Xiao-Dong Zhang

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease worldwide, yet approved pharmacotherapies remain limited. The ovarian tumor domain-containing protein 1 (OTUD1) has been implicated in metabolic regulation, but its role in MASLD remains unclear. OTUD1 expression was significantly elevated in liver samples from patients with MASLD and in high-fat diet (HFD)-fed mice, a finding further supported by two independent Gene Expression Omnibus (GEO) cohorts (GSE24807 and GSE126848). Studies using systemic Otud1 -knockout mice showed that Otud1 deficiency markedly alleviated insulin resistance and inflammation under HFD and high-fat, methionine-restricted, choline-deficient (HFMCD) diet conditions. To assess the hepatocyte-specific and therapeutic relevance of OTUD1, Otud1 was silenced in hepatocytes using AAV8-TBG-sh Otud1 , which significantly ameliorated HFMCD-induced steatohepatitis. Mechanistically, integrated interactome analyses identified heat shock protein 90α (HSP90α) as a direct substrate of OTUD1. OTUD1 bound to HSP90α and removed its K48-linked polyubiquitin chains at K283, thereby preventing its proteasomal degradation and enhancing its stability. This effect was required for OTUD1-driven lipid accumulation in hepatocytes, as the catalytically inactive OTUD1-C320S mutant failed to stabilize HSP90α or promote lipid deposition. Transcriptomic profiling further revealed that OTUD1 overexpression activated lipid metabolism and inflammatory pathways in OA/PA-treated LO2 cells. Together, these findings identify OTUD1 as a previously unrecognized driver of MASLD progression through the OTUD1–HSP90α axis and suggest that OTUD1 may serve as a potential therapeutic target for metabolic liver disease.

CLK2 deficiency sensitizes CRC cells and organoids to ferroptosis.

CLK2 deficiency disrupts the balance between HMOX1 and SLC7A11 through coordinated regulation of NRF2 and p53.

Representative proteins altered upon CLK2 overexpression from mass spectrometry differential abundance analysis

Supplementary Table 1. GSEA results for control group: Clk2−/− vs. Clk2+/+

CLK2 is highly expressed in CRC and its knockdown enhances sensitivity to Erastin–Oxaliplatin combination therapy in xenograft models.

Supplementary Table 2. GSEA results for AOM/DSS group: Clk2−/− vs. Clk2+/+

Ferroptosis, a form of regulated cell death driven by iron-dependent lipid peroxidation, plays a crucial role in colorectal cancer progression and therapeutic response. The nuclear factor erythroid 2–related factor 2 (NRF2) pathway is one of the critical axes in ferroptosis regulation, which governs oxidative stress resistance and iron homeostasis through its downstream targets, including heme oxygenase 1 (HMOX1), solute carrier family 7 member 11 (SLC7A11), and others. However, HMOX1 and SLC7A11 exhibit contrasting roles in ferroptosis, with HMOX1 promoting ferroptosis via iron accumulation and lipid peroxidation, whereas SLC7A11 inhibits ferroptosis by enhancing antioxidant defenses. In this study, we identified CLK2 as a key regulator of the delicate balance of the opposing effects of HMOX1 and SLC7A11. CDC-like kinase 2 (CLK2) stabilized Kelch-like ECH-associated protein 1 (KEAP1) to suppress NRF2 activity, resulting in the downregulation of HMOX1 and SLC7A11. Simultaneously, CLK2 downregulated p53, thereby relieving p53-mediated repression of SLC7A11. The dual regulation by CLK2 disrupted the balance between HMOX1 and SLC7A11, leading to excessive activation of HMOX1 in the absence of CLK2, ultimately sensitizing colorectal cancer cells to ferroptosis. Additionally, CLK2 promoted colorectal cancer proliferation and tumorigenesis in patient-derived organoids, cell lines, and mouse models. Furthermore, combining the ferroptosis inducer erastin with oxaliplatin significantly enhanced antitumor efficacy in CLK2-deficient xenograft models. Together, this study establishes CLK2 as a critical inhibitor of ferroptosis via the KEAP1/NRF2/HMOX1 and p53/SLC7A11 axes, supporting its potential as a therapeutic target for colorectal cancer.Significance:CLK2 blocks ferroptosis in colorectal cancer by regulating the HMOX1 and SLC7A11 balance through the KEAP1/NRF2 axis and p53 pathways, providing a strong rationale for targeting CLK2 to treat colon cancer.