PKC-ε regulates basolateral endocytosis in human T84 intestinal epithelia: role of F-actin and MARCKS

Song, Jae Chul; Hrnjez, Bruce J.; Farokhzad, Omid C.; Matthews, Jeffrey B.

doi:10.1152/ajpcell.1999.277.6.c1239

Cited by 88 publications

(78 citation statements)

References 45 publications

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“…Thus, formation of the PKCε-Lck module is crucial for the cardioprotective effects afforded by both chronic (PKCε transgenesis) and acute (ischemic preconditioning) activation of PKCε. Insofar as ischemic preconditioning represents a highly conserved biological response (having been described in the brain, kidney, gut, skeletal muscle, and liver) (1)(2)(3)9) and is the most powerful cardioprotective intervention identified thus far, the present results have broad implications for our understanding of ischemia/reperfusion injury and protection against tissue injury in general.…”

Section: Discussionmentioning

confidence: 72%

“…The role of PKCε as an essential protective kinase against ischemia was first demonstrated in cardiac tissue (4,5,(11)(12)(13). It has subsequently been shown that PKCε not only mediates protective signals in the heart but also functions as a protective kinase against ischemic injury in the gut (9), as an antiapoptotic kinase in the thyroid (6), and as a key molecule to precondition neurological functions in the brain (3,29,30), supporting a ubiquitous role for this enzyme in alleviating the consequences of ischemia. However, the precise molecular mechanisms by which this kinase exerts its salubrious effects remain largely undefined.…”

Section: Discussionmentioning

confidence: 99%

“…An understanding of the intracellular signaling mechanisms by which cells protect themselves against ischemia-induced damage bears great clinical significance with respect to the treatment and prevention of tissue injury (1)(2)(3). The ε isoform of protein kinase C (PKCε) is a member of the PKC family of serine/threonine kinases and has been implicated in the protection against injury in multiple organ systems (4)(5)(6)(7)(8)(9)(10)(11)(12)(13). In the heart, activation of PKCε has been shown to mediate the development of preconditioning (4,5,(11)(12)(13), a powerful cardioprotective adaptation that can be produced either by brief episodes of ischemia followed by reperfusion, or by the administration of pharmacological agents that can mimic the effects of ischemic preconditioning (1,(14)(15)(16)(17)(18).…”

Section: Introductionmentioning

confidence: 99%

“…Although the biological roles of both PKCε and Lck have been extensively studied in a variety of systems (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(26)(27)(28)(29)(30)(31)(32)(33), it is unknown whether these two kinases interact and, if so, in which specific manner they interact, and whether their coordinated interactions are required to govern signal transduction during the genesis of a biological phenotype (such as protection against ischemic injury). In the present investigation, we found that PKCε interacted with, phosphorylated, and activated Lck; that is, PKCε and Lck functioned as a signaling module.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Formation of protein kinase Cε-Lck signaling modules confers cardioprotection

Ping¹,

Song²,

Zhang³

et al. 2002

J. Clin. Invest.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Formation of protein kinase Cε-Lck signaling modules confers cardioprotection

Ping¹,

Song²,

Zhang³

et al. 2002

J. Clin. Invest.

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“…However, in several specific examples, MARCKS colocalizes with F-actin, and dissociation from actin is temporally associated with alterations in actin dynamics (22,23), or MARCKS localization is altered after treatment that disrupts actin filaments (18,22). Such data are most readily interpreted as direct effects of MARCKS on actin.…”

mentioning

confidence: 99%

MARCKS Is a Natively Unfolded Protein with an Inaccessible Actin-binding Site

Tapp

Al-Naggar

Yarmola

et al. 2005

Journal of Biological Chemistry

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Myristoylated alanine-rich C kinase substrate (MARCKS) is an unfolded protein that contains well characterized actin-binding sites within the phosphorylation site domain (PSD), yet paradoxically, we now find that intact MARCKS does not bind to actin. Intact MARCKS also does not bind as well to calmodulin as does the PSD alone. Myristoylation at the N terminus alters how calmodulin binds to MARCKS, implying that, despite its unfolded state, the distant N terminus influences binding events at the PSD. We show that the free PSD binds with site specificity to MARCKS, suggesting that long-range intramolecular interactions within MARCKS are also possible. Because of the unusual primary sequence of MARCKS with an overall isoelectric point of 4.2 yet a very basic PSD (overall charge of ؉13), we speculated that ionic interactions between oppositely charged domains of MARCKS were responsible for long-range interactions within MARCKS that sterically influence binding events at the PSD and that explain the observed differences between properties of the PSD and MARCKS. Consistent with this hypothesis, chemical modifications of MARCKS that neutralize negatively charged residues outside of the PSD allow the PSD to bind to actin and increase the affinity of MARCKS for calmodulin. Similarly, both myristoylation of MARCKS and cleavage of MARCKS by calpain are shown to increase the availability of the PSD so as to activate its actin-binding activity. Because abundant evidence supports the conclusion that MARCKS is an important protein in regulating actin dynamics, our data imply that post-translational modifications of MARCKS are necessary and sufficient to regulate actin-binding activity. Myristoylated alanine-rich C kinase substrate (MARCKS)1 is a well characterized, charge-polarized, natively unfolded molecule (1-3) with a centrally located active site known as the phosphorylation site domain (PSD). Consistent with the paradigm for natively unfolded proteins, MARCKS is thought to interact with several ligands so as to integrate information from various signal transduction pathways to produce an output signal that regulates cell motile and contractile function. Numerous studies of the MARCKS protein have utilized a peptide with a sequence that corresponds to the PSD peptide as a substitute for studying interactions between the intact protein and its multiple ligands (3, 4). Although this approach intuitively appears to be logical, given the unfolded state of the native protein, the substitution of the PSD peptide for the intact protein has never been rigorously justified. In fact, there are several reported experiments that imply that the PSD peptide behaves differently from intact MARCKS. The nonphosphorylated PSD peptide is known to have extended structure, to nucleate polymerization, and to cross-link F-actin filaments (5-7), presumably because of two binding sites with a site-specific K d of ϳ0.5 M for F-actin (8). Although the PSD of MARCKS and its homolog MARCKS-related protein have both been shown to bind to actin with si...

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Protein kinase C activation downregulates the expression and function of the basolateral Na+/K+/2Cl? cotransporter

et al. 1999

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The basolateral Na+/K+/2Cl(-) cotransporter (NKCC1) has been shown to be an independent regulatory site for electrogenic Cl(-) secretion. The proinflammatory phorbol ester, phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), inhibits basal and cyclic adenosine monophosphate (cAMP)-stimulated NKCC1 activity in T84 intestinal epithelial cells and decreases the steady state levels of NKCC1 mRNA in a time- and dose-dependent manner. The levels of NKCC1 protein also fall in accordance with the NKCC1 mRNA transcript and these levels are unaffected by 4alpha-phorbol, which does not activate PKC. Inhibition of maximal (cAMP-stimulated) NKCC1 functional activity by PMA was first detected by 1 h, whereas decreases in the steady state levels of NKCC1 mRNA were not detectable until 4 h. NKCC1 mRNA expression recovers toward control levels with extended treatment of cells with PMA suggesting that the PMA effects on NKCC1 expression are mediated through activation of PKC. Although NKCC1 mRNA and protein levels return to control values after extended PMA exposure, NKCC1 functional activity does not recover. Immunofluorescence imaging suggest that the absence of functional recovery is due to failure of newly synthesized NKKC1 protein to reach the cell surface. We conclude that NKCC1 has the capacity to be regulated at the level of de novo expression by PKC, although decreased NKCC1 expression alone cannot account for either early or late loss of NKCC1 function.

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PKC-ε regulates basolateral endocytosis in human T84 intestinal epithelia: role of F-actin and MARCKS

Cited by 88 publications

References 45 publications

Formation of protein kinase Cε-Lck signaling modules confers cardioprotection

Formation of protein kinase Cε-Lck signaling modules confers cardioprotection

MARCKS Is a Natively Unfolded Protein with an Inaccessible Actin-binding Site

Protein kinase C activation downregulates the expression and function of the basolateral Na+/K+/2Cl? cotransporter

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