Interleukin-1 inhibits voltage-dependent P/Q-type Ca2+ channel associated with the inhibition of the rise of intracellular free Ca2+ concentration and catecholamine release in adrenal chromaffin cells

Effects of interleukin (IL) on intracellular free Ca2+ concentration ([Ca2+]i) rise and catecholamine (CA) release were examined in isolated, cultured bovine adrenal chromaffin cells. IL-1α and IL-1β inhibited the rise of [Ca2+]i and CA release induced by acetylcholine (ACh) and excess KCl both in normal and in Ca2+-sucrose medium. IL-1 receptor antagonist, IL-1RA by pretreatment blocked the inhibitory actions of IL-1. IL-1α reduced CA release induced by veratridine in normal medium but not in the presence of diltiazem. Analysis using specific blockers for voltage-operated Ca2+ channels revealed that IL-1α specifically inhibited the P/Q-type Ca2+ channel to reduce [Ca2+]i rise induced by excess KCl. IL-1 did not affect [Ca2+]i rise induced either by bradykinin or caffeine in Ca2+- deprivated medium or via activation of store-operated Ca2+ channel. The inhibitory effects of IL-1 were blocked by pretreatments of cells with herbimycin A, U0126 and PD 98054, but not with SB202190, SP 600125 or pertussis toxin (PTX), inhibited the induction of the inhibitory action of IL-1.These results demonstrated that IL-1 inhibits stimulation-evoked [Ca2+]i rise and CA release in chromaffin cells by blocking voltage-operated P/O-type Ca2+ channels. The inhibitory action of IL-1 may be mediated through tyrosine kinase and MEK/ERK pathways

Inhibition by Interleukin-1 of Catechol-amhe Release from Adrenal Chromaffin Cells

本論文の一部は第36回歯科基礎医学会総会(1994年10月,大阪市)において発表した。(歯科基礎誌suppl,36,111,1994.

インターロイキン-1の副腎髄質カテコールアミン遊離抑制作用

本論文の一部は第36回歯科基礎医学会総会(1994年10月,大阪市)において発表した。(歯科基礎誌suppl,36,111,1994.

An alternative allosteric regulation mechanism of an acidophilic l-lactate dehydrogenase from Enterococcus mundtii 15-1A

A plant-derived Enterococcus mundtii 15-1A, that has been previously isolated from Brassica rapa L. subsp. nipposinica (L.H. Bailey) Hanelt var. linearifolia by our group, possesses two kinds of l-lactate dehydrogenase (l-LDH): LDH-1 and LDH-2. LDH-1 was activated under low concentration of fluctose-1,6-bisphosphate (FBP) at both pH 5.5 and 7.5. Although LDH-2 was also activated under the low concentration of FBP at pH 5.5, a high concentration of FBP is necessary to activate it at pH 7.5. The present study shows the crystal structures of the acidophilic LDH-2 in a complex with and without FBP and NADH. Although the tertiary structure of the ligands-bound LDH-2 is similar to that of the active form of other bacterial l-LDHs, the structure without the ligands is different from that of any other previously determined l-LDHs. Major structural alterations between the two structures of LDH-2 were observed at two regions in one subunit. At the N-terminal parts of the two regions, the ligands-bound form takes an α-helical structure, while the form without ligands displays more disordered and extended structures. A vacuum-ultraviolet circular dichroism analysis showed that the α-helix content of LDH-2 in solution is approximately 30% at pH 7.5, which is close to that in the crystal structure of the form without ligands. A D241N mutant of LDH-2, which was created by us to easily form an α-helix at one of the two parts, exhibited catalytic activity even in the absence of FBP at both pH 5.5 and 7.5