GLB1: Difference between revisions

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{{Infobox hormone
 
| name = Growth Hormone-Releasing Hormone
{{Infobox gene
| image = GHRH_structure.png
| name = GLB1
| width = 250px
| image = <!-- Image removed -->
| caption = Structure of Growth Hormone-Releasing Hormone
| caption = <!-- Caption removed -->
| symbol = GHRH
| HGNCid = 4296
| HGNCid = 4261
| symbol = GLB1
| OMIM = 139190
| alt_symbols = ELNR1, EBP, MPS4B
| EntrezGene = 2691
| EntrezGene = 2720
| HUGO = 4261
| OMIM = 611458
| RefSeq = NM_021081
| RefSeq = NM_000404
| UniProt = P01286
| UniProt = P16278
| chromosome = 3
| arm = p
| band = 21.33
}}
}}


'''Growth Hormone-Releasing Hormone''' ('''GHRH'''), also known as '''somatoliberin''', is a [[peptide hormone]] responsible for stimulating the release of [[growth hormone]] (GH) from the [[anterior pituitary gland]]. GHRH is produced in the [[hypothalamus]], specifically in the arcuate nucleus, and is released into the [[hypophyseal portal system]] to reach the pituitary gland.
'''GLB1''' is a [[gene]] that encodes the enzyme beta-galactosidase, which is involved in the [[metabolism]] of [[glycosaminoglycans]] and [[glycolipids]]. This enzyme is crucial for the [[lysosomal]] degradation of these substances. Mutations in the GLB1 gene can lead to several [[genetic disorders]].
 
== Function ==
The GLB1 gene provides instructions for making the enzyme beta-galactosidase. This enzyme is located in [[lysosomes]], which are compartments within cells that digest and recycle different types of molecules. Beta-galactosidase helps break down certain complex molecules, including [[glycosaminoglycans]] (GAGs) and [[glycolipids]].
 
== Clinical Significance ==
Mutations in the GLB1 gene are associated with several disorders:
 
* [[GM1 gangliosidosis]]: A rare [[lysosomal storage disorder]] characterized by the accumulation of GM1 gangliosides in the [[central nervous system]] and other tissues.
* [[Mucopolysaccharidosis type IVB]] (MPS IVB): Also known as Morquio B syndrome, this condition affects the [[skeletal system]] and other parts of the body.
 
== Pathophysiology ==
In GM1 gangliosidosis, mutations in the GLB1 gene reduce or eliminate the activity of beta-galactosidase. As a result, GM1 gangliosides accumulate to toxic levels, particularly in the brain, leading to the neurological symptoms of the disorder.


==Structure and Function==
In MPS IVB, the deficiency of beta-galactosidase leads to the accumulation of [[keratan sulfate]], a type of glycosaminoglycan, causing skeletal abnormalities and other symptoms.
GHRH is a peptide composed of 44 amino acids. It is encoded by the GHRH gene located on chromosome 20 in humans. The primary function of GHRH is to regulate the synthesis and secretion of growth hormone, which plays a crucial role in growth, metabolism, and body composition.


===Mechanism of Action===
== Diagnosis ==
GHRH binds to the GHRH receptor (GHRHR) on the surface of somatotroph cells in the anterior pituitary. This binding activates the [[adenylate cyclase]] pathway, leading to an increase in [[cyclic AMP]] (cAMP) levels. The rise in cAMP activates [[protein kinase A]] (PKA), which in turn stimulates the transcription of the growth hormone gene and the secretion of growth hormone into the bloodstream.
Diagnosis of disorders related to GLB1 mutations typically involves:


==Physiological Role==
* [[Genetic testing]] to identify mutations in the GLB1 gene.
Growth hormone has multiple physiological effects, including:
* [[Enzyme assay]] to measure the activity of beta-galactosidase in [[blood]] or [[tissue samples]].
* Stimulating growth in children and adolescents by promoting the growth of bones and cartilage.
* Increasing protein synthesis and muscle mass.
* Enhancing fat metabolism and reducing adipose tissue.
* Regulating carbohydrate metabolism and maintaining blood glucose levels.


==Clinical Significance==
== Treatment ==
Abnormalities in GHRH production or action can lead to various disorders:
Currently, there is no cure for disorders caused by GLB1 mutations. Treatment focuses on managing symptoms and may include:
* '''GHRH Deficiency''': Can result in growth hormone deficiency, leading to short stature and growth failure in children.
* '''GHRH Excess''': Rarely, tumors such as [[hypothalamic hamartomas]] can produce excess GHRH, leading to [[acromegaly]] or [[gigantism]] due to excessive growth hormone secretion.


==Therapeutic Use==
* [[Supportive care]]
Synthetic analogs of GHRH, such as sermorelin, have been used in diagnostic tests to assess growth hormone secretion and in the treatment of growth hormone deficiency.
* [[Physical therapy]]
* [[Surgical interventions]] for skeletal abnormalities


==Research and Development==
== See Also ==
Ongoing research is exploring the potential of GHRH analogs in treating conditions such as [[cachexia]] and [[muscle wasting]] associated with chronic diseases.
* [[Lysosomal storage disease]]
* [[Enzyme replacement therapy]]


==Also see==
== References ==
* [[Growth hormone]]
{{Reflist}}
* [[Hypothalamus]]
* [[Pituitary gland]]
* [[Endocrine system]]
* [[Hormone]]


{{Endocrinology}}
== External Links ==
{{Hormones}}
* [https://www.ncbi.nlm.nih.gov/gene/2720 GLB1 gene - NCBI]
* [https://ghr.nlm.nih.gov/gene/GLB1 GLB1 - Genetics Home Reference]


[[Category:Hormones]]
[[Category:Genes on human chromosome 3]]
[[Category:Peptide hormones]]
[[Category:Lysosomal storage disorders]]
[[Category:Endocrinology]]
[[Category:Genetic disorders with OMIM but no gene]]

Latest revision as of 20:44, 30 December 2024


GLB1
Symbol GLB1
HGNC ID 4296
Alternative symbols
Entrez Gene 2720
OMIM 611458
RefSeq NM_000404
UniProt P16278
Chromosome 3p21.33
Locus supplementary data


GLB1 is a gene that encodes the enzyme beta-galactosidase, which is involved in the metabolism of glycosaminoglycans and glycolipids. This enzyme is crucial for the lysosomal degradation of these substances. Mutations in the GLB1 gene can lead to several genetic disorders.

Function[edit]

The GLB1 gene provides instructions for making the enzyme beta-galactosidase. This enzyme is located in lysosomes, which are compartments within cells that digest and recycle different types of molecules. Beta-galactosidase helps break down certain complex molecules, including glycosaminoglycans (GAGs) and glycolipids.

Clinical Significance[edit]

Mutations in the GLB1 gene are associated with several disorders:

Pathophysiology[edit]

In GM1 gangliosidosis, mutations in the GLB1 gene reduce or eliminate the activity of beta-galactosidase. As a result, GM1 gangliosides accumulate to toxic levels, particularly in the brain, leading to the neurological symptoms of the disorder.

In MPS IVB, the deficiency of beta-galactosidase leads to the accumulation of keratan sulfate, a type of glycosaminoglycan, causing skeletal abnormalities and other symptoms.

Diagnosis[edit]

Diagnosis of disorders related to GLB1 mutations typically involves:

Treatment[edit]

Currently, there is no cure for disorders caused by GLB1 mutations. Treatment focuses on managing symptoms and may include:

See Also[edit]

References[edit]

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External Links[edit]