Identification of PINCH in Schwann cells and DRG neurons: Shuttling and signaling after nerve injury

• Published in: Glia 2003-02, Vol.41 (3), p.213-223
• Main Authors: Campana, W. Marie, Myers, Robert R., Rearden, Ann
• Format: Article
• Language: English
• Subjects: Active Transport, Cell Nucleus - genetics; Amino Acid Sequence; Animals; Antibody Specificity; Biological and medical sciences; Cells, Cultured; chronic constriction injury; Chronic Disease; DNA-Binding Proteins - analysis; DNA-Binding Proteins - genetics; DNA-Binding Proteins - immunology; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - cytology; integrin-linked kinase; Isolated neuron and nerve. Neuroglia; Molecular Sequence Data; Nerve Compression Syndromes - physiopathology; Neurons, Afferent - chemistry; Neurons, Afferent - cytology; nuclear localization; Rats; Schwann Cells - chemistry; Schwann Cells - cytology; Sciatic Nerve - physiopathology; Signal Transduction - physiology; spinal cord; Vertebrates: nervous system and sense organs
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.10138

Particularly interesting new cysteine‐histidine rich protein (PINCH) is a double zinc finger domain (LIM)‐only adapter protein that functions to recruit the integrin‐linked kinase (ILK) to sites of integrin activation. Genetic studies have shown that PINCH and ILK are required for integrin signaling. Since integrin activation is associated with Schwann cell migration, neurite outgrowth and regeneration, this study examined PINCH in the normal peripheral nervous system and after chronic constriction injury (CCI) in adult Sprague‐Dawley rats. Immunohistochemistry identified PINCH immunoreactivity in cell bodies of dorsal root ganglia (DRG) neurons, axons, satellite cells, and Schwann cells. PINCH immunostaining was localized to the membrane of uninjured DRG cell bodies consistent with its localization at a site of integrin activation. In contrast, 5 days following CCI, PINCH immunostaining was diffuse throughout the DRG cell cytoplasm. Confocal microscopy of primary and transformed Schwann cells localized PINCH in cytoplasmic, perinuclear and nuclear areas. Examination of the PINCH sequence revealed a putative leucine‐rich nuclear export signal (NES) and an overlapping basic nuclear localization signal (NLS). To demonstrate nuclear export of PINCH, rabbit anti‐PINCH IgG was microinjected into Schwann cell nuclei and allowed to combine with PINCH contained within the nucleus. Immunofluorescence showed that the PINCH and anti‐PINCH IgG complex rapidly translocated to the cytoplasm. Treatment with leptomycin B caused nuclear accumulation of PINCH, indicating that the CRM1 pathway mediates nuclear export of PINCH. ILK activity in Schwann cells was enhanced by platelet‐derived growth factor (PDGF) and tumor necrosis factor α. PINCH immunoprecipitates from PDGF‐ and TNFα‐stimulated Schwann cells contained several high‐molecular‐weight threonine‐phosphorylated proteins. Taken together, these results indicate that PINCH is an abundant shuttling/signaling protein in Schwann cells and DRG neurons. GLIA 41:213–223, 2003. © 2003 Wiley‐Liss, Inc.