Muscarinic acetylcholine receptor-mediated increase in angiotensin type 2 receptor mRNA in PC12 cells: Implication of protein kinase C

S89 MUSCARINIC

088 KAZUHIKO ‘Research

ACETYLCHOLINE

TYPE 2 RECEPTOR

SHIBATA’,

Laboratory

IKUKO MAKINO

*, KAZUHIDE

*Department

of Biodynamics,

Japan and “Division of Pharmacology,

RECEPTOR-MEDIATED

assigned to angiotensin

it has been recently receptors. expression

demonstrated

This finding suggest of the AT2 receptor

that

a-adrenergic

KATSURAGI’

School of Medicine,

Fukuoka University,

Although ATI receptors

type-2(AT2)

roles of AT2 receptors

receptor-mediated

that neurotransmitter

KINASE C

Fukuoka,

Health Sciences, Tokyo 158, Japan.

and

II, the hmctional

IN ANGIOTENSIN

OF PROTEIN

INOUE” AND TAKESHI

of Pharmacology,

National Institute of

Angiotensin 11 receptors are classified as type-l(AT1) classical hmctions

INCREASE

MRNA IN PC12 CELLS : IMPLICATION

with the protein

remain unassigned

seems to mediate the In neuronal cultures,

downregulation

in the densities

kinase C(PKC)

pathway

In the present study, we examined effects of

of angiotensin

can modulate

II

the gene

carbachol, which is one of the neurotransmitter

with the PKC pathway, on AT2 receptor mRNA level in PC12 cells. The mRNA level was measured by Northern blot analysis. The mRNA level was markedly increased 3-fold after exposure to carbachol( IO- 1000 fi M). On the other hand, nicotine had no effect. This increase was antagonized induced increase in AT2 mRNA.

by atropine( IO ,U M)

C, PKC inhibitor, inhibited carbachol-

These evidences suggest that PKC pathway play a role in the increase of AT2 mRNA

following activation of the muscarinic-acetylcholine

089

H-7 and calphostin

MAPPING OF A NOVEL NERVOUS SYSTEM

receptor

SUBTYPE

OF PROSTACYCLIN

RECEPTOR

YUMIKO WATANABE’, KIYOSHI MATSUMURA’, MASAAKI SUZUKI*, KOICHI HIROFUMI FUKUNAGAX, RYOJI NOYORI-7, AND YASUYOSHI WATANABE1 ‘Dept. of Neuroscience, Osaka Bioscience Institute, Biomolecular Sci., Fat. Engi., Gifu Univ., Gifu, ‘Dept.

IN THE CENTRAL

KAT03,

6-2-4 Furuedai, Suita-shi, Osaka 565-0874, *Dept. Chemistry, Fat. Sci., Nagoya Univ., Nagoya, Japan.

In the course of our search for the prostacyclin receptor in the CNS, we found a novel subtype of prostacyclin receptor designated as IP2, since its ligand specificity is clearly different from that of the known and cloned prostacyclin receptor in the platelets and peripheral tissues. (15R)-16-(m-Tolyl)17,18,19,20-tetranor-isocarbacyclin (15R-TIC) and 15deoxy-TIC are highly selective to this IP2. More recently, we found potent anti-apoptotic activities of these compounds (Satoh, T. et al., in this conference). Here, we performed the mapping study on 15R-[ZHJTIC binding sites in the frozen sections of rat brain by The binding was high in the lateral septal nucleus, centromedian, quantitative in vitro autoradiography. medial and lateral geniculate bodies, piriform, paraventricular, and reuniens nuclei of thalamus, entorhinal and some other cortices, anterior olfactory nucleus, ventral part of striatum, and dorsal cochlear nucleus. Scatchard plot analysis showed two components, namely, high-affinity binding sites with the Kd value less than 1 nM and medium-afinity binding sites with that at around 30 nM.

090

CLONING

YUKA KAWASAWA,

AND CHARACTERIZATION

KAZUHIKO

OF MOUSE LPA RECEPTOR

(PSP24)

KU.ME, TAKAO SHIMIZU

Dept. of Biochemistry and Molecular Biology. Fat. of Medicine. Univ. of Tokyo. Hongo. Bunkyo. Tokyo 113.0033

Japan

Lysophosphatidic acid (LPA; 1-acyl-sn-glycerol-3-phosphate), which is originally known as an intermediate of de ao~ao phospholipid synthesis. has recently been recognized as a phospholipid messenger with various biological activities. In 1996, two putative LPA receptors were cloned independently. Vzg (ventricular zone gene) -1 was cloned from mouse cerebral cortex-derived cell line. and PSP24 was cloned from Xerroplts oocytes. From their predicted amino acid sequences. these two receptors contained seven transmembrane-spanning domains. They share little sequence homology. however, and it is still controversial whether they actually function as a specific LPA receptor. To clarify the characteristics of mammalian LPA receptor. we isolated a mouse homologue of Xelroprrs PSP24. Since the amino acid sequence of mouse PSP24 has a 70 8 homology with Xerroplts PSP23. but has little homology with other LPA receptor gene candidates such as vzg-IiEdg-2 or Edg-1. mouse PSP24 is considered to belong to a distinct gene family. The analysis of mPSP24 gene expression in mouse multiple tissues revealed that it is highly expressed in the brain. The electrophysiological analysis by voltage-clamp technique using Xerropus oocytes showed that mouse PSP24overexpression potentiated LPA-induced Cl- current. These results raised the possibility that mPSP24 is an LPA receptor expressed in the nervous system.