Biomaterial Database

Co-expression of two distinct isoforms of 11 beta-hydroxysteroid dehydrogenase in the ovine placenta. 1995

K Yang

Lawson Research Institute, Department of Obstetrics and Gynecology, University of Western Ontario, St Joseph's Health Centre, London, Canada.

We have previously described two distinct isoforms of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) with respect to enzymatic activity in the ovine liver and kidney. To determine which isoform(s) is expressed in the ovine placenta, we studied the characteristics of 11 beta-HSD activity in placental tissues collected at days 140-143 of pregnancy. 11 beta-HSD activity was determined by a radiometric conversion assay using cortisol and cortisone as physiological substrates. At 100 nM cortisol, the placental 11 beta-HSD utilized NAD as cofactor, but displayed preference for NADP at 10 microM cortisol. Kinetic characteristics were examined in the presence of alternate cofactors, in order to determine whether this difference in the cofactor requirement represents distinct enzymes. With NAD as cofactor, the placental 11 beta-dehydrogenase had a Km (110 +/- 18 nM) compatible with the kidney enzyme, but displayed a Km (12 +/- 2 microM) similar/identical to the liver 11 beta-HSD when NADP was used. By contrast, the placental 11-oxoreductase showed preference for NADPH regardless of cortisone concentration. Kinetic analysis, using NADPH as cofactor, revealed a single species of 11-oxoreductase activity with a Km of 4 +/- 0.9 microM and a Vmax of 3.1 +/- 0.5 pmol/mg/min. Finally, since the NAD-dependent 11 beta-HSD in the ovine placenta displayed similar/identical kinetic characteristics to the enzyme described previously in the ovine kidney where a truncated 11 beta-HSD transcript was identified, we have also determined whether this transcript is expressed in the placenta by Northern blotting. It was found that the truncated 11 beta-HSD transcript was undetectable in the total RNA samples. These results demonstrate that both liver- and kidney-types of 11 beta-HSD activities are expressed in the ovine placenta, thus providing further evidence for the existence of a NAD-dependent 11 beta-HSD distinct from the well-characterized hepatic NADP-dependent enzyme. Furthermore, the lack of the truncated 11 beta-HSD transcript in the placenta suggests that the NAD-dependent enzyme identified in placenta and kidney is the product of a gene distinct from 11 beta-HSD.

UI	MeSH Term	Description	Entries
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D009243	NAD	A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)	Coenzyme I,DPN,Diphosphopyridine Nucleotide,Nadide,Nicotinamide-Adenine Dinucleotide,Dihydronicotinamide Adenine Dinucleotide,NADH,Adenine Dinucleotide, Dihydronicotinamide,Dinucleotide, Dihydronicotinamide Adenine,Dinucleotide, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide,Nucleotide, Diphosphopyridine
D009249	NADP	Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)	Coenzyme II,Nicotinamide-Adenine Dinucleotide Phosphate,Triphosphopyridine Nucleotide,NADPH,Dinucleotide Phosphate, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide Phosphate,Nucleotide, Triphosphopyridine,Phosphate, Nicotinamide-Adenine Dinucleotide
D010920	Placenta	A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES).	Placentoma, Normal,Placentome,Placentas,Placentomes
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D005260	Female		Females
D006854	Hydrocortisone	The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.	Cortef,Cortisol,Pregn-4-ene-3,20-dione, 11,17,21-trihydroxy-, (11beta)-,11-Epicortisol,Cortifair,Cortril,Epicortisol,Hydrocortisone, (11 alpha)-Isomer,Hydrocortisone, (9 beta,10 alpha,11 alpha)-Isomer,11 Epicortisol
D006913	Hydroxysteroid Dehydrogenases	Enzymes of the oxidoreductase class that catalyze the dehydrogenation of hydroxysteroids. (From Enzyme Nomenclature, 1992) EC 1.1.-.	Hydroxysteroid Dehydrogenase,Dehydrogenase, Hydroxysteroid,Dehydrogenases, Hydroxysteroid
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated