Nuclear phospholipase C beta1 and cellular differentiation.
Phosphoinositides (PI) are the most extensively studied lipids involved in cell signaling pathways. The bulk of PI is found in membranes where they are substrates for enzymes, such as kinases, phosphatases and phospholipases, which respond to the activation by cell-surface receptors. The outcome of the majority of signaling pathways involving lipid second messengers results in nuclear responses finally driving the cell into differentiation, proliferation or apoptosis. Some of these pathways are well established, such as that of PI-specific phospholipase C (PI-PLC), which cleaves phosphatidylinositol-4,5-bisphosphate (PIP2) into the two second messengers diacylglycerol (DAG) and inositol-1,4,5-trisphosphate (IP3). Two independent cycles of PI are present inside the cell. One is localized at the plasma membrane, while the most recently discovered PI cycle is found inside the nuclear compartment. The regulation of the nuclear PI pool is totally independent from the plasma membrane counterpart, suggesting that the nucleus constitutes a functionally distinct compartment of inositol lipids metabolism. In this report we will focus on the signal transduction-related metabolism of nuclear PI and review the most convincing evidence that the PI cycle is involved in differentiation programs in several cell systems.
Faenza
Irene
I
Cellular Signaling Laboratory, Department of Anatomical Sciences, University of Bologna, 40126 Bologna, Italy.
Bregoli
Lisa
L
Ramazzotti
Giulia
G
Gaboardi
Giancarlo
G
Follo
Matilde Y
MY
Mongiorgi
Sara
S
Billi
Anna Maria
AM
Manzoli
Lucia
L
Martelli
Alberto M
AM
Cocco
Lucio
L
D000818:Animals; D002453:Cell Cycle; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism; D008954:Models, Biological; D009132:Muscles / Q000378:metabolism; D054799:Phospholipase C beta / Q000378:metabolism / Q000502:physiology*; D020033:Protein Isoforms; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
D020033:Protein Isoforms; D014157:Transcription Factors; D054799:Phospholipase C beta