Activation of glucokinase gene expression by hepatic nuclear factor 4α in primary hepatocytes

Glucokinase (GK) is a key enzyme for glucose utilization in liver and shows a higher expression in the perivenous zone. In primary rat hepatocytes, the GK gene expression was activated by HNF (hepatic nuclear factor)-4α via the sequence −52/−39 of the GK promoter. Venous pO2 enhanced HNF-4 levels and HNF-4 binding to the GK—HNF-4 element. Thus, HNF-4α could play the role of a regulator for zonated GK expression.

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Human cell transformation by combined lineage conversion and oncogene expression

Oncogene ◽

10.1038/s41388-021-01940-0 ◽

2021 ◽

Author(s):

Biswajyoti Sahu ◽

Päivi Pihlajamaa ◽

Kaiyang Zhang ◽

Kimmo Palin ◽

Saija Ahonen ◽

...

Keyword(s):

Gene Expression ◽

Liver Cancer ◽

Human Cell ◽

Genetic Disease ◽

Cell Transformation ◽

Human Fibroblasts ◽

Driver Mutations ◽

Primary Hepatocytes ◽

Direct Support

AbstractCancer is the most complex genetic disease known, with mutations implicated in more than 250 genes. However, it is still elusive which specific mutations found in human patients lead to tumorigenesis. Here we show that a combination of oncogenes that is characteristic of liver cancer (CTNNB1, TERT, MYC) induces senescence in human fibroblasts and primary hepatocytes. However, reprogramming fibroblasts to a liver progenitor fate, induced hepatocytes (iHeps), makes them sensitive to transformation by the same oncogenes. The transformed iHeps are highly proliferative, tumorigenic in nude mice, and bear gene expression signatures of liver cancer. These results show that tumorigenesis is triggered by a combination of three elements: the set of driver mutations, the cellular lineage, and the state of differentiation of the cells along the lineage. Our results provide direct support for the role of cell identity as a key determinant in transformation and establish a paradigm for studying the dynamic role of oncogenic drivers in human tumorigenesis.

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Characterization of the Role of AMP-Activated Protein Kinase in the Regulation of Glucose-Activated Gene Expression Using Constitutively Active and Dominant Negative Forms of the Kinase

Molecular and Cellular Biology ◽

10.1128/mcb.20.18.6704-6711.2000 ◽

2000 ◽

Vol 20 (18) ◽

pp. 6704-6711 ◽

Cited By ~ 293

Author(s):

Angela Woods ◽

Dalila Azzout-Marniche ◽

Marc Foretz ◽

Silvie C. Stein ◽

Patricia Lemarchand ◽

...

Keyword(s):

Gene Expression ◽

Protein Kinase ◽

Fatty Acid Synthase ◽

Physiological Role ◽

Rat Hepatocytes ◽

Dominant Negative ◽

Ampk Activity ◽

Amp Activated Protein Kinase ◽

Constitutively Active

ABSTRACT In the liver, glucose induces the expression of a number of genes involved in glucose and lipid metabolism, e.g., those encoding L-type pyruvate kinase and fatty acid synthase. Recent evidence has indicated a role for the AMP-activated protein kinase (AMPK) in the inhibition of glucose-activated gene expression in hepatocytes. It remains unclear, however, whether AMPK is involved in the glucose induction of these genes. In order to study further the role of AMPK in regulating gene expression, we have generated two mutant forms of AMPK. One of these (α1312) acts as a constitutively active kinase, while the other (α1DN) acts as a dominant negative inhibitor of endogenous AMPK. We have used adenovirus-mediated gene transfer to express these mutants in primary rat hepatocytes in culture in order to determine their effect on AMPK activity and the transcription of glucose-activated genes. Expression of α1312 increased AMPK activity in hepatocytes and blocked completely the induction of a number of glucose-activated genes in response to 25 mM glucose. This effect is similar to that observed following activation of AMPK by 5-amino-imidazolecarboxamide riboside. Expression of α1DN markedly inhibited both basal and stimulated activity of endogenous AMPK but had no effect on the transcription of glucose-activated genes. Our results suggest that AMPK is involved in the inhibition of glucose-activated gene expression but not in the induction pathway. This study demonstrates that the two mutants we have described will provide valuable tools for studying the wider physiological role of AMPK.

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