For convenience, think of the zona glomerulosa as the first endocrine organ and the zonae fasciculata and reticularis collectively as a second separate endocrine organ, as distinguished by distinct control systems. (medscape.com)
Cytochrome P450c17, an enzyme complex present in Leydig cells, ovarian follicles, and the adrenal zonae fasciculata and reticularis, catalyzes both 17-hydroxylase and 17,20 lyase activity. (medscape.com)
Expression of CYP17A1 has been found in all of the traditional steroidogenic tissues except the placenta, including the zona reticularis and zona fasciculata of the adrenal cortex, the Leydig cells of the testes, the thecal cells of the ovaries, and, more recently, in luteinized granulosa cells in ovarian follicles. (wikipedia.org)
In contrast, cortisol synthesis and secretion is regulated by adrenocorticotropic hormone (ACTH), which stimulates the enzyme P-450scc (20, 22 desmolase) with subsequent increased production of all adrenal steroids in both the zona fasciculata and zona reticularis. (medscape.com)
Mineralocorticoid and glucocorticoid2
This example shows a deficiency in both the mineralocorticoid and glucocorticoid pathways. (medscape.com)
The example depicts a deficiency of 21-hydroxylase, resulting in deficient mineralocorticoid and glucocorticoid production and excessive androgen production. (medscape.com)
Mineralocorticoids2
It has both 17α-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces progestins, mineralocorticoids, glucocorticoids, androgens, and estrogens. (wikipedia.org)
Normal adrenal steroid biosynthesis results in three products: mineralocorticoids (aldosterone), glucocorticoids (cortisol), and androgens (androstenedione). (medscape.com)
Cortisol1
The 17α-hydroxylase activity of CYP17A1 is required for the generation of glucocorticoids such as cortisol, but both the hydroxylase and 17,20-lyase activities of CYP17A1 are required for the production of androgenic and oestrogenic sex steroids by converting 17α-hydroxypregnenolone to dehydroepiandrosterone (DHEA). (wikipedia.org)
Lyase activity2
CYP17A1 has both 17α-hydroxylase activity (EC 1.14.14.19) and 17,20-lyase activity (EC 1.14.14.32). (wikipedia.org)
Cytochrome b5 acts as a facilitator for 17,20 lyase activity of CYP17A1 and can donate a second electron to some P450s. (wikipedia.org)
Adrenal2
Furthermore, mutations in the CYP17A1 gene are associated with rare forms of congenital adrenal hyperplasia, in particular 17α-hydroxylase deficiency/17,20-lyase deficiency and isolated 17,20-lyase deficiency. (wikipedia.org)
Precursor hormones such as corticosterone are elevated, have glucocorticoid activity, and are adequate to prevent adrenal insufficiency. (medscape.com)
Mutations1
P450c17 is the product of the cytochrome P45017 alpha gene (CYP17A1), and specific mutations of this gene cause varying degrees of partial-to-severe isolated 17-hydroxylase deficiency, isolated 17,20 lyase deficiency, or combined deficiencies. (medscape.com)
Cytochrome4
Cytochrome P450 17A1 (steroid 17α-monooxygenase, 17α-hydroxylase, 17-alpha-hydroxylase, 17,20-lyase, 17,20-desmolase) is an enzyme of the hydroxylase type that in humans is encoded by the CYP17A1 gene on chromosome 10. (wikipedia.org)
non-primary source needed] CYP17A1 is a 57.4 kDa protein that belongs to the cytochrome P450 family. (wikipedia.org)
Based on its known structures while bound to two steroidal inhibitors, abiraterone and galeterone, CYP17A1 possesses the canonical cytochrome P450 fold present in other complex P450 enzymes that participate in steroidogenesis or cholesterol metabolism, though it orients the steroid ligands toward the F and G helices, perpendicular to the heme group, rather than the β1 sheet. (wikipedia.org)
CYP17A1 is a member of the cytochrome P450 superfamily of enzymes localized in the endoplasmic reticulum. (wikipedia.org)
Produces1
Overall, CYP17A1 is an important target for inhibition in the treatment of prostate cancer because it produces androgen that is required for tumor cell growth. (wikipedia.org)
Enzyme2
As an enzyme, CYP17A1 possesses an active site that associates with a heme prosthetic group to catalyze biosynthetic reactions. (wikipedia.org)
The decreased enzyme activity of CYP17A1 is related to infertility due to hypogonadotropic hypogonadism. (wikipedia.org)
Deficiency1
17-Hydroxylase (17-OH) deficiency syndrome is a rare genetic disorder of steroid biosynthesis that causes decreased production of glucocorticoids and sex steroids and increased synthesis of mineralocorticoid precursors. (medscape.com)
Steroid1
In humans, the CYP17A1 gene is largely associated with endocrine effects and steroid hormone metabolism. (wikipedia.org)
Gene2
The CYP17A1 gene resides on chromosome 10 at the band 10q24.3 and contains 8 exons. (wikipedia.org)
The CYP17A1 gene may also contain variants associated with increased risk of coronary artery disease. (wikipedia.org)
Production1
In humans the production of testosterone via pregnenolone to17-OHPreg and DHEA by the CYP17A1 requires POR. (wikipedia.org)
Treatment2
Exogenous glucocorticoid therapy is the treatment of choice and suppresses adrenocorticotropic hormone (ACTH) secretion, decreases 11-DOC and corticosterone levels, and normalizes serum potassium and blood pressure. (medscape.com)
Treatment with exogenous glucocorticoid decreases ACTH secretion and subsequent suppression of overproduced steroids. (medscape.com)
Adrenal insufficiency3
Precursor hormones such as corticosterone are elevated, have glucocorticoid activity, and are adequate to prevent adrenal insufficiency. (medscape.com)
The goal of therapy for adrenal hyperplasia is the replacement of glucocorticoid and mineralocorticoid to prevent signs of adrenal insufficiency and to prevent the accumulation of precursor hormones that cause virilization. (medscape.com)
In the growing child with adrenal insufficiency, long-term glucocorticoid replacement must be balanced to prevent symptoms of adrenal insufficiency while still allowing the child to grow at a normal rate and prevent symptoms of glucocorticoid excess. (medscape.com)
Mineralocorticoid4
17-Hydroxylase (17-OH) deficiency syndrome is a rare genetic disorder of steroid biosynthesis that causes decreased production of glucocorticoids and sex steroids and increased synthesis of mineralocorticoid precursors. (medscape.com)
This example shows a deficiency in both the mineralocorticoid and glucocorticoid pathways. (medscape.com)
The example depicts a deficiency of 21-hydroxylase, resulting in deficient mineralocorticoid and glucocorticoid production and excessive androgen production. (medscape.com)
After appropriate diagnostic studies are performed or after the results are known, glucocorticoid therapy, mineralocorticoid therapy, or both may be started. (medscape.com)
Adequate2
Prognosis is generally good-to-excellent with adequate glucocorticoid therapy and monitoring. (medscape.com)
Adequate glucocorticoid replacement should prevent excessive concentrations of ACTH from stimulating the adrenal glands to produce abnormal concentrations of adrenal androgens that result in further virilization. (medscape.com)
ACTH2
Exogenous glucocorticoid therapy is the treatment of choice and suppresses adrenocorticotropic hormone (ACTH) secretion, decreases 11-DOC and corticosterone levels, and normalizes serum potassium and blood pressure. (medscape.com)
Treatment with exogenous glucocorticoid decreases ACTH secretion and subsequent suppression of overproduced steroids. (medscape.com)
Suppression1
However, because of their increased potency, growth suppression and other signs of glucocorticoid excess are common. (medscape.com)