2. TIFA as a crucial mediator for NLRP3 inflammasome
Ting-Yang Lin, et al. Proc Natl Acad Sci U S A. 2016 Dec 27;113(52):15078-15083. doi: 10.1073/pnas.1618773114. Epub 2016 Dec 13.
Toll-like receptor-mediated NF-κB activation is a major innate immune reaction of vascular endothelial cells (ECs) in response to prooxidative and proinflammatory stimuli. We identified that TNF-α receptor-associated factor-interacting protein with a forkhead-associated domain (TIFA) is a regulator of priming (signal 1) and activating (signal 2) signals of nucleotide oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome in ECs. Oxidative and inflammatory stresses such as atheroprone flow and hyperlipidemia induce and activate TIFA in vitro and in vivo. For the priming of signal 1, sterol regulatory element-binding protein 2 transactivates TIFA, which in turn induces NF-κB activation and augments the transcription of NLRP3 inflammasome components. For the activation of signal 2, Akt is involved in TIFA Thr9 phosphorylation, which is essential for TIFA-TIFA homophilic oligomerization. Thr9 phosphorylation-dependent TIFA oligomerization facilitates the higher-order assembly of NLRP3 inflammasome, as indicated by the interaction between TIFA and caspase-1 in the activated ECs. Our results suggest that TIFA is a crucial mediator in the endothelial innate immune response by potentiating and amplifying NLRP3 inflammasome via augmenting signals 1 and 2.
3. The requirements for sterol regulatory element-binding protein (Srebp) and stimulatory protein 1 (Sp1)-binding elements in the transcriptional activation of two freshwater fish Channa striata and Danio rerio elovl5 elongase
Pei-Tian Goh, Meng-Kiat Kuah, Yen-Shan Chew, Hui-Ying Teh, Alexander Chong Shu-Chien Fish Physiol Biochem. 2020 Aug;46(4):1349-1359. doi: 10.1007/s10695-020-00793-w. Epub 2020 Apr 1.
Fish are a major source of beneficial n-3 LC-PUFA in human diet, and there is considerable interest to elucidate the mechanism and regulatory aspects of LC-PUFA biosynthesis in farmed species. Long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis involves the activities of two groups of enzymes, the fatty acyl desaturase (Fads) and elongase of very long-chain fatty acid (Elovl). The promoters of elovl5 elongase, which catalyses the rate-limiting reaction of elongating polyunsaturated fatty acid (PUFA), have been previously described and characterized from several marine and diadromous teleost species. We report here the cloning and characterization of elovl5 promoter from two freshwater fish species, the carnivorous snakehead fish (Channa striata) and zebrafish. Results show the presence of sterol-responsive elements (SRE) in the core regulatory region of both promoters, suggesting the importance of sterol regulatory element-binding protein (Srebp) in the regulation of elovl5 for both species. Mutagenesis luciferase and electrophoretic mobility shift assays further validate the role of SRE for basal transcriptional activation. In addition, several Sp1-binding sites located in close proximity with SRE were present in the snakehead promoter, with one having a potential synergy with SRE in the regulation of elovl5 expression. The core zebrafish elovl5 promoter fragment also directed in vivo expression in the yolk syncytial layer of developing zebrafish embryos.
