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14 p.-5 fig.-2 tab., Nuclear matrix constituent proteins (NMCPs), the structural components of the plant lamina, are considered to be the analogues of lamins in plants based on numerous structural and functional similarities. Current phylogenetic know-ledge suggests that, in contrast to lamins, which are widely distributed in eukaryotes, NMCPs are taxonomically re-stricted to Streptophyta. At present, most information about NMCPs comes from angiosperms, and virtually no data are available from more ancestral groups. In angiosperms, the NMCP family comprises two phylogenetic groups, NMCP1 and NMCP2, which evolved from the NMCP1 and NMCP2 progenitor genes. Based on sequence conservation and the presence of NMCP-specific domains, we determined the structure and number of NMCP genes present in different Streptophyta clades. We analysed 91 species of embryophytes and report additional NMCP sequences from mosses, liverworts, clubmosses, horsetail, ferns, gymnosperms, and Charophyta algae. Our results confirm an origin of NMCPs in Charophyta (the earliest diverging group of Streptophyta), resolve the number and structure of NMCPs in the different clades, and propose the emergence of additional NMCP homologues by whole-genome duplication events. Immunofluorescence microscopy demonstrated localization of a basal NMCP from the moss Physcomitrella patens at the nuclear envelope, suggesting a functional conservation for basal and more evolved NMCPs., This work was supported by the Spanish Ministry of Science and Innovation (BFU2010-15900) and CSIC (PIE 201020E019).

26 p.-3 fig.-3 fig. supl.-1 tab. supl., Nuclear lamina organization is similar in metazoan and plants though the latter lack orthologs of lamins, the main components of the metazoan lamina. Current evidence suggests that Nuclear Matrix Constituent Proteins (NMCPs) are the lamin analogues in plants as these proteins share several key features: higher-order secondary structure and domain layout, subnuclear distribution, and involvement in the regulation of nuclear shape and size, as well as in higher-order chromatin organization. Previously, we studied the NMCP family in flowering plants (angiosperms), in which it comprises two phylogenetic groups: NMCP1 and NMCP2. At present, in silico information about NMCP proteins in embryophytes is relatively advanced, though very few proteins, most of them of the NMCP1 type, have been extensively studied in vivo. We previously characterized the NCMP1 protein in the monocot Allium cepa. Here, we report the key features of a second protein of this species NMCP2, which presents a conserved sequence and domain layout. Immunofluorescence and immunoelectronmicroscopy evidence co-localization of endogenous AcNMCP2 and AcNMCP1 in the lamina, while Western blotting and immunoconfocal microscopy reveal a similar pattern of expression and distribution of both NMCP proteins in different root tissues. Our results provide novel insight about endogenous NMCP2-type proteins and complete the characterization of the NMCP family in A. cepa, thus advancing the current understanding of these structural proteins constituting the plant lamina., This work was supported by the Spanish Ministry of Science and Innovation [BFU2010-15900] and the Spanish National Research Council (CSIC) [PIE 201020E019].

The nucleoskeleton of plants contains a peripheral lamina (also called plamina) and, even though lamins are absent in plants, their roles are still fulfilled in plant nuclei. One of the most intriguing topics in plant biology concerns the identity of lamin protein analogues in plants. Good candidates to play lamin functions in plants are the members of the NMCP (nuclear matrix constituent protein) family, which exhibit the typical tripartite structure of lamins. This paper describes a bioinformatics analysis and classification of the NMCP family based on phylogenetic relationships, sequence similarity and the distribution of conserved regions in 76 homologues. In addition, NMCP1 in the monocot Allium cepa characterized by its sequence and structure, biochemical properties, and subnuclear distribution and alterations in its expression throughout the root were identified. The results demonstrate that these proteins exhibit many similarities to lamins (structural organization, conserved regions, subnuclear distribution, and solubility) and that they may fulfil the functions of lamins in plants. These findings significantly advance understanding of the structural proteins of the plant lamina and nucleoskeleton and provide a basis for further investigation of the protein networks forming these structures.

24 p.-6 fig., Este artículo pertenece a la Tesis presentada por Malgorzata Ciska con título: "Caracterización de AcNMCP1 una proteína implicada en organización nuclear de plantas."(https://digital.csic.es/handle/10261/98559), The nucleoskeleton of plants contains a peripheral lamina also called plamina, and even though lamins are absent in plants, their roles are still fulfilled in plant nuclei. One of the most intriguing topics in plant biology concerns the identity of lamin protein analogues in plants. Good candidates to play lamin functions in plants are the members of the NMCP (nuclear matrix constituent protein) family, which exhibit the typical tripartite structure of lamins. Here, we describe a bioinformatics analysis and the classification of the NMCP family based on phylogenetic relationships, sequence similarity and the distribution of conserved regions in 76 homologues. In addition, we characterized NMCP1 in the monocot Allium cepa, determining its sequence and structure, biochemical properties and sub-nuclear distribution, and identifying alterations in its expression throughout the root. Our results demonstrate that these proteins exhibit many similarities to lamins (structural organization, conserved regions, subnuclear distribution and solubility) and that they may fulfil the functions of lamins in plants. These findings significantly advance our understanding of the structural proteins of the plant lamina and nucleoskeleton, and they provide a basis for further investigation of the protein networks forming these structures., This work was supported by the Spanish Ministry of Science and Innovation [BFU2010-15900] and CSIC [PIE 201020E019]. Malgorzata Ciska was supported by a Junta de Ampliacion de Estudios grant (JAE): JAEPre_08_00012/JAEPre027.

34 p.-2 fig.-2 tab. Este artículo pertenece a la Tesis presentada por Malgorzata Ciska con título: "Caracterización de AcNMCP1 una proteína implicada en organización nuclear de plantas."(https://digital.csic.es/handle/10261/98559), Lamins are the main components of the metazoan lamina, and while the organization of the nuclear lamina of metazoans and plants is similar, there are apparently no genes encoding lamins or most lamin-binding proteins in plants. Thus, the plant lamina is not lamin-based and the proteins that form this structure are still to be characterized. Members of the plant NMCP/LINC/CRWN protein family share the typical tripartite structure of lamins, although the 2 exhibit no sequence similarity. However, given the many similarities between NMCP/LINC/CRWN proteins and lamins (structural organization, position of conserved regions, sub-nuclear distribution, solubility, and pattern of expression), these proteins are good candidates to carry out the functions of lamins in plants. Moreover, functional analysis of NMCP/LINC mutants has revealed their involvement in maintaining nuclear size and shape, another activity fulfilled by lamins. This review summarizes the current understanding of NMCP/LINC proteins and discusses future studies that will be required to demonstrate definitively that these proteins are plant analogs of lamins. © 2013 Landes Bioscience., We acknowledge support from the Spanish Ministry of Science and Innovation [BFU2010–15900] and the CSIC [PIE 201020E019]. Ciska M was supported by a grant from the Junta de Ampliación de Estudios (JAEPre_08_00012/JAEPre027) and by PIE 201020E019.