Characterization of a novel Dp71 dystrophin-associated protein complex (DAPC) present in the nucleus of HeLa cells: Members of the nuclear DAPC associate with the nuclear matrix

Abstract

, et al.. Characterization of a novel Dp71 dystrophin-associated protein complex (DAPC) present in the nucleus of HeLa cells: members of the nuclear DAPC associate with the nuclear matrix.. Experimental Cell Research, Elsevier, 2006, 312 (16) ABSTRACT: Dystrophin is an essential component in the assembly and maintenance of the dystrophinassociated protein complex (DAPC), which includes members of the dystroglycan, syntrophin, sarcoglycan and dystrobrevin protein families. Distinctive complexes have been described in the cell membrane of different tissues and cultured cells. In this work, we report the identification and characterization of a novel DAPC present in the nuclei of HeLa cells, which contains dystrophin Dp71 as a key component. Using confocal microscopy and cell fractionation analyses, we found the presence of Dp71, β-sarcoglycan, β-dystroglycan, α-and β-syntrophin, α1-and β-dystrobrevin and nNOS in the nuclei of HeLa cells. Furthermore, we demonstrated by coimmunoprecipitation experiments that most of these proteins form a complex in the nuclear compartment. Next, we analyze the possible association of the nuclear DAPC with the nuclear matrix. We found the presence of Dp71, β-dystroglycan, nNOS, β-sarcoglycan, α/β syntrophin, α1-dystrobrevin and β-dystrobrevin in the nuclear matrix protein fractions and in situ nuclear matrix preparations from HeLa cells. Moreover, we found that Dp71, β-dystroglycan and β-dystrobrevin co-immunoprecipitated with the nuclear matrix proteins lamin B1 and actin. The association of members of the nuclear DAPC with the nuclear matrix indicates that they may work as scaffolding proteins involved in nuclear architecture.

Dynamic Changes in the Subcellular Localization of Drosophila .BETA.-Sarcoglycan during the Cell Cycle

“…The presence of β-sarcoglycan in nuclei was previously reported in HeLa cells based on confocal microscopy and also its association with the nuclear matrix. Similar observations have also been made for Dp71 dystrophin, β-dystroglycan, α-and β-syntrophin, α1-and β-dystrobrevin (Fuentes-Mera et al, 2006). Moreover, Dp71 dystrophin is also localized in the nuclei of PC12 cells (Calderilla-Barbosa et al, 2006).…”

“…On the other hand, several recent studies have revealed that mammalian DGC components are also present in cytoplasm and nuclei (Calderilla-Barbosa et al, 2006;Fuentes-Mera et al, 2006;Marquez et al, 2003;Radojevic et al, 2000). However, no study which addresses their dynamics of distribution on cell cycle progression has been reported so far.…”

The Interaction with HMG20a/b Proteins Suggests a Potential Role for β-Dystrobrevin in Neuronal Differentiation

“…Although dystrobrevin, at first considered a cytoplasmic component of the DPC, has already been described in the nuclear compartment (37,41), iBRAF was so far regarded essentially as a nuclear protein (35). Our confocal microscopy results show that iBRAF and ␤-dystrobrevin colocalize in the nucleus as well as in the cytoplasm of co-transfected cells.…”

Nuclear Recruitment of Neuronal Nitric-oxide Synthase by α-Syntrophin Is Crucial for the Induction of Mitochondrial Biogenesis

“…However, ␣-Syntrophin and Dystrophin have been also observed in the inner nuclear membrane of cultured myocytes, and its level increases during myogenesis in nuclei (57,58). Interestingly, nNOS␣ has been revealed in the nuclear membrane of HeLa cells in association with Dystrophin and ␣-Syntrophin (46). We have demonstrated that nNOS was no more able to be translocated in the nucleus when ␣-Syntrophin was down-regulated.…”

“…␣-Syntrophin Is Implicated in nNOS Recruitment to Nuclei-␣-Syntrophin, which is a known interactor of nNOS at the sarcolemma (6), was found in the nuclear compartment of HeLa cells, and at this level it is part of the nuclear Dystrophin complex together with nNOS (46). Interestingly, ␣-Syntrophin was also localized in nuclei of C2C12 cells (55).…”