Sarcoglycan Research Articles

Aberrant Adenosine Triphosphate Release and Impairment of P2Y2-Mediated Signaling in Sarcoglycanopathies

Sarcoglycanopathies, limb-girdle muscular dystrophies (LGMD) caused by genetic loss-of-function of the membrane proteins sarcoglycans (SGs), are characterized by progressive degeneration of skeletal muscle. In these disorders, muscle necrosis is associated with immune–mediated damage, whose triggering and perpetuating molecular mechanisms are not fully elucidated yet. Extracellular adenosine triphosphate (eATP) seems to represent a crucial factor, with eATP activating purinergic receptors. Indeed, in vivo blockade of the eATP/P2X7 purinergic pathway ameliorated muscle disease progression. P2X7 inhibition improved the dystrophic process by restraining the activity of P2X7 receptors on immune cells. Whether P2X7 blockade can display a direct action on muscle cells is not known yet. In this study, we investigated eATP effects in primary cultures of myoblasts isolated from patients with LGMDR3 (α-sarcoglycanopathy) and in immortalized cells isolated from a patient with LGMDR5 (γ-sarcoglycanopathy). Our results demonstrated that, owing to a reduced ecto-ATPase activity and/or an enhanced release of ATP, patient cells are exposed to increased juxtamembrane concentrations of eATP and display a higher susceptivity to eATP signals. The purinoceptor P2Y2, which proved to be overexpressed in patient cells, was identified as a pivotal receptor responsible for the enhanced ATP-induced or UTP-induced Ca2+ increase in affected myoblasts. Moreover, P2Y2 stimulation in LDMDR3 muscle cells induced chemotaxis of immune cells and release of interleukin-8. In conclusion, a higher eATP concentration and sensitivity in primary human muscle cells carrying different α-SG or γ-SG loss-of-function mutations indicate that eATP/P2Y2 is an enhanced signaling axis in cells from patients with α-/γ-sarcoglycanopathy. Understanding the basis of the innate immune–mediated damage associated with the dystrophic process may be critical in overcoming the immunologic hurdles associated with emerging gene therapies for these disorders.

Analysis on sarcoglycans expression as markers of septic cardiomyopathy in sepsis-related death.

The post-mortem assessment of sepsis-related death can be carry out by many methods recently suggested as microbiological and biochemical investigations. In these cases, the cause of death is a multiple organ dysfunction due to a dysregulated inflammatory response occurring after the failure of infection control process. It was highlighted also that the heart can be a target organ in sepsis which determines the so-called septic cardiomyopathy characterized by myocardial depression. Several mechanisms to explain the pathophysiology of septic cardiomyopathy were suggested, but very few studies about the structural alterations of cardiac cells responsible for myocardial depression were carried out. The aim of this study was to evaluate whether sarcoglycans (SG) were involved in septic cardiac damage analyzing their expression in sepsis-related deaths and, particularly, if these proteins can be used as markers of septic myocardial dysfunction. Cases of septic-related death confirmed by clinical and autopsy records were investigated and compared to a control group of traumatic deaths. Indirect immunofluorescence analysis was performed to analyze α-SG, β-SG, δ-SG, ζ-SG, ε-SG, and γ-SG. Decrease of fluorescence staining pattern for all tested sarcoglycans was observed in the septic-related deaths compared to normal fluorescence staining pattern of control group. These results provide new findings about the myocytes structural alterations due to sepsis and suggest that these proteins could be used in forensic assessment of septic cardiomyopathy.

Effects of (-)-epicatechin on frontal cortex DAPC and dysbindin of the mdx mice.

Multiple components of the dystrophin-associated protein complex (DAPC) are expressed in numerous tissues including the brain. Members of the DAPC and dysbindin are abnormally expressed in the brain of Duchenne Muscular Dystrophy (DMD) patients, which has been associated with cognitive impairments. However, little is known about the expression pattern of individual members of the DAPC in animal models of DMD and their relationship with dysbindin. Ten mdx mice were randomly allocated into a control and intervention group [(-)-epicatechin (Epi) 1mg/kg/day for four weeks] and results compared to a wild-type mice. After sacrifice, brain pre-frontal cortices were collected for Western blotting and immunoprecipitation assays, and sagittal sections processed for immunohistochemistry. Epi promotes a partial recovery of DAPC members [α1-Syntrophin, sarcoglycans (SG), dystrophin 71 (Dp71)], dysbindin, and utrophin protein levels. Epi also appears to restore the association of DAPC between dysbindin, and utrophin with Dp71 and ε-SG. Co-immunostaining evidence increased protein levels of dysbindin, dystrophin, and ε-SG and their colocalization. Altogether, results suggest that Epi is capable of restoring pre-frontal cortex DAPC and dysbindin levels of mdx mice towards that of healthy brains. The functional implications of such studies warrant further investigation.

Nanospan, an alternatively spliced isoform of sarcospan, localizes to the sarcoplasmic reticulum in skeletal muscle and is absent in limb girdle muscular dystrophy 2F

BackgroundSarcospan (SSPN) is a transmembrane protein that interacts with the sarcoglycans (SGs) to form a tight subcomplex within the dystrophin-glycoprotein complex that spans the sarcolemma and interacts with laminin in the extracellular matrix. Overexpression of SSPN ameliorates Duchenne muscular dystrophy in murine models.MethodsStandard cloning approaches were used to identify nanospan, and nanospan-specific polyclonal antibodies were generated and validated. Biochemical isolation of skeletal muscle membranes and two-photon laser scanning microscopy were used to analyze nanospan localization in muscle from multiple murine models. Duchenne muscular dystrophy biopsies were analyzed by immunoblot analysis of protein lysates as well as indirect immunofluorescence analysis of muscle cryosections.ResultsNanospan is an alternatively spliced isoform of sarcospan. While SSPN has four transmembrane domains and is a core component of the sarcolemmal dystrophin-glycoprotein complex, nanospan is a type II transmembrane protein that does not associate with the dystrophin-glycoprotein complex. We demonstrate that nanospan is enriched in the sarcoplasmic reticulum (SR) fractions and is not present in the T-tubules. SR fractions contain membranes from three distinct structural regions: a region flanking the T-tubules (triadic SR), a SR region across the Z-line (ZSR), and a longitudinal SR region across the M-line (LSR). Analysis of isolated murine muscles reveals that nanospan is mostly associated with the ZSR and triadic SR, and only minimally with the LSR. Furthermore, nanospan is absent from the SR of δ-SG-null (Sgcd−/−) skeletal muscle, a murine model for limb girdle muscular dystrophy 2F. Analysis of skeletal muscle biopsies from Duchenne muscular dystrophy patients reveals that nanospan is preferentially expressed in type I (slow) fibers in both control and Duchenne samples. Furthermore, nanospan is significantly reduced in Duchenne biopsies.ConclusionsAlternative splicing of proteins from the SG-SSPN complex produces δ-SG3, microspan, and nanospan that localize to the ZSR and the triadic SR, where they may play a role in regulating resting calcium levels as supported by previous studies (Estrada et al., Biochem Biophys Res Commun 340:865–71, 2006). Thus, alternative splicing of SSPN mRNA generates three protein isoforms (SSPN, microspan, and nanospan) that differ in the number of transmembrane domains affecting subcellular membrane association into distinct protein complexes.

Sarcoglycan sub-complex in the adipose organ: a molecular and immunofluorescence study

The sarcoglycan sub-complex (SGC) is made up of six glycoproteins which connect the cytoskeleton to the extracellular matrix in skeletal muscle. Recent data show that this complex is also expressed in epithelial tissue such as gingival, breast and prostatic ones [1]. The adipose organ is organized in multiple fat depots consisting of white and brown adipose cells. White adipocytes can store energy in triglycerides; brown adipocytes can dissipate energy for thermogenesis. It has been demonstrated that white adipocytes transdifferentiate to brown adipocytes after cold exposure [3]. In this study we examined the expression of sarcoglycans (SGs) in the adipose organ from two groups of mice: the first group was exposed at 25 C°, as control, and the second one was exposed at low temperature (4 C°) for 24 hours and 4 days. Fat depots from the visceral and interscapular region, but also from the mammary gland, have been examined by histological, immunofluorescence and molecular techniques. Results have shown that SGC is expressed in the adipose organ, both in brown and white adipocytes of mice exposed at 25 C°. The main results is that the expression level of all sarcoglycans increase in cold exposure experiment. For the first time the expression of all SGs in the adipose organ has been demonstrated, both at mRNA and protein levels. Since we found an increase in SGs expression after transdifferentiation from white to brown adipocytes cold exposure induced, we hypothesize that sarcoglycans could be associated with β3 adrenergic receptor; sarcoglycans associations with other receptors, as GABAr, has been already demonstrated in central nervous system. Although that, the function of these glycoproteins in the adipose organ remain still unclear and further investigation are required.

Physiopathology of vesico-ureteral reflux.

Vescico-Ureteral Reflux (VUR) is a common condition in childhood, caused by a congenital anomaly at the Vescico-Ureteral Junction (VUJ) level. It seems that the main cause could be an abnormal embryological development occurred during the early stage of fetal life.Refluxing ureteral endings show structural and functional anomalies: previous studies have shown a significant decrease in alfa actin, miosin and desmin contents as well as an high rate of atrophy and muscular degeneration with disorganized muscular fibres. The roles played by Cajal cells and Connexin 43 in generating peristaltic waves appears to be fundamental for the physiological VUJ function and activity. Attention was focused also on the congenital muscular deficiency of the RUs, on regard to general morphology, smooth muscle cells architecture, inflammatory markers and the distribution of collagen composition.This review will discuss and investigate the importance of the modified configuration of Sarcoglycan (SG) sub complex (particularly the deficiency of the ε-SG and the increased expression of the α-SG), the role played by Cajal Cells, the intravescical tunnel length to ureteral diameter ratio as possible causes of the functional alterations in the refluxing ureteral ends leading towards the VUJ incompetence.

A novel mutation in alpha sarcoglycan gene in an Iranian family with limb girdle muscular dystrophy 2D

Objective and importance: The sarcoglycanopathies (SGPs) are a subgroup of autosomal recessive limb girdle muscular dystrophies. They are caused by mutations in gamma, alpha, beta, and delta sarcoglycans (SGs) genes. Alpha-SGPs are the most frequent form of SGPs. Muscle biopsy studies in patients with SGPs have indicated that loss of one SG subunit leads to instability of whole SG complex. Autozygosity mapping is a powerful gene mapping approach for rare recessive inherited disorders in consanguineous families.Clinical presentation: In the present study, proband was a 9 year old girl from consanguineous parents. She was diagnosed at the age of 5 when she had problems climbing stairs. Her creatine kinase level was 16428 U/L. Proximal weakness and ankle contracture were also observed in the patient.Techniques: Autozygosity mapping, using short tandem repeat (STR) markers linked to the SG genes, showed co-segregation of the phenotype with STR markers linked to the SGCA (Alpha-sarcoglycan) gene. Her muscle biopsy also suggested alpha sarcoglycanopathy. Mutation analyses revealed a novel homozygous deletion of 11 base pairs in exon 4 of this gene. This deletion introduces a premature termination codon after the 4th amino acid. This will eliminate the expression of the downstream part of the extracellular domain of the protein. This domain has a critical role by associating with other molecules of dystrophin–glycoprotein complexes.Conclusion: IHC (Immunohistochemistry) studies combined with autozygosity mapping and mutation screening is an efficient diagnostic method in the SGPs.

A rare form of limb girdle muscular dystrophy (type 2E) seen in an Iranian family detected by autozygosity mapping

Sarcoglycanopathies (SGPs) constitute a subgroup of autosomal recessive limb girdle muscular dystrophies (LGMDs) which are caused by mutations in sarcoglycan (SGs) genes. SG proteins form a core complex consisting of α, β, γ and δ sarcoglycans which are encoded by SGCA, SGCB, SGCG and SGCD genes, respectively. Genetic defect, in any of these SG proteins, results in instability of the whole complex. This effect can be helpful in interpreting muscle biopsy results. Autozygosity mapping is a gene mapping approach which can be applied in large consanguineous families for tracking the defective gene in most autosomal recessive disorders. In the present study, we used autozygosity mapping, to find the gene responsible for muscular dystrophy. Proband was a 10-year-old boy referred to our center for ruling out DMD (Duchenne muscular dystrophy). According to the pedigree and clinical reports, we assessed him for SGPs. Haplotyping, using the four short tandem repeat (STR) markers for each of the SG genes, showed that the phenotype may segregate with SGCB gene; and observing two crossing overs which occurred within the gene suggested that the mutation might be in the first two exons of SGCB gene. Mutation analysis showed a 26 bp duplication (10 bp before the initiation codon till 13 bp after the ATG start codon). This will cause a frameshift in protein synthesis.

Sarcoglycan sub-complex and Satellite cells in masseter muscle of crossbite patients

Crossbite is a lateral misalignment of the dental arches. Subjects with unilateral posterior crossbite exhibit different kinematics of the mandible during mastication when chewing on the affected side, resulting in an increased frequency of reverse chewing cycles; moreover, the masseter of the affected side results less active than the counterpart (Piancino et al., 2006). An our immunofluorescence study on masseter muscle of crossbite patients has shown that in the affected side there is a lower expression of muscle specific integrins than the counterpart (Cutroneo et al., 2012). So, we hypothesized that integrins could be correlated with contraction activity in mastication, maybe promoting the production of new muscle fibers. Another our tractography study on crossbite patients has shown an increment of muscle fibers number in non affected side. On this basis in the present work we investigated the number of satellite cells in masseter muscle of crossbite patients, both in affected and non affected side. Since the existence of a bidirectional signaling between integrins and sarcoglycans we have also investigated the expression of the sarcoglycan subcomplex. Results show that the number of satellite cells in non affected side is higher than affected side. Moreover, in according with our previous results about integrins, even the sarcoglycan sub-complex show to be less expressed in the affected side than the counterpart. These data support that in non affected masseter muscle a new fibers production activity takes place which, in turns, determines a muscular hyperplasia. Based on our results, the myogenesis in masseter muscle could be regulated by sarcoglycan and integrin protein systems.

An immunofluorescence study of the sarcoglycan sub- complex in gingival epithelium both in normal and in pathological conditions

Sarcoglycans are transmembrane glycoproteins which provide the connection between cytoskeleton and extracellular matrix. Sarcoglycans have been found in many kind of tissues as epithelial tissues where they seem to be involved in cell-cell and cell-extracellular matrix adhesion by their cadherin-like domains; by that, it was supported that sarcoglycans could be also involved in pathological condition of epithelial tissue. Moreover, we have already tested sarcoglycans in altered gingival epithelia of patients treated with bisphosphonates where we have observed that the sarcoglycans staining pattern is influenced by inflammatory condition. For these reasons we have continued our immunofluorescence study on sarcoglycans in gingival epithelia of patients treated with bisphosphonates and also in gingival epithelia of patients affected by periodontitis and scleroderma, two different pathological conditions where it is possible to observe inflammation and alteration of the gingival epithelium. Results obtained from normal samples have shown the presence of a staining pattern for each sarcoglycan in gingival epithelium; pathological results, instead, have shown that the entire sarcoglycan sub-complex changes in staining pattern level depending on the inflammation and alteration degree of the gingival epithelia. All these finding suggest us that sarcoglycans could play a key role in maintenance of epithelia architecture by their machanosignaling function, providing cell-cell and cell-extracellular matrix adhesion using their cadherin like domain.

Map of the sarcoglycan sub-complex in rat brain

The sarcoglycan-sub-complex is made up of six glycoproteins which play mechanosignaling functions, connecting the extracellular matrix to cytoskeleton. This protein complex has been identified in different kind of tissues; in central nervous system, instead, only the ζ-sarcoglycans and the e-sarcoglycans are considered to be present, where they seem to play a different role from the role played in muscle. Although that, previous our study have shown the expression of the entire sarcoglycan sub-complex in some region of the rat brain and the colocalization of this complex with post-synaptic receptors as GABA and DOPA receptors. Since we found that each sarcoglycan changes in staining pattern level among the brain regions, in the present study we performed, for the first time, a map of sarcoglycans expression in whole brain of rat and we examined which kind of post-synaptic receptor colocalizes with sarcoglycans in each part of brain. Results have shown that in rat brain the staining pattern level for each sarcoglycan and the different kind of colocalization between sarcoglycans and post-synaptic receptors, sarcoglycan/GABA or sarcoglycan/ DOPA, are characteristic of each brain region. These results support a role of the sarcoglycan sub-complex in post-synaptic neurotransmission, maybe modulating post-synaptic receptor assembly and stabilization.

The dystrophin-glycoprotein complex and the vinculintalin- integrin system in sternocleidomastoid muscle of baboon

The dystrophin glycoprotein complex and the vinculin-talin-integrin system are two costameric protein systems which play several and important roles in muscle tissue. In particular, sarcoglycans and integrins, by a bidirectional signaling, seem to cooperate in lateral transmission of contraction forces. These protein systems have been well described in human muscle tissue and also in primates, as chimpanzee. Our previous study performed on masseter muscle of baboon, have shown interesting results about the presence of negative fibers for sarcoglycans and integrins in low dominance baboons, a social group characterized by a major aggressiveness than high dominance. These results suggested as that in low dominance baboons alternative isoforms of sarcoglycans and integrins could be exist. In the present study we continued the investigation of the entire protein complexes, not only sarcoglycans and integrins, in another type of skeletal muscle of baboons, the sternocleidomastoid both in high and in low dominance. Results have shown that also in sternocleidomastoid of low dominance baboons fibers negative for the tested proteins exist. These results confirm our previous findings on masseter of baboon and support our hypothesis about the presence of alternative protein systems which could be correlated with the aggressiveness degree and which could be involved in evolution of the species.

Expression of Sarcoglycans in the Human Cerebral Cortex: An Immunohistochemical and Molecular Study

The sarcoglycan (SG) complex (SGC) is a subcomplex within the dystrophin-glycoprotein complex (DGC) and is composed of several transmembrane proteins (α, β, δ, γ, ε and ζ). The DGC supplies a transmembranous connection between the subsarcolemmal cytoskeleton networks and the basal lamina in order to protect the lipid bilayer and to provide a scaffold for signaling molecules in all muscle cells. In addition to its role in muscle tissue, dystrophin and some DGC components are expressed in neurons and glia. Very little is known about the SG subunits in the central nervous system (CNS) and some data suggested the presence of ε and ζ subunits only. In fact, mutations in the ε-SG gene cause myoclonus-dystonia, indicating its importance for brain function. To determine the presence and localization of SGC in the human cerebral cortex, we performed an investigation using immunofluorescence, immunoblotting and reverse transcriptase polymerase chain reaction. The results showed that all SG subunits are expressed in the human cerebral cortex, particularly in large neurons but also in astrocytes. These data suggest that the SG subcomplex may be involved in the organization of CNS synapses.

Sarcoglycan subcomplex: state of the art

sarcoglycan subcomplex: state of the art

Sarcoglycan sub-complex in WAG/Rij rats, a model of absence epilepsy: an immunofluorescence study

It is known that even in Central Nervous System the Dystrophin Glycoprotein Complex (DGC) exists but differs in composition from the DGC core present in muscle for the presence of several isoforms of dystrophin and for the existence of a sarcoglycan sub-complex which is made up only for e- and ζ-sarcoglycans; for these reasons it was called “DGC-like”. Although that, in our previous studies we have found that all sarcoglycans are present in human cerebral cortex and in different regions of rat’s brain, suggesting that the composition of the brain DGC is not different from the muscle DGC but differing just for the function. In fact, our previous data showing the colocalization between sarcoglycans and GABAA Re receptors in rat’s cerebral and cerebellar cortex, thalamus and hippocampus suggested us that in brain sarcoglycans could be associated with synaptic neurotransmission. To better understand which kind of relationship between sarcoglycans and GABAA receptors exists, we aim to investigate α-,β-,γ-,δ-,e- and ζ-sarcoglycans and the GABAA Re in the brain of the WAG/Rij rats, a model of absence epilepsy, using immunofluorescence techniques; we have observed cerebral cortex, thalamus and hippocampus, the structures mainly involved in absence epilepsy, comparing this to normal rat’s brain. Results show that the GABAA Re receptors staining pattern is different from the normal rat’s brain presenting an abnormal fluorescence distribution consisting in discontinuous clusters around the cellular body. Sarcoglycans, instead, have shown the typical “spot-like” staining pattern around the cellular body, sometimes colocalizing with GABAA Re receptor; moreover, they seem to have an higher staining pattern than normal rat’s brain. In our opinion these results, showing an alteration of GABAA Re receptor pattern distribution and a normal or increased sarcoglycans staining pattern, allow us to hypothesize that the sarcoglycans in absence epilepsy are likely to compensate for the alteration in GABAA Re receptor distribution. That support the opinion about the involvement of sarcoglycans in cellular signalling and receptor assembly regulating indirectly synaptic neurotransmission both in normal and in pathological condition.

Sarcoglycans and integrins in masseter muscle of baboons: an immunohistochemical and molecular study

The sarcoglycans subcomplex consists of six transmenbrane proteins (α,β,δ,γ,e,ζ), functionally connected by a bidirectional signalling with integrins, transmembrane receptors that play a key role in cell adhesion and differentiation. b1D-integrin is detected only in skeletal and cardiac muscle, while low amounts of b1A were detected in striated muscles. b1D was associated with α7A and α7B in adult skeletal. Although numerous studies have been carried out on these proteins in many muscle types, insufficient data exist on their behaviour in masseter muscle, an highly unusual muscle for the presence, in addition to slow and fast fibers, of hybrid fibers types important for the specific functional demands of masseter. Our studies on normal human masseter muscle and on masseter of subjects with right crossbite, showed that integrins play a role in the functional activity of muscle and in the optimization of contractile forces. Also, we studied these proteins in masseter of chimpanzees, alpha and non-alpha male subjects. These results have shown a different quantitative composition of integrins in alpha male in respect to non-alpha male hypothesizing a key role for integrins and sarcoglycans in the determination of contraction force. Here, we analyzed masseter muscle obtained from baboons, animals similar in phylogeny with humans and chimpanzees, individuating subjects with high and low dominance. Our immunohistochemical results, confirmed also by Western Blotting analysis, show that, in high dominance subjects, stainings for sarcoglycans and integrins were normal; interestingly, in low dominance subjects stainings for these proteins were normal, lower or absent in different fibers of the same microscopic field. Thus, preliminary analysis on cell cultures of myoblasts and myotubes, at different days of differentiation, immunolabelled with antibodies against sarcoglycans and integrins, have demonstrated a similar behaviour, showing cells with an higher or lower staining for these proteins. In our opinion, these results provide the first suggestion that integrins and sarcoglycans in masseter muscle play a key role regulating muscular functional activity and allowing the optimization of contractile forces of this muscle.

Founder Mutation for a-sarcoglycan-LGMD2D in a Magdalen Islands Acadian Cluster

We have recruited a group of four living and reviewed the records of six deceased distantly related French-Canadians of Acadian descent affected by a childhood-onset form of recessive limb-girdle muscular dystrophy (LGMD). All cases originate from the small archipelago of the Magdalen Islands (population: 13,000) isolated in the Gulf of St-Lawrence. Based on the likely sharing of the same founder mutation we completed a 319K SNPs genome-wide scan to identify the disease locus and then screen candidate genes in this region. All patients had normal initial motor milestones. They presented with limb girdle weakness at the average age of seven years (5-11). Progressive weakness led to loss of ambulation at a wide range of ages (10-39). Patients also developed macroglossia, large calves and mild to moderate contractures, hyperlordosis and decreased pulmonary function. Creatine kinase levels were elevated (1,800-10,000 U/L) in the first decades, but decreased with progression of disease. Homozygosity mapping uncovered a shared chromosomal region of 6.33Mb. The alpha sarcoglycan (SGCA) gene, mutated in LGMD2D, lay in this candidate interval. Sequencing of all SGCA exons uncovered a shared homozygous missense mutation (c. 229C>T, p.R77C), the most common SGCA mutation internationally reported. Using demographic data, we estimated a high carrier rate of 1/22. The p.R77C mutation has also been observed in many populations, including in France and Spain (Basques). This corresponds to the first reported recessive founder disease for the Magdalen Islands, an archipelago settled in the XIXth century, largely by Acadian immigrants.

Sarcoglycans in cerebellar cortex: an immunohistochemical study

Sarcoglycans are transmembrane glycoproteins which link each others to form the sarcoglycans sub-complex. This protein system plays a key role in fibers stabilization during muscle activity. Sarcoglycans have been mainly studied on muscle tissue but they aren’t muscle specific. In fact, our previous studies have shown that all of sarcoglycans isoforms are also expressed in various non-muscular tissues and in particular in brain where it was known that only e- and ξ-sarcoglycans were present. We have yet tested α-, β-, γ-, δ- and e-sarcoglycans in rat’s cerebellar cortex and we have found that each glycoprotein is expressed with an immunofluorescence pattern that was detectable mainly in a single cells layer, probably the Purkinje cells layer. In order to verify if this single cells layer could correspond to Purkinje cells layer, we carried out a double immunofluorescence reaction with α,-β,-γ,-δ,-e and –ξ sarcoglycans antibody and CAR VIII antibody, a carbonic anhydrases protein which marks the Purkinje cells. Our results have confirmed that the fluorescence pattern of each sarcoglycans was mainly detectable in Purkinje cells and some fluorescences pattern is also detectable in molecular layer. We have not found sarcoglycans positivity in granular cells layer. Moreover we have found that, in cerebellar cortex, sarcoglycans present a double type of staining pattern: the first one is a “spot-like” staining pattern, detectable around the cellular soma; the second one is a linear staining pattern, detectable on the cellular extension. These results suggest us that in the soma of the Purkinje cells, sarcoglycans may play a role in cellular signalling, regulating the assembly of post-synaptic receptor. We think that sarcoglycans may be associated with inhibitory GABAA Re receptors. It is therefore possible that the linear fluorescence present in some cellular extension could correspond to some interneurons with inhibitory activity.

Sarcoglycan subcomplex on normal and pathological prostatic tissue : an immunohistochemical and molecular study

The sarcoglycan complex (SGC) is a multimember transmembrane complex interacting with other member of dystrophin-glycoprotein complex (DGC) in order to provide a mechano-signaling connection from the cytoskeleton to the extracellular matrix in myocytes. Previous investigations have demonstrated that in skeletal and cardiac muscle, the SGC is a heterotetrameric unit constituted by the alfa, beta, gamma and delta-sarcoglycans. Other authors demonstrated that the expression of alfa-sarcoglycan is restricted to striated muscle cells, whereas epsilon-sarcoglycan, is also expressed in several other tissues. Moreover, further analysis showed the presence, in vascular and visceral smooth muscle, of other sarcoglycan subcomplex, consisting of epsilon, beta, gamma and delta-sarcoglycan, associated with sarcospan. In order to verify composition of sarcoglycan subcomplex in other tissues, we analyzed glandular epithelium of prostate, testing it both in normal and in pathological conditions. In particular we performed immunofluorescence reactions using all sarcoglycans alfa, beta, gamma, delta and epsilon) on biopsies of ten normal subjects, and ten subjects with prostatic hyperplasia and prostatic cancer. Our results showed that in normal prostate all tested sarcoglycan are detectable both in epithelial and in myoepithelial cells; whereas in biopsies of prostatic hyperplasia all sarcoglycans were less detectable, whereas in prostatic carcinoma they were almost absent in both cell types. These data demonstrated that also in epithelium of prostate, as well as in all epithelia previously tested by us, the sarcoglycan subcomplex play a key role in mediating the signalling between cell and extracellular matrix; moreover, the absence of all sarcoglycans in pathological glandular tissue, and in particular in mioepithelial cells, demonstrated that this glycoprotein can play an important role in signalling for contraction of these cells.

Sarcoglycans in brain

Sarcoglycans in brain