PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

Poole, Daniel P.; Furness, John B.

doi:10.1152/ajpgi.00222.2006

Cited by 12 publications

(10 citation statements)

References 52 publications

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“…To determine whether the PKC/CPI-17 or Rho/ROCK signaling pathways (24,28,47,48,53,63) are involved in the increased tonic contraction in SMB (Ϫ/Ϫ) ileum and antrum, intact tissue strips were contracted with KPSS in the presence of the PKC inhibitors Gö 6976 or GF 109203X or the ROCK inhibitors Y27632 or H1152. The area under the active force curve (from peak force to 10 min after the peak force) and 10-min tonic force were measured with or without these inhibitors.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanism underlying the latch state is unknown. Several regulatory mechanisms have been hypothesized including altered kinetics of phosphorylated vs. dephosphorylated myosin cross bridges (7, 21), cytoskeletal remodeling (19,26,35,41,45), calponin-or caldesmon-dependent actin-to-myosin crosslinks (57, 59), second messenger pathway regulation of MLCK/MLCP activity (24,28,47,48,53,63), and the kinetic properties of actomyosin ATPase of different myosin isoforms [nonmuscle (NM) and smooth muscle (SM) myosin II isoforms; Refs. 16,32,33,[37][38][39]42,51,65].…”

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confidence: 99%

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SMB myosin heavy chain knockout enhances tonic contraction and reduces the rate of force generation in ileum and stomach antrum

Huang

Babu

Periasamy

et al. 2013

American Journal of Physiology-Cell Physiology

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The role of SMA and SMB smooth muscle myosin heavy chain (MHC) isoforms in tonic and phasic contractions was studied in phasic (longitudinal ileum and stomach circular antrum) and tonic (stomach circular fundus) smooth muscle tissues of SMB knockout mice. Knocking out the SMB MHC gene eliminated SMB MHC protein expression and resulted in upregulation of the SMA MHC protein without altering the total MHC protein level. Switching from SMB to SMA MHC protein expression decreased the rate of the force transient and increased the sustained tonic force in SMB((-/-)) ileum and antrum with high potassium (KPSS) but not with carbachol (CCh) stimulation. The increased tonic contraction under the depolarized condition was not through changes in second messenger signaling pathways (PKC/CPI-17 or Rho/ROCK signaling pathway) or LC(20) phosphorylation. Biochemical analyses showed that the expression of contractile regulatory proteins (MLCK, MLCP, PKCδ, and CPI-17) did not change significantly in tissues tested except for PKCα protein expression being significantly decreased in the SMB((-/-)) antrum. However, specifically activating PKCα with phorbol dibutyrate (PDBu) was not significantly different in knockout and wild-type tissues, with total force being a fraction of the force generation with KPSS or CCh stimulation in SMB((-/-)) ileum and antrum. Taken together, these data show removing the SMB MHC protein expression with a compensatory increase in the SMA MHC protein results in enhanced sustained KPSS-induced tonic contraction with a reduced rate of force generation in these phasic tissues.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

SMB myosin heavy chain knockout enhances tonic contraction and reduces the rate of force generation in ileum and stomach antrum

Huang

Babu

Periasamy

et al. 2013

American Journal of Physiology-Cell Physiology

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“…We observed that, under the same conditions leading to inhibition of oxalate transport, carbachol also induced significant PKC-␦ translocation from the cytosol to the membrane of T84 cells, thus providing further evidence that PKC-␦ is the likely involved PKC isoform. Of interest in this regard is that PKC-␦ mediates carbachol-induced amylase release from pancreas (54), and carbachol-induced tonic contraction of the guinea pig ileum (64).…”

Section: Discussionmentioning

confidence: 99%

Cholinergic signaling inhibits oxalate transport by human intestinal T84 cells

Hassan

Cheng

Aronson

2012

American Journal of Physiology-Cell Physiology

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Urolithiasis remains a very common disease in Western countries. Seventy to eighty percent of kidney stones are composed of calcium oxalate, and minor changes in urinary oxalate affect stone risk. Intestinal oxalate secretion mediated by anion exchanger SLC26A6 plays a major constitutive role in limiting net absorption of ingested oxalate, thereby preventing hyperoxaluria and calcium oxalate urolithiasis. Using the relatively selective PKC-δ inhibitor rottlerin, we had previously found that PKC-δ activation inhibits Slc26a6 activity in mouse duodenal tissue. To identify a model system to study physiologic agonists upstream of PKC-δ, we characterized the human intestinal cell line T84. Knockdown studies demonstrated that endogenous SLC26A6 mediates most of the oxalate transport by T84 cells. Cholinergic stimulation with carbachol modulates intestinal ion transport through signaling pathways including PKC activation. We therefore examined whether carbachol affects oxalate transport in T84 cells. We found that carbachol significantly inhibited oxalate transport by T84 cells, an effect blocked by rottlerin. Carbachol also led to significant translocation of PKC-δ from the cytosol to the membrane of T84 cells. Using pharmacological inhibitors, we observed that carbachol inhibits oxalate transport through the M(3) muscarinic receptor and phospholipase C. Utilizing the Src inhibitor PP2 and phosphorylation studies, we found that the observed regulation downstream of PKC-δ is partially mediated by c-Src. Biotinylation studies revealed that carbachol inhibits oxalate transport by reducing SLC26A6 surface expression. We conclude that carbachol negatively regulates oxalate transport by reducing SLC26A6 surface expression in T84 cells through signaling pathways including the M(3) muscarinic receptor, phospholipase C, PKC-δ, and c-Src.

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“…It is unclear, however, what role(s) PKC and ROCK play in the phosphorylation of CPI-17 and MYPT1 and whether or not there is any cross-talk between the two pathways during bladder smooth muscle contraction as has been suggested in other smooth muscles (Niiro et al, 2003). For example, activation of ROCK by PKC, specifically the PKCδ isoform, has been shown to be involved in several cell functions, including vascular smooth muscle migration and contraction (Kandabashi et al, 2003; Ohtsu et al, 2005; Poole and Furness, 2007). …”

Section: Introductionmentioning

confidence: 99%

Phorbol 12,13-Dibutyrate-Induced, Protein Kinase C-Mediated Contraction of Rabbit Bladder Smooth Muscle

Wang¹,

Kendig²,

Trappanese³

et al. 2012

Front. Pharmacol.

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Contraction of bladder smooth muscle is predominantly initiated by M3 muscarinic receptor-mediated activation of the Gq/11-phospholipase C β-protein kinase C (PKC) and the G12/13-RhoGEF-Rho kinase (ROCK) pathways. However, these pathways and their downstream effectors are not well understood in bladder smooth muscle. We used phorbol 12,13-dibutyrate (PDBu), and 1,2-dioctanoyl-sn-glycerol (DOG), activators of PKC, in this investigation. We were interested in dissecting the role(s) of PKC and to clarify the signaling pathways in bladder smooth muscle contraction, especially the potential cross-talk with ROCK and their downstream effectors in regulating myosin light chain phosphatase activity and force. To achieve this goal, the study was performed in the presence or absence of the PKC inhibitor bisindolylmaleimide-1 (Bis) or the ROCK inhibitor H-1152. Phosphorylation levels of Thr38-CPI-17 and Thr696/Thr850 myosin phosphatase target subunit (MYPT1) were measured during PDBu or DOG stimulation using site specific antibodies. PDBu-induced contraction in bladder smooth muscle involved both activation of PKC and PKC-dependent activation of ROCK. CPI-17 as a major downstream effector, is phosphorylated by PKC and ROCK during PDBu and DOG stimulation. Our results suggest that Thr696 and Thr850-MYPT1 phosphorylation are not involved in the regulation of a PDBu-induced contraction. The results also demonstrate that bladder smooth muscle contains a constitutively active isoform of ROCK that may play an important role in the regulation of bladder smooth muscle basal tone. Together with the results from our previous study, we developed a working model to describe the complex signaling pathways that regulate contraction of bladder smooth muscle.

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PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

Abstract: Poole DP, Furness JB. PKC ␦-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle.

Cited by 12 publications

References 52 publications

SMB myosin heavy chain knockout enhances tonic contraction and reduces the rate of force generation in ileum and stomach antrum

SMB myosin heavy chain knockout enhances tonic contraction and reduces the rate of force generation in ileum and stomach antrum

Cholinergic signaling inhibits oxalate transport by human intestinal T84 cells

Phorbol 12,13-Dibutyrate-Induced, Protein Kinase C-Mediated Contraction of Rabbit Bladder Smooth Muscle

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