alpha-Fetoprotein gene expression. Control of alpha-fetoprotein mRNA levels in cultured rat hepatoma cells.

Cell hydration changes critically affect liver metabolism and gene expression. In the course of gene expression studies using nylon cDNA-arrays we found that hyperosmolarity (405 mosmol/l) suppressed the betaine-homocysteine methyltransferase ( Bhmt) mRNA expression in H4IIE rat hepatoma cells. This was confirmed by Northern blot and real-time quantitative RT-PCR analysis, which in addition unraveled a pronounced induction of Bhmt mRNA expression by hypoosmotic (205 mosmol/l) swelling. Osmotic regulation of Bhmt mRNA expression was largely paralleled at the levels of Bhmt protein and enzymatic activity. Like hyperosmotic NaCl, hyperosmotic raffinose but not hyperosmotic urea suppressed Bhmt mRNA expression, suggesting that cell shrinkage rather than increased ionic strength or hyperosmolarity per se is the trigger. Hypoosmolarity increased the expression of a reporter gene driven by the entire human BHMT promoter, whereas destabilization of BHMT mRNA was observed under hyperosmotic conditions. Osmosensitivity of Bhmt mRNA expression was impaired by inhibitors of tyrosine kinases and cyclic nucleotide-dependent kinases. The osmotic regulation of BHMT may be part of a cell volume-regulatory response and additionally lead to metabolic alterations that depend on the availability of betaine-derived methyl groups.

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Osmoregulated taurine transport in H4IIE hepatoma cells and perfused rat liver

Biochemical Journal ◽

10.1042/bj3210683 ◽

1997 ◽

Vol 321 (3) ◽

pp. 683-690 ◽

Cited By ~ 57

Author(s):

Ulrich WARSKULAT ◽

Matthias WETTSTEIN ◽

Dieter HÄUSSINGER

Keyword(s):

Rat Liver ◽

Hepatoma Cells ◽

Cell Swelling ◽

Mrna Levels ◽

Taurine Transport ◽

H4iie Cells ◽

Taurine Uptake ◽

Rat Hepatoma ◽

Taurine Efflux ◽

Rat Hepatoma Cells

The effects of aniso-osmotic exposure on taurine transport were studied in H4IIE rat hepatoma cells. Hyperosmotic (405 mosmol/l) exposure of H4IIE cells stimulated Na+-dependent taurine uptake and led to an increase in taurine transporter (TAUT) mRNA levels, whereas hypo-osmotic (205 mosmol/l) exposure diminished both taurine uptake and TAUT mRNA levels when compared with normo-osmotic (305 mosmol/l) control incubations. Taurine uptake increased 30Ő40-fold upon raising the ambient osmolarity from 205 to 405 mosmol/l. When H4IIE cells and perfused livers were preloaded with taurine, hypo-osmotic cell swelling led to a rapid release of taurine from the cells. The taurine efflux, but not taurine uptake, was sensitive to 4,4ƀ-di-isothiocyanatostilbene-2,2ƀ-disulphonic acid (DIDS), suggestive of an involvement of DIDS-sensitive channels in mediating volume-regulatory taurine efflux. Whereas in both H4IIE rat hepatoma cells and primary hepatocytes TAUT mRNA levels were strongly dependent upon ambient osmolarity, mRNAs for other osmolyte transporters, i.e. the betaine transporter BGT-1 and the Na+/myo-inositol transporter SMIT, were not detectable. In line with this, myo-inositol uptake by H4IIE hepatoma cells was low and was not stimulated by hyperosmolarity. However, despite the absence of BGT-1 mRNA, a slight osmosensitive uptake of betaine was observed, but the rate was less than 10% of that of taurine transport. This study identifies a constitutively expressed and osmosensitive TAUT in H4IIE cells and the use of taurine as a main osmolyte, whereas betaine and myo-inositol play little or no role in the osmolyte strategy in these cells. This is in contrast with rat liver macrophages, in which betaine has been shown to be a major osmolyte.

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mRNA Levels of Related Abcb Genes Change Opposite to Each Other upon Histone Deacetylase Inhibition in Drug-Resistant Rat Hepatoma Cells

PLoS ONE ◽

10.1371/journal.pone.0084915 ◽

2014 ◽

Vol 9 (1) ◽

pp. e84915 ◽

Cited By ~ 4

Author(s):

Ádám Sike ◽

Enikő Nagy ◽

Balázs Vedelek ◽

Dávid Pusztai ◽

Péter Szerémy ◽

...

Keyword(s):

Histone Deacetylase ◽

Hepatoma Cells ◽

Mrna Levels ◽

Drug Resistant ◽

Histone Deacetylase Inhibition ◽

Rat Hepatoma ◽

Rat Hepatoma Cells

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Supervised generative design of regulatory DNA for gene expression control

10.1101/2021.07.15.452480 ◽

2021 ◽

Author(s):

Jan Zrimec ◽

Xiaozhi Fu ◽

Azam Sheikh Muhammad ◽

Christos Skrekas ◽

Vykintas Jauniskis ◽

...

Keyword(s):

Gene Expression ◽

De Novo ◽

Regulatory Region ◽

Genomic Data ◽

Mrna Levels ◽

Expression Levels ◽

Expression Control ◽

Gene Expression Control ◽

Gene Regulatory ◽

Regulatory Dna

In order to control gene expression, regulatory DNA variants are commonly designed using random synthetic approaches with mutagenesis and screening. This however limits the size of the designed DNA to span merely a part of a single regulatory region, whereas the whole gene regulatory structure including the coding and adjacent non-coding regions is involved in controlling gene expression. Here, we prototype a deep neural network strategy that models whole gene regulatory structures and generates de novo functional regulatory DNA with prespecified expression levels. By learning directly from natural genomic data, without the need for large synthetic DNA libraries, our ExpressionGAN can traverse the whole sequence-expression landscape to produce sequence variants with target mRNA levels as well as natural-like properties, including over 30% dissimilarity to any natural sequence. We experimentally demonstrate that this generative strategy is more efficient than a mutational one when using purely natural genomic data, as 57% of the newly-generated highly-expressed sequences surpass the expression levels of natural controls. We foresee this as a lucrative strategy to expand our knowledge of gene expression regulation as well as increase expression control in any desired organism for synthetic biology and metabolic engineering applications.

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