Effects of the phospholipid environment in the plasma membrane on receptor interaction with the adenylyl cyclase complex of intact cells.

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Christian Jansson, Ann-Sofi Härmälä, Diana M. Toivola, Peter Slotte
Förläggare: ELSEVIER SCIENCE BV
Publiceringsår: 1993
Tidskrift: BBA - Biochimica et Biophysica Acta
Tidskriftsakronym: BIOCHIM BIOPHYS ACTA
Volym: 1145
Nummer: 2
Artikelns första sida, sidnummer: 311
Artikelns sista sida, sidnummer: 319
Antal sidor: 9
ISSN: 0006-3002


Abstrakt

In this study we have examined the effects of variations of the plasma membrane phospholipid and cholesterol content on the metabolic functions of the adenylyl cyclase complex in intact cells. Exposure of cells to 0.1 U/ml of sphingomyelinase led to the degradation of 75, 55 and 40% of the cellular total sphingomyelin mass in human skin fibroblasts (HSF), Chinese hamster lung fibroblasts (CHLF) and rat liver hepatocytes (RLH), respectively. Degradation of sphingomyelin in native cells led in turn to a reduction (within 60 min) of the plasma membrane cholesterol content (by 25, 15 and 10%, respectively). This manipulation of the plasma membrane lipid content did not affect the forskolin or prostaglandin E1-induced activation of adenylyl cyclase (as measured from the conversion of [H-3]adenine via [H-3]ATP to [H-3]cAMP). These manipulations did, however, increase the basal rate of [H-3]cAMP formation in rat liver hepatocytes (but not in the fibroblast cell types). With Chinese hamster lung fibroblasts, transfected to express an alpha2-adrenergic receptor, it was observed that the alpha2-adrenergic receptor-induced inhibition of adenylyl cyclase activity was slightly (but significantly) diminished in sphingomyelin and cholesterol-depleted cells. With isolated rat liver hepatocytes it was observed that the glucagon (receptor) mediated activation of adenylyl cyclase was also reduced in sphingomyelinase-treated cells. In another set of experiments, CHLF and RLH cells were exposed for 2 h to vesicles prepared from dilauroylphosphatidylcholine, to increase the lateral packing density in the outer leaflet of the plasma membrane. In such treated cells, the receptor-coupling to adenylyl cyclase was markedly reduced both in CHLF (the alpha2-adrenergic receptor) and RLH (the glucagon-receptor) cells. We conclude that the direct activation of adenylyl cyclase (i.e., by forskolin) is not markedly affected by manipulations outer leaflet phospholipid composition (either reduction of sphingomyelin or increase of phosphatidylcholine), whereas receptor-coupled events clearly are.


Nyckelord

ADENYLYL CYCLASE COMPLEX, alpha(2)-adrenergic receptor, CYCLIC AMP, (FIBROBLAST)

Senast uppdaterad 2019-17-06 vid 04:12