The genetic basis of resistance to anticoagulants in rodents.
Anticoagulant compounds, i.e., derivatives of either 4-hydroxycoumarin (e.g., warfarin, bromadiolone) or indane-1,3-dione (e.g., diphacinone, chlorophacinone), have been in worldwide use as rodenticides for >50 years. These compounds inhibit blood coagulation by repression of the vitamin K reductase reaction (VKOR). Anticoagulant-resistant rodent populations have been reported from many countries and pose a considerable problem for pest control. Resistance is transmitted as an autosomal dominant trait although, until recently, the basic genetic mutation was unknown. Here, we report on the identification of eight different mutations in the VKORC1 gene in resistant laboratory strains of brown rats and house mice and in wild-caught brown rats from various locations in Europe with five of these mutations affecting only two amino acids (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln, Leu128Ser). By recombinant expression of VKORC1 constructs in HEK293 cells we demonstrate that mutations at Tyr139 confer resistance to warfarin at variable degrees while the other mutations, in addition, dramatically reduce VKOR activity. Our data strongly argue for at least seven independent mutation events in brown rats and two in mice. They suggest that mutations in VKORC1 are the genetic basis of anticoagulant resistance in wild populations of rodents, although the mutations alone do not explain all aspects of resistance that have been reported. We hypothesize that these mutations, apart from generating structural changes in the VKORC1 protein, may induce compensatory mechanisms to maintain blood clotting. Our findings provide the basis for a DNA-based field monitoring of anticoagulant resistance in rodents.
Pelz
Hans-Joachim
HJ
Biologische Bundesanstalt für Land-und Forstwirtschaft, Institut für Nematologie und Wirbeltierkunde, 48161 Münster, Germany.
Rost
Simone
S
Hünerberg
Mirja
M
Fregin
Andreas
A
Heiberg
Ann-Charlotte
AC
Baert
Kristof
K
MacNicoll
Alan D
AD
Prescott
Colin V
CV
Walker
Anne-Sophie
AS
Oldenburg
Johannes
J
Müller
Clemens R
CR
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D002460:Cell Line; D003062:Codon; D004252:DNA Mutational Analysis; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014443:Tyrosine / Q000737:chemistry; D064417:Vitamin K Epoxide Reductases; D014859:Warfarin / Q000494:pharmacology
D000925:Anticoagulants; D003062:Codon; D011994:Recombinant Proteins; D014443:Tyrosine; D014859:Warfarin; D006899:Mixed Function Oxygenases; C578523:VKORC1 protein, human; D064417:Vitamin K Epoxide Reductases