The heat shock protein 70 (Hsp70) family of molecular chaperones is essential for nearly every cell to support protein homeostasis through folding, signaling, and quality control. Hsp70 functionality critically depends on co-chaperones, including the GrpE-like family of nucleotide exchange factors (NEFs), first identified in Escherichia coli as GrpE. These factors have long been recognized for their ability to catalyze the release of Hsp70 nucleotide and protein substrates, but recent structural and functional studies have revealed that GrpE-like NEFs are more than passive exchange catalysts, instead acting as dynamic regulators that coordinate chaperone activity with cellular stress responses, organelle-specific demands, and allosteric control of substrate binding and release. In this review, we synthesize decades of research on GrpE-like proteins across bacteria and eukaryotes, culminating in high-resolution structures of the human mitochondrial NEF, GrpEL1, in complex with mitochondrial Hsp70. We examine how architectural features of GrpE-like NEFs have evolved to meet specialized demands, such as thermosensing in bacteria, redox-responsive regulation in vertebrates, and coordination of protein import in mitochondria. We further describe how discrete structural domains dynamically control chaperone cycling, including nucleotide and substrate release, and how gene duplication and domain specialization have driven functional diversification in higher eukaryotes. Finally, we highlight emerging evidence linking NEF activity to mitochondrial homeostasis, stress adaptation, and disease, reframing GrpE-like NEFs as tunable regulators rather than static cofactors. This perspective positions them as stress-adaptive control points in proteostasis and offers a conceptual framework for understanding how ancient chaperone systems have evolved to meet the regulatory needs of modern and complex eukaryotic cells.
The liver is a common site for cancer metastasis and a key metabolic organ. Lipid metabolism irregularities are linked to liver metastasis risk, but the mechanisms are not fully understood. Herein, in colorectal cancer liver metastasis (CRLM) clinical samples, lipid metabolism was broadly dysregulated, and lipid metabolites accumulated, as shown by integrated transcriptome and lipidomics analyses. Functionally, lipid deposition promotes liver metastasis in vitro and in vivo. Mechanistically, lipid deposition significantly enhances YTHDF3-mediated m6A modification and degradation of PPARα, which is crucial for liver metastasis. This process reduces the β-hydroxybutyrylation of YTHDF3, thereby promoting LLPS and increasing the stability of YTHDF3, which in turn facilitates the progression of CRC and liver metastasis. Furthermore, lipid deposition induces the interaction between STAT3 and YAP, activating YTHDF3 transcription. These two regulatory mechanisms synergize to drive YTHDF3 accumulation in lipid-rich metastatic lesions. In summary, our findings reveal that lipid deposition promotes LLPS-mediated m6A modification and decreases β-hydroxybutyrylation in liver metastasis, offering new strategies for the treatment of CRLM.
Fibrosis, resulting from excess extracellular matrix (ECM) deposition, is a feature of adipose tissue (AT) dysfunction and obesity-related insulin resistance. Emerging evidence indicates that adipogenic stem and precursor cells (ASPCs) are a crucial origin of ECM proteins and possess the potential to induce AT fibrosis. Here, we employed single-cell RNA-seq and identified a unique subset of ASPCs that were closely associated with ECM function. Within this subset, we discerned a notable upregulation in the expression of fibulin-7 (FBLN7), a secreted glycoprotein, in obese mice. Similarly, in humans, FBLN7 levels exhibited an increase in visceral fat among obese individuals and demonstrated a correlation with clinical metabolic traits. Functional studies further revealed that, in response to caloric excess, ASPC-specific FBLN7 knockout mice displayed a diminished state of AT fibrosis inflammation, along with improved systemic metabolic health. Notably, the depletion of FBLN7 in ASPCs suppressed TGF-β-induced fibrogenic responses, whereas its overexpression amplified such responses. Mechanistically, FBLN7 interacted with thrombospondin-1 (TSP1) via its EGF-like calcium-binding domain, thereby enhancing the stability of the TSP1 protein. This, in turn, facilitated the conversion of latent TGF-β to its bioactive form, subsequently promoting TGFBR1/Smad signaling pathways. Furthermore, we developed an anti-FBLN7 neutralizing antibody, which could dramatically alleviate diet-induced AT fibrosis. These results suggest that FBLN7, produced by ASPCs, exerts a major influence in the development of AT fibrosis and may represent a potential target for therapeutic intervention.
Cardiovascular disease (CVD) research is hindered by limited comprehensive analyses of plasma proteome across disease subtypes. Here, we systematically investigated the associations between plasma proteins and cardiovascular outcomes in 53,026 UK Biobank participants over a 14-year follow-up. Association analyses identified 3,089 significant associations involving 892 unique protein analytes across 13 CVD outcomes. The most notable associations included NT-proBNP for atrial fibrillation (P = 6.31 × 10−313), followed by NPPB (P = 1.03 × 10−164) and GDF15 for heart failure (P = 1.21 × 10−166). Among 445 unique proteins significantly linked to 18 cardiovascular metrics, LEP (RVEDV: β = −9.03, P = 2.76 × 10−51) and FABP4 (RVEDV: β = −10.18, P = 2.42 × 10−32) emerged as the strongest correlates of cardiac structure and function. Our integrated prediction model performed excellently across the majority of CVD outcomes, achieving an AUC of 0.86 for abdominal aneurysm. Two-sample Mendelian randomization analysis revealed 225 proteins causally linked to CVDs, with LPA showing the strongest coronary artery disease association (OR = 1.13 [1.10–1.17], P = 2.38 × 10−15), many of which are targets of existing drugs, suggesting repurposing opportunities. Mediation analysis revealed broad-spectrum mediators (e.g., IGFBP4 and GDF15, each influencing 9 cardiovascular outcomes) and outcome-specific protein mediators, with modifiable risk factors such as smoking and BMI predominantly mediating protein-CVD associations.This comprehensive longitudinal study provides unprecedented insights into plasma proteome influences on cardiovascular health interactions, offering novel perspectives for CVD diagnosis, prediction, and prevention.
Epithelial ovarian cancer (EOC) is an aggressive malignancy with limited therapeutic options. Poly(ADP-ribose) polymerase inhibitors (PARPi) have shown remarkable efficacy, especially in BRCA-mutant patients, and are approved as maintenance therapy to prevent recurrence after initial response to chemotherapy. However, the development of PARPi resistance poses a major clinical challenge. This study utilized a whole-genome CRISPR-Cas9 genetic screening to identify genes associated with PARPi sensitivity upon knockout. Based on the screening and validated through further experiments, we confirmed that CLK1 knockdown is synthetically lethal with PARPi in ovarian cancer. The combination of the PARPi Olaparib and CLK1 inhibitor TG003 exhibited potent anti-proliferative effects both in vitro and in vivo. Mechanistically, CLK1 inhibition downregulated the functional ERCC1-202 isoform, resulting in enhanced DNA damage and apoptosis. Our findings reveal a novel mechanism underlying PARPi sensitivity and suggest that targeting CLK1 in combination with PARPi may represent a promising therapeutic strategy for PARPi-resistant ovarian cancer.