Ubiquitin fold modifier 1 activates NF-κB pathway by down-regulating LZAP expression in the macrophage of diabetic mouse model

Abstract

Inflammatory response is closely related with the development of many serious health problems worldwide including diabetes mellitus (DM). Ubiquitin-fold modifer 1 (Ufm1) is a newly discovered ubiquitin-like protein, while its function remains poorly investigated, especially in inflammatory response and DM. In the present study, we analyzed the role of Ufm1 on inflammatory response in DM, and found that the proinflammatory cytokine levels (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β) and Ufm1 expression were highly increased both in the peritoneal macrophages of db/db mice and Raw264.7 cells induced by lipopolysaccharide (LPS). Western blot and luciferase reporter assay showed that NF-κB pathway was obviously activated in macrophages and the expression of LZAP, an inhibitor of NF-κB pathway, was down-regulated. With the LZAP knockdown plasmid and activation plasmid, we demonstrated that NF-κB/p65 activation was inhibited by LZAP in macrophages. The interaction of Ufm1 and LZAP was further proved with co-immunoprecipitation assay in HEK293 and Raw264.7 cells. The LZAP expression was also related with the presence of Ufm1 demonstrated by Ufm1 knockdown plasmid and activation plasmid. Besides that, we finally proved that the expression and activation of Ufm1 induced by LPS were regulated by JNK/ATF2 and JNK/c-Jun pathway with the use of SP600125. In conclusion, the present study demonstrated that Ufm 1 could activate NF-κB pathway by down-regulating LZAP in macrophage of diabetes, and its expression and activation were regulated by JNK/ATF2 and c-Jun pathway.

Highly Specialized Ubiquitin-Like Modifications: Shedding Light into the UFM1 Enigma

“…Given the role of UFMylation in maintain ER homeostasis and in participating in the ER stress response, it is unsurprising that UFM1 is involved in ER-phagy as well [ 38 ]. These findings consolidate that UFM1 expression levels are upregulated in response to ER stress while perturbation of the UFMylation system induces UPR, thus connecting UFMylation rather unsurprisingly to various diseases including cancer, type 2 diabetes (T2D), cardiovascular diseases, and alcoholic hepatitis [ 31 , 33 , 75 , 80 , 83 , 84 , 85 ].…”

“…Corroborating its role in modulating transcription, UFM1 has been implicated in orchestrating cellular signal transduction pathways such as the NF-kB and JNK signaling cascades [ 83 , 96 , 97 ]. Initial studies described that both UFL1 and the adaptor protein C53 (CDK5RAP3), reported to function as a tumor suppressor [ 43 , 98 , 99 , 100 ], regulates NF-kB signaling by associating directly with RELA (p65), abolishing its phosphorylation to enhance interaction with HDAC thereby stimulating NF-κb activity [ 47 ].…”

“…Recent studies have demonstrated a protective role for UFMylation against cardiac myopathy, as UFL1 depletion in cardiomyocytes, which induces ER stress, led to increased fibrosis, decreased cardiac contractility and hypertrophy under pressure overload compared to the controls [ 84 ]. In line with the biological function of UFL1 and its activator DDRGK1, these UFMylation proteins safeguard from the effects of prolonged ER stress in pancreatic beta-cells and other endo- and exocrine cells and thus possibly contributing to the development of type 2 diabetes, steatohepatitis, pancreatitis, ischemic heart injury, as well inflammatory bowel disease [ 33 , 64 , 75 , 83 , 113 , 114 ]. Moreover, UFM1 possibly plays a contribution to tumorigenesis, as demonstrated by the UFMylation of ASC1 and the subsequent transactivation of the ERα [ 34 ] and its role in PI3K signaling in gastric cancer [ 57 ].…”

Decrypting UFMylation: How Proteins Are Modified with UFM1

“…While the discovery of UFM1 was in 2004, only in the last few years has the importance of this modification begun to appear. An increasing body of evidence connects UFM1 to a wide spectrum of human diseases, including hematopoietic diseases, heart diseases, diabetes, intestinal exocrine disease, schizophrenia, and cancer [ 15 , 53 , 54 , 67 , 68 , 69 , 70 , 71 ]. In parallel, UFM1 has been shown essential for embryonic development, and the prevention of this modification in mice causes severe anemia that leads to the death of the embryo [ 72 ].…”

A Concerted Action of UBA5 C-Terminal Unstructured Regions Is Important for Transfer of Activated UFM1 to UFC1

“…Recently, new ufmylation targets involved in cancer progression [ 16 , 17 ], DNA damage response [ 18 , 19 ], translation machinery [ 20 ] and ribosome functioning [ 13 , 14 ] have been identified. Taking in account the broad range of biological pathways affected by ufmylation, it is not surprising that impaired ufmylation can be connected to many human diseases [ 16 , 21 , 22 , 23 , 24 ] and seems to be essential for embryonic development [ 25 , 26 , 27 ].…”