IndraLab
Statements
RPS6KB1 is active.
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"Mtorc1 promotes protein synthesis by phosphorylating the eukaryotic initiation factor 4e (eif4e)- binding protein 1 (4e-bp1) and the p70 ribosomal s6 kinase 1 (s6k1). In vitro activation of p70alfa by mtor-catalyzed phosphorylation involving p70alfa thr-412. Mtor-catalyzed p70alfa phosphorylation in vitro is accompanied by a substantial restoration in p70alfa kinase activity toward its physiologic substrate, the 40 s ribosomal protein s6. In response to insulin and nutrients, mtorc1, consisting of mtor, raptor (regulatory-associated protein of mtor), and mlst8, is activated and phosphorylates eukaryotic initiation factor 4e-binding protein (4ebp) and p70 s6 kinase to promote protein synthesis and cell size."
"Mtorc1 promotes protein synthesis by phosphorylating the eukaryotic initiation factor 4e (eif4e)- binding protein 1 (4e-bp1) and the p70 ribosomal s6 kinase 1 (s6k1). In vitro activation of p70alfa by mtor-catalyzed phosphorylation involving p70alfa thr-412. Mtor-catalyzed p70alfa phosphorylation in vitro is accompanied by a substantial restoration in p70alfa kinase activity toward its physiologic substrate, the 40 s ribosomal protein s6. In response to insulin and nutrients, mtorc1, consisting of mtor, raptor (regulatory-associated protein of mtor), and mlst8, is activated and phosphorylates eukaryotic initiation factor 4e-binding protein (4ebp) and p70 s6 kinase to promote protein synthesis and cell size."
"A regulatory link between p70s6k and pkb was demonstrated, as pdk1 was found to selectively phosphorylate p70s6k at thr229. More importantly, pdk1 activated p70s6k in vitro and in vivo, whereas the catalytically inactive pdk1 blocked insulin-induced activation of p70s6k. One of the most studied events controlled by ptdins(3,4,5)p3, comprises the activation of a of agc family protein kinases, including isoforms of protein kinase b (pkb)/akt, p70 ribosomal s6 kinase (s6k), serum- and glucocorticoid-induced protein kinase (sgk) and protein kinase c (pkc), which play crucial roles in regulating physiological processes relevant to metabolism, growth, proliferation and survival. Here, we review recent biochemical, genetic and structural studies on the 3-phosphoinositide-dependent protein kinase-1 (pdk1), which phosphorylates and activates the agc kinase members regulated by pi 3-kinase. We also discuss whether inhibitors of pdk1 might have chemotherapeutic potential in the treatment of cancers in which the pdk1-regulated agc kinases are constitutively activated. Phosphorylation and activation of p70s6k by pdk1."
"A regulatory link between p70s6k and pkb was demonstrated, as pdk1 was found to selectively phosphorylate p70s6k at thr229. More importantly, pdk1 activated p70s6k in vitro and in vivo, whereas the catalytically inactive pdk1 blocked insulin-induced activation of p70s6k. one of the most studied signalling events controlled by ptdins(3,4,5)p3, comprises the activation of a group of agc family protein kinases, including isoforms of protein kinase b (pkb)/akt, p70 ribosomal s6 kinase (s6k), serum- and glucocorticoid-induced protein kinase (sgk) and protein kinase c (pkc), which play crucial roles in regulating physiological processes relevant to metabolism, growth, proliferation and survival. Here, we review recent biochemical, genetic and structural studies on the 3-phosphoinositide-dependent protein kinase-1 (pdk1), which phosphorylates and activates the agc kinase members regulated by pi 3-kinase. We also discuss whether inhibitors of pdk1 might have chemotherapeutic potential in the treatment of cancers in which the pdk1-regulated agc kinases are constitutively activated."
"Mtorc1 promotes protein synthesis by phosphorylating the eukaryotic initiation factor 4e (eif4e)- binding protein 1 (4e-bp1) and the p70 ribosomal s6 kinase 1 (s6k1). In vitro activation of p70alfa by mtor-catalyzed phosphorylation involving p70alfa thr-412. Mtor-catalyzed p70alfa phosphorylation in vitro is accompanied by a substantial restoration in p70alfa kinase activity toward its physiologic substrate, the 40 s ribosomal protein s6. in response to insulin and nutrients, mtorc1, consisting of mtor, raptor (regulatory-associated protein of mtor), and mlst8, is activated and phosphorylates eukaryotic initiation factor 4e-binding protein (4ebp) and p70 s6 kinase to promote protein synthesis and cell size."
"Mtorc1 promotes protein synthesis by phosphorylating the eukaryotic initiation factor 4e (eif4e)- binding protein 1 (4e-bp1) and the p70 ribosomal s6 kinase 1 (s6k1). In vitro activation of p70alfa by mtor-catalyzed phosphorylation involving p70alfa thr-412. Mtor-catalyzed p70alfa phosphorylation in vitro is accompanied by a substantial restoration in p70alfa kinase activity toward its physiologic substrate, the 40 s ribosomal protein s6. In response toinsulinand nutrients, mtorc1, consisting of mtor, raptor (regulatory-associated protein of mtor), and mlst8, is activated and phosphorylates eukaryotic initiation factor 4e-binding protein (4ebp) and p70 s6 kinase to promote protein synthesis and cell size."
"The activation of p70s6k is associated with multiple phosphorylations at two sets of sites. The first set, s411, s418, t421, and s424, reside within the autoinhibitory domain, mutations of s371 abolished kinase activity. In mitotic hela cells, when the activity of cdc2 is high, s6k1 is phosphorylated at multiple ser/thr, pro (s/tp) sites, including ser(371), ser(411), thr(421), and ser(424)."
"The activation of p70s6k is associated with multiple phosphorylations at two sets of sites. The first set, s411, s418, t421, and s424, reside within the autoinhibitory domain, mutations of s371 abolished kinase activity. In mitotic hela cells, when the activity of cdc2 is high, s6k1 is phosphorylated at multiple ser/thr, pro (s/tp) sites, including ser(371), ser(411), thr(421), and ser(424)."
"Thr229 phosphorylation requires prior phosphorylation of the Ser/Thr-Pro sites in the autoinhibitory domain and Thr389 in the linker domain,[…] Moreover, in vitro mTOR directly phosphorylates Ser371, and this event modulates Thr389phosphorylation by mTOR, compatible with earlier in vivo findings."
"Thr229 phosphorylation requires prior phosphorylation of the Ser/Thr-Pro sites in the autoinhibitory domain and Thr389 in the linker domain,[…] Moreover, in vitro mTOR directly phosphorylates Ser371, and this event modulates Thr389phosphorylation by mTOR, compatible with earlier in vivo findings."
"Interestingly, phosphorylation at several ser/thr residues within the c-terminal autoinhibitory tail appears to either activate or inhibit s6k1, depending on the cell cycle phase. phosphorylation of those residues (featured by the thr-421/ser-424 site) during mitosis pursued by cdk1 inactivates s6k1 we then assessed the phosphorylation status of the mitosis-specific inhibitory residue of s6k1, thr-421/ser-424, which is targeted by mitotic cdk1."
"A physical interaction exists between cdc2 and s6k1, and this interaction is enhanced in mitotic cells. These results suggest that cdc2 provides a signal that triggers inactivation of s6k1 in mitosis, presumably serving to spare energy for costly mitotic processes at the expense of ribosomal protein synthesis."
"Interestingly, phosphorylation at several ser/thr residues within the c-terminal autoinhibitory tail appears to either activate or inhibit s6k1, depending on the cell cycle phase. phosphorylation of those residues (featured by the thr-421/ser-424 site) during mitosis pursued by cdk1 inactivates s6k1 we then assessed the phosphorylation status of the mitosis-specific inhibitory residue of s6k1, thr-421/ser-424, which is targeted by mitotic cdk1."
"A regulatory link between p70s6k and pkb was demonstrated, as pdk1 was found to selectively phosphorylate p70s6k at thr229. More importantly, pdk1 activated p70s6k in vitro and in vivo, whereas the catalytically inactive pdk1 blocked insulin-induced activation of p70s6k. one of the most studied signalling events controlled by ptdins(3,4,5)p3, comprises the activation of a group of agc family protein kinases, including isoforms of protein kinase b (pkb)/akt, p70 ribosomal s6 kinase (s6k), serum- and glucocorticoid-induced protein kinase (sgk) and protein kinase c (pkc), which play crucial roles in regulating physiological processes relevant to metabolism, growth, proliferation and survival. Here, we review recent biochemical, genetic and structural studies on the 3-phosphoinositide-dependent protein kinase-1 (pdk1), which phosphorylates and activates the agc kinase members regulated by pi 3-kinase. We also discuss whether inhibitors of pdk1 might have chemotherapeutic potential in the treatment of cancers in which the pdk1-regulated agc kinases are constitutively activated."
"A regulatory link between p70s6k and pkb was demonstrated, as pdk1 was found to selectively phosphorylate p70s6k at thr229. More importantly, pdk1 activated p70s6k in vitro and in vivo, whereas the catalytically inactive pdk1 blocked insulin-induced activation of p70s6k. One of the most studied events controlled by ptdins(3,4,5)p3, comprises the activation of a of agc family protein kinases, including isoforms of protein kinase b (pkb)/akt, p70 ribosomal s6 kinase (s6k), serum- and glucocorticoid-induced protein kinase (sgk) and protein kinase c (pkc), which play crucial roles in regulating physiological processes relevant to metabolism, growth, proliferation and survival. Here, we review recent biochemical, genetic and structural studies on the 3-phosphoinositide-dependent protein kinase-1 (pdk1), which phosphorylates and activates the agc kinase members regulated by pi 3-kinase. We also discuss whether inhibitors of pdk1 might have chemotherapeutic potential in the treatment of cancers in which the pdk1-regulated agc kinases are constitutively activated. Phosphorylation and activation of p70s6k by pdk1."
RPS6KB1 is kinase-active.
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"the treatment of SV40-immortalized human corneal epithelial cells (HCE-T cells) with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), widely used as an AMPK activator, inhibits p70 S6 kinase a (p70a) activities. AICAR treatment also inhibits phosphorylation of Thr-412 in p70a, which is indispensable for its activity."
"the treatment of SV40-immortalized human corneal epithelial cells (HCE-T cells) with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), widely used as an AMPK activator, inhibits p70 S6 kinase a (p70a) activities. AICAR treatment also inhibits phosphorylation of Thr-412 in p70a, which is indispensable for its activity."
"##from text## Phosphorylation of p70 S6 kinase on Thr389 is essential for the activation of the kinase [22]. In the presence of insulin, the intensity of the Thr389 p70 S6 kinase bands was significantly increased after 15 min exposure and reached 2.02 ± 0.31 after 15 min and 1.36 ± 0.17 after a 16 hour incubation period when compared to respective controls which were made equal to one (mean ± SE, t-test, p < 0.05, n = 4)."
"altered glucose availability, which regulates AMPK activity, also modulates the activity of p70 S6k. AICAR treatment also inhibits phosphorylation of Thr-412 in the p70 S6 kinase (p70 S6k), which is indispensable for the activity. In addition to the mTOR signal acting as a priming switch that modulates p70 S6k activation, AMPK appears to provide an overriding switch linking p70 S6k regulation to cellular energy metabolism."
"T229 is situated in the catalytic domain of p70S6K, and in addition to T389, its phosphorylation is necessary for full activation of the protein. Residues T421 and S424 are situated in the autoinhibitory/pseudosubstrate domain of the C-terminus, and phosphorylation of these residues is proposed to be one of the early steps of p70S6K activation (2)"
"from full text - T229 is situated in the catalytic domain of p70S6K, and in addition to T389, its phosphorylation is necessary for full activation of the protein. Residues T421 and S424 are situated in the autoinhibitory/pseudosubstrate domain of the C-terminus, and phosphorylation of these residues is proposed to be one of the early steps of p70S6K activation (2)."
"The initially identified sites of phosphorylation (of RPS6KBP1), S411, S418, T421 and S424 are all flanked by a proline in the +1 position and reside within the putative autoinhibitory domain of Module IV [22]. Peptides which correspond in sequence to this domain inhibit the kinase [51], consistent with the hypothesis that Module IV acts as an autoinhibitory domain. These four residues are hypophosphorylated in quiescent cells, and become hyperphosphorylated in response to serum [23]. Substitution of these S/T-P sites with alanines [23] suppresses activation of the kinase, whilst the corresponding acidic residue replacements raise basal kinase activity [10]."
"from full text - T229 is situated in the catalytic domain of p70S6K, and in addition to T389, its phosphorylation is necessary for full activation of the protein. Residues T421 and S424 are situated in the autoinhibitory/pseudosubstrate domain of the C-terminus, and phosphorylation of these residues is proposed to be one of the early steps of p70S6K activation (2)."
"The initially identified sites of phosphorylation (of RPS6KBP1), S411, S418, T421 and S424 are all flanked by a proline in the +1 position and reside within the putative autoinhibitory domain of Module IV [22]. Peptides which correspond in sequence to this domain inhibit the kinase [51], consistent with the hypothesis that Module IV acts as an autoinhibitory domain. These four residues are hypophosphorylated in quiescent cells, and become hyperphosphorylated in response to serum [23]. Substitution of these S/T-P sites with alanines [23] suppresses activation of the kinase, whilst the corresponding acidic residue replacements raise basal kinase activity [10]."
"To test whether mTOR would also phosphorylate Ser371 in vitro, Myc-S6K-WT derived from 293 cells pretreated with rapamycin was used as a direct substrate for HA-tagged mTOR immunopurified from 293 cells. The results show that Myc-mTOR-WT induces increased Ser371 phosphorylation in vitro as assessed by Western blot analysis with the Ser371 anti-phosphospecific antibody following electrophoresis on low acrylamide gels (Fig. 5A), consistent with in vivo findings (Fig. 2A). In contrast, HA-mTOR-KI had no effect. More importantly, in the presence of rapamycin and FKBP12, but not in the presence of either component alone, phosphorylation of Ser371 by mTOR is abolished (Fig. 5A), consistent with the in vivo finding (Fig. 4). In parallel, incubation of S6K1-E389D3E with HA-mTOR-WT also led to increased S6K1-E389D3E activation and Ser371 phosphorylation, in an FKBP-12/rapamycin-sensitive manner (Fig. 5B and data not shown). Furthermore, the extent of both responses was similar to those observed in vivo (compare Figs. 4B and 5B). Therefore, Ser371 phosphorylation appears to be directly regulated by mTOR in vitro and in vivo. (From full text) Incubation of either S6 kinase variant with wild type, but not kinase-inactive, mTOR led to increased Thr389 phosphorylation, with the extent of Thr389 phosphorylation much higher in S6K1-S371A than in wild type S6K1 (Fig. 6B). However, to achieve the same level of activity as S6K1-WT, S6K1-S371A apparently requires much higher levels of Thr389 phosphorylation (Fig. 6B), consistent with detailed titration studies (data not shown). Although unexpected, these findings are compatible with Ser371 phosphorylation regulating Thr389 phosphorylation and with its ability to directly affect S6K1 activity. (From full text)"
"Effect of Ser371 on S6K1 Activation-- As shown previously (13), substitution of an alanine or an aspartate for Ser371 blocks serum- or insulin-induced Thr389 phosphorylation and S6K1 activation (Fig. 6A). However, substitution of an acidic residue at Thr389 in the S6K1-E389D3E background fails to rescue kinase activity (13), suggesting that Ser371 phosphorylation contributes directly to S6K1 activation independent of its role in regulating Thr389 phosphorylation. To test this possibility in vitro, either S6K1 or S6K1-S371A, from 293 cells pretreated with rapamycin, were incubated with either HA-mTOR-WT or HA-mTOR-KI. Both S6K1 variants displayed basal levels of phosphorylated Thr229, which were not altered by incubation with either mTOR variant (Fig. 6B). However, incubation of either S6 kinase variant with wild type, but not kinase-inactive, mTOR led to increased Thr389 phosphorylation, with the extent of Thr389 phosphorylation much higher in S6K1-S371A than in wild type S6K1 (Fig. 6B). However, to achieve the same level of activity as S6K1-WT, S6K1-S371A apparently requires much higher levels of Thr389 phosphorylation (Fig. 6B), consistent with detailed titration studies (data not shown). Although unexpected, these findings are compatible with Ser371 phosphorylation regulating Thr389 phosphorylation and with its ability to directly affect S6K1 activity. (From full text)"
"from full text - T229 is situated in the catalytic domain of p70S6K, and in addition to T389, its phosphorylation is necessary for full activation of the protein. Residues T421 and S424 are situated in the autoinhibitory/pseudosubstrate domain of the C-terminus, and phosphorylation of these residues is proposed to be one of the early steps of p70S6K activation (2)."
RPS6KB1 is kinase-inactive.
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RPS6KB1 is inactive.
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