High expression of stanniocalcin in differentiated brain neurons

Abstract

Stanniocalcin (STC) is a glycoprotein hormone first found in fish, in which it regulates calcium homeostasis and protects against hypercalcemia. Human and mouse stc cDNA were recently cloned. We found a dramatically upregulated expression of STC during induced neural differentiation in a human neural crest-derived cell line, Paju. Immunohistochemical staining of sections from human and adult mouse brain revealed abundant presence of STC in the neurons with no activity in the glial cells. STC expression was not seen in immature brain neurons of fetal or newborn mice. Given that STC has been found to regulate calcium/phosphate metabolism in some mammalian epithelia, we suggest that STC may act as a regulator of calcium homeostasis in terminally differentiated brain neurons.

Figure 1.

Induction of stc expression in Paju cells by treatment with PMA. A: DD of mRNAs from indicated times of PMA treatment. Arrow: Position of the stc sequence. B: Top: Northern blot analysis with human stc cDNA of stc mRNA expression during PMA-induced neural differentiation. Bottom: Hybridization with a human glyceraldehyde-3-phosphate dehydrogenase probe to demonstrate equal loading. The same filter was stripped and reprobed.

Figure 2.

Western blot analysis with rabbit antibodies to human STC of lysates of Paju cells treated with PMA for indicated times.

Figure 3.

Immunofluorescencent staining of Paju cells after 0, 24, and 48 hours of PMA treatment with STC antibodies (D to F); A to C are the corresponding phase-contrast pictures.

Figure 4.

Immunohistochemical stainings of different parts of normal human brain. A: Parietal cortex. B: Parietal cortex stained with STC antibodies preabsorbed with recombinant STC protein (control). C: Cerebellum. C, inset: Larger magnification of Purkinje cells. D: Nucleus dentatus. D, inset: Larger magnification of the neuronal staining.

Figure 5.

Immunohistochemical stainings of mouse brain with antibodies to STC (A to C) and with preabsorbed antibodies (D to F). A and D: Brain tissue from 15-day-old embryo. B and E: Cortex from a newborn mouse, inset: Cerebellum. C and F: Adult mouse parietal cortex, inset: Cerebellum.