO Rep.. 2008; 9: 916-922Google Scholar). the the to of a nascent the process is by transient or post-translational (1Trombetta E.S. Parodi A.J. Annu. Rev. Cell Dev. Biol.. 2003; 19: 649-676Google Scholar). The transient lysine acetylation of BACE1 to both the of the nascent protein and its ability to leave the early secretory pathway (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). The with the membrane protein BACE1 and in our previous (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google that biochemical have been in the secretory pathway to acetylation and deacetylation of BACE1, and is that we are the biochemical characterization of an membrane transporter that is in the The transporter the donor of the acetyl for the of acetylation is for the activity of ATase1 and which are in the ER/ERGIC ceramide regulates the steady-state levels of the transporter in the efficiency of the lumen of the ER (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). Finally, we reported that the which is for the acetyl from nascent BACE1, is in the Golgi apparatus (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar). when that the of the acetylation/deacetylation have been the secretory pathway to of the and enzymes and the of the biochemical The subcellular of ATase1 and ATase2 a ERGIC localization that to the ER to the Golgi apparatus and supplemental This is with the fact that the of ATase1 or ATase2 the two intermediates of BACE1 that are in the ER/ERGIC system and supplemental that the both as enzymes and of nascent The fact that the lysine residues that are acetylated in BACE1 to be the of the protein and to the catalytic of the enzyme (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar) that the nascent with the above the of BACE1 are retained and degraded in the early secretory pathway by PCSK9/NARC-1 (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, M.C. Costantini C. Puglielli L. EMBO Rep.. 2008; 9: 916-922Google Scholar). In the is from degradation in the early secretory pathway. we could a mechanism in which a the acetyltransferases and the regulates the steady-state levels of BACE1 be from degradation whereas BACE1 The in been to regulate cell and very early in during the process of L. Dev. Biol.. Scholar). The molecular and to of protein modification in the early secretory pathway in the lumen of the we a biochemical for the proteins ATase1 and the reported by L. Dev. Biol.. Scholar) to a of enzymes in events such as cell and The cell following of ATase2 to this post-translational of membrane proteins in the ER and Golgi apparatus are for the and of the it is that the enzymes involved in such be (1Trombetta E.S. Parodi A.J. Annu. Rev. Cell Dev. Biol.. 2003; 19: 649-676Google Scholar, Jr., R.E. Imperiali B. Curr. Opin. Chem. Biol.. 2002; 6: 844-850Google Scholar, Scholar). The fact that the events described of the aging program mediated by the of in L. Neurobiol. Aging.. 2008; 29: 795-811Google Scholar, C. 2005; Scholar, 2003; Scholar, L. Dev. 2002; Scholar), in the rate of Aβ generation (5Costantini C. Ko M.H. Jonas M.C. Puglielli L. Biochem. J.. 2007; 407: 383-395Google Scholar, 7Puglielli L. Ellis B.C. Saunders A.J. Kovacs D.M. J. Biol. Chem.. 2003; 278: 19777-19783Google Scholar, 8Costantini C. Weindruch R. Della Valle G. Puglielli L. Biochem. J.. 2005; 391: 59-67Google Scholar, 9Costantini C. Scrable H. Puglielli L. EMBO J.. 2006; 25: 1997-2006Google Scholar) a in late-onset AD This be by the fact that ceramide levels are in late-onset AD when compared with age-matched controls D.M. Jr., J. J. 2002; Scholar, J. 2004; Scholar). it is that the biochemical characterization of the acetylation/deacetylation may lead to the identification of novel pharmacological strategies for the prevention of late-onset We and for of an early of this and the of the Puglielli for and We for the