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Biochemistry > Cell Signaling Vitamin D3 > Flashcards

Cell Signaling Vitamin D3 Flashcards

1
Q

Where do we get most of our vitamin D?

A

the sun and our diet

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2
Q

Children with vitamin D deficiency tend to have …

A

cavities

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3
Q

Which step of vitamin D3 synthesis does the sun catalyze?

A

Pro (7-dehydrocholesterol) to previtamin D3

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4
Q

What is the biologically active form of vitamin D3?

A

1,25(OH)2D3

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5
Q

What organ provides the majority of the circulating 1,25(OH)2D3?

A

kidney

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6
Q

Serum levels measure what vitamin D molecule?

A

25(OH)D3 because it is the main circulatory form

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7
Q

What protein usually binds thing in the blood?

A

Albumin

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8
Q

What is another name for 1,25(OH)2D3?

A

calcitriol

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9
Q

What is another name for vitamin D2?

A

Ergocalciferol

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10
Q

What is another name for vitamin D3?

A

cholecalciferol

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11
Q

Vitamin D2

A

Plant/fungi form; most commonly found in dietary supplements and fortified foods. Less absorbable, less potent, shorter acting.

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12
Q

Vitamin D receptor (VDR)

A
  • Transcription factor widely distributed in the body
  • Upon binding 1,25-(OH)2D3, VDR forms a heterodimeric complex with other nuclear hormone receptors, particularly the Retinoid-X-Receptor.
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13
Q

Vitamin D3 is modified by what organ before the kidney?

A

Liver

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14
Q

Vitamin D3 is required for proper ____ and ____ absorption needed to build strong bones and teeth.

A

calcium; phosphorus

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15
Q

Vitamin D metabolites are transported in the blood bound to?

A

Vitamin D binding protein and serum albumin

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16
Q

Vitamin D3 induces what in the gut?

A

Calcium absorption

17
Q

Calmodulin

A

Binding protein that helps calcium be absorbed into the body.

18
Q

Vitamin D Receptor affects:

A
  1. Genes regulating Ca transport (TRPV6)
  2. Genes needed to form bone
  3. RANKL/ osteoclast formation
  4. Antimicrobial peptides like defensins/cathelicidin
19
Q

Name an antimicrobial peptide that is vitamin D3 dependent

A

defensins and cathelicidin

20
Q

Rickets

A
  • Vitamin D/calcium/phosphate deficiency
  • Most common in countries that do not fortify their foods and have low exposure to sunlight
  • Prominence of the costochondrial junction, deformities of the back, bowing of the legs, parietal flattening, delayed eruption of the permeant dentition and enamel defects
21
Q

Type I rickets

A
  • Manifests by age 2, usually by 6mo
  • Low circulating 1,25(OH)2D3
  • Defect in 1-hydrolase
22
Q

Type II Rickets

A
  • Normal at birth, bone disease before age 2
  • Normal or high circulating levels of 1,25(OH)2D3
  • Due to mutations in VDR receptor
  • Alopecia
23
Q

Osteomalacia

A

Similar to rickets; Softening of the bones due to inadequate levels of calcium and phosphate which are most commonly due to vitamin D deficiency

24
Q

Vitamin D resistant rickets

A

caused by an inactivating mutation in the nuclear vitamin D receptor.

25
Q

Plaque Psoriasis

A

Immune mediated disease affecting the skin with no cure however vitamin D3 can help control symptoms.

26
Q

Parathyroid Hormone (PTH)

A
  • Increases calcium levels and stimulates production of 1,25(OH)2D3
  • Synthesized and secreted by chief cells of the parathyroid gland
27
Q

Calcitonin

A

Decreases calcium levels

28
Q

Cathelicidin

A
  • Found in lysosomes of macrophages and polymorphonuclear leukocytes (PMNs).
  • Serve a critical role in mammalian innate immune defense against invasive bacterial infection.
29
Q

What foods are high in vitamin D3?

A

fish oil, milk

30
Q

What regulates the expression of 1-hydroxylase?

A

PTH

31
Q

What kind of receptor does vitamin D3 use to mediate its effects?

A

intracellular but some effects are thought to be mediated through membrane receptor

32
Q

Vitamin D deficiency is associated with…

A

cancer, cardiovascular disease, hypertension, stroke, diabetes, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, osteoporosis, periodontal disease, macular degeneration, mental illness, propensity to fall, and chronic pain.

33
Q

TRPV6

A

positively regulates intracellular calcium transport

34
Q
A

Biochemistry (10 decks)

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