Novel Biosynthetic Pathway for Secosteroids and the Skin

描述(申请人提供)：细胞色素P450scc系统可以有效地将7-脱氢胆固醇(7-DHC)转化为7-脱氢孕烯醇酮(7-DHP)，并羟化维生素D2和D3，以及麦角甾醇。因此，我们发现了产生新的生物活性产物的新的类固醇/类固醇生成途径。皮肤通路将引发大多数内分泌、自体或旁分泌模式的作用。在SLOS中，UVB光诱导的转化(仅针对皮肤)将与来自体循环的底物(5，7-甾二烯)进行，以产生VitDL化合物。这些新的途径可以产生许多分子，其结构取决于类固醇合成系统的局部类型和活性，以及对UVB光子的访问。为了验证这一假设，我们设计了以下具体目标。1.对P450scc衍生的20-羟基维生素D3及其光解衍生物20，22-二羟基维生素D3，17a，24-二羟基麦角甾醇、20-羟基维生素D2和17a，20-二羟基维生素D2的生物活性进行了测定。上述影响将与母体化合物，即维生素D3和2，以及麦角甾醇进行比较；2.测试7-DHP、其羟基衍生物及其光解(UVB诱导)转化的第二甾体产物的生物活性；3.7-DHP的酶转化为羟基衍生物的表征，特别是在17、20、21和11位。研究将包括合成标准以充分表征反应产物的化学结构和性质。4.验证了UVB对7-DHP及其羟基或17a，24-二羟基麦角甾体的B环分子内重排的预测作用，得到了预期的VitDL-衍生物。还将对所得分子的结构稳定性进行测试；5.确定P450scc在5，7-二烯酯醇、维生素D和麦角甾醇体内代谢中的作用：a)与肾上腺细胞系相比，P450scc在培养的皮肤细胞中体内转化7-DHC的特征。还将调查细胞暴露在紫外线辐射下后产生的Secosterid。b)在培养的皮肤细胞中P450scc转化维生素D和麦角固醇的特征。6.明确了7-DHP、其羟基和Seco衍生物以及维生素D(修饰或未修饰)对P450scc介导的胆固醇合成孕烯醇酮的影响。

DESCRIPTION (provided by applicant): Cytochrome P450scc system can efficiently transform 7-dehydrocholesterol (7-DHC) to 7- dehydropregnenolone (7-DHP) and hydroxylate vitamin D2 and D3, and ergosterol. Thus, we uncovered novel steroido/secosteroidogenic pathways generating new biologically active products. The cutaneous pathway would elicit mostly intra-, auto- or paracrine modes of action. In SLOS, UVB light-induced conversions (exclusive for the skin) would proceed with substrates derived from the systemic circulation (5, 7-steroidal dienes) to generate vitDL compounds. These novel pathways could generate a number of molecules with structures determined by the local type and activity of steroidogenic system, as well as the access to UVB photons. To test this hypothesis the following specific aims have been designed. 1. Testing the biological activity of P450scc derived 20-hydroxyvitamin D3 and 20,22 dihydroxyvitamin D3, 17a,24- dihydroxyergosterol, its photolytic derivative, and of 20-hydroxyvitamin D2 and 17a, 20-dihydroxyvitamin D2. The above effects will be compared to the parent compounds, i.e. vitamins D3 and 2, and ergosterol.; 2. Testing the biological activity of 7-DHP, its hydroxyderivatives and the secosteroidal products of their photolytical (UVB-induced) transformation; 3. Characterization of the enzymatic conversion of 7-DHP into hydroxy-derivatives, particularly at positions 17, 20, 21 and 11. The studies will include synthesis of the standards to fully characterize the chemical structures and properties of the reaction products. 4. Testing the predicted action of UVB in inducing B-ring intramolecular rearrangements of 7-DHP and its hydroxy- derivatives or 17a,24-dihydroxyergostero resulting in the anticipated vitDL - derivatives. Tests of the structural stability of the resulting molecules will also be performed; 5. Defining a role for the P450scc in the in vivo metabolism of 5, 7- dienesterols, vitamin D and ergosterol: a) characterization of 7-DHC transformation by P450scc in vivo in cultured skin cells in comparison to an adrenal cell line. Secosteroids production after exposure of the cells to ultraviolet radiation will also be investigated.; b) characterization of vitamin D and ergosterol transformation by P450scc in cultured skin cells. 6. Defining the effect of 7-DHP, its hydroxy and seco-derivatives and of vitamin D (modified or unmodified) on P450scc mediated pregnenolone production from cholesterol.