To test whether the stimulation of iodine coupling to thyroglobulin by TSH is dependent on Gq/G11, we measured the amount of iodine incorporated into thyroid proteins. in the body. It regulates O2 consumption as well as lipid and carbohydrate metabolism and is required for normal growth and maturation (1, 2). The primary regulator of thyroid gland growth and function in the adult organism is the thyroid-stimulating hormone (TSH). Lack of TSH or TSH action results in a reduced weight of the adult thyroid gland and almost abolishes thyroid function, leading to hypothyroidism (3C5). Conversely, pathologically elevated serum TSH levels stimulate thyroid hormone production and thyroid growth, leading to hyperthyroidism and goiter (6). TSH regulates thyroid function through a G proteinCcoupled receptor on thyrocytes (7C9). TSH receptorCdependent activation of the Gs/adenylyl cyclaseCmediated pathway has been suggested to account for most of the biological effects of Bavisant dihydrochloride TSH on thyroid cells, such as the stimulation of iodine uptake, hormone secretion, and proliferation (7). Consistent with this, thyroid glands of mice lacking the TSH receptor have defects in producing iodinated thyroglobulin, but the ability to take up iodine and to organify it can be restored by the adenylyl cyclase activator forskolin (4). Nongoitrous hypothyroidism has also been observed in patients with one defective allele of the gene encoding Gs (or in transgenic mice overexpressing the Gs-coupled adenosine A2 receptor, a constitutively active mutant of Gs, or cholera toxin in thyroids causes hyperfunctioning thyroid adenomas (12C17). In various species, including humans, TSH can also induce the Gq/G11-mediated stimulation of phospholipase CC (PLC-), leading to mobilization of intracellular Ca2+ ([Ca2+]i) by inositol 1,4,5-trisphosphate and formation of diacyl glycerol (18C20). However, the role of the Gq/G11-mediated signaling pathway in thyroid function Bavisant dihydrochloride is unclear. There is evidence that the constitutive activation of the Gq/G11/PLC- pathway in thyrocytes of mice overexpressing an active mutant of the 1B adrenergic receptor further promotes malignant transformation of the thyroid gland (21), but it is unclear whether Gq/G11 mediate a growth-promoting effect under more physiological conditions. In order to understand the role of Gq/G11-mediated signaling in thyroid follicular cells, we have generated mice lacking the subunits of Gq/G11 selectively in thyrocytes. Because Gq/G11-deficient mice die in utero (22), we used KIAA1732 Bavisant dihydrochloride a floxed allele of the gene encoding Gq (Cre reporter mouse line (24), 3 of the 4 tested transgenic founder lines showed Cre-mediated recombination exclusively in the thyroid gland (see Supplemental Figure 1, available online with this article; doi:10.1172/JCI30380DS1). Cre activity was observed in virtually all thyrocytes, but not in Bavisant dihydrochloride other cells of the thyroid gland, like parathyroid cells or stromal cells (Figure ?(Figure1A1A and data not shown). As expected from the time course of thyroglobulin promoter activity, no recombination was seen on E10.5 (Figure ?(Figure1A).1A). However, Cre-mediated recombination was observed by P2. There was no indication of altered thyroid histology or serum TSH and thyroid hormone levels in mice expressing Cre compared with wild-type Bavisant dihydrochloride littermates (Figure ?(Figure1A1A and data not shown). Open in a separate window Figure 1 Validation of thyrocyte-specific deletion of the genes encoding Gq and G11. (A) Cre reporter animals (Cre reporter) carrying no Cre gene (top row) or carrying the Cre gene under the control of the thyroglobulin promoter (Tg-Cre; bottom) were analyzed at the indicated ages, and -galactosidase staining was performed on whole-mount preparations as well as on sections (far right.