Activation of a novel microglial gene encoding a lysosomal membrane protein in response to neuronal apoptosis.
In an attempt to understand the molecular mechanism of microglial activation in response to neuronal death or degeneration, we have employed cerebellar cell cultures prepared from P7 rats and grown in normal K(+) (5.4 mM) medium. Under this condition, glial cells respond to degeneration and cell death of granule neurons that begins to occur at 4 days in vitro (DIV). Here we describe a novel gene, granule cell death-10 (gcd-10) that is expressed in microglia and up-regulated in an early period of granule cell death. gcd-10 is homologous to the mouse lysosomal-associated multispanning membrane protein (LAPTm5) with hematopoietic origin. Immunocytochemistry and vital staining with acridine orange revealed that GCD-10 was localized at the perinuclear area of cultured microglia and COS 1 cells infected with a GCD-10-expressing adenoviral vector. In cerebellar cell cultures, however, GCD-10 was markedly up-regulated and widely distributed to the cytoplasm, which paralleled the localization of the ED1 antigen, the lysosomal marker. In vivo, gcd-10 is expressed mainly in the brain and the spleen, and was up-regulated upon nerve injury in retina 7 days after optic nerve transection. These findings suggest that gcd-10 is involved in the dynamics of lysosomal membranes associated with microglial activation both in vitro and in vivo.
Origasa
M
M
Molecular Neurobiology Laboratory, Division of Biological Science, Graduate School of Science, Hokkaido University, North Ward N10 W8, Sapporo 060-0810, Japan.
Tanaka
S
S
Suzuki
K
K
Tone
S
S
Lim
B
B
Koike
T
T
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D019771:Axotomy; D001483:Base Sequence; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D017874:Immediate-Early Proteins / Q000235:genetics; D007150:Immunohistochemistry; D008247:Lysosomes / Q000737:chemistry / Q000502:physiology*; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics*; D017628:Microglia / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000737:chemistry / Q000166:cytology*; D009900:Optic Nerve / Q000166:cytology / Q000502:physiology; D020221:Optic Nerve Injuries / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation / Q000502:physiology
D051017:Apoptosis Regulatory Proteins; D018076:DNA, Complementary; D017874:Immediate-Early Proteins; C484408:Laptm5 protein, mouse; C434245:Laptm5 protein, rat; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins