Nuclear particles containing RNA polymerase III complexes associated with the junctional plaque protein plakophilin 2

Mertens, Claudia; Hofmann, Ilse; Wang, Zhengxin; Teichmann, Martin; Chong, Setareh Sepehri; Schnölzer, Martina; Franke, Werner W.

doi:10.1073/pnas.141219498

Cited by 108 publications

(101 citation statements)

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“…The plakophilins, which are armadillo-related proteins, contain ten 42-amino acid armadillorepeat motifs and are located in the outer dense plaque of desmosomes linking desmosomal cadherins with desmoplakin and the intermediate filament system 8 . Like other armadillo-repeat proteins, plakophilins are also found in the nucleus, where they may have a role in transcriptional regulation 9 . Plakophilin-2 exists in two alternatively spliced isoforms (2a and 2b), interacts with multiple other cell adhesion proteins and is the primary cardiac plakophilin 8,10 .…”

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confidence: 99%

Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy

et al. 2004

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Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy

et al. 2004

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“…Note that most of the symplekin is recovered in particles with a peak value of ϳ11S, whereas minor portions appear with a mean peak corresponding to ϳ65S or in the pellet. Interestingly, all so far characterized nuclear forms of junctional plaque proteins have in common that they are somehow involved in processes of transcription, splicing, or 3Ј-end processing: Plakophilin 2 has been detected in RNA polymerase III complexes, p120 ctn and ␤-catenin are involved in regulations of RNA polymerase II transcription, and protein 4.1 has been found in splicing factors (Behrens et al, 1996;Huber et al, 1996;Molenaar et al, 1996;Krauss et al, 1997;Lallena et al, 1998;Daniel and Reynolds, 1999;Mertens et al, 2001). Symplekin is the first protein associated with factors involved in 3Ј-end processing of premRNA in the nucleus as well as in cytoplasmic translational control.…”

Section: Molecular Biology Of the Cell 1672mentioning

confidence: 99%

“…To elucidate the nuclear function(s) of symplekin we have applied biochemical methods for isolating and characterizing the protein, using methods that recently have been successful in studies of the nuclear forms of plakophilin PKP2, which has been shown to be part of RNA polymerase III complexes (Mertens et al, 2001). For the sake of clarity we have further decided to start with the exceptionally large nuclei of Xenopus laevis oocytes ("germinal vesicles") allowing both mass and manual isolations with minimal cytoplasmic contamination as well as the preparation of enucleated "ooplasms," and thus the parallel analysis of both karyoplasm and cytoplasm (cf.…”

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confidence: 99%

Symplekin, a Constitutive Protein of Karyo- and Cytoplasmic Particles Involved in mRNA Biogenesis inXenopus laevisOocytes

Hofmann¹,

Schnölzer

Kaufmann

et al. 2002

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Symplekin is a dual location protein that has been localized to the cytoplasmic plaques of tight junctions but also occurs in the form of interchromatin particles in the karyoplasm. Here we report the identification of two novel and major symplekin-containing protein complexes in both the karyo-and the cytoplasm of Xenopus laevis oocytes. Buffer-extractable fractions from the karyoplasm of stage IV-VI oocytes contain an 11S particle, prepared by immunoselection and sucrose gradient centrifugation, in which symplekin is associated with the subunits of the cleavage and polyadenylation specificity factor (CPSF). Moreover, in immunofluorescence microscopy nuclear symplekin colocalizes with protein CPSF-100 in the "Cajal bodies." However, symplekin is also found in cytoplasmic extracts of enucleated oocytes and egg extracts, where it occurs in 11S as well as in ca. 65S particles, again in association with CPSF-100. This suggests that, in X. laevis oocytes, symplekin is possibly involved in both processes, 3Ј-end processing of pre-mRNA in the nucleus and regulated polyadenylation in the cytoplasm. We discuss the possible occurrence of similar symplekin-containing particles involved in mRNA metabolism in the nucleus and cytoplasm of other kinds of cells, also in comparison with the nuclear forms of other dual location proteins in nuclei and cell junctions. INTRODUCTIONCell biologists had recently to recognize, much to their surprise, that certain proteins appear, often in the same cells, as "dual location proteins," i.e., as general constituents of two rather distant and different structures: On the one hand, they occur as components of cytoskeletal plaques of a specific kind of intercellular junction, and on the other hand, they are located in karyoplasmic, interchromatinic granules, even in cells devoid of any junctions. Examples include the plakophilins PKP 1-3, typical of desmosomal plaques (Mertens et al., 1996;Schmidt et al., 1997Schmidt et al., , 1999Bonné et al., 1999), the adherens junction proteins, ARVCF (Borrmann, 2000;Borrmann et al., 2000; for cDNA transfection experiments see also Mariner et al., 2000), afadin (Mandai et al., 1997) and protein 4.1 (Krauss et al., 1997;Lallena et al., 1998), and the tight junction plaque proteins ZO-1 (Gottardi et al., 1996), symplekin (Keon et al., 1996), Ash-1 (Nakamura et al., 2000), and ZONAB (Balda and Matter, 2000). Obviously, this constitutively dual location at junctions and in nuclei has to be distinguished from observations of transient nuclear accumulations of certain other junctional plaque proteins in special stages of the cell cycle or differentiation or upon expression of certain transfected cDNAs or genes (for examples see, e.g., Funayama et al., 1995;Karnovsky and Klymkowsky, 1995;Behrens et al., 1996;Huber et al. 1996;Molenaar et al., 1996;Schneider et al., 1996;Yost et al., 1996;Daniel and Reynolds, 1999; for reviews see Behrens, 2000;Hü bner et al., 2001).Such a constitutively dual localization has also been reported in many diverse cultured cells and...

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“…Nuclear plakophilin-2 localization has been previously reported; however, the functional role of plakophilin-2 in the nucleus is currently unknown (Mertens et al 1996). Previous reports have identified RNA polymerase III as a nuclear binding partner of plakophilin-2 (Mertens et al 2001); however, the functional consequences of this interaction have not been investigated. Attempts to identify additional nuclear binding partners in A431 cells were unsuccessful.…”

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Arrhythmogenic Right Ventricular Cardiomyopathy Plakophilin-2 Mutations Disrupt Desmosome Assembly and Stability

Hall

et al. 2009

Cell Communication & Adhesion

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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by lifethreatening ventricular arrhythmias and fibrofatty replacement of the cardiac tissue. Desmosomes are prominent cell-cell junctions found in a variety of tissues that resist mechanical stress, including the heart, and recruit the intermediate filament cytoskeleton to sites of cell-cell contact. Mutations in several desmosomal components including plakophilin-2 have been identified in ARVC patients; however, the molecular interactions disrupted by plakophilin-2 mutations are currently unknown. To understand the pathological basis of ARVC, the authors analyzed desmosome assembly and stability in epithelial cell lines expressing mutants of plakophilin-2 found in ARVC patients. Mutant plakophilin-2 proteins were unable to disrupt established desmosomes when expressed in an E-cadherinÁexpressing epithelial cell model; however, they were unable to initiate de novo assembly of desmosomes in an N-cadherinÁexpressing epithelial cell model. These studies expand our understanding of desmosome assembly and dynamics.

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Nuclear particles containing RNA polymerase III complexes associated with the junctional plaque protein plakophilin 2

Cited by 108 publications

References 45 publications

Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy

Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy

Symplekin, a Constitutive Protein of Karyo- and Cytoplasmic Particles Involved in mRNA Biogenesis inXenopus laevisOocytes

Arrhythmogenic Right Ventricular Cardiomyopathy Plakophilin-2 Mutations Disrupt Desmosome Assembly and Stability

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