CK2-mediated phosphorylation of a type II regulatory subunit of cAMP-dependent protein kinase from the mollusk Mytilus galloprovincialis

Bardales, José R.; Hellman, Ulf; Villamarín, J. Antonio

doi:10.1016/j.abb.2007.02.008

Cited by 8 publications

(8 citation statements)

References 44 publications

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“…No significant differences among C-subunit isoforms regarding the values of apparent K m for Kemptide and V max were observed. Furthermore, all the mussel isozymes were inhibited by the protein kinase inhibitor peptide [PKI (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)] with similar I 50 values ( Table 2). The ability of mussel C-subunit isoforms to phosphorylate proteins in vitro was also investigated.…”

Section: Kinetic Characterization Of C-subunit Isoforms and Protein Pmentioning

confidence: 70%

“…Interestingly, both isoforms have identical apparent molecular masses of 54 kDa, but they differ in: (a) their isoelectric point; (b) their biochemical properties; (c) their antigenicity; and (d) their tissue distribution [12][13][14]. According to its physicochemical and biochemical properties, a partial amino acid sequence from R myt1 showed a clear homology with the type I R-subunits from both mammalian and invertebrate sources [13]; likewise, R myt2 was shown to be homologous to the type II R-subunits from the same species [14].…”

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confidence: 99%

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Identification of multiple isoforms of the cAMP‐dependent protein kinase catalytic subunit in the bivalve mollusc Mytilus galloprovincialis

2008

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Several isoforms of the cAMP‐dependent protein kinase catalytic subunit (C‐subunit) were separated from the posterior adductor muscle and the mantle tissues of the sea mussel Mytilus galloprovincialis by cation exchange chromatography, and identified by: (a) protein kinase activity; (b) antibody recognition; and (c) peptide mass fingerprinting. Some of the isozymes seemed to be tissue‐specific, and all them were phosphorylated at serine and threonine residues and showed slight but significant differences in their apparent molecular mass values, which ranged from 41.3 to 44.5 kDa. The results from the MS analysis suggest that at least some of the mussel C‐subunit isoforms arise as a result of alternative splicing events. Furthermore, several peptide sequences from mussel C‐subunits, determined by de novo sequencing, showed a high degree of homology with the mammalian Cα‐isoform, and contained some structural motifs that are essential for catalytic function. On the other hand, no significant differences were observed in the kinetic parameters of C‐subunit isoforms, determined by using synthetic peptides as substrate and inhibitor. However, the C‐subunit isoforms separated from the mantle tissue differed in their ability to phosphorylate in vitro some proteins present in a mantle extract.

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Section: Kinetic Characterization Of C-subunit Isoforms and Protein Pmentioning

confidence: 70%

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confidence: 99%

Identification of multiple isoforms of the cAMP‐dependent protein kinase catalytic subunit in the bivalve mollusc Mytilus galloprovincialis

2008

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“…First, only R myt2 , but not R myt1 , was phosphorylated in vitro by the own PKA C-subunit (Cao et al 1995;Díaz-Enrich et al 2003), and also by casein kinase-2 (CK2). CK2-mediated phosphorylation significantly decreases the ability of R myt2 to inhibit C-subunit in the absence of cAMP (Bardales et al 2007). On the other hand, the affinity of R myt1 for cAMP was twofold higher than that R myt2 (Bardales et al 2004).…”

Section: Discussionmentioning

confidence: 98%

“…In order to better understand these regulatory mechanisms, we carried out a study to characterize the PKA from the sea mussel Mytilus galloprovincialis. To date, we have identified and purified two different isoforms of the R-subunit, named R myt1 and R myt2 , whose partial sequences were homologous to those of mammalian RI-and RII-type, respectively (Díaz Enrich et al 2003; Bardales et al 2007). Although both R myt1 and R myt2 show identical apparent molecular mass, they differ at their physico-chemical, biochemical and immunogenic properties (Cao et al 1995;Rodriguez et al 1998; Bardales et al 2007).…”

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confidence: 98%

“…To date, we have identified and purified two different isoforms of the R-subunit, named R myt1 and R myt2 , whose partial sequences were homologous to those of mammalian RI-and RII-type, respectively (Díaz Enrich et al 2003; Bardales et al 2007). Although both R myt1 and R myt2 show identical apparent molecular mass, they differ at their physico-chemical, biochemical and immunogenic properties (Cao et al 1995;Rodriguez et al 1998; Bardales et al 2007). On the other hand, we have also identified and purified several isoforms of the C-subunit, likely generated from an only gene by alternate splicing events (Bardales et al 2008).…”

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Differential distribution of cAMP-dependent protein kinase isoforms in the mantle of the bivalve mollusc Mytilus galloprovincialis

2009

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Two different isoforms of the regulatory (R) subunit of cAMP-dependent protein kinase (PKA), named R(myt1) and R(myt2), had previously been identified in the sea mussel Mytilus galloprovincialis. R(myt1) and R(myt2) were differentially distributed in the various cell types comprising the mussel mantle. R(myt1) was found the only isoform to be present in the auxiliary cells of female follicles and the cubic epithelium of the middle fold of mantle edge. In contrast, only the R(myt2) isoform was detected in the subepithelial connective tissue, the endothelium of haemolymph vessels, the adipogranular and vesicular cells of reserve connective tissue, and the spermatozoa. Finally, both R(myt1) and R(myt2) coexist in some cell types but they show a different cellular localization: R(myt1) was localized in the cytoplasm whereas R(myt2) was mainly detected in the cell apical edge, cell periphery, cilia and sperm flagella. Interestingly, both R(myt1) and R(myt2) were absent in oocytes within the female gonadal follicles but, in contrast, they were highly expressed in follicle-released oocytes collected after spawning. Taken together the results show that mussel PKA isoforms are differentially distributed in the mantle cell types, which suggests that they are involved in the regulation of distinct cellular functions. On the other hand, the expression of R(myt1) and R(myt2) proteins is associated with the meiosis resumption of oocytes at the prophase I stage, which occurs in parallel to spawning.

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Apigenin, a chemopreventive bioflavonoid, induces AMP‐activated protein kinase activation in human keratinocytes

Tong

Smith

Pelling

2011

Molecular Carcinogenesis

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AMP-activated protein kinase (AMPK) is a cellular energy sensor that is conserved in eukaryotes. Although AMPK is traditionally thought to play a major role in the regulation of cellular lipid and protein metabolism, recent discoveries reveal that AMPK inhibits mammalian target of rapamycin (mTOR) signaling and connects with several tumor suppressors such as liver kinase B1 (LKB1), p53, and tuberous sclerosis complex 2 (TSC2), indicating that AMPK may be a potential target for cancer prevention and treatment. For the first time, we demonstrated that apigenin, a naturally occurring nonmutagenic flavonoid, induced AMPK activation in human keratinocytes (both cultured HaCaT cell line and primary normal human epidermal keratinocytes). Through experiments with over-expression of constitutively active Akt and knockdown of LKB1 expression by siRNAs, we further found that the activation of AMPK by apigenin was not dependent on its inhibition of Akt, and was independent of the activation of upstream kinase LKB1. Instead, another upstream kinase of AMPK, calcium/calmodulin-dependent protein kinase kinase-β (CaMKKβ), was required for apigenin-induced AMPK activation. We have demonstrated that knockdown of CaMKKβ expression by siRNA or inhibition of CaMKKβ activity by either CaMKK inhibitor STO-609 or BAPTA-AM (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester; a chelator of intracellular Ca(2+)) prevented apigenin-induced AMPK activation. Apigenin-induced AMPK activation inhibited mTOR signaling and further induced autophagy in human keratinocytes. These results suggest that one of the mechanisms by which apigenin exerts its chemopreventive action may be through activation of AMPK and induction of autophagy in human keratinocytes.

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CK2-mediated phosphorylation of a type II regulatory subunit of cAMP-dependent protein kinase from the mollusk Mytilus galloprovincialis

Cited by 8 publications

References 44 publications

Identification of multiple isoforms of the cAMP‐dependent protein kinase catalytic subunit in the bivalve mollusc Mytilus galloprovincialis

Identification of multiple isoforms of the cAMP‐dependent protein kinase catalytic subunit in the bivalve mollusc Mytilus galloprovincialis

Differential distribution of cAMP-dependent protein kinase isoforms in the mantle of the bivalve mollusc Mytilus galloprovincialis

Apigenin, a chemopreventive bioflavonoid, induces AMP‐activated protein kinase activation in human keratinocytes

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