Genomic organization and the promoter region of the round-spotted pufferfish (Tetraodon fluviatilis) CDC37 gene

Tsai, Shu-Chuan; Leu, Jiann Horng; Chou, Chih Ming; Yeh, Maw Sheng; Huang, Fore‐Lien; Huang, Chang Jen

doi:10.1016/s0167-4781(00)00138-x

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…We have recently cloned and sequenced several fish PEPCKs (H L Booth, E R Busby & T P Mommsen, unpublished observations) and now have the tools to examine hormone-dependent induction of hepatic PEPCK. Also, cAMP responsive element binding proteins (CREBs) have already been described for fish genes (Tsai et al 2000), but knowledge is still fairly limited, yet interactions between PGs and CREBs in mammalian liver are common (Rudnick et al 2001). Short-term activation of gluconeogenesis as noted in the rockfish could be based on increased transport of lactate/pyruvate and decreased futile cycling through protein kinase-dependent inactivation of pyruvate kinase (Mommsen & Moon 1990).…”

Section: Mechanisms Of Action -Gluconeogenesismentioning

confidence: 99%

Novel role for prostaglandin E2 in fish hepatocytes: regulation of glucose metabolism

Busby

Cooper

Mommsen

2002

Journal of Endocrinology

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Prostaglandin E 2 (PGE 2 ) potently activated glycogenolysis and gluconeogenesis in isolated rockfish (Sebastes caurinus) hepatocytes. The average degree of activation for glycogenolysis was 6·4 0·67-fold (mean S.E.M.; n=37), and could be as much as 19-fold. Analysis of doseconcentration relationships between glycogenolytic actions and PGE 2 concentrations yielded an EC 50 around 120 nM in hepatocyte suspensions and 2 nM for hepatocytes immobilized on perifusion columns. For the activation of gluconeogenesis (1·74 0·14-fold; n=10), the EC 50 for suspensions was 60 nM. Intracellular targets for PGE 2 actions are adenylyl cyclase, protein kinase A and glycogen phosphorylase. Concentrations of cAMP increased with increasing concentrations of PGE 2 , and peaked within 2 min of hormone application. In the presence of the phosphodiesterase inhibitor, isobutyl-3-methylxanthine, peak height was increased and peak duration extended. The protein kinase A inhibitor, Rp-cAMPS, counteracted the activation of glycogenolysis by PGE 2 , implying that the adenylyl cyclase/protein kinase A pathway is the most important, if not exclusive, route of message transduction. PGE 2 activated plasma membrane adenylyl cyclase and hepatocyte glycogen phosphorylase in a dose-dependent manner. The effects were specific for PGE 2 ; smaller degrees of activation of glycogenolysis were noted for PGE 1 , 11-deoxy PGE 1 , 19-R-hydroxy-PGE 2 , and prostaglandins of the A, B and F -series. The selective EP 2 -receptor agonist, butaprost, was as effective as PGE 2 , suggesting that rockfish liver contains prostaglandin receptors pharmacologically related to the EP 2 receptors of non-hepatic tissues of mammals. Rockfish hepatocytes quickly degraded added PGE 2 (t Y =17-26 min). A similar ability to degrade PGE 2 has been noted in catfish (Ameiurus nebulosus) hepatocytes, but no glycogenolytic or gluconeogenic actions of the hormone are noted for this species.We conclude that PGE 2 is an important metabolic hormone in fish liver, with cAMP-mediated actions on glycogen and glucose metabolism, and probably other pathways regulated by cAMP and protein kinase A. The constant presence of EP 2 -like receptors is a unique feature of the fish liver, with interesting implications for function and evolution of prostaglandin receptors in vertebrates.

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Section: Mechanisms Of Action -Gluconeogenesismentioning

confidence: 99%