Title
Endoplasmic reticulum stress leads to the selective transcriptional downregulation of the glucoamylase gene in Aspergillus niger
Author
Al-Sheikh, H.
Watson, A.J.
Lacey, G.A.
Punt, P.J.
MacKenzie, D.A.
Jeenes, D.J.
Pakula, T.
Penttilä, M.
Alcocer, M.J.C.
Archer, D.B.
TNO Voeding
Publication year
2004
Abstract
We describe a new endoplasmic reticulum (ER)-associated stress response in the filamentous fungus Aspergillus niger. The inhibition of protein folding within the ER leads to cellular responses known collectively as the unfolded protein response (UPR) and we show that the selective transcriptional downregulation of the gene encoding glucoamylase, a major secreted protein, but not two non-secreted proteins, is an additional consequence of ER stress. The transcriptional downregulation effect is shown by nuclear run-on studies to be at the level of transcription, rather than mRNA stability, and is found to be mediated through the promoter of gIaA in a region more than 1 kb upstream of the translational start. The inhibition of protein folding in the ER can be induced in a variety of ways. We examined the effects of dithiothreltol (DTT), a reducing agent that causes the formation of unfolded proteins. Although a general downregulation of transcription was seen with DTT treatment, we show that selective downregulation was observed with the gIaA, gene compared with genes encoding the non-secreted proteins γ-actin and glyceraldehyde 3′-phosphate dehydrogenase. The DTT-treated fungal cells also showed evidence for the induction of the UPR because expression of bipA and pdiA, encoding an ER-resident chaperone and foldase, respectively, are upregulated and splicing of hscA, the gene encoding the transcription factor responsible for induction of the UPR, occurs allowing the production of an active HacA protein. As a preliminary attempt to investigate if the transcriptional downregulation effect was mediated through HacA (i.e. part of the UPR), we examined ER stress induced through antisense technology to lower the level of PDI in the ER of A. niger. Although the transcription of gIaA was attenuated in that strain of A. niger, UPR was not evident, suggesting that the transcriptional downregulation mechanism is controlled differently from the UPR.
Subject
Biology
Biotechnology
actin
chaperone
dithiothreitol
gamma actin
glucan 1,4 alpha glucosidase
glyceraldehyde 3 phosphate dehydrogenase
protein HacA
unclassified drug
article
Aspergillus niger
bipa gene
down regulation
endoplasmic reticulum
fungal cell
fungal gene
fungal strain
gene expression
gene induction
genetic code
glaa gene
nonhuman
pdiA gene
priority journal
promoter region
protein folding
protein secretion
RNA splicing
RNA stability
stress
transcription regulation
upregulation
Aspergillus niger
Dithiothreitol
Down-Regulation
Endoplasmic Reticulum
Fungal Proteins
Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Fungal
Glucan 1,4-alpha-Glucosidase
HSP70 Heat-Shock Proteins
Oligonucleotides, Antisense
Promoter Regions (Genetics)
Protein Folding
Transcription, Genetic
Aspergillus
Aspergillus niger
Fungi
To reference this document use:
http://resolver.tudelft.nl/uuid:3bfe74db-a1c3-4d78-b40e-6b7332997180
DOI
https://doi.org/10.1111/j.1365-2958.2004.04236.x
TNO identifier
237946
ISSN
0950-382X
Source
Molecular Microbiology, 53 (6), 1731-1742
Document type
article