Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2009 Aug;20(8):1787-96.
doi: 10.1681/ASN.2009010118. Epub 2009 Jun 25.

BRG1 increases transcription of proinflammatory genes in renal ischemia

Masayo Naito  1 , Richard A Zager, Karol Bomsztyk
Affiliations

BRG1 increases transcription of proinflammatory genes in renal ischemia

Masayo Naito et al. J Am Soc Nephrol. 2009 Aug.

Abstract

Acute kidney injury stimulates renal production of inflammatory mediators, including TNF-alpha and monocyte chemoattractant protein 1 (MCP-1). These responses reflect, in part, injury-induced transcription of proinflammatory genes by proximal tubule cells. Because of the compact structure of chromatin, a series of events at specified loci remodel chromatin to provide access for transcription factors and RNA polymerase II (Pol II). Here, we examined the role of Brahma-related gene-1 (BRG1), a chromatin remodeling enzyme, in the transcription of TNF-alpha and MCP-1 in response to renal ischemia. Two hours after renal ischemic injury in mice, renal TNF-alpha and MCP-1 mRNA increased and remained elevated for at least 1 wk. Matrix chromatin immunoprecipitation assays revealed sustained increases in Pol II at these genes, suggesting that the elevated mRNA levels were, at least in part, transcriptionally mediated. The profile of BGR1 binding to the genes encoding TNF-alpha and MCP-1 resembled Pol II recruitment. Knockdown of BRG1 by small interfering RNA blocked an ATP depletion-induced increase in TNF-alpha and MCP-1 transcription in a human proximal tubule cell line; this effect was associated with decreased recruitment of BRG1 and Pol II to these genes. In conclusion, BRG1 promotes increased transcription of TNF-alpha and MCP-1 by the proximal tubule in response to renal ischemia.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Expression of TNF-α and MCP-1 genes after I/R. RNA was extracted from mouse cortical samples at 2 h, 3 d, or 7 d after 30 min of I/R (formula image). The contralateral kidneys, not subjected to I/R, served as time-matched controls (■). The mRNA levels of TNF-α and MCP-1 were assessed by competitive PCR and are expressed as a ratio to the simultaneously obtained glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcript. Data are means ± 1 SD (n = 4 mice).
Figure 2.
Figure 2.
Profiles of Pol II, H3K4m3, H2AZ, and BRG1 after I/R along the TNF-α gene. Renal cortical chromatin was prepared from mice subjected to unilateral I/R (■). Renal cortical chromatin from the contralateral kidney of the same mouse was used as control (formula image). (A) Levels at the TNF-α first (exon 1) and last (exon 4) exons were assessed using matrix ChIP assays., (B) Levels measured in an intergenic region 5 kb downstream of the end of the TNF-α gene served as a control. Data are percentage of input DNA, mean ± 1 SD (n = 3 mice).
Figure 3.
Figure 3.
Profiles of Pol II, H3K4m3, H2A.Z, and BRG1 after I/R along the MCP-1 gene. Renal cortical chromatin was prepared from mice subjected to unilateral I/R (■). Renal cortical chromatin from contralateral kidney of the same mouse was used as control (formula image). (A) Levels at the MCP-1 first (exon 1) and last (exon 3) exons were assessed using matrix ChIP assays. (B) Levels measured in an intergenic region 5 kb downstream of the end of the MCP-1 gene served as a control. Data are percentage of input DNA, mean ± 1 SD (n = 3 mice).
Figure 4.
Figure 4.
(A and B) Effects of ATP depletion on density profiles of BRG1, Pol II, H3K4m3, and H2A.Z at the TNF-α (A) and MCP-1 (B) genes in proximal tubule HK-2 culture. Cells were subjected to 4 h of ATP depletion and 2 h of recovery (ATP depletion; see the Concise Methods section) (). Simultaneously treated cells, subjected to the same experimental protocol but without a previous ATP depletion (AA + DOG exposure), served as controls (Control). Chromatin was isolated and sheared. Density of given factors and marks at the first and the last exons of TNF-α and MCP-1 genes were assessed using matrix ChIP assays. Data are percentage of input DNA, mean ± 1 SD (n = 3 experiments).
Figure 5.
Figure 5.
Effects of siRNA BGR1 knockdown on the ATP depletion–induced expression of TNF-α and MCP-1 genes in proximal tubule HK-2 cell culture. After transfection with either BRG1 siRNA (■) or noncomplementary (NC) siRNA (formula image), HK-2 cells were treated either without (Control) or with (ATP depletion AA + DOG). Total RNA was extracted and reverse-transcribed, and transcript levels were assessed by real-time PCR done in triplicate using specific primers. mRNA levels are expressed as percentage of β-actin transcript. Data are means ± 1 SD (n = 3 experiments).
Figure 6.
Figure 6.
Effects of siRNA-induced BGR1 knockdown on the ATP depletion–induced co-recruitment of Pol II and BRG1 to the TNF-α gene in HK-2 cells. Cells were transfected with either BRG1 siRNA (■) specific or NC siRNA (formula image). After transfection, HK-2 cells were treated either without (Control) or with (ATP depletion) AA + DOG; chromatin was extracted and sheared. Density at the TNF-α first (exon 1) and last (exon 4) exons were assessed using matrix ChIP assay. Data are percentage of input DNA, mean ± 1 SD (n = 3 experiments).
Figure 7.
Figure 7.
Effects of siRNA BGR1 knockdown on the ATP depletion–induced co-recruitment of Pol II and BRG1 to the MCP-1 gene in HK-2 cells. Cells were transfected with either BRG1 siRNA (■) specific or NC siRNA (formula image). After transfection, HK-2 cells were treated either without (Control) or with (ATP depletion) AA + DOG; chromatin was extracted and sheared. Density at the MCP-1 first (exon 1) and last (exon 3) exons were assessed using matrix ChIP assay. Data are percentage of input DNA, mean ± 1 SD (n = 3 experiments).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Zager RA, Johnson AC, Lund S: ‘Endotoxin tolerance’: TNF-alpha hyper-reactivity and tubular cytoresistance in a renal cholesterol loading state. Kidney Int 71: 496–503, 2007 - PubMed
    1. Zager RA, Johnson AC, Hanson SY, Lund S: Acute nephrotoxic and obstructive injury primes the kidney to endotoxin-driven cytokine/chemokine production. Kidney Int 69: 1181–1188, 2006 - PubMed
    1. Zager RA, Johnson AC, Lund S, Hanson S: Acute renal failure: Determinants and characteristics of the injury-induced hyperinflammatory response. Am J Physiol Renal Physiol 291: F546–F556, 2006 - PubMed
    1. Ramesh G, Zhang B, Uematsu S, Akira S, Reeves WB: Endotoxin and cisplatin synergistically induce renal dysfunction and cytokine production in mice. Am J Physiol Renal Physiol 293: F325–F332, 2007 - PubMed
    1. Leemans JC, Stokman G, Claessen N, Rouschop KM, Teske GJ, Kirschning CJ, Akira S, van der Poll T, Weening JJ, Florquin S: Renal-associated TLR2 mediates ischemia/reperfusion injury in the kidney. J Clin Invest 115: 2894–2903, 2005 - PMC - PubMed

Publication types

MeSH terms