Targeted inactivation of the mouse alpha 2-macroglobulin gene.
The mouse alpha 2-macroglobulin gene was inactivated in embryonic stem cells by homologous recombination. Liver alpha 2-macroglobulin mRNA and plasma protein was absent in homozygotes and reduced to 50% in heterozygotes. alpha 2-Macroglobulin-deficient mice were viable and produced normally sized litters with normal sex ratio over 3 generations. Characterization of adult homozygotes included diets with different fat content, treatments with endotoxin, bleomycin, carbon tetrachloride, and ethionine to test for immune system, lung, liver, and pancreas toxicity, respectively. Knock-out mice were more resistant to endotoxin but more sensitive to a choline-free diet supplemented with ethionine. Regulation of murinoglobulin mRNA expression during pregnancy was analyzed as a possible back-up mechanism for the deficiency in alpha 2-macroglobulin. In addition, expression of mRNA was studied, coding for alpha 2-macroglobulin receptor/lipoprotein receptor-related protein, low density lipoprotein receptor, and very low density lipoprotein receptor and for some common ligands, i.e. apolipoprotein E, lipoprotein lipase, and the 44-kDa heparin binding protein. Their differential regulation in the knock-out mice relative to C57B1 mice was evident and is discussed. The impressive 15-fold increase in maternal liver murinoglobulin mRNA at partum in the knock-out mice indicated increased consumption, compared to only 4-fold in normal mice. Thus, murinoglobulin appears as the major proteinase inhibitor around partum, obviously solicited to a much greater extend in alpha 2-macroglobulin-deficient mice.
Umans
L
L
Department of Human Genetics, K. U. Leuven, Belgium.
Serneels
L
L
Overbergh
L
L
Lorent
K
K
Van Leuven
F
F
Van den Berghe
H
H
D000818:Animals; D001761:Bleomycin / Q000633:toxicity; D002251:Carbon Tetrachloride / Q000633:toxicity; D004731:Endotoxins / Q000633:toxicity; D005260:Female; D015870:Gene Expression; D018390:Gene Targeting; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010195:Pancreatitis / Q000209:etiology; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018110:Receptors, Lipoprotein / Q000235:genetics; D011995:Recombination, Genetic; D012712:Serum Globulins / Q000235:genetics; D013234:Stem Cells / Q000378:metabolism; D018243:Teratocarcinoma / Q000209:etiology; D000511:alpha-Macroglobulins / Q000172:deficiency / Q000235:genetics*
D004731:Endotoxins; D012333:RNA, Messenger; D018110:Receptors, Lipoprotein; D012712:Serum Globulins; D000511:alpha-Macroglobulins; C044177:murinoglobulin; D001761:Bleomycin; D002251:Carbon Tetrachloride