Expression and regulation of glucocorticoid-induced leucine zipper in the developing anterior pituitary gland

Abstract

The expression profile of glucocorticoid-induced leucine zipper (GILZ) in the anterior pituitary during the second half of embryonic development in the chick is consistent with in vivo regulation by circulating corticosteroids. However, nothing else has been reported about the presence of GILZ in the neuroendocrine system. We sought to characterize expression and regulation of GILZ in the chicken embryonic pituitary gland and determine the effect of GILZ overexpression on anterior pituitary hormone levels. Pituitary GILZ mRNA levels increased during embryogenesis to a maximum on the day of hatch, and decreased through the first week after hatch. GILZ expression was rapidly upregulated by corticosterone in embryonic pituitary cells. To determine whether GILZ regulates hormone gene expression in the developing anterior pituitary, we overexpressed GILZ in embryonic pituitary cells and measured mRNA for the major pituitary hormones. Exogenous GILZ increased prolactin mRNA above basal levels, but not as high as that in corticosterone-treated cells, indicating that GILZ may play a small role in lactotroph differentiation. The largest effect we observed was a twofold increase in FSH b subunit in cells transfected with GILZ but not treated with corticosterone, suggesting that GILZ may positively regulate gonadotroph development in a manner not involving glucocorticoids. In conclusion, this is the first report to characterize avian GILZ and examine its regulation in the developing neuroendocrine system. We have shown that GILZ is upregulated by glucocorticoids in the embryonic pituitary gland and may regulate expression of several pituitary hormones.

Glucocorticoid‐Induced Leucine Zipper (GILZ) Controls Inflammation and Tissue Damage after Spinal Cord Injury

“…We have previously reported that GILZ modulates the immune response after SCI suggesting a potential role due to therapeutic effects . Moreover, GILZ appears to be a marker of response to GC and is basally expressed in central nervous system .…”

“…It mediates a number of GC effects such as control of cell proliferation, apoptosis, and differentiation, including in T cells . Notably, GILZ is expressed in different areas of the CNS, such as forebrain, spinal cord, and cerebellum .…”

Glucocorticoid‐induced leucine zipper (GILZ): a new important mediator of glucocorticoid action

“…Moreover, GILZ is up-regulated by GCs and IL-10 in human mast cells (59); by GCs and IL-15 in natural killer (NK) and NKT cells (60); by GCs, erythropoietin (Epo), and stem cell factor (SCF) in primary erythroid progenitors (61); and by GCs, IL-10, and transforming growth factor ␤ (TGF-␤) in human immature DCs (35). Furthermore, GILZ is up-regulated by GCs in embryonic pituitary gland in the chick and regulates the expression of several pituitary hormones (62).…”

Identification of glucocorticoid-induced leucine zipper as a key regulator of tumor cell proliferation in epithelial ovarian cancer

“…It is rapidly induced by glucocorticoids in T lymphocytes [ 6 - 8 ], macrophages, dendritic cells and mast cells [ 9 - 11 ]. GILZ expression in the anterior pituitary during embryonic development in the chick is consistent with regulation by corticosteroids [ 12 ]; in the kidney cortical collecting duct, GILZ is induced by aldosterone [ 13 ]; and in human cervical adenocarcinoma HeLa cells, GILZ expression is controlled by estradiol [ 14 ].…”