Only low levels of exogenous N-acetyltransferase can be achieved in transgenic mice

Cao, Wenwu; Chau, Binh; Hunter, Robert J.; Strnatka, Diana; McQueen, Charlene A.; Erickson, Robert P.

doi:10.1038/sj.tpj.6500319

Cited by 23 publications

(17 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The mouse albumin enhancer/promoter has been shown to direct efficient liver-specific transgene expression (Pinkert et al, 1987) and was chosen because we found it to drive expression of a luciferase reporter in HepG2 cells more effectively than the endogenous human NAT2 promoter. We identified only one viable founder animal, which was found to contain a single copy of the transgene, consistent with previous attempts by others to generate NAT transgenic mice in which only low-copy founders were identified and/or lethality was observed (Cao et al, 2005). It has been postulated that overexpression of human NAT transgenes, particularly human NAT1, may be detrimental dur- tg Nat1/2(Ϫ/Ϫ) female mouse.…”

Section: Discussionsupporting

confidence: 73%

“…Another human NAT2 transgenic mouse model, constructed using the cytomegalovirus promoter, yielded only a 2-fold increase in NAT activity for isoniazid (Cao et al, 2005). Studies attempting to express human NAT1 in transgenic mice have succeeded in producing only low levels of expression, suggesting that high levels of human NAT1 either alone or in combination with endogenous mouse Nat2 activity may be detrimental to the animal .…”

Section: Sugamori Et Almentioning

confidence: 99%

See 1 more Smart Citation

Liver-Selective Expression of Human ArylamineN-Acetyltransferase NAT2 in Transgenic Mice

Sugamori¹,

Brenneman²,

Grant³

2011

Drug Metab Dispos

View full text Add to dashboard Cite

ABSTRACT:Human arylamine N-acetyltransferase 2 (NAT2) mediates the biotransformation of arylamine drugs and procarcinogens into either innocuous or reactive DNA-damaging metabolites and is expressed predominantly in liver. Interspecies differences and incongruous results between in vitro, in vivo, and epidemiological studies make it difficult to extrapolate animal results to human risk. We have generated human NAT2 transgenic mice on both C57BL/6 (hNAT2 tg ) and Nat1/2 null backgrounds [hNAT2 tg Nat1/2(؊/؊)], in which liver-selective expression of human NAT2 is driven by the mouse albumin promoter. We detected expression of the human NAT2 transcript and protein in mouse liver by real-time PCR and Western blot analysis. NAT2 enzyme activity, measured using the human NAT2-selective substrate sulfamethazine (SMZ), was 40-to 80-fold higher in liver cytosols from hNAT2 tg Nat1/2(؊/؊) mice than in wild-type mice. An unexpected gender difference was observed, with males displaying 2-fold higher activity than females. Transgenic mice also had an increased in vivo plasma clearance of SMZ and higher levels of N-acetylated SMZ than wild-type mice. Liver expression of human NAT2 did not affect the disposition of the human NAT1-selective substrate p-aminosalicylic acid (PAS), because hNAT2 tg Nat1/2(؊/؊) mice displayed in vivo PAS pharmacokinetic profiles similar to those of Nat1/2(؊/؊) mice. The metabolism of 4-aminobiphenyl was similar between hNAT2 tg Nat1/2(؊/؊) and wild-type mice with the exception of a more liver-restricted pattern in hNAT2 tg Nat1/2(؊/؊) mice and lower activity in females.Overall, the hNAT2 tg Nat1/2(؊/؊) mouse mimics human expression of NAT2 and may thus be of value in clarifying the role of human NAT2 in arylamine clearance, detoxification, and bioactivation.

show abstract

Section: Discussionsupporting

confidence: 73%

Section: Sugamori Et Almentioning

confidence: 99%

Liver-Selective Expression of Human ArylamineN-Acetyltransferase NAT2 in Transgenic Mice

Sugamori¹,

Brenneman²,

Grant³

2011

Drug Metab Dispos

View full text Add to dashboard Cite

show abstract

“…Mice engineered with constructs designed to drive overexpression of (HUMAN)NAT1 exhibit poor survival and the progeny of the few surviving founders only exhibit small increases in hepatic pABA acetylation [32], [33], suggesting that (HUMAN)NAT1 overexpression during development could be harmful, possibly due to disruption of folate homeostasis. Moreover, the overexpression of (HUMAN)NAT1 in mice provokes NTDs usually associated with folate deficiency [32], [34], [35] and has complex effects on the incidence and severity of orofacial clefting [33].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the overexpression of (HUMAN)NAT1 in mice provokes NTDs usually associated with folate deficiency [32], [34], [35] and has complex effects on the incidence and severity of orofacial clefting [33].…”

Section: Introductionmentioning

confidence: 99%

From Arylamine N-Acetyltransferase to Folate-Dependent Acetyl CoA Hydrolase: Impact of Folic Acid on the Activity of (HUMAN)NAT1 and Its Homologue (MOUSE)NAT2

et al. 2014

View full text Add to dashboard Cite

Acetyl Coenzyme A-dependent N-, O- and N,O-acetylation of aromatic amines and hydrazines by arylamine N-acetyltransferases is well characterised. Here, we describe experiments demonstrating that human arylamine N-acetyltransferase Type 1 and its murine homologue (Type 2) can also catalyse the direct hydrolysis of acetyl Coenzyme A in the presence of folate. This folate-dependent activity is exclusive to these two isoforms; no acetyl Coenzyme A hydrolysis was found when murine arylamine N-acetyltransferase Type 1 or recombinant bacterial arylamine N-acetyltransferases were incubated with folate. Proton nuclear magnetic resonance spectroscopy allowed chemical modifications occurring during the catalytic reaction to be analysed in real time, revealing that the disappearance of acetyl CH 3 from acetyl Coenzyme A occurred concomitantly with the appearance of a CH 3 peak corresponding to that of free acetate and suggesting that folate is not acetylated during the reaction. We propose that folate is a cofactor for this reaction and suggest it as an endogenous function of this widespread enzyme. Furthermore, in silico docking of folate within the active site of human arylamine N-acetyltransferase Type 1 suggests that folate may bind at the enzyme’s active site, and facilitate acetyl Coenzyme A hydrolysis. The evidence presented in this paper adds to our growing understanding of the endogenous roles of human arylamine N-acetyltransferase Type 1 and its mouse homologue and expands the catalytic repertoire of these enzymes, demonstrating that they are by no means just xenobiotic metabolising enzymes but probably also play an important role in cellular metabolism. These data, together with the characterisation of a naphthoquinone inhibitor of folate-dependent acetyl Coenzyme A hydrolysis by human arylamine N-acetyltransferase Type 1/murine arylamine N-acetyltransferase Type 2, open up a range of future avenues of exploration, both for elucidating the developmental role of these enzymes and for improving chemotherapeutic approaches to pathological conditions including estrogen receptor-positive breast cancer.

show abstract

“…

Aims To determine whether increased N-acetyltransferase (NAT) activity might have a toxic effect during development and an influence on folate levels since previous work has shown that only low levels of exogenous NAT can be achieved in constitutionally transgenic mice (Cao, et al, 2005)

Main Methods A human NAT1 tet-inducible construct was used that would not be expressed until the inducer was delivered. Human NAT1 cDNA was cloned into pTRE2 and injected into mouse oocytes.

…”

mentioning

confidence: 99%

N-acetyltransferase 2 activity and folate levels

et al. 2010

View full text Add to dashboard Cite

Aims-To determine whether increased N-acetyltransferase (NAT) activity might have a toxic effect during development and an influence on folate levels since previous work has shown that only low levels of exogenous NAT can be achieved in constitutionally transgenic mice (Cao, et al, 2005) Main Methods- 1.A human NAT1 tet-inducible construct was used that would not be expressed until the inducer was delivered. Human NAT1 cDNA was cloned into pTRE2 and injected into mouse oocytes. Two transgenic lines were crossed to mouse line TgN(rtTahCMV)4Uh containing the CMV promoted "tet on ." 2.Measurements of red blood cell folate levels in inbred strains of mice were performed. Key findings- 1.Only low levels of human NAT1 could be achieved in kidney (highly responsive in other studies) whether the inducer, doxycycline, was given by gavage or in drinking water.2. An inverse correlation of folate levels with Nat2 enzyme activity was found.Significance-Since increasing NAT1 activity decrease folate in at least one tissue, the detrimental effect of expression of human NAT1 in combination with endogenous mouse Nat2 may be a consequence of increased catabolism of folate.

show abstract

Only low levels of exogenous N-acetyltransferase can be achieved in transgenic mice

Cited by 23 publications

References 37 publications

Liver-Selective Expression of Human ArylamineN-Acetyltransferase NAT2 in Transgenic Mice

Liver-Selective Expression of Human ArylamineN-Acetyltransferase NAT2 in Transgenic Mice

From Arylamine N-Acetyltransferase to Folate-Dependent Acetyl CoA Hydrolase: Impact of Folic Acid on the Activity of (HUMAN)NAT1 and Its Homologue (MOUSE)NAT2

N-acetyltransferase 2 activity and folate levels

Contact Info

Product

Resources

About