Редактирование: CYP7B1

Cytochrome P450 7B1 (24-hydroxycholesterol 7-alpha-hydroxylase) (EC 1.14.14.26) (25/26-hydroxycholesterol 7-alpha-hydroxylase) (EC 1.14.14.29) (3-hydroxysteroid 7-alpha hydroxylase) (Oxysterol 7-alpha-hydroxylase)

==Publications==

{{medline-entry
|title=[[CYP7B1]]-mediated metabolism of dehydroepiandrosterone and 5alpha-androstane-3beta,17beta-diol--potential role(s) for estrogen signaling.
|pubmed-url=https://pubmed.ncbi.nlm.nih.gov/18331353
|abstract=[[CYP7B1]], a cytochrome P450 enzyme, metabolizes several steroids involved in hormonal signaling including 5alpha-androstane-3beta,17beta-diol (3beta-Adiol), an estrogen receptor agonist, and dehydroepiandrosterone, a precursor for sex hormones. Previous studies have suggested that [[CYP7B1]]-dependent metabolism involving dehydroepiandrosterone or 3beta-Adiol may play an important role for estrogen receptor beta-mediated signaling. However, conflicting data are reported regarding the influence of different [[CYP7B1]]-related steroids on estrogen receptor beta activation. In the present study, we investigated [[CYP7B1]]-mediated conversions of dehydroepiandrosterone and 3beta-Adiol in porcine microsomes and human kidney cells. As part of these studies, we compared the effects of 3beta-Adiol (a [[CYP7B1]] substrate) and 7alpha-hydroxy-dehydroepiandrosterone (a [[CYP7B1]] product) on estrogen receptor beta activation. The data obtained indicated that 3beta-Adiol is a more efficient activator, thus lending support to the notion that [[CYP7B1]] catalysis may decrease estrogen receptor beta activation. Our data on metabolism indicate that the efficiencies of [[CYP7B1]]-mediated hydroxylations of dehydroepiandrosterone and 3beta-Adiol are very similar. The enzyme catalyzed both reactions at a similar rate and the K(cat)/K(m) values were in the same order of magnitude. A high dehydroepiandrosterone/3beta-Adiol ratio in the incubation mixtures, similar to the ratio of these steroids in many human tissues, strongly suppressed [[CYP7B1]]-mediated 3beta-Adiol metabolism. As the efficiencies of [[CYP7B1]]-mediated hydroxylation of dehydroepiandrosterone and 3beta-Adiol are similar, we propose that varying steroid concentrations may be the most important factor determining the rate of [[CYP7B1]]-mediated metabolism of dehydroepiandrosterone or 3beta-Adiol. Consequently, tissue-specific steroid concentrations may have a strong impact on [[CYP7B1]]-dependent catalysis and thus on the levels of different [[CYP7B1]]-related steroids that can influence estrogen receptor beta signaling.
|mesh-terms=* Aging
* Androstane-3,17-diol
* Animals
* Cell Line
* Cytochrome P-450 Enzyme System
* Dehydroepiandrosterone
* Estrogen Receptor beta
* Estrogens
* Female
* Gene Expression Regulation
* Humans
* Hydroxylation
* Kinetics
* Male
* Organ Specificity
* Signal Transduction

|full-text-url=https://sci-hub.do/10.1111/j.1742-4658.2008.06336.x
}}
{{medline-entry
|title=Expression of key enzymes in bile acid biosynthesis during development: [[CYP7B1]]-mediated activities show tissue-specific differences.
|pubmed-url=https://pubmed.ncbi.nlm.nih.gov/11971943
|abstract=The developmental variation of cytochrome P450 (CYP)7A1, [[CYP7B1]], [[CYP27A1]], and 3beta-hydroxy-Delta(5)-C(27)-steroid dehydrogenase, key enzymes in bile acid biosynthesis, were investigated in pigs of different ages. As part of these studies, peptide sequences from a purified pig liver oxysterol 7alpha-hydroxylase were analyzed. The sequences showed a high degree of identity with those of murine and human [[CYP7B1]]. Enzymatic activities and mRNA levels of [[CYP27A1]] and 3beta-hydroxy-Delta(5)-C(27)-steroid dehydrogenase were similar in livers of newborn and 6-month-old pigs. Enzymatic activity mediated by [[CYP7A1]] increased several-fold between infancy and adolescence. Hepatic [[CYP7A1]] and [[CYP7B1]] mRNA levels increased several-fold with age. Hepatic microsomal 7alpha-hydroxylation of 27-hydroxycholesterol and dehydroepiandrosterone, substrates typical for [[CYP7B1]], increased about 5-fold between infancy and adolescence whereas the activities in kidney microsomes decreased at least 10-fold. In conclusion, the results indicate that the expression of [[CYP27A1]] and 3beta-hydroxy-Delta(5)-C(27)-steroid dehydrogenase are similar in livers of newborn and 6-month-old pigs whereas the levels of [[CYP7A1]] increase. The finding that the levels of [[CYP7B1]] increase with age in the liver but decrease in the kidney suggest a tissue-specific developmental regulation of [[CYP7B1]]. The age-dependent variation in the liver and kidney suggests that hormonal factors are involved in the regulation of [[CYP7B1]].
|mesh-terms=* Aging
* Amino Acid Sequence
* Animals
* Animals, Newborn
* Base Sequence
* Bile Acids and Salts
* Cytochrome P-450 Enzyme System
* Cytochrome P450 Family 7
* Gene Expression Regulation, Developmental
* Gene Expression Regulation, Enzymologic
* Humans
* Kinetics
* Male
* Mice
* Mitochondria, Liver
* Molecular Sequence Data
* Orchiectomy
* Organ Specificity
* Peptide Fragments
* Polymerase Chain Reaction
* Progesterone Reductase
* RNA, Messenger
* Sequence Alignment
* Sequence Homology, Amino Acid
* Steroid Hydroxylases
* Swine
* Transcription, Genetic


}}