» Articles » PMID: 22647600

Akt1 and Akt2 Protein Kinases Differentially Contribute to Macrophage Polarization

Abstract

Activated macrophages are described as classically activated or M1 type and alternatively activated or M2 type, depending on their response to proinflammatory stimuli and the expression of genetic markers including iNOS, arginase1, Ym1, and Fizz1. Here we report that Akt kinases differentially contribute to macrophage polarization, with Akt1 ablation giving rise to an M1 and Akt2 ablation resulting in an M2 phenotype. Accordingly, Akt2(-/-) mice were more resistant to LPS-induced endotoxin shock and to dextran sulfate sodium (DSS)-induced colitis than wild-type mice, whereas Akt1(-/-) mice were more sensitive. Cell depletion and reconstitution experiments in a DSS-induced colitis model confirmed that the effect was macrophage-dependent. Gene-silencing studies showed that the M2 phenotype of Akt2(-/-) macrophages was cell autonomous. The microRNA miR-155, whose expression was repressed in naive and in LPS-stimulated Akt2(-/-) macrophages, and its target C/EBPβ appear to play a key role in this process. C/EBPβ, a hallmark of M2 macrophages that regulates Arg1, was up-regulated upon Akt2 ablation or silencing. Overexpression or silencing of miR-155 confirmed its central role in Akt isoform-dependent M1/M2 polarization of macrophages.

Citing Articles

Akt2 inhibition alleviates temporomandibular joint osteoarthritis by preventing subchondral bone loss.

Feng S, Cao M, Gao C, Li Y, Lei J, Fu K Arthritis Res Ther. 2025; 27(1):43.

PMID: 40016746 PMC: 11866854. DOI: 10.1186/s13075-025-03506-x.


Ferroptosis Plays a Pivotal Role in Activating and Modulating Specific Intracellular Signaling Pathways Integrated into the Therapeutic Management of Colorectal Cancer.

Monemi M, Ahmed H, Kareem R, Taher W, Alwan M, Jawad M Int J Mol Cell Med. 2025; 13(4):374-386.

PMID: 39895914 PMC: 11786127. DOI: 10.22088/IJMCM.BUMS.13.4.374.


Role of macrophage polarization in diabetic foot ulcer healing: A bibliometric study.

Zhang Y, Sun L, Wang Y, Zhan S World J Diabetes. 2025; 16(1):99755.

PMID: 39817209 PMC: 11718451. DOI: 10.4239/wjd.v16.i1.99755.


Metabolic Reprograming of Macrophages: A New Direction in Traditional Chinese Medicine for Treating Liver Failure.

Zhang J, Li N, Hu X J Immunol Res. 2025; 2024():5891381.

PMID: 39741958 PMC: 11688140. DOI: 10.1155/jimr/5891381.


AKT kinases as therapeutic targets.

Hassan D, Menges C, Testa J, Bellacosa A J Exp Clin Cancer Res. 2024; 43(1):313.

PMID: 39614261 PMC: 11606119. DOI: 10.1186/s13046-024-03207-4.


References
1.
Mao C, Tili E, Dose M, Haks M, Bear S, Maroulakou I . Unequal contribution of Akt isoforms in the double-negative to double-positive thymocyte transition. J Immunol. 2007; 178(9):5443-53. DOI: 10.4049/jimmunol.178.9.5443. View

2.
Ohashi K, Parker J, Ouchi N, Higuchi A, Vita J, Gokce N . Adiponectin promotes macrophage polarization toward an anti-inflammatory phenotype. J Biol Chem. 2009; 285(9):6153-60. PMC: 2825410. DOI: 10.1074/jbc.M109.088708. View

3.
Lawrence T, Natoli G . Transcriptional regulation of macrophage polarization: enabling diversity with identity. Nat Rev Immunol. 2011; 11(11):750-61. DOI: 10.1038/nri3088. View

4.
Wirtz S, Neufert C, Weigmann B, Neurath M . Chemically induced mouse models of intestinal inflammation. Nat Protoc. 2007; 2(3):541-6. DOI: 10.1038/nprot.2007.41. View

5.
Fernandez-Hernando C, Ackah E, Yu J, Suarez Y, Murata T, Iwakiri Y . Loss of Akt1 leads to severe atherosclerosis and occlusive coronary artery disease. Cell Metab. 2007; 6(6):446-57. PMC: 3621848. DOI: 10.1016/j.cmet.2007.10.007. View