Immunophilin deficiency augments Ca2+-dependent glutamate release from mouse cortical astrocytes

Abstract

SUMMARYImmunophilins are receptors for immunosuppressive drugs such as the macrolides cyclosporin A (CsA) and FK506; correspondingly these immunophilins are referred as cyclophilins and FK506-binding proteins (FKBPs). In particular, CsA targets cyclophilin D (CypD), which can modulate mitochondrial Ca 2+ dynamics. Since mitochondria have been implicated in the regulation of astrocytic cytosolic Ca 2+ (Ca 2+ cyt ) dynamics and consequential Ca 2+ -dependent exocytotic release of glutamate, we investigated the role of CypD in this process. Cortical astrocytes isolated from CypD deficient mice Ppif −/− displayed reduced mechanically-induced Ca 2+ cyt increases, even though these cells showed augmented exocytotic release of glutamate, when compared to responses obtained from astrocytes isolated from wild-type mice. Furthermore, acute treatment with CsA to inhibit CypD modulation of mitochondrial Ca 2+ buffering, or with FK506 to inhibit FKBP12 interaction with inositol-trisphosphate receptor of the endoplasmic reticulum, led to similar reductive effects on astrocytic Ca 2+ cyt dynamics, but also to an enhanced Ca 2+ -dependent exocytotic release of glutamate in wild-type astrocytes. These findings point to a possible role of immunophilin signal transduction pathways in astrocytic modulation of neuronal activity at the tripartite synapse.

Chemically functionalized single-walled carbon nanotubes enhance the glutamate uptake characteristics of mouse cortical astrocytes

“…Purified astrocytic cultures were made using a modification (Gottipati et al 2012; Reyes et al 2011) of the originally described shaking procedure (McCarthy and de Vellis 1980). Briefly, visual cortices were dissected from 0- to 2-day-old C57BL/6 mice pups and treated with papain in the presence of L-cysteine, neutralized with trypsin inhibitor and triturated in cell culture medium containing α-minimum essential medium (without phenol red; Invitrogen) supplemented with fetal bovine serum (10%, Hyclone), sodium bicarbonate (14 mM), sodium pyruvate (1 mM), D-glucose (20 mM), L-glutamine (2 mM), penicillin (100 I.U./ml) and streptomycin (100 μg/ml) (pH 7.35).…”

Changes in the Morphology and Proliferation of Astrocytes Induced by Two Modalities of Chemically Functionalized Single-Walled Carbon Nanotubes are Differentially Mediated by Glial Fibrillary Acidic Protein

“…4,14,18 The area and perimeter of the cells were obtained using a self-designed algorithm, involving the stitching/autoleveling step when needed (see Figure S1 of ref (4)), which were further used to calculate the FF as we described elsewhere. 4 …”

Enhanced Ca2+-dependent glutamate release from astrocytes of the BACHD Huntington's disease mouse model

“…background strain mice (FvB/N, The Jackson Laboratory). We used 1-to 2-day-old BACHD and WT mice to obtain purified cortical astrocyte culture (>99%) grown in flasks and on polyethyleneimine (PEI, 1mg/ml)-coated coverslips, as we previously described (Reyes et al, 2011). At least three independent cultures were used for imaging data collection and analysis.…”