Tissue expression of ketohexokinase in cats

Springer, Nora L.; Lindbloom-Hawley, Sara; Schermerhorn, Thomas

doi:10.1016/j.rvsc.2008.11.004

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…Percent (%) nucleotide identity is highest with pancreatic GK cDNAs from primates (>90%) and slightly less with rodent pancreatic GK cDNAs. The latter finding is consistent with a trend observed in other feline genes involved in carbohydrate metabolism, such as G6PC (glucose-6-phosphatase catalytic subunit) [13] and KHK (ketohexokinase) [14], which have shown greater nucleotide identity with primate and canine sequences than with rodent species. The ten putative exons identified in feline GK have homology with established exon sequences of human pancreatic GK.…”

Section: Discussionsupporting

confidence: 88%

Cloning and characterization of feline islet glucokinase

et al. 2014

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BackgroundGlucokinase (GK) is a metabolic enzyme encoded by the GCK gene and expressed in glucose-sensitive tissues, principally pancreatic islets cell and hepatocytes. The GK protein acts in pancreatic islets as a “glucose sensor” that couples fluctuations in the blood glucose concentration to changes in cellular function and insulin secretion. GCK and GK have proposed importance in the development and progression of diabetes mellitus and are potential therapeutic targets for diabetes treatment. The study was undertaken to determine the nucleotide sequence of feline pancreatic GK cDNA, predict the amino acid sequence and structure of the feline GK protein, and perform comparative bioinformatic analysis of feline cDNA and protein. Routine PCR techniques were used with cDNA from feline pancreas. Clones were assembled to obtain the full length cDNA. Protein prediction and modeling were performed using bioinformatic tools.ResultsFull-length feline pancreatic GK cDNA contains a 1398 nucleotide coding sequence with high identity to other pancreatic GK cDNAs. The deduced 465 amino acid feline protein has 15 amino acid substitutions not found in other mammalian GK proteins but maintains high structural homology with human GK. Feline pancreatic GK is highly conserved at nucleotide and protein levels. Residues crucial for substrate binding and catalysis are completely conserved in the feline protein.ConclusionMolecular analysis predicts that feline pancreatic GK functions similarly to other mammalian GK proteins.

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Section: Discussionsupporting

confidence: 88%

Cloning and characterization of feline islet glucokinase

et al. 2014

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“…These animals do not seek sweet foods but can tolerate carbohydrate, including fructose in moderate amounts [although they are prone to develop hyperglycemia owing to a lack of hepatic glucokinase (Schermerhorn, 2013)]. They can even use fructose's energy, as they synthesize fructolytic enzymes in their liver (Springer et al, 2009). However, dietary sugars fail to enhance the gut hexose absorptive capacity of these animals as they do for other mammals (Buddington et al, 1991).…”

Section: Overviewmentioning

confidence: 99%

Fructose-containing caloric sweeteners as a cause of obesity and metabolic disorders

Tappy

2018

Journal of Experimental Biology

103

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Compared with other carbohydrates, fructose-containing caloric sweeteners (sucrose, high-fructose corn syrup, pure fructose and fructose-glucose mixtures) are characterized by: a sweet taste generally associated with a positive hedonic tone; specific intestinal fructose transporters, i.e. GLUT5; a two-step fructose metabolism, consisting of the conversion of fructose carbones into ubiquitous energy substrates in splanchnic organs where fructolytic enzymes are expressed, and secondary delivery of these substrates to extrasplanchnic tissues. Fructose is a dispensable nutrient, yet its energy can be stored very efficiently owing to a rapid induction of intestinal fructose transporters and of splanchnic fructolytic and lipogenic enzymes by dietary fructose-containing caloric sweeteners. In addition, compared with fat or other dietary carbohydrates, fructose may be favored as an energy store because it uses different intestinal absorption mechanisms and different inter-organ trafficking pathways. These specific features make fructose an advantageous energy substrate in wild animals, mainly when consumed before periods of scarcity or high energy turnover such as migrations. These properties of fructose storage are also advantageous to humans who are involved in strenuous sport activities. In subjects with low physical activity, however, these same features of fructose metabolism may have the harmful effect of favoring energy overconsumption. Furthermore, a continuous exposure to high fructose intake associated with a low energy turnover leads to a chronic overproduction of intrahepatic trioses-phosphate production, which is secondarily responsible for the development of hepatic insulin resistance, intrahepatic fat accumulation, and increased blood triglyceride concentrations. In the long term, these effects may contribute to the development of metabolic and cardiovascular diseases.

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“…The reason for abundant fructokinase expression in the feline liver is not clear since fructose, a simple sugar, is not expected in substantial quantity in a carnivore diet. KHK is widely expressed in feline tissues, including tissues (e.g., spleen) that have no role in nutrient metabolism (80). A similar pattern of KHK expression was previously defined in non-carnivore mammals (85), which led investigators to hypothesize possible roles for KHK in cell function in addition to its role in dietary fructose metabolism (85, 86).…”

Section: Carnivore Hepatic Glucose-sensing Pathwaysmentioning

confidence: 99%

Normal Glucose Metabolism in Carnivores Overlaps with Diabetes Pathology in Non-Carnivores

Schermerhorn

2013

Front. Endocrinol.

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Carnivores, such as the dolphin and the domestic cat, have numerous adaptations that befit consumption of diets with high protein and fat content, with little carbohydrate content. Consequently, nutrient metabolism in carnivorous species differs substantially from that of non-carnivores. Important metabolic pathways known to differ between carnivores and non-carnivores are implicated in the development of diabetes and insulin resistance in non-carnivores: (1) the hepatic glucokinase (GCK) pathway is absent in healthy carnivores yet GCK deficiency may result in diabetes in rodents and humans, (2) healthy dolphins and cats are prone to periods of fasting hyperglycemia and exhibit insulin resistance, both of which are risk factors for diabetes in non-carnivores. Similarly, carnivores develop naturally occurring diseases such as hemochromatosis, fatty liver, obesity, and diabetes that have strong parallels with the same disorders in humans. Understanding how evolution, environment, diet, and domestication may play a role with nutrient metabolism in the dolphin and cat may also be relevant to human diabetes.

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Tissue expression of ketohexokinase in cats

Cited by 13 publications

References 10 publications

Cloning and characterization of feline islet glucokinase

Cloning and characterization of feline islet glucokinase

Fructose-containing caloric sweeteners as a cause of obesity and metabolic disorders

Normal Glucose Metabolism in Carnivores Overlaps with Diabetes Pathology in Non-Carnivores

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