Npas4, a novel helix-loop-helix PAS domain protein, is regulated in response to cerebral ischemia.
Basic helix-loop-helix PAS domain proteins form a growing family of transcription factors. These proteins are involved in the process of adaptation to cellular stresses and environmental factors such as a change in oxygen concentration. We describe the identification and characterization of a recently cloned PAS domain protein termed Npas4 in ischemic rat brain. Using gene expression profiling following middle cerebral artery occlusion, we showed that the Npas4 mRNA is differentially expressed in ischemic tissue. The full-length gene was cloned from rat brain and its spatial and temporal expression characterized with in situ hybridization and Northern blotting. The Npas4 mRNA is specifically expressed in the brain and is highly up-regulated in ischemic tissues following both focal and global cerebral ischemic insults. Immunohistochemistry revealed a strong expression in the limbic system and thalamus, as well as in layers 3 and 5 in the cortex of the unchallenged brain. When overexpressed in HEK 293 cells, Npas4 appears as a protein of approximately 100 kDa. In brain samples, however, in addition to the 100 kDa band a specific 200 kDa immunoreactive band was also detected. Ischemic challenge lead to a decrease in the 200 kDa form and a simultaneous increase in the 100 kDa immunoreactivity. This could indicate a novel regulatory mechanism for activation and/or deactivation of this protein in response to ischemic brain injury.
Shamloo
Mehrdad
M
AGY Therapeutics, South San Francisco, California 94080, USA. Mehrdad_shamloo@affymax.com
Soriano
Liza
L
von Schack
David
D
Rickhag
Mattias
M
Chin
Daniel J
DJ
Gonzalez-Zulueta
Mirella
M
Gido
Gunilla
G
Urfer
Roman
R
Wieloch
Tadeusz
T
Nikolich
Karoly
K
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D005786:Gene Expression Regulation / Q000502:physiology*; D018257:Helix-Loop-Helix Motifs; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization; D020244:Infarction, Middle Cerebral Artery / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013347:Subcellular Fractions / Q000378:metabolism; D016708:Synaptophysin / Q000378:metabolism; D013997:Time Factors
D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016708:Synaptophysin; C516513:Npas4 protein, rat