HNF 462 1st Edition Lecture 13Outline of Last LectureI. Food Sourcesa. Plantsb. AnimalsII. Formation of Vitamin D in the SkinIII. Activation of Vitamin D3IV. Absorption in the GutV. Cellular AbsorptionOutline of Current LectureI. General Vitamin D Cont.a. Storageb. Excretionc. Functionsd. Deficiencye. Toxicityf. Sun ExposureII. Transcription FactorsIII. Vitamin A in DNAIV. Vitamin D in DNACurrent Lecture: Vitamins A and D and Gene Regulation1. General Vitamin D Cont.a. Storagei. Very little stored in liverii. Blood is largest pool of calcidiol (same as 25-hydroxy D3)iii. Skin and adipose reserves of cholecaliferolThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Excretioni. Hydroxylation at the 24th carbon in the kidney when D3 is in excessii. Primarily excreted via feces, some via urinec. Functionsi. Regulation of serum calcium and phosphorus homeostasisd. Deficiencyi. Rickets in children: abnormal bone formation, especially in the legsii. Osteomalacia in adultse. Toxicity and RDAi. Controversy revolving current RDA and UL valuesf. Sun Exposurei. 5-15 min of sun exposure during the summer is sufficient to produce enough Vitamin D 2. Transcription Factorsa. Proteins that bind to DNA b. Help in the process of DNARNAc. Ligands: proteins or other small molecules that bind to transcription factors (include vitamins A and D)3. Vitamin A in DNAa. Bind to RARE sites, then recruit other transcription factorsb. Transcription factor complex involved in facilitating or blocking the binding of RNA Pol IIc. Retinoic Acid (all-trans or 9-cis): bind to CRABP, transferred to cell nucleus, and binds to receptor on DNAd. Regulates genes involved in cellular differentiationi. Keratinocytesii. Immune Cellsiii. Cancer cells4. Vitamin D in DNAa. Bind to VRRE sites, then recruit other transcription factorsb. Transcription factor complex involved in facilitating or blocking the binding of RNA Pol IIc. Active form binds to receptor on DNAd. Can recruit and activator or repressore. Regulates genes involved in Ca homeostasisi. Intestinal absorptionii. Reabsorption of Caiii. Bone reabsorption of
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