Colocalization of latexin with carboxypeptidase A in the infragranular neurons of cerebral cortex

s13.5

217

COLOCALIZATION OF LATEXIN WITH CARBOXYPEPTIDASE NEURONS OF CEREBRAL CORTEX

A IN THE INFRAGRANULAR

KEIKO TAKIGUCHI-HAYASHI, KANAKO HIRATA, YOSHIHIKO URATANI, NOBUHIKO MIYASAKA, ISHIDA, AKIRA OOMORI, SACHIYO ICHINOSE, MING-HA0 JIN, YASUYOSHI ARIMATSU Mitsubishi

Kasei Institute of Life Sciences.

11 Minamiooya,

Machida-shi,

MAMI

Tokyo 194-85 11. Japan

Latexin is a carboxypeptidase A (CPA) inhibitor expressed in certain cortico-cortical projection neurons located in the infragranular layers of lateral cortical areas of adult rats and mice. To understand a physiological function of latexin in the cerebral cortex, we previously analyzed colocalization of latexin with protein phosphatase inhibitor-l and with Al-opioid receptor (K. Takiguchi-Hayashi & Y. Arimatsu, Neurosci. Res. Suppl. 21. S44, 1997). In the present study, we examined colocalization of latexin with CPA by immunohistochemistry. Restricted and similar distribution profiles were observed within the cerebral cortex for latexin- and CPA-immunopositive neurons. In double immunofluorescence experiments in some cortical areas, it was shown that all of latexin-immunopositive neurons were also CPAimmunopositive. These observations suggest that latexin play a role together with CPA in the cortico-cortical circuit.

218

MAJOR POPULATION OF 85kDa CYTOSOLIC LOCALIZED IN NEURONS IN RAT BRAIN.

PHOSPHOLIPASE

A2 mRNA SIGNALS

KOJI KISHIMOTOl, KIYOSHI MATSUMURA’,2, YOSKY KATAOKA’, HIROSHI MORIII.3. and YASUYOSHI WATANABE’. 1Dept. of Neuroscience, Osaka Bioscience Inst., 6-2-4 Furuedai, Suita-shi, Osaka 565-0874, 2Dept. of Biological Information, Graduate School of Informatics, Kyoto Univ., Sakyo-ku, Kyoto 606-8501, 3Dept. of Molecular Genetics, National Inst. for Longevity Sciences, 36-3 Oobu, Aichi 474-003 I, Japan. Ca2+-sensitive 85-kDa cytosolic phospholipase A2 (cPLA2) is a key enzyme for arachidonic acid release. Arachidonic acid and its metabolites have been suggested to be involved in various neuronal functions. For better understanding of the mechanisms controlling arachidonate production in the central nervous system, we investigated regional and cellular localization of cPLA2 mRNA in the normal rat brain using Northern blot analysis and in siru hybridization. Expression of cPLA2 mRNA was observed in most regions of the brain. Considerable levels of signals were detected in the gray matter. Furthermore, intense signals were observed in the pineal gland. In addition, the signals were increased by cycloheximide in the same cell populations originally possessing mRNA signals. The finding that cPLA2 mRNA is predominantly expressed in neurons may support an idea that arachidonic acid and its metabolites play important roles in neurotransmission and regulation in the central nervous system.

219

NEURON-SPECIFIC

JUNJI YAMADA,

DISTRIBUTION

YU KURAMOCHI,

Dept. of Clin. Biochem.,

OF LONG-CHAIN

MICHIKO HIRATA, TAKAFUMl

II has been well known thal a very high activity of long-chain as rBACH, from rat brain cytosol. Subcellular

fractionation

activity found in the brain tissue. distribution

WATANABE,

and examined

its cellular

and immunotitration Immunoblots

acyl-CoA

hydrolase

We purified and characterized

IN RAT BRAIN

and TETSUYA

SUGA

distribution

revealed

is present in the brain tissue, suggesting

a long-chain

hydrolase,

in the brain using an antibody

that rBACH accounted

referred to

raised against

for at least 70% of the enzyme

high level in the pons and medulla.

to neurons. with the cell bodies and dendrites,

but not axons. showmg

to various nuclei. some neuronal cells, such as mitral cells in the olfactory bulb, pyramidal Purkinje cells in the cerebellum,

acyl-CoA

of the cytosol prepared from rat brain regional blocks indicated the broad

of this enzyme over the brain, with a relatively

rBACH was localized

HYDROLASE

Sch. of Phnrm., Tokyo Univ. of Pharm. and Life Sci.. Hachioji. Tokyo 192-0392

some specific role of this enzyme in the brain.

rBACH.

ACYL-CoA

were also immunostained

with the anti-rBACH

antibody.

By immunohistochemistry, immunostaining.

In addition

cells in the cerebral cortex. and