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Abstract: Phototropin receptor kinases play an important role in optimising plant growth in response to blue light. Much is known regarding their photochemical reactivity, yet little progress has been made to identify downstream signalling components. Here, we isolated several interacting proteins for Arabidopsis phototropin 1 (phot1) by yeast two-hybrid screening. These include members of the NPH3/RPT2 (NRL) protein family, proteins associated with vesicle trafficking, and the 14-3-3 lambda (λ) isoform from Arabidopsis. 14-3-3λ and phot1 were found to colocalise and interact in vivo. Moreover, 14-3-3 binding to phot1 was limited to non-epsilon 14-3-3 isoforms and was dependent on key sites of receptor autophosphorylation. No 14-3-3 binding was detected for Arabidopsis phot2, suggesting that 14-3-3 proteins are specific to phot1 signalling. Structured summary: MINT-7146953: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF7 (uniprotkb:Q9LFJ7) by two hybrid (MI:0018) MINT-7147335: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 phi (uniprotkb:P46077) by far Western blotting (MI:0047) MINT-7146854: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with RPT2 (uniprotkb:Q682S0) by two hybrid (MI:0018) MINT-7147215: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by anti tag coimmunoprecipitation (MI:0007) MINT-7147044, MINT-7147185, MINT-7147200, MINT-7147413: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by far Western blotting (MI:0047) MINT-7146983: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with 14-3-3 lambda (uniprotkb:P48349) by two hybrid (MI:0018) MINT-7146871: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with NPH3-like (uniprotkb:Q9S9Q9) by two hybrid (MI:0018) MINT-7146905: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF2 (uniprotkb:Q9M1P5) by two hybrid (MI:0018) MINT-7147364: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 upsilon (uniprotkb:P42645) by far Western blotting (MI:0047) MINT-7147234: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 kappa (uniprotkb:P48348) by far Western blotting (MI:0047) [Copyright &y& Elsevier]

Abstract: A novel cyclin, CCNY, was identified as a PFTK1 interacting protein in a yeast two-hybrid screen. The cyclin box in CCNY and the PFTAIRE motif in PFTK1 are both required for the interaction which was confirmed by in vivo and in vitro assays. Two transcripts (4 and 2kb), of CCNY were detected by Northern blot analysis and CCNY was enriched at the plasma membrane due to an N-terminal myristoylation signal. We propose that binding of CCNY to PFTK1 enhances PFTK1 kinase activity and changes its intracellular location. Structured summary: MINT-7147585, MINT-7147598, MINT-7147614, MINT-7147628, MINT-7147647, MINT-7147665, MINT-7147680: pftk1 (uniprotkb:O94921) physically interacts (MI:0915) with CCNY (uniprotkb:Q8ND76) by two hybrid (MI:0018) MINT-7147725, MINT-7147743: pftk1 (uniprotkb:O94921) physically interacts (MI:0914) with CCNY (uniprotkb:Q8ND76) by anti tag coimmunoprecipitation (MI:0007) MINT-7147758: pftk1 (uniprotkb:O35495) physically interacts (MI:0914) with CCNY (uniprotkb:Q8BGU5) by anti bait coimmunoprecipitation (MI:0006) MINT-7147695, MINT-7147713: pftk1 (uniprotkb:O94921) and CCNY (uniprotkb:Q8ND76) colocalize (MI:0403) by fluorescence microscopy (MI:0416) [Copyright &y& Elsevier]

Abstract: Plants have evolved distinct mechanisms to link Rho-type (Rop) GTPases to downstream signaling pathways as compared to other eukaryotes. Here, experimental data are provided that members of the Medicago, as well as Arabidopsis, receptor-like cytoplasmic kinase family (RLCK Class VI) were strongly and specifically activated by GTP-bound Rop GTPases in vitro. Deletion analysis indicated that the residues implicated in the interaction might be distributed on various parts of the kinases. Using a chimaeric Rop GTPase protein, the importance of the Rho-insert region in kinase activation could also be verified. These data strengthen the possibility that RLCKs may serve as Rop GTPase effectors in planta. [Copyright &y& Elsevier]

Abstract: p110C, a 50-kDa isoform of the PITSLRE kinase family, was demonstrated to play an important role in cell apoptosis. However, how p110C exactly promotes apoptosis is unclear. Our previous study showed that p110C interacted with p21-activated kinase 1 (PAK1), an important kinase of the proapoptotic BCL-2 family member BAD, and evidently inhibited its kinase activity. Here, we report that overexpression of p110C leads to decreased phosphorylation of BAD and its subsequent translocation from cytosol to mitochondria, which in turn induces the release of cytochrome c and the onset of apoptosis. Knocking down endogenous BAD expression will inhibit p110C induced apoptosis. Two kinase dead forms of p110C, D149N and K36N, lose the ability to inhibit the kinase activity of PAK1 and fail to induce the translocation of BAD and the BAD and such proapoptotic ability is associated with the kinase activity of p110C. [Copyright &y& Elsevier]

Recently, LiCl has been shown to inhibit amyloid β peptide secretion in association with diminished glycogen synthase kinase β (GSK3β) activity. However, it remains unclear if direct inhibition of GSK3β activity will result in decreased Aβ production. Frequently rearranged in advanced T-cell lymphomas 1 (FRAT1) protein is a negative regulator of GSK3α/β kinase activity. To examine whether direct inhibition of GSK3α/β kinase activity can lower Aβ production, a FRAT1 peptide was expressed in swAPP751 cells that produce high levels of Aβ. Our data demonstrate that cellular expression of FRAT1 peptide in swAPP751 cells increases both GSK3α and β phosphorylation on Ser21 and Ser9, respectively, while inhibiting kinase activity of both isoforms. Moreover, as a result of FRAT1 expression, the production of both total Aβ and Aβ1-42 was significantly decreased. Thus, we provide evidence that direct regulation of GSK3α/β by FRAT1 peptide significantly decreases Aβ production in swAPP751 cells. [Copyright &y& Elsevier]