Naslov
Cytoskeleton in experimental cisplatin nephrotoxicity in rat

Autori
Herak-Kramberger, Carol M. ; Ljubojević, Marija ; Sabolić, Ivan

Izvornik
Nephrology, dialysis, transplantation (0931-0509) 18 (2003), Suppl. 4;

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, kongresno priopcenje, znanstveni

Ključne riječi
CDDP; heavy metal nephrotoxicity; actin; tubulin; nephron

Sažetak
Cisplatin (cis-diaminodichloroplatinum, CDDP) causes nephrotoxicity with a two-stage hypoosmotic polyuria as a major symptom, showing an early and a late peak one day (D1) and ~5 days (D5), respectively, following drug administration. Recent studies showed that some toxic metals interfere with polymerization of cytoskeletal elements, disrupt intracellular vesicle trafficking and targeting of transporters to the specific cell membrane domains, and damage the cell polarity, structure and function (Am J Physiol 283:F1389, 2002). In experiments in vitro, CDDP affected polymerization of actin and tubulin monomers into filaments and microtubules, respectively, whereas its possible effect on cytoskeleton in nephron cells in vivo has not been reported. In this work we compared the abundance of actin and -tubulin in tissue homogenates from the kidney cortex (C), outer stripe (OS), and inner stripe + inner medulla (ISIM) by immunoblotting, and the distribution pattern of actin filaments and microtubules in tissue cryosections by immunofluorescence cytochemistry (IF) in adult male Wistar rats at two polyuric peaks following treatment with a single dose of CDDP (5 mg/kg b.m., i.p.) or 0.9% NaCl (controls). On D1, the CDDP-treated rats had hypoosmotic polyuria and phosphaturia. In these rats, the density of the 42 kDa actin band in the C and OS homogenates was unchanged, whereas in the ISIM, it was lower by 38% compared with controls. By IF, the overall distribution and the intensity of actin staining in C, OS, and IS of CDDP-treated rats remained unchanged ; in the IM interstitium, it was strongly decreased. The 55 kDa a-tubulin band remaind unchanged in tissue homogenates, but the IF staining was stronger in all the zones, suggesting that the existing amount of protein may be hyperpolymerized. On D5, CDDP-treated rats had heavily damaged proximal tubule S3 segments, hypoosmotic polyuria, glucosuria, proteinuria, enzymuria and phospaturia. Compared with controls, the abundance of actin in tissue homogenates increased 85 % (C), 18-fold (OS), and 89% (ISIM). By IF, actin was diminished in the brush-border of C convoluted tubules, without redistribution. In the OS, the S3 brush border was largely lost, actin was redistributed all around the cell periphery, indicating the loss of cell polarity, and its staining intensity was dramatically enhanced. Similar pattern of actin staining was observed in the tubules of IS and IM. The abundance of a-tubulin in tissue homogenates from CDDP-treated rats increased slightly in the C and strongly (6-fold) in the OS, and remained unchanged in the ISIM. By IF, a bundle-like structure and the intensity of microtubule staining in C tubules remained unchanged, whereas in the S3, microtubules were deranged and their staining strongly enhanced. Numerous mitosis indicated an active regenerative processes in the OS. The staining pattern in the IS and IM was similar to that in controls. Our findings indicate that the interference of cisplatin with cytoskeleton in nephron cells may contribute to the development of structural and functional damages in the CDDP nephrotoxicity.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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