Yao Li

Background: Idiopathic pulmonary fibrosis (IPF) is closely associated with fibroblast proliferation, macrophage polarization, and the accumulation of extracellular matrix (ECM). Targeting CSF-1R can rebalance macrophages, reduce ECM deposition, and block pro-fibrotic signaling. Methods: A Fab fragment targeting CSF-1R was screened via phage display. After sequence optimization, it was constructed into an IgG1 antibody (BC006). In vitro activity, domain binding, and signaling blockade were investigated, and in vitro safety indicators were evaluated. Efficacy was assessed using an induced IPF organoid-on-a-chip and bleomycin-induced mouse model. In vivo safety evaluation was conducted in cynomolgus monkeys. Results: BC006 showed an EC₅₀ value of 226 ± 57 nM and a KD of 30 ± 2 nM. It specifically bound to the Ig4-5 domain of CSF-1R by inhibiting receptor dimerization without blocking ligand binding. It could dose-dependently inhibit the differentiation of monocytes into M2 macrophages and exert anti-IPF effects. In the induced IPF organoid-on-a-chip model, BC006 maintained lung barrier function and decreased α-SMA and Collagen I. It also improved lung function and attenuated the degree of fibrosis in the mouse model. Moreover, BC006 had no ADCC, CDC, cytokine release, or hemagglutination, and demonstrated favorable safety profiles in cynomolgus monkeys. Conclusions: BC006 is a novel anti-fibrosis antibody specifically targeting the CSF-1R Ig4-5 domain and offers a new therapeutic strategy for IPF.

Silent information regulator 2 (SIRT2) has been described to have dual roles as an oncogene and tumor suppressor gene in non-small cell lung cancer, but its functional selection and the precise mechanisms of its action remain to be elucidated. lung adenocarcinoma (LUAD) tissue microarrays and cell lines were used to detect SIRT2 expression using Immunohistochemistry and Western blotting. SIRT2 overexpression, knockdown, and knockout LUAD cells were constructed to test SIRT2 function in vitro and in vivo, and targeted metabolomics, proteomics, and acetylation analyses were performed to explore the detailed mechanisms by which SIRT2 affects the biological characteristics of LUAD. SIRT2 is not only downregulated in LUAD tissues and cells, but also associated with poor prognosis in LUAD patients, not in lung squamous cell carcinoma. We also found that hypoxia-induced increasement in lactate levels led to this decreased SIRT2 expression. Remarkably, SIRT2 deficiency promotes the proliferation and metastasis of LUAD cells in vitro and in vivo, while SIRT2 overexpression exerts the opposite function. Mechanistically, SIRT2 deficiency leaded to increased acetylation levels of multiple enzymes involved in glycolysis, tricarboxylic acid cycle, fatty acid oxidation, and glutaminolysis. And results of co-inmunoprecipitation showed that SIRT2 bound to the above enzymes. Accordingly, SIRT2-deficient LUAD cells showed altered metabolic activities such as glycolysis, pentose phosphate pathway, TCA cycle, serine metabolism, and urea cycle. Notably, SIRT2 deletion increases glycolytic capacity of LUAD cells by increasing the acetylation modification of LDHA at the K118 site. This study reveals that hypoxia-induced lactate elevation decreases SIRT2 expression to promote LUAD progression, with the mechanism related to promoting glycolysis by increasing LDHA acetylation. In addition, decreased SIRT2 expression has also been found to cause alterations in many metabolic pathways with no verification mechanism.

Mitophagy is a selective process that targets the damaged, dysfunctional, or superfluous mitochondria for degradation through autophagy. The SCF^FBXL4 E3 ubiquitin ligase complex suppresses basal mitophagy by targeting BNIP3 and BNIP3L, two key mitophagy cargo receptors, for ubiquitin-proteasomal degradation. FBXL4 loss-of-function mutations lead to excessive BNIP3/3L-dependent mitophagy, thereby causing a devastating multi-system disorder called mitochondrial DNA depletion syndrome, type 13 (MTDPS13). PPTC7, a mitochondrial matrix phosphatase, is essential for proper mitochondrial function and biogenesis. Here, we show that a proportion of PPTC7 is located on the outer mitochondrial membrane, where it interacts with FBXL4 and BNIP3/3L. PPTC7 decreases BNIP3/3L protein stability in a protein phosphatase activity-independent manner. Using in vitro cell culture and Pptc7 knockout mouse model, we demonstrate that PPTC7 deficiency activates high levels of basal mitophagy in a BNIP3/3L-dependent manner. Mechanistically, PPTC7 facilitates SCF^FBXL4-mediated ubiquitin-proteasomal degradation of BNIP3/3L. Overall, these findings establish PPTC7 as an essential co-factor of the SCF^FBXL4 complex and a suppressor of BNIP3/3L-dependent mitophagy.

Mutations in the DDHD2 (DDHD domain containing 2) gene cause autosomal recessive spastic paraplegia type 54 (SPG54), a rare neurodegenerative disorder characterized by the early childhood onset of progressive spastic paraplegia. DDHD2 is reported as the principal brain triacylglycerol (TAG) lipase whose dysfunction causes massive lipid droplet (LD) accumulation in the brains of SPG54 patients. However, the precise functions of DDHD2 in regulating LD catabolism are not yet fully understood. In a recent study, we demonstrate that DDHD2 interacts with multiple members of the Atg8-family proteins (MAP1LC3/LC3s, GABARAPs), which play crucial roles in lipophagy. DDHD2 possesses two LC3-interacting region (LIR) motifs that contribute to its LD-eliminating activity. Moreover, DDHD2 enhances the colocalization between LC3B and LDs to promote lipophagy. LD·ATTEC, a compound that tethers LC3 to LDs to enhance their macroautophagic/autophagic clearance, effectively counteracts DDHD2 deficiency-induced LD accumulation. These findings provide insights into the dual functions of DDHD2 as a TAG lipase and cargo receptor for lipophagy in neuronal LD catabolism, and also suggest a potential therapeutic approach for treating SPG54 patients.

Data from m⁶A-Mediated Biogenesis of circDDIT4 Inhibits Prostate Cancer Progression by Sequestrating ELAVL1/HuR

Data from m⁶A-Mediated Biogenesis of circDDIT4 Inhibits Prostate Cancer Progression by Sequestrating ELAVL1/HuR

One of the most significant discoveries resulting from the sequencing of the human genome is the realization that a large portion (over 85%) of the genome is transcribed into RNA, yet less than 2% of it encodes protein-coding genes

The pathologic significance of the circular RNA DDIT4 (circDDIT4), which is formed by backsplicing at the 3′-untranslated region (UTR) with a 5′ splice acceptor site in exon 2 of linear DDIT4 mRNA, has yet to be determined. Our study found that circDDIT4 is downregulated in prostate cancer and functions as a tumor suppressor during prostate cancer progression. By competitively binding to ELAV-like RNA binding protein 1 (ELAVL1/HuR) through its 3′-UTR, circDDIT4 acts as a protein sponge to decrease the expression of prostate cancer–overexpressed anoctamin 7 (ANO7). This promotes prostate cancer cell apoptosis while inhibiting cell proliferation and metastasis. Furthermore, we discovered that N6-methyladenosine (m6A) modification facilitates the biogenesis of circDDIT4. The methyltransferase complex consisting of WTAP/METTL3/METTL14 increases the level of circDDIT4, while the RNA demethylase FTO decreases it. Implications: These findings suggest that abnormal cotranscriptional modification of m6A promotes prostate cancer initiation and progression via a circular RNA-protein-cell signaling network.