Italian Journal of Anatomy and Embryology - contenuto non piu disponibile

Sarcoglycans (SGC) are four transmembrane proteins: α-, β-, γ-, δ-sarcoglycans, which are type II transmembrane. αand γ-sarcoglycan are expressed exclusively in skeletal and cardiac muscle, whereas βe δ-sarcoglycan are more widely distributed. A fifth sarcoglycan, e-sarcoglycan, homologous to α-sarcoglycan, but like γ-sarcoglycan is widely expressed in various tissues. Authors suggested that e-sarcoglycan can replace α-sarcoglycan in smooth muscle, but more recent investigations [1-2] demonstrated the contemporary presence of those two proteins, that play a different roles in the same tissue. In order to verify the exact role of sarcoglycans, in this study, we examined coronal sections of cerebral hemispheres of the rat brain. The sections were divided in frontal, parietal, temporal, and occipital zones. We analyzed the samples by immunohistochemistry, immunoperoxidase, and western blot techniques. For immunohistochemistry, we performed triple localization reactions matching antibodies to all sarcoglycans with antibodies to SMI, in order to evidence the neurons, and to GFAP, in order to evidence the glial cells; in all reaction we added also the DAPI to better visualize the nuclei of neurons. Our results showed that α-sarcoglycan nearly absent, whereas other sarcoglycans were diffusely expressed, including the e-sarcoglycan. Furthermore, analyzing the patterns for βand γ-sarcoglycan, these proteins showed a different expression in distinct tested zones. Our results suggest a differential behaviour of SGC in the cerebral cortex as demonstrated by the absence of the classic relationship between αand e-sarcoglycans, known in muscle and non-muscle tissues. Moreover, the overexpression of all sarcoglycans, both in glial cells and in neurons, suggests an increased presence of these proteins in synaptic zones.