Involvement of reversible binding to alpha 2u-globulin in 1,4-dichlorobenzene-induced nephrotoxicity.
Similarly to unleaded gasoline, 1,4-dichlorobenzene (1,4-DCB) administered for 2 years caused a dose-related increase in the incidence of renal tumors in male but not in female rats or in either sex of mice. Unleaded gasoline and 2,2,4-trimethylpentane (TMP), a component of unleaded gasoline, increased protein droplet formation and cell proliferation in male but not in female rat kidneys. These protein droplets contained, alpha 2u-globulin, a male rat-specific low-molecular-weight protein and 2,4,4-trimethyl-2-pentanol, a metabolite of TMP that was reversibly bound to this protein. Studies were undertaken to determine if 1,4-DCB produced similar effects; 1,2-DCB was used for comparison since it did not produce renal carcinogenesis in male rats. Gel filtration chromatography of a 116,000g supernatant prepared from kidneys of 1,4-[14C]DCB-treated rats showed that radiolabel coeluted with alpha 2u-globulin as one sharp peak as opposed to a multipeak pattern observed for 1,2-[14C]DCB; the maximal quantity of radiolabel for 1,4-DCB was twice that for 1,2-DCB. Equilibrium dialysis of kidney cytosol in the presence or absence of sodium dodecyl sulfate demonstrated that the radiolabel was reversibly bound to alpha 2u-globulin; the amount for 1,4-[14C]DCB-treated rats was almost twice as much as that for 1,2-[14C]DCB-treated rats. 1,2-DCB was also shown to be covalently bound to renal alpha 2u-globulin, and covalently bound to liver and plasma high-molecular-weight proteins. 1,4-DCB and, to a minor extent, 2,5-dichlorophenol, the major metabolite of 1,4-DCB, were reversibly bound to renal alpha 2u-globulin from 1,4-DCB-treated rats. 1,4-DCB increased protein droplet formation in male but not in female rat kidneys, whereas equimolar doses of 1,2-DCB showed no effect in either sex. Renal cell proliferation, measured by [3H]thymidine incorporation into renal DNA, was increased after 1,4-DCB but not after 1,2-DCB treatment. Nephrotoxicity and biochemical alterations induced by 1,4-DCB resemble those of unleaded gasoline and suggest that a similar mechanism is involved in the induction of alpha 2u-globulin nephropathy in male rats.
Charbonneau
M
M
Chemical Industry Institute of Toxicology, Department of Biochemical Toxicology and Pathobiology, Research Triangle Park, North Carolina 27709.
Strasser
J
J
Lock
E A
EA
Turner
M J
MJ
Swenberg
J A
JA
D000510:Alpha-Globulins / Q000378:metabolism*; D000818:Animals; D002722:Chlorobenzenes / Q000378:metabolism / Q000633:toxicity*; D002853:Chromatography, Liquid; D004247:DNA / Q000096:biosynthesis; D003956:Dialysis; D007668:Kidney / Q000187:drug effects*; D008297:Male; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D012737:Sex Factors; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014018:Tissue Distribution
D000510:Alpha-Globulins; D002722:Chlorobenzenes; D011506:Proteins; D012967:Sodium Dodecyl Sulfate; C004726:2-dichlorobenzene; D004247:DNA; C018511:4-dichlorobenzene; D013936:Thymidine