rAAV8-733-Mediated Gene Transfer of CHIP/Stub-1 Prevents Hippocampal Neuronal Death in Experimental Brain Ischemia.

Brain ischemia is a major cause of adult disability and death, and it represents a worldwide health problem with significant economic burden for modern society. The identification of the molecular pathways activated after brain ischemia, together with efficient technologies of gene delivery to the CNS, may lead to novel treatments based on gene therapy. Recombinant adeno-associated virus (rAAV) is an effective platform for gene transfer to the CNS. Here, we used a serotype 8 rAAV bearing the Y733F mutation (rAAV8-733) to overexpress co-chaperone E3 ligase CHIP (also known as Stub-1) in rat hippocampal neurons, both in an oxygen and glucose deprivation model in vitro and in a four-vessel occlusion model of ischemia in vivo. We show that CHIP overexpression prevented neuronal degeneration in both cases and led to a decrease of both eIF2α (serine 51) and AKT (serine 473) phosphorylation, as well as reduced amounts of ubiquitinated proteins following hypoxia or ischemia. These data add to current knowledge of ischemia-related signaling in the brain and suggest that gene therapy based on the role of CHIP in proteostasis may provide a new venue for brain ischemia treatment.

Paracrine interaction between bone marrow-derived stem cells and renal epithelial cells.

BACKGROUND/AIMS: Renal tubular cells are the main target of ischemic insult associated with acute renal injury. Low oxygen and nutrient supplies result in ATP depletion, leading to cell death and loss of renal function. A possible mechanism by which bone marrow-derived cells support renal tissue regeneration relies on the capacity of mononuclear cells (BMMC), particularly mesenchymal stem cells (MSC), to secrete paracrine factors that mediate support for kidney regeneration. METHODS: BMMC/MSC and renal cells (LLC-PK(1) from pig and IRPTC from rat) were co-cultured under stressful conditions (ATP depletion and/or serum free starvation), physically separated by a microporous membrane (0.4 µm), was used to determine whether bone marrow-derived cells can interact with renal cells in a paracrine manner. RESULTS: This interaction resulted in stimulation of renal cell proliferation and the arrest of cell death. MSC elicit effective responses in renal cells in terms of stimulating proliferation and protection. Such effects are observed in renal cells co-cultured with rat BMMC/MSC, an indication that paracrine mechanisms are not entirely species-specific. CONCLUSION: The paracrine action of BMMC/MSC was influenced by a renal cell stimulus released during stress, indicating that cross-talk with injured cells is required for renal regeneration supported by bone marrow-derived cells.

Interleukin-4 blocks thapsigargin-induced cell death in rat rod photoreceptors: involvement of cAMP/PKA pathway.

Although the photoreceptors cell death is the main cause of some retinopathies diseases, the mechanisms involved in this process are poorly understood. The neuroprotective effects of interleukin-4 (IL-4) have been shown in several tissues, including retina. We demonstrate that treatment of rat retinal explants with IL-4 completely inhibited the thapsigargin-induced rod photoreceptor cell death after 24 hr in culture. We also showed that IL-4 receptor alpha subunit (IL-4Ralpha) is abundantly present in retina. Colocalization of IL-4Ralpha and rhodopsin indicate a direct effect of this cytokine in rod photoreceptor cells. Moreover, IL-4 increased the intracellular levels of cAMP in 7.4-fold, indicating that the neuroprotective effect of this cytokine was completely blocked by RpcAMP, an inhibitor of protein kinase (PKA). Our data demonstrate, for the first time, the neuroprotective effect of IL-4 through cAMP/PKA pathway in thapsigargin-induced photoreceptor cell death.

CHIP, a carboxy terminus HSP-70 interacting protein, prevents cell death induced by endoplasmic reticulum stress in the central nervous system.

Endoplasmic reticulum (ER) stress and protein misfolding are associated with various neurodegenerative diseases. ER stress activates unfolded protein response (UPR), an adaptative response. However, severe ER stress can induce cell death. Here we show that the E3 ubiquitin ligase and co-chaperone Carboxyl Terminus HSP70/90 Interacting Protein (CHIP) prevents neuron death in the hippocampus induced by severe ER stress. Organotypic hippocampal slice cultures (OHSCs) were exposed to Tunicamycin, a pharmacological ER stress inducer, to trigger cell death. Overexpression of CHIP was achieved with a recombinant adeno-associated viral vector (rAAV) and significantly diminished ER stress-induced cell death, as shown by analysis of propidium iodide (PI) uptake, condensed chromatin, TUNEL and cleaved caspase 3 in the CA1 region of OHSCs. In addition, overexpression of CHIP prevented upregulation of both CHOP and p53 both pro-apoptotic pathways induced by ER stress. We also detected an attenuation of eIF2a phosphorylation promoted by ER stress. However, CHIP did not prevent upregulation of BiP/GRP78 induced by UPR. These data indicate that overexpression of CHIP attenuates ER-stress death response while maintain ER stress adaptative response in the central nervous system. These results indicate a neuroprotective role for CHIP upon UPR signaling. CHIP emerge as a candidate for clinical intervention in neurodegenerative diseases associated with ER stress.

Rod photoreceptor cell death is induced by okadaic acid through activation of PKC and L-type voltage-dependent Ca2+ channels and prevented by IGF-1.

Retinal dystrophies involve extensive photoreceptor apoptosis. Neuroprotective effects of insulin-like growth factor (IGF)-1 have been demonstrated in various tissues, including the retina. The aim of this study was to investigate: (i) the action of IGF-1 upon selective photoreceptor death induced by okadaic acid (OA); and (ii) signaling pathways related to both OA-induced cell death and IGF-1 neuroprotective effect. Retinal explants were incubated with 5nM OA, a protein phosphatase type 1 and type 2A inhibitor, which induces cell death detected by the identification of pyknotic morphology of photoreceptors immunostained for rhodopsin. OA increased both the number of pyknotic Rho 4D2(+) profiles, and Ca(2+) influx, measured through the incorporation of (45)CaCl(2), in a dose- and time-dependent way, while treatment with 10ng/mL IGF-1 abrogated both effects. Treatment with phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, modulated OA effects, indicating the involvement of PKC. Furthermore, either 10microM chelerythrine chloride, an inhibitor of PKC, or 10microM nifedipine, a L-voltage-sensitive Ca(2+) channel blocker, inhibited both Ca(2+) influx and cell death induced by OA. The data show that okadaic acid induces rod photoreceptor cell death in retinal tissue through activation of PKC and ensuing Ca(2+) influx through L-type Ca(2+) channels, which is counteracted by a neuroprotective effect of IGF-1.

Interleukin-4 as a neuromodulatory cytokine: roles and signaling in the nervous system.

Although interleukin (IL)-4 is described as a prototypical anti-inflammatory cytokine, in recent years its role as a neuromodulatory cytokine has been extensively discussed. This review highlights the pivotal contributions of IL-4 during the development and normal physiology of neural cells as well as IL-4 connections with the pathophysiology of degenerative or inflammatory processes observed in the central and peripheral nervous system.