The translationally repressed pollen-specific ntp303 mRNA is stored in non-polysomal mRNPs during pollen maturation

Honys, David; Combe, Jonathan P.; Twell, David; Čapková, Věra

doi:10.1007/s004970000047

Cited by 38 publications

(52 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The presence of enhanced levels of these factors in anthers and pollen is consistent with previous expression studies showing higher levels of initiation factors in the meristematic regions that contain higher numbers of dividing and expanding cells Rodriguez et al, 1998). Whereas anthers contain actively expanding immature pollen grains, there is good evidence to indicate that early pollen tube growth following germination is strictly dependent upon the efficient translation of mRNAs stored as mRNPs in mature dehydrated pollen (Mascarenhas, 1990;Honys et al, 2000). The translation initiation factors, including NteIF4E, NteIFiso4E, and tobacco T eIF4A are likely to be major constituents of these mRNP complexes.…”

Section: Discussionsupporting

confidence: 88%

Translation initiation factors eIF4E and eIFiso4E are required for polysome formation and regulate plant growth in tobacco

et al. 2005

Self Cite

View full text Add to dashboard Cite

eIF4E and eIFiso4E T AbstractEukaryotic initiation factor eIF4E plays a pivotal role in translation initiation. As a component of the ternary eIF4F complex, eIF4E interacts with the mRNA cap structure to facilitate recruitment of the 40S ribosomal subunit onto mRNA. Plants contain two distinct cap-binding proteins, eIF4E and eIFiso4E, that assemble into different eIF4F complexes. To study the functional roles of eIF4E and eIFiso4E in tobacco, we isolated two corresponding cDNAs, NteIF4E1 and NteIFiso4E1, and used these to deplete cap-binding protein levels in planta by antisense downregulation. Antibodies raised against recombinant NteIF4E1 detected three distinct cap-binding proteins in tobacco leaf extracts; NteIF4E and two isoforms of NteIFiso4E. The three cap-binding proteins were immuno-detected in all tissues analysed and were coordinately regulated, with peak expression in anthers and pollen. Transgenic tobacco plants showing significant depletion of either NteIF4E or the twoNteIFiso4E isoforms displayed normal vegetative development and were fully fertile.Interestingly, NteIFiso4E depletion resulted in a compensatory increase in NteIF4E levels, whereas the down-regulation of NteIF4E did not trigger a reciprocal increase in NteIFiso4E levels. The antisense depletion of both NteIF4E and NteIFiso4E resulted in plants with a semi-dwarf phenotype and an overall reduction in polyribosome loading, demonstrating that both eIF4E and eIFiso4E support translation initiation in planta, which suggests their potential role in the regulation of plant growth.

show abstract

Section: Discussionsupporting

confidence: 88%

Translation initiation factors eIF4E and eIFiso4E are required for polysome formation and regulate plant growth in tobacco

et al. 2005

Self Cite

View full text Add to dashboard Cite

show abstract

“…The parameters compared included the ultracentrifugation speed and duration as well as various sucrose concentrations in the cushion. In comparison with the original protocol (60% sucrose cushion; Figure 2A), 33 no changes in the EPP profile and yet a higher yield were obtained after 3 h and 20 min sedimentation though 30% sucrose under 60 000 rpm ( Figure 2C). Alternatively, SEC was employed for the direct isolation of EPP complexes from postmitochondrial supernatant without presedimentation through sucrose cushion.…”

Section: Epps Are Present In Growing Pollenmentioning

confidence: 82%

“…The presence of EPPs in immature and mature pollen was demonstrated previously. 33 During the progamic phase, EPPs were detectable in activated pollen grains after 30 min imbibition in the cultivation medium as well as in growing pollen tubes cultivated in vitro for 4 h and even 24 h (Figure 1). 2-D SDS-PAGE gels were loaded with proteins isolated from an equal amount of mature dry pollen (40 mg).…”

Section: Epps Are Present In Growing Pollenmentioning

confidence: 99%

“…33 These mRNP complexes containing translationally silent ntp303 mRNAs are resistant to polysomal destabilizing components and co-sediment with polysomes. 33 Here, we analyzed the size and structure of large ribonucleoprotein particles (EPP) complexes by means of the size exclusion chromatography and electron microscopy. The association of EPPs with cytoskeleton was determined by fluorescence microscopy and Western blot immunodetection.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cytoskeleton-Associated Large RNP Complexes in Tobacco Male Gametophyte (EPPs) Are Associated with Ribosomes and Are Involved in Protein Synthesis, Processing, and Localization

et al. 2009

View full text Add to dashboard Cite

The progamic phase of male gametophyte development involves activation of synthetic and catabolic processes required for the rapid growth of the pollen tube. It is well-established that both transcription and translation play an important role in global and specific gene expression patterns during pollen maturation. On the contrary, germination of many pollen species has been shown to be largely independent of transcription but vitally dependent on translation of stored mRNAs. Here, we report the first structural and proteomic data about large ribonucleoprotein particles (EPPs) in tobacco male gametophyte. These complexes are formed in immature pollen where they contain translationally silent mRNAs. Although massively activated at the early progamic phase, they also serve as a long-term storage of mRNA transported along with the translational machinery to the tip region. Moreover, EPPs were shown to contain ribosomal subunits, rRNAs and a set of mRNAs. Presented results extend our view of EPP complexes from mere RNA storage and transport compartment in particular stages of pollen development to the complex and well-organized machinery devoted to mRNA storage, transport and subsequent controlled activation resulting in protein synthesis, processing and precise localization. Such an organization is extremely useful in fast tip-growing pollen tube. There, massive and orchestrated protein synthesis, processing, and transport must take place in accurately localized regions. Moreover, presented complex role of EPPs in tobacco cytoplasmic mRNA and protein metabolism makes them likely to be active in another plant species too. Expression of vast majority of the closest orthologues of EPP proteins also in Arabidopsis male gametophyte further extends this concept from tobacco to Arabidopsis, the model species with advanced tricellular pollen.

show abstract

“…To date, it has been demonstrated that RNA-binding proteins are important for post-transcriptional regulation and maturation of transcripts (Palanivelu et al 2000;Coller et al 1998). Furthermore, it has been known that the translation from mRNA was repressed in mature pollen grains (Mascarenhas 1993;Honys et al 2000). Furthermore, Lorkovic et al indicated that AtRBP45s still participated in the undefined steps of pre-mRNA maturation in plants (Lorkovic et al 2000).…”

mentioning

confidence: 99%

Molecular characterization of two anther-specific genes encoding putative RNA-binding proteins, AtRBP45s, in Arabidopsis thaliana

et al. 2006

View full text Add to dashboard Cite

RRM (RNA-recognition motif) domain is important for the post-transcriptional regulation of gene expression including RNA processing. In our previous study, we found one anther-and/or pollen-specific gene ( LjRRM1 , previously named as LjMfb-U93 ) in model legume, Lotus japonicus . Because of the richness of genomic information of another model plant, Arabidopsis thaliana , for functional analysis, we identified and characterized the orthologous genes in A. thaliana . By comparison of the partial nucleotide sequence of LjRRM1 to the public database, we identified three homologous genes ( AtRBP45a , AtRBP45b , and AtRBP45c ) in A. thaliana genome. Based on promoter analysis, both AtRBP45a and AtRBP45c were specifically expressed in immature anther tissues (tapetum cells) and mature pollen grains of transgenic plants. This expression pattern of AtRBP45a and AtRBP45c is quite similar to that of LjRRM1 , indicating that AtRBP45a and AtRBP45c would be orthologous to LjRRM1 . Because in another previous experiment, it was shown that proteins having RRM domains were related to premRNA maturation, and as a conclusion, it is possible that LjRRM1 , AtRBP45a , and AtRBP45c genes encoding RNA-binding proteins are functionally involved in the repression of translation in mature pollen grains in L. japonicus and A. thaliana .

show abstract

The translationally repressed pollen-specific ntp303 mRNA is stored in non-polysomal mRNPs during pollen maturation

Cited by 38 publications

References 46 publications

Translation initiation factors eIF4E and eIFiso4E are required for polysome formation and regulate plant growth in tobacco

Translation initiation factors eIF4E and eIFiso4E are required for polysome formation and regulate plant growth in tobacco

Cytoskeleton-Associated Large RNP Complexes in Tobacco Male Gametophyte (EPPs) Are Associated with Ribosomes and Are Involved in Protein Synthesis, Processing, and Localization

Molecular characterization of two anther-specific genes encoding putative RNA-binding proteins, AtRBP45s, in Arabidopsis thaliana

Contact Info

Product

Resources

About