This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Endocrine Regulation of Growth”.
1. Which is the critical dorsal neuroepithelial signal required for organ commitment of the anterior pituitary gland?
a) Bone morphogenic protein 4
b) Muscle morphogenic protein 7
c) Venal morphogenic protein 11
d) Arterial ventral protein 9
View Answer
Explanation: The initiation of development of the anterior pituitary gland depends on the capacity of the oral ectoderm to respond to inducing factors from the ventral diencephalon neural epithelium. The ventral diencephalon’s bone morphogenic protein 4 (BMP4) signals are the essential dorsal neuroepithelial signal needed for the anterior pituitary gland’s organ commitment.
2. Which protein is expressed in the diencephalon in distinct overlapping patterns with BMP4 along with fibroblast growth factor 8 (FGF8)?
a) Ltn82b
b) Wnt5a
c) Tbg89
d) Aeg780
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Explanation: The diencephalon also expresses Wnt5a and fibroblast growth factor 8 (FGF8) in distinct overlapping patterns with BMP4. Subsequently, a BMP2 signal emerges from the boundary of an oral ectoderm region in which Sonic hedgehog (SHH) expression is selectively removed from the developing Rathke’s pouch, initially expressed universally in the oral ectoderm.
3. Give an example of the dorsally expressed transcription factor determined by the FGF8 gradient that is expressed in the diencephalon?
a) Islet-1
b) Brn4
c) Nkx-3.1
d) P-Frk
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Explanation: The BMP2 ventral-dorsal signal and the FGF8 dorsalventral signal tend to produce gradients of opposing activity that are suggested to dictate overlapping patterns of particular transcription factors. Dorsal cell phenotypes are determined by the FGF8 gradient, and dorsally expressed transcription factors include Nkx-3.1, Six3, Pax6, and PIT11 prophet (PROP1).
4. In the regulation of mammalian development, the pituitary gland is important.
a) True
b) False
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Explanation: Pituitary gland is an important endocrine gland that has a major role in mammalian development. Pituitary gland secretes several hormones in response to the signalling hormones synthesized from the hypothalamus. Example is the secretion of TSH, LH, FSH, etc.
5. The anterior pituitary, via the portal circulatory system, receives guiding signals from the hypothalamus.
a) True
b) False
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Explanation: The anterior pituitary receives hypothalamus control signals through the portal circulatory system. A means of contact between the hypothalamus neurons and the anterior pituitary is provided by this portal system in the pituitary stalk. In patients with hypopituitarism, Magnetic Resonance Imaging (MRI) of the pituitary stalk transmits valuable anatomical information.
6. Give an example of the ventrally expressed transcription factor determined by the FGF8 gradient that is expressed in the diencephalon?
a) Nkx-3.1
b) Islet-1 (Isl1)
c) Six3
d) PIT11
View Answer
Explanation: For terminal differentiation of the ventral cell types, temporally specific BMP2 signal attenuation is necessary, and ventrally expressed transcription factors include islet-1 (Isl1), Brn4, P-Frk, and GATA2. For somatotrophic, lactotrophic and thyrotrophic growth, PIT1 (encoded by the POU1F1 gene) is required.
7. Which among the following is included in the set of transcription factors that are typical of the gonadotroph cell type induced by GATA 2 expression?
a) SF-1
b) Nkx-3.1
c) Six3
d) P-Frk
View Answer
Explanation: In the absence of PIT1, the expression of GATA2 appears to be sufficient to induce the entire collection of transcription factors, including SF-1, P-Frk, and Isl-1, which are characteristic of the gonadotrophic cell type. Conversely, for the differentiation of PIT1-positive cells into somatotroph/lactotroph fates, the absence of GATA2 dorsally is important.
8. Which protein is involved in the sharp attenuation boundary of the ventral signals that dictate the cell lineage of thyrotrophs and gonadotrophs?
a) PIT11
b) SF-1
c) Six3
d) Pax6
View Answer
Explanation: Pax6 has a role in the sharp attenuation boundary of the ventral signals that dictate the lineages of thyrotroph and gonadotroph cells. In the absence of Pax6, at the expense of somatotroph and lactotroph cell types, the ventral lineages, especially thyrotrophs, become dorsally extended.
9. Which endocrine gland is represented in the diagram given below?
a) Hypothalamus
b) Adrenal gland
c) Liver
d) Pancreas
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Explanation: The hypothalamus absorbs signals from other regions of the brain and the environment, leading to the release of factors that regulate the synthesis of the pituitary hormone. Hypothalamic peptide-synthesizing neurons end in the infundibulum, join the primary plexus of the hypophyseal portal circulation, and are transported to the capillaries of the anterior pituitary through the hypophyseal portal veins.
10. Which is the hypothalamic peptide that has been shown to be effective in the release of pituitary cells from cultured GH?
a) LCAP
b) PACAP
c) RASCAP
d) FELCAP
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Explanation: A hypothalamic peptide that has been shown to be effective in releasing GH from cultured pituitary cells is pituitary adenylate cyclase-activating polypeptide (PACAP). It belongs to a hormone superfamily that includes glucagon, secretin, glucagon-like peptide 1 (GLP1), GLP2, GHRH, and vasoactive intestinal polypeptide (VIP)
11. What are Synthetic hexapeptides capable of stimulating GH secretion termed as?
a) GH secretagogues
b) GH translocases
c) GH penetrants
d) GH stimulants
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Explanation: GH secretagogues are called synthetic hexapeptides capable of inducing GH secretion. These peptides induce GH release and enhance the GH response to GHRH, while they function at receptors distinct from those for GHRH, at hypothalamic and pituitary sites.
12. Which cells of the stomach produce a natural ligand called ghrelin in the stomach?
a) Oxyntic cells
b) Acinar cells
c) Parafollicular cells
d) Kupfer cells
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Explanation: A natural ligand named ghrelin, a 28-amino-acid protein with a serine 3 residue n-octanoylated, was identified by Kojima and colleagues. It is provided primarily by stomach oxyntic cells and by the hypothalamus, heart, lung, and adipose tissue. Ghrelin has a strong, GH-releasing effect linked to the dose and potentiates the GHRH-dependent secretion of GH.
13. Binding of ghrelin to which among the following receptors results in GH release?
a) GHSR-1a
b) JKLI-4c
c) GHSR-1b
d) GHLP-1b
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Explanation: GH release results from ghrelin binding on somatotrophs in the pituitary and on GHRH-containing neurons in the hypothalamus to the growth hormone secretagogue 1a receptor (GHSR-1a). Several studies have shown that ghrelin has a broad range of effects, including immune function, metabolism of the bone, gastrointestinal motility, proliferation of cells, and cardiovascular system effects.
14. Which transcription enzymes are activated by GHR signalling?
a) ERK1 and ERK2
b) RNAPOL1 and RNAPOL2
c) Taqpol1 and Taqpol2
d) TRK1 and TRK2
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Explanation: GHR signalling has been shown to also contribute to extracellular related kinase 1 (ERK1) and ERK2 activation to increase transcription. As with a JAK2 oriented but SRC independent process, a JAK2-independent but SRC-dependent phosphorylation has been modelled.
15. What was insulin like growth factors primarily known as?
a) Sulfation factors
b) Acetylation factors
c) Phosphoryl kinases
d) Sulfating kinases
View Answer
Explanation: The IGFs (somatomedins) are a peptide family that is partly dependent on GH and mediates many of GH’s anabolic and mitogenic actions. They were originally identified by their ability to promote the absorption of [35S]-sulfate into rat cartilage in 1957 and were named sulfation factors.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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