Glycoprotein III (Clusterin, Sulfated Glycoprotein 2) in Endocrine, Nervous, and Other Tissues: Immunochemical Characterization, Subcellular Localization, and Regulation of Biosynthesis

Abstract

Specific antisera were raised against the A and B chains of glycoprotein III. Immunoblotting revealed that in adrenal medulla both chains migrate very closely together in two-dimensional electrophoresis. Both chains with slightly differing molecular sizes are found in several endocrine tissues and in brain, kidney, liver, and serum. The mRNA has an analogous widespread distribution. In primary cultures of chromaffin cells the level of message becomes significantly increased by treatment with histamine or 12-O-tetradecanoylphorbol 13-acetate/forskolin. However, the increase is small when compared with that of secretogranin II. The subcellular localization of glycoprotein III in endocrine organs and in the posterior pituitary was investigated by subcellular fractionation and immunoelectron microscopy. Glycoprotein III was found to be confined to the large dense-core vesicles of these organs. For a discussion of the function of glycoprotein III, its localization in these organelles has to be taken into account.

Clusterin is expressed in the anterior and intermediate lobes, but not in the posterior pituitary of sheep

“…This finding is similar to that of Laslop et al (1993), who observed higher amounts of mRNA in bovine anterior pituitary extracts, but clusterin protein in both pituitary lobes. In the sheep brain extracts analysed, the highest clusterin hybridisation densities were found in the medial basal hypothalamus and spinal cord, both areas in which neuronal clusterin gene expression has been reported (Messmer-Joudrier et al 1996, Wener et al 1997.…”

“…These observations led us to investigate clusterin expression in the ovine pituitary gland, with the aim of determining the distribution of clusterin mRNA and protein in the different parts of this tissue. In previous studies of bovine pituitary, the protein was detected in both the anterior and posterior lobes (Laslop et al 1993). However, the site of clusterin mRNA transcription remains unclear.…”

“…However, the site of clusterin mRNA transcription remains unclear. Aronow et al (1993) did not detect clusterin mRNA in mouse anterior pituitary, whereas Laslop et al (1993) (Fleming et al 1997) was used as a positive control on Northern blots probed with the growth hormone gene probe.…”

“…However, the site of clusterin mRNA transcription remains unclear. Aronow et al (1993) did not detect clusterin mRNA in mouse anterior pituitary, whereas Laslop et al (1993) (Fleming et al 1997) was used as a positive control on Northern blots probed with the growth hormone gene probe.Pituitary glands for immunohistochemistry and in situ hybridisation were obtained from five 4-to 6-year-old Romney ewes killed with Euthatal (Southern Veterinary Supplies, Christchurch, New Zealand; 100 mg/kg, i.v. ), at the mid-luteal phase of the oestrous cycle.…”

Clusterin Is a Secreted Marker for a Hypoxia-Inducible Factor-Independent Function of the von Hippel-Lindau Tumor Suppressor Protein

“…52,53 Its predominant form is a secreted heterodimeric glycoprotein of 75 to 80 kd and is highly conserved across species, showing 70 to 80% identity at the amino acid level among mammals. Clusterin expression tends to increase with senescence or during cellular transformation, although whether such increases are causal with respect to these two cellular phenotypes is unclear.…”