Vitamin D is present in two forms, ergocalciferol (vitamin D2) produced by plants and cholecalciferol (vitamin D3) produced by animal tissues or by the action of ultraviolet light on 7-dehydrocholesterol in human skin. Both forms of vitamin D are biologically inactive pro-hormones that must undergo sequential hydroxylations in the liver and the kidney before they can bind to and activate the vitamin D receptor. The hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D], plays an essential role in calcium and phosphate metabolism, bone growth, and cellular differentiation. Renal synthesis of 1,25(OH)2D from its endogenous precursor, 25-hydroxyvitamin D (25OHD), is the rate-limiting and is catalyzed by the 1alpha-hydroxylase. Vitamin D dependent rickets type I (VDDR-I), also referred to as vitamin D 1alpha-hydroxylase deficiency or pseudovitamin D deficiency rickets, is an autosomal recessive disorder characterized clinically by hypotonia, muscle weakness, growth failure, hypocalcemic seizures in early infancy, and radiographic findings of rickets. Characteristic laboratory features are hypocalcemia, increased serum concentrations of parathyroid hormone (PTH), and low or undetectable serum concentrations of 1,25(OH)2D despite normal or increased concentrations of 25OHD. Recent advances have showed in the cloning of the human 1alpha-hydroxylase and revealed mutations in its gene that cause VDDR-I. This review presents the biology of vitamin D, and 1alpha-hydroxylase mutations with clinical findings.
Animals ; Biology ; Bone Development ; Calcitriol ; Calcium ; Cholecalciferol ; Clone Cells ; Cloning, Organism ; Dehydrocholesterols ; Ergocalciferols ; Humans ; Hydroxylation ; Hypocalcemia ; Kidney ; Liver ; Muscle Hypotonia ; Parathyroid Hormone ; Receptors, Calcitriol ; Rickets ; Seizures ; Skin ; Ultraviolet Rays ; Vitamin D ; Vitamins

Vibrio vulnificus cytolysin (VVC) has been implicated as one of the important virulence determinants of V. vulnificus that causes serious septicemia and wound infection. An attempt was made to investigate that VVC could act as a ligand which stimulates intracellular signaling systems. Cholesterol dose-dependently blocked VVC hemolytic activity through oli-gomerization of cytolysin. Among cholesterol derivatives including 7-dehydrocholesterol, cholesteryl esters, deoxycholate, and cholestane tested, only 7-dehydrocholesterol induced oligomerization as well as inactivation of VVC. These results show that oligomerization of VVC is completely dependent on three-dimensional structure of cholesterol where specific interaction of cholesterol at oligomerization sites of VVC is very selective. These findings support the idea that cholesterol which constitute many of cellular plasma membrane could be a receptor of VVC on plasma membrane of target cells.
Animals ; Bacterial Toxins/antagonists & inhibitors/chemistry/metabolism ; Cholesterol/chemistry/*pharmacology ; Cytotoxins/antagonists & inhibitors/*chemistry/*metabolism ; Dehydrocholesterols/chemistry/pharmacology ; Dose-Response Relationship, Drug ; Erythrocytes/drug effects ; Hemolysis/drug effects ; Mice ; Molecular Structure ; Signal Transduction ; Substrate Specificity ; Vibrio/*chemistry

The key challenge to generate engineered cells by synthetic biology for producing 7-dehydrocholesterol (7-DHC) in a high titer is the match between functional module and chassis. Our study focused on solving this problem by combining different promoters and yeast chassis to increase 7-DHC production. To optimize the chassis in order to accumulate zymosterol, the substrate for 7-DHC synthesis, we overexpressed truncated HMG-CoA reductase (tHmglp) and squalene epoxidase (Erglp), both are key genes of yeast endogenous zymosterol biosynthetic pathway. In addition, we knocked out C-24 methyl transferase (Erg6p) and C-22 dehydrogenase (Erg5p) to inhibit the conversion of zymosterol to ergosterol. By introducing heterologous C-24 reductase under three promoters with different strengths, namely TDH3p, PGK1p and TDH1p, we constructed functional modules of diverse activities. Nine engineeredcells were generated based on the combination of these three modules and three chassis. The result shows that the engineered cell composed of functional module regulated by TDH3p and chassis SyBE_000956 had the highest 7-DHC production, indicating a better match than others. This study provides evidences for importance of match and empirical support for rational design of subsequent researches.
Cholesterol ; metabolism ; Cytochrome P-450 Enzyme System ; genetics ; Dehydrocholesterols ; metabolism ; Gene Knockout Techniques ; Hydroxymethylglutaryl CoA Reductases ; metabolism ; Industrial Microbiology ; Methyltransferases ; genetics ; Promoter Regions, Genetic ; Saccharomyces cerevisiae ; genetics ; metabolism ; Saccharomyces cerevisiae Proteins ; genetics ; Synthetic Biology

Smith-Lemli-Opitz syndrome (SLOS) is a rare, autosomal recessive disease caused by an inborn error in cholesterol synthesis. Patients with this disease suffer from multiple malformations due to reduced activity of 7-dehydrocholesterol reductase (DHCR7), which increases 7-dehydrocholesterol (7DHC) and 8-dehydrocholesterol (8DHC) concentrations and decreases cholesterol concentration in body fluids and tissue. The SLOS phenotypic spectrum ranges from a mild disorder with behavioral and learning problems to a lethal disease characterized by multiple malformations. Here, we describe a newborn male with ambiguous genitalia who was diagnosed to have type II SLOS during the neonatal period. A clinical examination revealed low levels of unconjugated estriol in the maternal serum, and a variety of fetal ultrasound anomalies, including prenatal growth retardation. After birth, the infant was diagnosed to have congenital heart disease (Tetralogy of Fallot with severe pulmonary artery stenosis), cleft lip and palate, micrognathia, postaxial polydactyly, ambiguous genitalia, and cataracts. Clinical investigation revealed extremely low plasma cholesterol levels and the presence of mutation (homozygote of p.Arg352Gln) in the DHCR7 gene. The patient underwent palliative heart surgery (to widen the pulmonary artery) and received intravenous lipid supplementation. Cholesterol levels increased slightly, but not to normal values. The patient died from cardiopulmonary failure and sepsis 72 days after birth. This report provides the first description of a Korean patient with SLOS confirmed by verification of DHCR7 gene mutation and illustrates the need for early recognition and appropriate diagnosis of this disease.
Body Fluids ; Cataract ; Cholestadienols ; Cholesterol ; Cleft Lip ; Dehydrocholesterols ; Disorders of Sex Development ; Estriol ; Heart Diseases ; Humans ; Infant ; Infant, Newborn ; Learning ; Male ; Oxidoreductases ; Oxidoreductases Acting on CH-CH Group Donors ; Palate ; Parturition ; Plasma ; Polydactyly ; Pulmonary Artery ; Reference Values ; Sepsis ; Smith-Lemli-Opitz Syndrome ; Thoracic Surgery