Adenosine–deaminase–deficient mice die perinatally and exhibit liver–cell degeneration, atelectasis and small intestinal cell death

Abstract

We report the generation and characterization of mice lacking adenosine deaminase (ADA). In humans, absence of ADA causes severe combined immunodeficiency. In contrast, ADA-deficient mice die perinatally with marked liver-cell degeneration, but lack abnormalities in the thymus. The ADA substrates, adenosine and deoxyadenosine, are increased in ADA-deficient mice. Adenine deoxyribonucleotides are only modestly elevated, whereas S-adenosylhomocysteine hydrolase activity is reduced more than 85%. Consequently, the ratio of S-adenosylhomocysteine (AdoMet) to S-adenosyl homocysteine (AdoHcy) is reduced threefold in liver. We conclude that ADA plays a more critical role in murine than human fetal development. The murine liver pathology may be due to AdoHcy-mediated inhibition of AdoMet-dependent transmethylation reactions.

Metabolites from apoptotic thymocytes inhibit thymopoiesis in adenosine deaminase–deficient fetal thymic organ cultures

“…Three-color immunofluorescence showed that most of the γδ T cells were from the CD4 -CD8 + and CD4 -CD8 -populations ( Figure 1, b and g). These data show a dramatic difference in the sensitivity of αβ versus γδ T-cell (6). It is important to determine whether a selective sparing of γδ T cells also occurs in ADA-deficient humans.…”

“…In experiments using C57BL/6 fetuses, thymuses were separated into individual lobes that were randomized and cultured on Gelfoam rafts in RPMI 1640 supplemented with 10% FCS, 2 mM glutamine, nonessential amino acids, 5 × 10 -5 M 2-mercaptoethanol, penicillin (100 U/ml), streptomycin (100 µg/ml), and amphotericin B (2.5 µg/ml) in the presence and absence of 5 µM dCF (Parke Davis, Ann Arbor, Michigan, USA; and SuperGen Inc., San Ramon, California, USA). S-adenosylhomocysteine (SAH) hydrolase enzyme assays were performed as described previously (6).…”

“…dATP accumulates and SAH hydrolase enzyme activity is inhibited by about 90%. These features of the human disease were also observed in thymuses of Ada gene-targeted mice (6,7). Fourth, the use of dCF to mimic ADA deficiency makes it possible to perform experiments with transgenic and gene-targeted mice, which may give insight into the pathogenesis of the disease.…”

“…In vitro culture models require the addition of exogenous ADA substrates, making it impossible to draw conclusions about the relative contribution of Ado and dAdo in vivo. Conventional ADA-deficient mice die of liver failure in the immediate perinatal period (6,7), and normal mice treated with the specific and potent ADA inhibitor 2′-deoxycoformycin (dCF) (8) show signs of hepatic and adrenal toxicity (9). The problem of liver toxicity in ADA-deficient mice has been solved by the introduction of an Ada minigene expressed in the placenta (10).…”

Efficient studies of long-distance Bmp5 gene regulation using bacterial artificial chromosomes

“…This BAC clone (551) then was coinjected into fertilized mouse eggs with a separate DNA construct containing a minimal heat-shock promoter driving a lacZ reporter gene (31). The coinjection approach avoids complex cloning steps with large DNA fragments and takes advantage of the fact that coinjected DNA fragments usually cointegrate at a common site (32)(33)(34). The coinjection of BAC 551 and the hsplacZ cassette yielded embryos that show reporter expression simultaneously in all of the sites detected previously by individual phage subclones (Fig.…”