Calcineurin is essential for DNA synthesis in Swiss 3T3 fibroblasts

Tomono, Masahiro; Toyoshima, Kotaro; Ito, Motohiro; Amano, Hisao

doi:10.1042/bj3170675

Cited by 30 publications

(17 citation statements)

References 32 publications

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“…Because protein synthesis is required for cells to exit from G 0 and enter the cell cycle, an effect of the immunosupressants could also block mitogenesis. In fact, both CsA and FK506, but not a Ca 2ϩ /calmodulin-dependent protein kinase II inhibitor, inhibited DNA synthesis in fibroblasts (46). At present, however, there is no obvious mechanism by which CN might regulate the translation machinery.…”

Section: Discussionmentioning

confidence: 99%

Calcineurin mediates pancreatic growth in protease inhibitor-treated mice

Tashiro¹,

Samuelson²,

Liddle³

et al. 2004

American Journal of Physiology-Gastrointestinal and Liver Physi

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. Calcineurin mediates pancreatic growth in protease inhibitor-treated mice. Am J Physiol Gastrointest Liver Physiol 286: G784-G790, 2004. First published December 18, 2003 10.1152/ ajpgi.00446.2003.-CCK acts on pancreatic acinar cells to increase intracellular Ca 2ϩ leading to secretion of digestive enzymes and, in the long term, pancreatic growth. Calcineurin (CN) is a serine/ threonine-specific protein phosphatase activated by Ca 2ϩ and calmodulin that recently has been shown to participate in the growth regulation of cardiac and skeletal myocytes. We therefore tested the effect of two different CN inhibitors, cyclosporine A (CsA) and FK506, on mouse pancreatic growth induced by oral administration of the synthetic protease inhibitor camostat, a known stimulator of endogenous CCK release. Mice were fed a powdered diet with or without 0.1% camostat. Pancreatic wet weight, protein, and DNA were increased in response to camostat in a time-dependent manner over 10 days in ICR mice but not in CCK-deficient mice. Both CsA (15 mg/kg) and FK506 (3 mg/kg) given twice daily blocked the increase in pancreatic wet weight and protein and DNA content induced by camostat. The increase in plasma CCK induced by camostat was not blocked by CsA or FK506. Camostat feeding also increased the relative amount of CN protein, whereas levels of MAPKs, ERKs, and p38 were not altered. In summary, 1) CCK released by chronic camostat feeding induces pancreatic growth in mice; 2) this growth is blocked by treatment with both CsA and FK506, indicating a role for CN; 3) CCK stimulation also increases CN protein. In conclusion, activation and possibly upregulation of CN may participate in regulation of pancreatic growth by CCK in mice.cholecystokinin; camostat; FK506; cyclosporine A A VARIETY OF GASTROINTESTINAL peptides have been implicated in the regulation of proliferation and differentiation in the mature gastrointestinal tract and the pancreas (30,56). It is well known that feeding initiates pancreatic protein synthesis and secretion and that adaptation to a high-protein diet results in pancreatic growth (17, 18). More detailed studies have shown that among gastrointestinal peptides, CCK is released in response to dietary protein leading to pancreatic growth. Injection of CCK increases pancreatic wet weight and protein and DNA content in vivo over 4-10 days (8,37,40,43). Oral administration of soybean trypsin inhibitor (5, 44) or the synthetic protease inhibitor camostat (10,15,37,52,55), as well as pancreaticobiliary diversion (13, 39), increase the release of endogenous CCK into the blood and induce pancreatic growth. Moreover, CCK-A receptor antagonists that block the action of exogenous and endogenous CCK inhibit pancreatic growth (10, 13, 37, 39, 52). Therefore, most of the studies of pancreatic growth have been focused on CCK as a key regulator.In pancreatic acinar cells, the intracellular mechanisms of enzyme secretion have been well documented. CCK activates the release of intracellular Ca 2ϩ and the influx of Ca 2ϩ and generate...

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Section: Discussionmentioning

confidence: 99%

Calcineurin mediates pancreatic growth in protease inhibitor-treated mice

Tashiro¹,

Samuelson²,

Liddle³

et al. 2004

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…In mammals, calcineurin mediates T cell and B cell proliferation (15,24,25,36) and has been implicated in urotensin II-mediated proliferation of airway SMC (7), angiotensin II-induced cardiac fibroblast hyperplasia (12), and pituitary cell proliferation (11). Indeed, calcineurin has been shown to be essential for DNA synthesis in Swiss 3T3 fibroblasts (47), where inhibitors of calcineurin block the fibroblast growth factor-mediated expression of cyclins A and E (48).…”

Section: Discussionmentioning

confidence: 99%

“…Both c-Myb and calcineurin influence Ca 2ϩ -mediated signals of cell cycle (1,22,47,48 influx and a c-Myb-dependent reduction in Ca 2ϩ efflux mediated via repression of PMCA1 (1,22,23,40,41). Indeed, ϳ60% of the c-Myb effect on VSMC proliferation is exerted via PMCA1 repression (22).…”

Section: Discussionmentioning

confidence: 99%

Calcineurin-independent regulation of plasma membrane Ca²⁺ ATPase-4 in the vascular smooth muscle cell cycle

Afroze

Yang

Wang

et al. 2003

American Journal of Physiology-Cell Physiology

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. Calcineurinindependent regulation of plasma membrane Ca 2ϩ ATPase-4 in the vascular smooth muscle cell cycle. Am J Physiol Cell Physiol 285: C88-C95, 2003; 10.1152/ajpcell.00518.2002.-Calcineurin mediates repression of plasma membrane Ca 2ϩ -ATPase-4 (PMCA4) expression in neurons, whereas c-Myb is known to repress PMCA1 expression in vascular smooth muscle cells (VSMC). Here, we describe a novel mouse VSMC line (MOVAS) in which 45 Ca efflux rates decreased 50%, fura 2-AM-based intracellular Ca 2ϩ concentrations ([Ca 2ϩ ]i) increased twofold, and real-time RT-PCR and Western blot revealed a ϳ40% decrease in PMCA4 expression levels from G 0 to G1/S in the cell cycle, where PMCA4 constituted ϳ20% of total PMCA protein. Although calcineurin activity increased fivefold as MOVAS progressed from G0 to G1/S, inhibition of this increase with either BAPTA or retroviral transduction with peptide inhibitors of calcineurin (CAIN), or its downstream target nuclear factor of activated T cells (NFAT) (VIVIT), had no effect on the repression of PMCA4 mRNA expression at G1/S. By contrast, Ca 2ϩ -independent activity of the calmodulin-dependent protein kinase-II (CaMK-II) increased eightfold as MOVAS progressed from G0 to G1/S, and treatment with an inhibitor of CaMK-II (KN-93) or transduction of a c-Myb-neutralizing antibody significantly alleviated the G1/S-associated repression of PMCA4. These data show that G1/S-specific PMCA4 repression in proliferating VSMC is brought about by c-Myb and CaMK-II and that calcineurin may regulate cell cycle-associated [Ca 2ϩ ]i through alternate targets. /calmodulin-mediated signals act at multiple points in the cell cycle, including the G 0 /G 1 transition, the initiation of S-phase, and the initiation and completion of M phase (reviewed in Refs. 4,31,38,and 44 ] i ) needed for G 1 -to-S transitions in rat vascular smooth muscle cells (VSMC) (22, 23).We previously showed that the cell cycle-associated repression of PMCA1 expression during G 0 to G 1 /S progression in rat VSMC is mediated by the c-Myb transcription factor (1). However, the mechanism(s) underlying the cell cycle-associated repression of PMCA4 had not been elucidated. Guerini et al. (18) demonstrated in mouse neurons that PMCA4 expression can be repressed by a calcineurin-dependent pathway. Given this result, we hypothesized that G 1 /Sassociated repression of PMCA4 expression in VSMC may also be mediated by calcineurin. To explore these mechanisms in cell culture, we generated a clonal, immortalized mouse VSMC line (MOVAS). Immunostaining for smooth muscle-specific proteins such as SM22␣, calponin, smooth muscle-specific ␣-actin and desmin, as well as SM22␣ promoter-driven enhanced green fluorescent protein (EGFP) expression, confirm the lineage and phenotype of these cells. 45 Ca efflux assays and fura 2-based ratiometric Ca 2ϩ imaging reveal regulated Ca 2ϩ efflux and [Ca 2ϩ ] i at the G 1 /S transition point. Western blot and real time RT-PCR reveal cell cycle-regulated repression of mouse PMCA1 and PMCA4. Drugs in...

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“…1 In several cell types, DNA synthesis is completely inhibited when extracellular Ca 2+ was chelated by EGTA, or when the influx of extracellular Ca 2+ was blocked by cobalt. 2,3 Similarly, depletion of extracellular Ca 2+ during the first 8 h after growth factor stimulation resulted in an inhibition of DNA synthesis in human fibroblasts. 4 In addition, depletion of intracellular Ca 2+ stores with pharmacological agents, such as the sarco-endoplasmic reticulum Ca 2+ ATPase (SERCA) inhibitor thapsigargin, resulted in significant abrogation or delay of progression to S phase.…”

Section: Ca 2+ /Cam Play a Role In Cell Cycle Progressionmentioning

confidence: 99%