Proteomic Analysis of MG132-Treated Germinating Pollen Reveals Expression Signatures Associated with Proteasome Inhibition

Abstract

Chemical inhibition of the proteasome has been previously found to effectively impair pollen germination and tube growth in vitro. However, the mediators of these effects at the molecular level are unknown. By performing 2DE proteomic analysis, 24 differentially expressed protein spots, representing 14 unique candidate proteins, were identified in the pollen of kiwifruit (Actinidia deliciosa) germinated in the presence of the MG132 proteasome inhibitor. qPCR analysis revealed that 11 of these proteins are not up-regulated at the mRNA level, but are most likely stabilized by proteasome inhibition. These differentially expressed proteins are predicted to function in various pathways including energy and lipid metabolism, cell wall synthesis, protein synthesis/degradation and stress responses. In line with this evidence, the MG132-induced changes in the proteome were accompanied by an increase in ATP and ROS content and by an alteration in fatty acid composition.

Cytological and Proteomic Analyses of Osmunda cinnamomea Germinating Spores Reveal Characteristics of Fern Spore Germination and Rhizoid Tip Growth*

“…However, the fern spore germination happens in the medium, therefore, it is somewhat more complex and affected by various environmental factors, such as light, gravity, calcium, phytohormone, and temperature (6). The protein functional skew in fern spores and pollen grains revealed from this study and recent proteomics studies on germinating pollen from kiwifruit (Actinidia deliciosa) (71,72), Nicotiana tabacum (73), rice (Oryza sativa) (26), Brassica napus (74), Pinus strobus (75), Picea meyeri (76,77), Picea wilsonii (78) and Arabidopsis (79,80) presented new evidence for the differentiation of fern spores and spermatophyte pollen (Fig. 10).…”

“…No photosynthetic proteins were found in pollen. This highlights that the remodeling of pollen tube cell wall, the loosening and hydrolyzing stigma surface cell and transmitting track of pistil, The data of germinating pollen were summarized and reclassified based on pollen proteomic studies on Oryza sativa (26), Actinidia deliciosa (71,72), Nicotiana tabacum (73), Brassica napus (74), Pinus strobus (75), Picea meyeri (76,77), Picea wilsonii (78), and Arabidopsis thaliana (79,80). The y axis represents the reclassified functional categories, and the x axis shows the percentage of identified proteins.…”

Proteasome-mediated remodeling of the proteome and phosphoproteome during kiwifruit pollen germination

“…Gel-based proteomic analysis revealed 11 unique candidate protein species whose abundance was directly/indirectly regulated by the proteasome during germination in kiwifruit pollen [18].…”

In‐Depth Proteome Analysis of Ricinus communis Pollens

“…The pollen tube grows from the tip region, with the deposition of the membrane and cell wall material on the tip, a process known as tip growth . To date, most of the proteomic studies are dedicated to either mature or germinated pollens, while comparative studies focused on mature, germinated, and other developmental stages of pollens are scarce. Zou et al .…”

“…A high proportion of the identified proteins is related to carbohydrate and energy metabolism (Tables S1 and S2, Supporting Information). We identified a complete set of the proteins involved in the glycolytic pathway, where previous studies detected only a few of the proteins from this pathway. Similarly, several proteins associated with the TCA cycle, electron transport chain, and pentose phosphate pathway were also identified (Table S2, Supporting Information).…”