Benítez L, Fanjul LF, Ruiz de Galarreta CM, Quintana Aguiar J, González Reyes J, Hernández I, Santana Delgado P, Cabrera Oliva J, Alonso Solís R, Estévez Rosas F. Partial characterization of a thyrotropin releasing hormone-sensitive glycosyl-phosphatidylinositol in pituitary lactotrophes.
Neurosci Lett 1995;
187:37-40. [PMID:
7617297 DOI:
10.1016/0304-3940(95)11332-q]
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Abstract
Metabolic labelling experiments performed with cultured pituitary lactotrophes revealed the presence of a glycosyl-phosphatidylinositol (GPtdIns) structurally related to GPtdIns lipids isolated from other cell types as demonstrated by: (i) metabolic incorporation of [3H]galactose, [3H]glucosamine and [3H]inositol into the polar inositolphosphoglycan moiety (InsPG) and [3H]myristate and [3H]palmitate into the diacylglycerol (DAG) backbone of GPtdIns; (ii) sensitivity of the [3H]labelled GPtdIns to nitrous acid deamination and; (iii) sensitivity of GPtdIns to phosphatidylinositol (PtdIns)-specific phospholipase C (PLC) hydrolysis. In cultured pituitary cells labelled to isotopic steady state with 10 microCi/ml of [3H]glucosamine, treatment with hypothalamic TRH (10(-6) M) induced a rapid and transient hydrolysis (ca. 50%) of the labelled GPtdIns. Moreover, as demonstrated in [3H]inositol labelled cells, treatment with thyrotropin releasing hormone (TRH) elicited the cleavage of [3H]GPtdIns in a similar manner, and this effect was followed by the phosphoinositide (PtdIns, PtdInsP and PtdInsP2) hydrolysis 30 s later. These results suggest that the phosphodiesterase cleavage of GPtdIns could be an early event implicated in TRH action in pituitary lactotrophes.
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