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SIRT2 deficiency modulates macrophage polarization and susceptibility to experimental colitis.

Lo Sasso G, Menzies KJ, Mottis A, Piersigilli A, Perino A, Yamamoto H, Schoonjans K, Auwerx J - PLoS ONE (2014)

Bottom Line: Notably, under basal condition, Sirt2 deficiency does not affect the basal phenotype and intestinal morphology Sirt2 deficiency, however, affects macrophage polarization, creating a pro-inflammatory milieu in the immune cells compartment.In fact, SIRT2 deletion promotes inflammatory responses by increasing NF-κB acetylation and by reducing the M2-associated anti-inflammatory pathway.Finally, we speculate that the activation of SIRT2 may be a potential approach for the treatment of inflammatory bowel disease.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

ABSTRACT

Background: SIRT2 belongs to a highly conserved family of NAD+-dependent deacylases, consisting of seven members (SIRT1-SIRT7), which vary in subcellular localizations and have substrates ranging from histones to transcription factors and enzymes. Recently SIRT2 was revealed to play an important role in inflammation, directly binding, deacetylating, and inhibiting the p65 subunit of NF-κB.

Methods: A Sirt2 deficient mouse line (Sirt2-/-) was generated by deleting exons 5-7, encoding part of the SIRT2 deacetylase domain, by homologous recombination. Age- and sex-matched Sirt2-/- and Sirt2+/+ littermate mice were subjected to dextran sulfate sodium (DSS)-induced colitis and analyzed for colitis susceptibility.

Results: Sirt2-/- mice displayed more severe clinical and histological manifestations after DSS colitis compared to wild type littermates. Notably, under basal condition, Sirt2 deficiency does not affect the basal phenotype and intestinal morphology Sirt2 deficiency, however, affects macrophage polarization, creating a pro-inflammatory milieu in the immune cells compartment.

Conclusion: These data confirm a protective role for SIRT2 against the development of inflammatory processes, pointing out a potential role for this sirtuin as a suppressor of colitis. In fact, SIRT2 deletion promotes inflammatory responses by increasing NF-κB acetylation and by reducing the M2-associated anti-inflammatory pathway. Finally, we speculate that the activation of SIRT2 may be a potential approach for the treatment of inflammatory bowel disease.

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Generation and characterization of the Sirt2−/− mouse model.(A) Schematic representation of the gene targeting strategy for exons 5–7 of the Sirt2 gene. (B) Western blot analysis of SIRT2 expression in the liver, heart, and colon of Sirt2+/+ and Sirt2−/− mice. (C) Genotype and sex distributions of newborn mice summarized from 162 colonies. (D) Body weight and body composition of Sirt2+/+ and Sirt2−/− mice.
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pone-0103573-g001: Generation and characterization of the Sirt2−/− mouse model.(A) Schematic representation of the gene targeting strategy for exons 5–7 of the Sirt2 gene. (B) Western blot analysis of SIRT2 expression in the liver, heart, and colon of Sirt2+/+ and Sirt2−/− mice. (C) Genotype and sex distributions of newborn mice summarized from 162 colonies. (D) Body weight and body composition of Sirt2+/+ and Sirt2−/− mice.

Mentions: To study the possible involvement of SIRT2 in the pathogenesis of colitis, we first generated a Sirt2 deficient mouse line (Sirt2−/−) by targeting part of the SIRT2 deacetylase domain (exons 5–7), by homologous recombination in ES cells (Figure 1A). In silico translation of this Sirt2-deletion product, results in short incomplete peptides when examining all potential reading frames. As a result, no SIRT2 protein was detected in any of the tissues analyzed from Sirt2−/− mice (Figure 1B). The offspring of heterozygous Sirt2+/− breeders were born under normal Mendelian (+/+ : +/− : −/− = 24.7% : 48.1% : 27.2%) and sex ratios (male : female = 48.1% : 51.9%) (Figure 1C), with no differences observed in body weight or body composition between Sirt2−/− and Sirt2+/+ mice (Figure 1D). Colon morphology of Sirt2+/+ and Sirt2−/− mice was then examined under basal conditions. The morphological analysis of the colons did not reveal any qualitative and/or quantitative differences, in terms of crypts depth, epithelial cell differentiation, wall thickness or density of leukocytes in the colon between the two genotypes (Figure 2A). Moreover, the immunohistochemical quantification of macrophages (F4/80+ cells) within the tunica mucosa of the colon revealed no differences between the two groups (Figure 2B). Thus, Sirt2 deficiency does not appear to affect the basal phenotype and intestinal morphology of Sirt2−/− mice when compared with their wild type counterparts.


SIRT2 deficiency modulates macrophage polarization and susceptibility to experimental colitis.

Lo Sasso G, Menzies KJ, Mottis A, Piersigilli A, Perino A, Yamamoto H, Schoonjans K, Auwerx J - PLoS ONE (2014)

Generation and characterization of the Sirt2−/− mouse model.(A) Schematic representation of the gene targeting strategy for exons 5–7 of the Sirt2 gene. (B) Western blot analysis of SIRT2 expression in the liver, heart, and colon of Sirt2+/+ and Sirt2−/− mice. (C) Genotype and sex distributions of newborn mice summarized from 162 colonies. (D) Body weight and body composition of Sirt2+/+ and Sirt2−/− mice.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4114785&req=5

pone-0103573-g001: Generation and characterization of the Sirt2−/− mouse model.(A) Schematic representation of the gene targeting strategy for exons 5–7 of the Sirt2 gene. (B) Western blot analysis of SIRT2 expression in the liver, heart, and colon of Sirt2+/+ and Sirt2−/− mice. (C) Genotype and sex distributions of newborn mice summarized from 162 colonies. (D) Body weight and body composition of Sirt2+/+ and Sirt2−/− mice.
Mentions: To study the possible involvement of SIRT2 in the pathogenesis of colitis, we first generated a Sirt2 deficient mouse line (Sirt2−/−) by targeting part of the SIRT2 deacetylase domain (exons 5–7), by homologous recombination in ES cells (Figure 1A). In silico translation of this Sirt2-deletion product, results in short incomplete peptides when examining all potential reading frames. As a result, no SIRT2 protein was detected in any of the tissues analyzed from Sirt2−/− mice (Figure 1B). The offspring of heterozygous Sirt2+/− breeders were born under normal Mendelian (+/+ : +/− : −/− = 24.7% : 48.1% : 27.2%) and sex ratios (male : female = 48.1% : 51.9%) (Figure 1C), with no differences observed in body weight or body composition between Sirt2−/− and Sirt2+/+ mice (Figure 1D). Colon morphology of Sirt2+/+ and Sirt2−/− mice was then examined under basal conditions. The morphological analysis of the colons did not reveal any qualitative and/or quantitative differences, in terms of crypts depth, epithelial cell differentiation, wall thickness or density of leukocytes in the colon between the two genotypes (Figure 2A). Moreover, the immunohistochemical quantification of macrophages (F4/80+ cells) within the tunica mucosa of the colon revealed no differences between the two groups (Figure 2B). Thus, Sirt2 deficiency does not appear to affect the basal phenotype and intestinal morphology of Sirt2−/− mice when compared with their wild type counterparts.

Bottom Line: Notably, under basal condition, Sirt2 deficiency does not affect the basal phenotype and intestinal morphology Sirt2 deficiency, however, affects macrophage polarization, creating a pro-inflammatory milieu in the immune cells compartment.In fact, SIRT2 deletion promotes inflammatory responses by increasing NF-κB acetylation and by reducing the M2-associated anti-inflammatory pathway.Finally, we speculate that the activation of SIRT2 may be a potential approach for the treatment of inflammatory bowel disease.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

ABSTRACT

Background: SIRT2 belongs to a highly conserved family of NAD+-dependent deacylases, consisting of seven members (SIRT1-SIRT7), which vary in subcellular localizations and have substrates ranging from histones to transcription factors and enzymes. Recently SIRT2 was revealed to play an important role in inflammation, directly binding, deacetylating, and inhibiting the p65 subunit of NF-κB.

Methods: A Sirt2 deficient mouse line (Sirt2-/-) was generated by deleting exons 5-7, encoding part of the SIRT2 deacetylase domain, by homologous recombination. Age- and sex-matched Sirt2-/- and Sirt2+/+ littermate mice were subjected to dextran sulfate sodium (DSS)-induced colitis and analyzed for colitis susceptibility.

Results: Sirt2-/- mice displayed more severe clinical and histological manifestations after DSS colitis compared to wild type littermates. Notably, under basal condition, Sirt2 deficiency does not affect the basal phenotype and intestinal morphology Sirt2 deficiency, however, affects macrophage polarization, creating a pro-inflammatory milieu in the immune cells compartment.

Conclusion: These data confirm a protective role for SIRT2 against the development of inflammatory processes, pointing out a potential role for this sirtuin as a suppressor of colitis. In fact, SIRT2 deletion promotes inflammatory responses by increasing NF-κB acetylation and by reducing the M2-associated anti-inflammatory pathway. Finally, we speculate that the activation of SIRT2 may be a potential approach for the treatment of inflammatory bowel disease.

Show MeSH
Related in: MedlinePlus