Traumatically injured astrocytes release a proteomic signature modulated by STAT3‐dependent cell survival

Abstract

Molecular markers associated with CNS injury are of diagnostic interest. Mechanical trauma generates cellular deformation associated with membrane permeability with unknown molecular consequences. We used an in vitro model of stretch-injury and proteomic analyses to determine protein changes in murine astrocytes and their surrounding fluids. Abrupt pressure-pulse stretching resulted in the rapid release of 59 astrocytic proteins with profiles reflecting cell injury and cell death, i.e. mechanoporation and cell lysis. This acute trauma-release proteome was overrepresented with metabolic proteins compared to the uninjured cellular proteome, bearing relevance for post-traumatic metabolic depression. Astrocyte-specific deletion of signal transducer and activator of transcription 3 (STAT3-CKO) resulted in reduced stretch-injury tolerance, elevated necrosis and increased protein release. Consistent with more lysed cells, more protein complexes, nuclear and transport proteins were released from STAT3-CKO versus non-transgenic astrocytes. STAT3-CKO astrocytes had reduced basal expression of GFAP, lactate dehydrogenase B (LDHB), aldolase C (ALDOC) and astrocytic phosphoprotein 15 (PEA15), and elevated levels of tropomyosin (TPM4) and α actinin 4 (ACTN4). Stretching caused STAT3 dependent cellular depletion of PEA15 and GFAP, and its filament disassembly in subpopulations of injured astrocytes. PEA15 and ALDOC signals were low in injured astrocytes acutely after mouse spinal cord crush injury and robustly expressed in reactive astrocytes one day post-injury. In contrast, α crystallin (CRYAB) was present in acutely injured astrocytes, and absent from uninjured and reactive astrocytes, demonstrating novel marker differences among post-injury astrocytes. These findings reveal a proteomic signature of traumatically-injured astrocytes reflecting STAT3-dependent cellular survival with potential diagnostic value.

GSEA of mouse and human mitochondriomes reveals fatty acid oxidation in astrocytes

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Astrocyte Structural and Molecular Response to Elevated Intraocular Pressure Occurs Rapidly and Precedes Axonal Tubulin Rearrangement within the Optic Nerve Head in a Rat Model

“…These astrocyte extensions further couple the meningeal vasculature to axons [13, 14], and are involved in neural development and synapse formation [15], metabolic and ionic support of ONH axons [16–18], facilitate mitochondrial transcellular degradation from retinal ganglion cell axons [19], and phagocytosis of myelin segments within the optic nerve [20, 21]. ONH astrocytes are also mechanosensitive [22–24] and dynamically respond to elevated IOP by retracting or reorienting their extensions [8, 12]. The reaction of ONH astrocytes to elevated IOP may lead to loss of structural and biochemical support of axons and eventual axon degeneration [25–28].…”

Silencing miR‐21 induces polarization of astrocytes to the A2 phenotype and improves the formation of synapses by targeting glypican 6 via the signal transducer and activator of transcription‐3 pathway after acute ischemic spinal cord injury

“…Concerning the underlying mechanism, past studies have shown that STAT3-conditional knockout astrocytes expressed lower GFAP (31). We therefore hypothesized that STAT3 is potentially important in regulating the markers of A1 and A2.…”