Zoukhri D, Hodges R R, Sergheraert C, Toker A, Dartt D A
Schepens Eye Research Institute, Boston, Massachusetts, USA.
Am J Physiol. 1997 Jan;272(1 Pt 1):C263-9. doi: 10.1152/ajpcell.1997.272.1.C263.
In the present study, we have synthesized and N-myristoylated peptides derived from the pseudosubstrate sequences of protein kinase C (PKC)-alpha, -delta, and -epsilon [Myr-PKC-alpha-(15-28), Myr-PKC-delta-(142-153), and Myr-PKC-epsilon-(149-164)], three isoforms present in rat lacrimal gland, and a peptide derived from the sequence of the endogenous inhibitor of protein kinase A [Myr-PKI-(17-25)]. Lacrimal gland acini were preincubated for 60 min with the myristoylated peptides (10(-10) to 3 x 10(-7) M), then protein secretion was stimulated with a phorbol ester, phorbol 12,13-dibutyrate (10(-6) M); vasoactive intestinal peptide (10(-8) M); a cholinergic agonist, carbachol (10(-5) M); or an alpha 1-adrenergic agonist, phenylephrine (10(-4) M), for 20 min. In intact lacrimal gland acini, Myr-PKC-alpha-(15-28) inhibited phorbol 12,13-dibutyrate-induced protein secretion. This effect was not reproduced by the acetylated peptide or by the myristoylated PKI, which inhibited vasoactive intestinal peptide-induced protein secretion, a response mediated by protein kinase A. Carbachol-induced protein secretion was inhibited by all three peptides. In contrast, phenylephrine-induced protein secretion was inhibited only by Myr-PKC-epsilon-(149-164), whereas Myr-PKC-alpha-(15-28) and Myr-PKC-delta-(142-153) had a stimulatory effect. None of these myristoylated peptides affected the calcium increase evoked by cholinergic or alpha 1-adrenergic agonists. We concluded that phorbol ester- and receptor-induced protein secretion involve different PKC isoforms in lacrimal gland.
在本研究中，我们合成了源自蛋白激酶C（PKC）-α、-δ和-ε[肉豆蔻酰化PKC-α-(15 - 28)、肉豆蔻酰化PKC-δ-(142 - 153)和肉豆蔻酰化PKC-ε-(149 - 164)]假底物序列的N-肉豆蔻酰化肽，这三种同工型存在于大鼠泪腺中，还合成了源自蛋白激酶A内源性抑制剂序列的一种肽[肉豆蔻酰化PKI-(17 - 25)]。将泪腺腺泡与肉豆蔻酰化肽（10⁻¹⁰至3×10⁻⁷M）预孵育60分钟，然后用佛波酯、佛波醇12,13 - 二丁酸酯（10⁻⁶M）；血管活性肠肽（10⁻⁸M）；胆碱能激动剂卡巴胆碱（10⁻⁵M）；或α1 - 肾上腺素能激动剂去氧肾上腺素（10⁻⁴M）刺激蛋白分泌20分钟。在完整的泪腺腺泡中，肉豆蔻酰化PKC-α-(15 - 28)抑制佛波醇12,13 - 二丁酸酯诱导的蛋白分泌。乙酰化肽或肉豆蔻酰化PKI未重现这种效应，肉豆蔻酰化PKI抑制血管活性肠肽诱导的蛋白分泌，这是一种由蛋白激酶A介导的反应。卡巴胆碱诱导的蛋白分泌受到所有三种肽的抑制。相反，去氧肾上腺素诱导的蛋白分泌仅受到肉豆蔻酰化PKC-ε-(149 - 164)的抑制，而肉豆蔻酰化PKC-α-(15 - 28)和肉豆蔻酰化PKC-δ-(142 - 153)具有刺激作用。这些肉豆蔻酰化肽均未影响胆碱能或α1 - 肾上腺素能激动剂引起的钙增加。我们得出结论，佛波酯和受体诱导的蛋白分泌在泪腺中涉及不同的PKC同工型。
