Combined Proteomic and Cytological Analysis of Ca2+-Calmodulin Regulation inPicea meyeriPollen Tube Growth    

Abstract

Ca 2+ -calmodulin (Ca 2+ -CaM) is a critical molecule that mediates cellular functions by interacting with various metabolic and signaling pathways. However, the protein expression patterns and accompanying serial cytological responses in Ca 2+ -CaM signaling deficiency remain enigmatic. Here, we provide a global analysis of the cytological responses and significant alterations in protein expression profiles after trifluoperazine treatment in Picea meyeri, which abrogates Ca 2+ -CaM signaling. Ninety-three differentially displayed proteins were identified by comparative proteomics at different development stages and were assigned to different functional categories closely related to tip growth machinery. The inhibition of Ca 2+ -CaM signaling rapidly induced an increase in extracellular Ca 2+ influx, resulting in dramatically increased cytosolic Ca 2+ concentrations and ultrastructural abnormalities in organelles as the primary responses. Secondary and tertiary alterations included actin filament depolymerization, disrupted patterns of endocytosis and exocytosis, and cell wall remodeling, ultimately resulting in perturbed pollen tube extension. In parallel with these cytological events, time-course experiments revealed that most differentially expressed proteins showed time-dependent quantitative changes (i.e. some signaling proteins and proteins involved in organelle functions and energy production changed first, followed by alterations in proteins related to cytoskeletal organization, secretory pathways, and polysaccharide synthesis). Taken together, Ca 2+ -CaM dysfunction induced serial cytological responses and temporal changes in protein expression profiles, indicating the pivotal role of Ca 2+ -CaM in the regulation of tip growth machinery.

Evidence for the possible involvement of calmodulin in regulation of steady state levels of Hsp90 family members (Hsp87 and Hsp85) in response to heat shock in sorghum

“…It is also pertinent to mention that despite the possible non-specific effects of these antagonists, several studies carried out recently have used this system and demonstrated CaM-specific inhibition. 8,[31][32][33][34][35][36] Furthermore, the differential changes in steady state levels of Hsp70 and Hsp90 in response to Ca 2+ channel blockers and CaM, as observed in the present study, also imply that the effect of these compounds on the two classes of proteins was specific and was not the result of a general effect on all proteins.…”

A loss-of-function mutation in Calmodulin2 gene affects pollen germination in Arabidopsis thaliana

“…A tipfocused gradient of cytosolic-free calcium is present in growing pollen tubes and CAM activity has been reported to display a similar tip-focused gradient (Rato et al 2004). The pivotal role played by CAM in pollen tube growth regulation has been demonstrated by the use of CAM antagonists (Rato et al 2004;Chen et al 2009) or anti-CAM antiserum (Ma et al 1999) but to our knowledge, no direct genetic evidence for a specific role for a CAM gene in pollen function was yet presented. Our data, suggesting for CAM2 a role as a Ca 2?…”

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.…”