Naslov
Sex hormones regulate the expression and cellular distribution of megalin in the rat kidney

Autori
Herak-Kramberger, Carol-Mirna ; Kušec, Vesna ; Sabolić, Ivan

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts of the HDBMB 2004 / Dumić, Jerka - Zagreb : Hrvatsko društvo za biokemiju i molekularnu biologiju (HDBMB), 2004, 86-86

Skup
Congress of the Croatian Society of Biochemistry and Molecular Biology HDBMB 2004

Mjesto i datum
HOC Bjelolasica, Hrvatska, 30.09.2004. - 02.10.2004

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
gender differences; brush-border membrane; endocytic vesicles; membrane transporters

Sažetak
Megalin (Meg) is a multi-ligand endocytic receptor, a key player in reabsorption of protein and various other nutrients and toxins filtered in the proximal tubule (PT). Meg is localized exclusively in the apical/subapical domain of PT cells, being distributed in the brush-border membrane and endosomal compartment. Factors that regulate the expression and cellular distribution of Meg in PT cells are not known. The aim of this work was to study the effect of sex hormones on the expression and cellular distribution of Meg in the rat PT. We investigated the expression of this transporter and its cellular distribution by immunofluorescence cytochemistry in cryosections of the fixed kidney tissue from adult female rats in various estrous stages. The 4 distinct estrus stages (estrus, proestrus, diestrus 1, diestrus 2) were determined by vaginal smear cytology and verified by measuring sex hormones in the serum. To determine the role of individual sex hormones in Meg expression, adult male rats were castrated (CAS) and treated with either testosterone (T), estrogen (E) or progesterone (P), while adult female rats were ovariectomized (OV) and treated with E, and the abundance of Meg was determined by Western blotting (WB) in total cell membranes (TCM) isolated from the kidney cortex (C) and outer stripe (OS). In the estrus, Meg was strongly stained in the apical/subapical domain of PT cells. In the proestrus and diestrus 1, the staining was largely diminished in the apical domain and dispersed throughout the cytoplasm in granules of variable sizes, whereas the staining in diestrus 2 was between these two extremes. By WB in TCM isolated from the male kidney tissues, the abundance of Meg in the OS membranes was strongly diminished by T, whereas in the E-treated CAS males and OV females, the abundance of Meg in the OS membranes was clearly enhanced. P had no significant effect. We conclude that the expression and cellular distribution of Meg in the rat PT is affected by estrus, T and E. These findings indicate that reabsorbtion of proteins and other bioactive molecules filtered in the rat PT may be affected by sex hormones via Meg expression.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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