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Biology subjects

Grabek, A.

Publications and source records attributed to Grabek, A..

2 recordsLinked to original sources

Adrenal cortex size, homeostasis and tumorigenesis is regulated by gonadal hormones via androgen receptor/β-catenin signalling crosstalk.

Female bias is highly prevalent among adrenal cortex hyperplasia and neoplasia, but the reasons behind this phenomenon are poorly understood. In this article, we show that overexpression of the secreted WNT agonist R-spondin-1 leads to ectopic activation of WNT/{beta}-catenin signalling and causes sex-specific adrenocortical hyperplasia in mice. While female adrenals show ectopic proliferation, male adrenals display excessive immune system activation and cortical thinning. Using a combination of genetic manipulations and hormonal treatment, we show that gonadal androgens suppress ectopic proliferation in the adrenal cortex and determine the selective activation of WNT-related genes Axin2 and Wnt4. Notably, genetic removal of androgen receptor (AR) from adrenocortical cells restores the mitogenic effect of WNT/{beta}-catenin signalling. This is the first demonstration that AR activity in the adrenal cortex determines susceptibility to canonical WNT signalling-induced hyperplasia. TeaserActivation of R-spondin signaling in the adrenal cortex leads to a sexually dimorphic phenotype causing tumors in females and immune cell recruitment in males

cancer biology↗

Pituitary stem cells produce paracrine WNT signals to control the expansion of their descendant progenitor cells

In response to physiological demand, the pituitary gland generates new hormone-secreting cells from committed progenitor cells throughout life. It remains unclear to what extent pituitary stem cells (PSCs), which uniquely express SOX2, contribute to pituitary growth and renewal. Moreover, neither the signals that drive proliferation nor their sources have been elucidated. We have used genetic approaches in the mouse, showing that the WNT pathway is essential for proliferation of all lineages in the gland. We reveal that SOX2+ stem cells are a key source of WNT ligands. By blocking secretion of WNTs from SOX2+ PSCs in vivo, we demonstrate that proliferation of neighbouring committed progenitor cells declines, demonstrating that progenitor multiplication depends on the paracrine WNT secretion from SOX2+ PSCs. Our results indicate that stem cells can hold additional roles in tissue expansion and homeostasis, acting as paracrine signalling centres to coordinate the proliferation of neighbouring cells.

developmental biology↗