Monoclonal antibodies against plant proteins recognise animal intermediate filaments

Abstract

Four monoclonal antibodies were raised against polypeptides present in a high-salt detergent-insoluble fraction from cells of Chlamydomonas reinhardtii. Indirect immunofluorescence microscopy of fibroblasts and epithelial cells grown in culture using these plant antibodies revealed staining arrays identical to those obtained with well characterised antibodies to animal intermediate filaments. Immunofluorescence microscopy of Chlamydomonas with these monoclonal antibodies and a monoclonal antibody that recognises all animal intermediate filaments (anti-IFA) gave a diffuse, patchy cytoplasmic staining pattern. Both the plant antibodies and anti-IFA stained interphase onion root tip cells in a diffuse perinuclear pattern. In metaphase through to telophase, the labelling patterns colocalised with those of microtubules. Labelling of the phragmoplast was also detected but not staining of the preprophase band. On Western blots of various animal cell lines and tissues, all the antibodies labelled known intermediate filament proteins. On Western blots of whole Chlamydomonas proteins, all the antibodies labelled a broad band in the 57,000 Mr range, and three antibodies labelled bands around 66,000 and 140,000 Mr but with variable intensities. On Western blots of whole onion root tip proteins, all the antibodies labelled 50,000 Mr (two to three bands) polypeptides and a diffuse band around 60,000 Mr and three of the antibodies also labelled several polypeptides in the 90,000-200,000 Mr range. The consistent labelling of these different bands by several different monoclonal antibodies recognising animal intermediate filaments makes these polypeptides putative plant intermediate filament proteins.

Identification and localization of proteins immunologically related to intermediate filament proteins in sea urchin eggs and embryos

“…Similar results were obtained in the case of mitosis in plant cell suspensions [Dawson et al, 1985;Parke et al, 1987;Goodbody et al, 19891. In addition to microtubules, mitotic spindle from sea urchin eggs have been shown to be composed of spindle fibers of 3-4 nm [Salmon, 19821 and some proteins behaving like IFs proteins in terms of their solubility Rebhun and Palazzo, 19881.…”

Putative Arabidopsis homologues of metazoan coiled‐coil cytoskeletal proteins

“…For example, the coiled‐coil domain of EHD2 (EH domain‐containing) inhibits endocytosis in plants and influences actin organization, and its inhibitory effect on endocytosis may be through actin redistribution (Bar et al, 2009). The coiled‐coil domain of CHUP1 (chloroplast unusual positioning 1) prevents chloroplast aggregation and participates in chloroplast relocation movement via the actin cytoskeleton (Oikawa et al, 2008). Myosins are well‐known cytoskeletal coiled‐coil domain proteins, which in plants play key roles in linking organelles to the actin cytoskeleton as well as creating cytoplasmic streaming through their movement along actin filaments (Li and Nebenfűhr, 2008).…”

Ultrastructural and cytochemical investigations on the functional role of proteinaceous nuclear inclusions (PNIs) in chlorenchyma plant cells

“…What is the relation between PNIs and other types of inclusions with the same structural polymorphism, either in plant cells -especially the P-proteins of sieveelements [2] -or in animal cells -in particular the neuronal nuclear inclusions [7, 39,64]? And finally, what is their relation with plant and animal intermediate filaments [8,17,25,27,32,44,54] and with nuclear inclusions that occur under pathological conditions, virus infections, cellular aging and stress [22,34,35,46]?…”

“…In particular the thickness, 8.0-12.0 nm, of IFs, their structural organization in protofilaments with a helical order and their tendency to build wide paracrystals or cytoplasmic and nuclear fibrillar bundles (FBs) are reminiscent to PNIs [44]. It is known the different groups of intermediate filaments share a common antigenic determinant which reacts with a monoclonal antibody referred to as anti-IFA [57] and is has been proved more than once that plant cell fibrillar bundles (FBs) contain polypeptides which are antigenically correlated to the intermediate filaments in animal cells [17,27,32,54]. The structural similarities and the recent confirmation of the occurrence of intermediate filaments in the plant cell nucleus [8,25] appear to suggest a cytoskeletal or specifically nucleoskeletal nature of PNIs.…”