Differential expression of utrophin and dystrophin in CNS neurons: An in situ hybridization and immunohistochemical study

Abstract

The cellular distribution of utrophin, the autosomal homologue of dystrophin, was investigated in developing and adult rat and mouse brain by in situ hybridization and immunohistochemistry. Digoxigenin-labeled cRNA probes complementary to N-terminal, rod-domain, and C-terminal encoding sequences of utrophin were used to differentiate between full-length and short C-terminal isoforms. Largely overlapping distribution patterns were seen for the three probes in neurons of cerebral cortex, accessory olfactory bulb, and several sensory and motor brainstem nuclei as well as in blood vessels, pia mater, and choroid plexus. The C-terminal probe was detected in addition in the main olfactory bulb, striatum, thalamic reticular nucleus, and hypothalamus, suggesting a selective expression of G-utrophin in these neurons. Western blot analysis with isoform-specific antisera confirmed the expression of both full-length and G-utrophin in brain. Immunohistochemically, only full-length utrophin was detected in neurons, in close association with the plasma membrane. In addition, intense staining was seen in blood vessels, meninges, and choroid plexus, selectively localized in the basolateral membrane of immunopositive epithelial cells. The expression pattern of utrophin was already established at early postnatal stages and did not change thereafter. Double-labeling analysis revealed that utrophin and dystrophin are differentially expressed on the cellular and subcellular levels in juvenile and adult brain. Likewise, in mice lacking full-length dystrophin isoforms (mdx mice), no change in utrophin expression and distribution could be detected in brain, although utrophin was markedly up-regulated in muscle cells. These results suggest that utrophin and dystrophin are independently regulated and have distinct functional roles in CNS neurons.

Molecular and synaptic organization of GABAA receptors in the cerebellum: Effects of targeted subunit gene deletions

“…While the relevance of the DGC in specific GABAergic synapses is unclear, it is required for proper expression of long-term depression in PC (49), suggesting a role in synaptic plasticity. A similar situation occurs in the cerebral cortex and hippocampal formation, where large subsets of inhibitory synapses are associated with the DGC (45). In the hippocampus, absence of the DGC leads to alterations of short-and long-term synaptic plasticity (50,51).…”

“…However, the DGC cannot be essential for the formation of GABAergic synapses or clustering of GABA A receptors, since it is absent in many other brain areas, such as thalamus, basal ganglia, tectum, etc. Furthermore, dystrophin expression occurs after formation of GABAergic synapses during postnatal development (45).…”

Molecular and functional heterogeneity of GABAergic synapses

“…These studies reveal a systematic colocalization with proteins of the GABAergic PSD in a subset of neurons of cortical areas, including the entire cerebral cortex, hippocampal formation (where Dp71 is selectively present in dentate gyrus granule cells), tectum, and cerebellum. In the hippocampus, the DGC appears to be restricted to principal cells, and is present selectively on the soma and proximal dendrites, suggesting an association with perisomatic synapses (formed by basket cells) [99,87].…”

Dp71 gene disruption alters the composition of the dystrophin-associated protein complex and neuronal nitric oxide synthase expression in the hypothalamic supraoptic and paraventricular nuclei

“…As previously described, we found these proteins to be localized around vessels, notably in endothelial cells and in astrocyte end feet surrounding the vessels (Khurana et al 1992, Knuesel et al 2000, Haenggi et al 2004. Like dystrophins, utrophins are attached to the cell membrane (Khurana et al 1992) and are associated with the same proteins and glycoproteins as those associated with dystrophins (Matsumura et al 1992).…”