The type 2 inositol 1,4,5-trisphosphate receptor, emerging functions for an intriguing Ca²âº-release channel.
Biochim Biophys Acta
; 1853(9): 1992-2005, 2015 Sep.
Article
em En
| MEDLINE
| ID: mdl-25499268
ABSTRACT
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) type 2 (IP3R2) is an intracellular Ca²âº-release channel located on the endoplasmic reticulum (ER). IP3R2 is characterized by a high sensitivity to both IP3 and ATP and is biphasically regulated by Ca²âº. Furthermore, IP3R2 is modulated by various protein kinases. In addition to its regulation by protein kinase A, IP3R2 forms a complex with adenylate cyclase 6 and is directly regulated by cAMP. Finally, in the ER, IP3R2 is less mobile than the other IP3R isoforms, while its functional properties appear dominant in heterotetramers. These properties make the IP3R2 a Ca²âº channel with exquisite properties for setting up intracellular Ca²âº signals with unique characteristics. IP3R2 plays a crucial role in the function of secretory cell types (e.g. pancreatic acinar cells, hepatocytes, salivary gland, eccrine sweat gland). In cardiac myocytes, the role of IP3R2 appears more complex, because, together with IP3R1, it is needed for normal cardiogenesis, while its aberrant activity is implicated in cardiac hypertrophy and arrhythmias. Most importantly, its high sensitivity to IP3 makes IP3R2 a target for anti-apoptotic proteins (e.g. Bcl-2) in B-cell cancers. Disrupting IP3R/Bcl-2 interaction therefore leads in those cells to increased Ca²âº release and apoptosis. Intriguingly, IP3R2 is not only implicated in apoptosis but also in the induction of senescence, another tumour-suppressive mechanism. These results were the first to unravel the physiological and pathophysiological role of IP3R2 and we anticipate that further progress will soon be made in understanding the function of IP3R2 in various tissues and organs.
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Base de dados:
MEDLINE
Assunto principal:
Cálcio
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Sinalização do Cálcio
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Retículo Endoplasmático
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Receptores de Inositol 1,4,5-Trifosfato
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article