Expression of Cellular FLICE Inhibitory Proteins (cFLIP) in Normal and Traumatic Murine and Human Cerebral Cortex

Abstract

Cellular Fas-associated death domain-like interleukin-1-beta converting enzyme (FLICE) inhibitory proteins (cFLIPs) are endogenous caspase homologues that inhibit programmed cell death. We hypothesized that cFLIPs are differentially expressed in response to traumatic brain injury (TBI). cFLIP-alpha and cFLIP-delta mRNA were expressed in normal mouse brain-specifically cFLIP-delta (but not cFLIP-alpha) protein was robustly expressed. After controlled cortical impact (CCI), cFLIPalpha expression increased initially then decreased to control levels at 12 h, increasing again at 24-72 h (Po0.05). cFLIP-delta expression was decreased in brain homogenates by 12 h after CCI, then increased again at 24 to 72 h (Po0.05). cFLIP-delta immunostaining was markedly reduced in injured cortex, but not hippocampus, at 3 to 72 h after CCI. In cortex, reduced cFLIP-delta staining was found in TUNEL-positive cells, but in hippocampus TUNEL-positive cells expressed cFLIP-delta immunoreactivity. cFLIP-delta was increased in a subset of reactive astrocytes in pericontusional cortex and hippocampus at 48 to 72 h. Low levels of both cFLIP isoforms were detected in human cortical tissue with no TBI, from four patients undergoing brain surgery for epilepsy and o24 h post mortem from three patients without CNS pathologic assessment. In cortical tissue surgically removed o18 h after severe TBI (n ¼ 3), cFLIP-alpha expression was increased relative to epilepsy controls (Po0.05) but not relative to post-mortem controls. The data suggest differential spatial and temporal regulation of cFLIP-alpha and cFLIP-delta expression that may influence the magnitude of cell death and further implicate programmed mechanisms of cell death after TBI.

Reduction of Caspase-8 and -9 Cleavage Is Associated With Increased c-FLIP and Increased Binding of Apaf-1 and Hsp70 After Neonatal Hypoxic/Ischemic Injury in Mice Overexpressing Hsp70

“…Although we did not observe changes in FDR expression after H/I in either Hsp70 Tg or Wt mice, we detected a biphasic response of c-FLIP (Figure 4), a Fas-mediated signal transduction protein, similar to the finding reported after traumatic brain injury. 25 c-FLIP was increased initially then decreased to control level at 12 hours, increasing robustly again at 24 hours after H/I in the Hsp70 Tg mice. FLIP acts as an endogenous cytoplasmic decoy 26 for caspase-8, competitively inhibiting its binding to Fasassociated protein death domain and its subsequent autocatalytic cleavage to active forms.…”

The cell survival kinase SGK1 and its targets FOXO3a and NDRG1 in aged human brain

“…For Western blots, tissues were lysed and proteins separated by SDS‐PAGE as described previously . Lysis buffer contained: 50 mM Tris‐HCl pH 7.4, 150 mM NaCl, 50 mM NaF, 2 mM EDTA, 5 mM EGTA, 10% v/v glycerol, 1% v/v Triton X‐100, supplemented just before use with 1 mM PMSF and 1% v/v protease inhibitory cocktail (P‐2714, Sigma‐Aldrich).…”

“…Proteins were visualized by chemiluminescence (ECL+ kit, GE Healthcare) and semiquantitative densitometric analysis carried out using ImageJ software (see http://rsb.info.nih.gov/ij/). SGK1 abundance was expressed relative to the housekeeping protein β‐actin .…”

C5a induces caspase‐dependent apoptosis in brain vascular endothelial cells in experimental lupus

“…Alternatively, FADD can recruit the initiator caspase, procaspase 10 and the caspase 8/10 regulator c-FLIP (FADD-like interleukin-1b-converting enzyme-inhibitory protein). 41,46,47 An additional apoptotic pathway includes CIDEB, a member of the CIDE [cell death-inducing DFF45 (DNA fragmentation factor 45)-like effector] family of apoptosis-inducing factors, 48,49 and was found to be up-regulated in the spinal cord consistent with neuronal apoptosis after nerve injury. The N-terminal region of CIDEs is homologous to the CIDE-N domains in DFF40/ CAD (caspase-activated nuclease) and its inhibitor [DFF45/ICAD (inhibitor of CAD)], which are two subunits of the DFF complex.…”