Calpain 1 and Calpastatin expression is developmentally regulated in rat brain.
Calpains and caspases are cysteine endopeptidases which share many similar substrates. Caspases are essential for caspase-dependent apoptotic death where calpains may play an augmentive role, while calpains are strongly implicated in necrotic cell death morphologies. Previous studies have demonstrated a down-regulation in the expression of many components of the caspase-dependent cell death pathway during CNS development. We therefore sought to determine if there is a corresponding upregulation of calpains. The major CNS calpains are the mu-and m-isoforms, composed of the unique 80 kDa calpain 1 and 2 subunits, respectively, and the shared 28 kDa small subunit. In rat brain, relative protein and mRNA levels of calpain 1, calpain 2, caspase 3, and the endogenous calpain inhibitor-calpastatin, were evaluated using western blot and real-time RT-PCR. The developmental time points examined ranged from embryonic day 18 until postnatal day 90. Calpain 1 and calpastatin protein and mRNA levels were low at early developmental time points and increased dramatically by P30. Conversely, caspase-3 expression was greatest at E18, and was rapidly downregulated by P30. Calpain 2 protein and mRNA levels were relatively constant throughout the E18-P90 age range examined. The inverse relationship of calpain 1 and caspase 3 levels during CNS development is consistent with the shift from caspase-dependent to caspase-independent cell death mechanisms following CNS injury in neonatal vs. adult rat brain.
Li
Yanzhang
Y
Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536-0509, USA.
Bondada
Vimala
V
Joshi
Aashish
A
Geddes
James W
JW
D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D001921:Brain / Q000254:growth & development*; D001923:Brain Chemistry / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D002154:Calpain / Q000096:biosynthesis*; D053148:Caspase 3 / Q000096:biosynthesis; D008928:Mitochondria / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; C033668:calpastatin; D002154:Calpain; D053148:Caspase 3