This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Nuclear Receptor Ligands”.
1. What is the advantage of having lipophilicity in the nuclear receptor ligands?
a) Helps in absorption to GI tract
b) Helps in absorption to the lymphatic duct
c) Helps in absorption to the liver
d) Helps in absorption to the trachea
View Answer
Explanation: The lipophilicity of ligands with nuclear receptors makes it possible to absorb them from the gastrointestinal tract. This promotes their use for different disease states in replacement or pharmacologic therapies.
2. Which among the following are classic hormones that use nuclear receptor ligands?
a) Fatty acids and oxysterols
b) Thyroid hormone and steroid hormones
c) 9-cis-Retinoic acid
d) Bile acids
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Explanation: Thyroid and steroid hormones are the classic hormones that use nuclear receptors for signaling. Thyroid and steroid hormones are the classic hormones that use nuclear receptors for signaling.
3. Which among the following is the hormone that mediate the signals of multiple hormones?
a) 1,25-(OH)2-Vitamin D3
b) 9-cis-Retinoic acid
c) Nuclear receptor 3C2 (NR3C2)
d) Aldosterone
View Answer
Explanation: The signals of multiple hormones can be regulated by certain receptors. For example, the mineralocorticoid receptor, also known as the 3C2 aldosterone receptor or nuclear receptor (NR3C2), has equal affinity to cortisol 7 and is likely to function in certain tissues as a glucocorticoid receptor.
4. In the genome, no nuclear receptor ligands are specifically encoded.
a) True
b) False
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Explanation: No ligands for nuclear receptors are specifically expressed in the genome, unlike polypeptide hormones that act by cell surface receptors. All ligands of the nuclear receptor are small and lipophilic.
5. The function of nuclear receptor ligands and their receptors is to translate cue environments into changes in gene expression.
a) True
b) False
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Explanation: A general characteristic of naturally occurring ligands of nuclear receptors is that all are derived from precursors that are dietary, environmental, or metabolic. The function of these ligands/cues and their receptors in this context is to translate signals from the external and internal environments into gene expression changes.
6. Which are the two vitamins that act as ligands for nuclear receptors?
a) Vitamin A and Vitamin K
b) Vitamin A and Vitamin D
c) Vitamin E and Vitamin C
d) Vitamin A and Vitamin C
View Answer
Explanation: Vitamins are important ingredients in a healthy diet. Two fat-soluble vitamins, A and D, are precursors of significant signaling molecules which act as nuclear receptor ligands. Nuclear receptors (NRs) are proteins that in two strongly preserved domains, the DNA binding (DBD) and the ligand binding domains (LBD), share significant amino acid sequence similarity.
7. Which is the most potent natural ligand of the vitamin D receptor?
a) 1,25-dihydroxyvitamin D3
b) 25-hydroxyvitamin D
c) 9-cis-Retinoic acid
d) Nuclear receptor 3C2 (NR3C2)
View Answer
Explanation: 1,25-dihydroxyvitamin D3, calcitriol), is the most potent natural ligand of the vitamin D receptor (VDR). This is the converted form of vitamin D in the kidney. In human skeletal muscle cells, the vitamin D receptor (VDR) has been found to influence the metabolism of muscle cells by binding to vitamin D metabolites.
8. Which among the following is a high affinity ligand for retinoic acid receptors (RARs)?
a) 9-cis-Retinoic acid
b) 25-hydroxyvitamin D
c) Nuclear receptor 3C2 (NR3C2)
d) All-trans-retinoic acid
View Answer
Explanation: Vitamin A is processed in the liver and is activated by all-trans-retinoic acid metabolism, which is a high-affinity retinoic acid receptor (RAR)ligand. In paracrine as well as endocrine pathways, 9-cis-retinoic acid is likely to act as a signaling molecule.
9. 9-cis-isomer is a ligand for which nuclear receptor?
a) Retinoid X receptor (RXR)
b) Retinoic acid receptors (RARs)
c) Vitamin D receptor
d) Vitamin A receptor
View Answer
Explanation: Retinoic acid is also converted to its 9-cis isomer, which is a ligand for the retinoid X receptor (RXR). These retinoids and their receptors are important for multiple organ and tissue growth. There are three receptors for retinoic X (RXR): RXR-alpha, RXR-beta and RXR-gamma, encoded by the genes RXRA, RXRB and RXRG.
10. Which among the following constitute the best-defined subfamily of metabolite-sensing nuclear receptors?
a) Retinoid X receptor (RXR)
b) Peroxisome proliferator-activated receptors (PPARs)
c) Vitamin D receptor
d) Retinoic acid receptors (RARs)
View Answer
Explanation: Certain nuclear receptors react to endogenous metabolic products that occur naturally. The best described subfamily of metabolite-sensing nuclear receptors is the peroxisome proliferator-activated receptors (PPARs).
11. Which among the following molecules can activate all the three PPAR subtypes?
a) Cholesterol
b) Carbohydrate
c) Fatty Acids
d) Proteins
View Answer
Explanation: The receptors regulated by peroxisome proliferator (PPARs) constitute the best described subfamily of nuclear receptors that detect metabolites. All three subtypes of PPAR are activated by fatty acids that are polyunsaturated.
12. Which is the PPAR that is primarily expressed in the liver?
a) PPAR-Beta
b) PPAR-Alpha
c) PPAR-Omega
d) PPAR-Gamma
View Answer
Explanation: PPAR alpha is expressed predominantly in the liver. Eicosanoid, 8(S) hydroxy eicosatetraenoic acid is the natural ligand with the highest affinity for PPAR alpha. Peroxisome proliferator-activated receptors (PPARs) are transcription factors activated by ligands in the superfamily of nuclear hormone receptors.
13. Where is PPAR-gamma primarily expressed in the human body?
a) Liver
b) Kidney
c) Adipocytes
d) Pancreas
View Answer
Explanation: PPAR-Gamma is expressed predominantly in adipocytes and is essential for the adipocyte lineage to be distinguished. PPAR-Gamma is also expressed in other types of cells, including colonocytes, macrophages, and endothelial vascular cells, where physiological and pathological functions can be performed.
14. Which Peroxisome proliferator-activated receptors (PPARs) is the target of thiazolidinedione (TZD) antidiabetic drugs?
a) PPAR- Beta
b) PPAR- Alpha
c) PPAR- Omega
d) PPAR- Gamma
View Answer
Explanation: A new class of oral antidiabetic agents is Thiazolidinediones (TZDs). In Type 2 (noninsulin dependent) diabetic patients, they selectively enhance or partially mimic certain insulin acts, triggering a slowly generated antihyperglycemic impact. PPAR-Gamma seems to be the target of antidiabetic thiazolidinedione (TZD) drugs that enhance insulin sensitivity. These pharmaceutical agents bind to PPAR-Gamma with very minute affinity.
15. Which nuclear receptor is activated by oxysterol intermediates in cholesterol biosynthesis?
a) Liver X receptor (LXR)
b) Peroxisome proliferator-activated receptors (PPARs)
c) Vitamin D receptor
d) Retinoic acid receptors (RARs)
View Answer
Explanation: In cholesterol biosynthesis, another metabolite-responsive nuclear receptor which is the liver X receptor (LXR), is activated by oxysterol intermediates. There is a significantly impaired capacity of mice missing LXR-alpha to metabolize cholesterol.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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