The SWI/SNF chromatin remodeling factor DPF3 regulates metastasis of ccRCC by modulating TGF-β signaling

Integrating machine learning and multi-omics analysis to unveil key programmed cell death patterns and immunotherapy targets in kidney renal clear cell carcinoma

Kidney renal clear cell carcinoma (KIRC), a cancer characterized by substantial immune infiltration, exhibits limited sensitivity to conventional radiochemotherapy. Although immunotherapy has shown efficacy in some patients, its applicability is not universally effective. Studies have indicated that programmed cell death (PCD) can modulate the activity of immune cells and participate in the regulation of antitumor immune responses. However, systematic research on how various PCD patterns in KIRC affect the responsiveness to immunotherapy is lacking and requires in-depth investigation. We utilized a combination of 101 machine learning algorithms to analyze the TCGA-KIRC cohort and the GSE22541 KIRC patients, screening for cell death patterns closely associated with prognosis from 18 potential modes. Integrating multi-omics analysis, including immune cell infiltration, phenotyping, functional analysis, immune checkpoint exploration, and gene set enrichment analysis (GSEA), we explored the relationship between key cell death patterns and patients' responses to immunotherapy. Finally, potential drug targets were identified through drug sensitivity screening and molecular docking techniques. Our sophisticated risk assessment model successfully identified two PCD patterns, Anoikis and lysosome-dependent cell death (LDCD), closely associated with the prognosis of KIRC patients, with the high-risk group exhibiting poor outcomes. Immune cell analysis revealed upregulated expression of T follicular helper (Tfh) cells in both PCD patterns. Analysis of immune checkpoints disclosed enhanced expression of human leukocyte antigen E (HLA-E) across both patterns. Frequent mutations in the TTN and MUC16 genes were observed in the Anoikis pattern, whereas in the LDCD pattern, although the high-risk group had a higher mutation rate, there was no significant difference in tumor mutational burden. GSEA analysis indicated significant enrichment of the primary immunodeficiency pathway in the Anoikis high-risk group and significant enrichment of the spliceosomal tri-snrnp complex assembly pathway in the LDCD high-risk group. Drug sensitivity analysis showed notable sensitivity to SB505124 in both PCD patterns. HMOX1 and PIK3CG were identified as common genes in the two key PCD patterns, and molecular docking analysis confirmed stable binding affinity between Carnosol and HMOX1, and between PROTAC and PIK3CG. Our study identifies Anoikis and LDCD as prognostic PCD patterns in KIRC, with key immune cells, genetic mutations, and drug sensitivity profiles. HMOX1 and PIK3CG are common genes with stable binding to Carnosol and PROTAC, respectively, while SB505124 shows significant sensitivity to both PCD modes, suggesting potential therapeutic targets.

Exploration of the influence of environmental changes on the conformational and amyloidogenic landscapes of the zinc finger protein DPF3a by combining biophysical and molecular dynamics approaches

In the past few years, the double PHD fingers 3 (DPF3) protein isoforms (DPF3b and DPF3a) have been identified as new amyloidogenic intrinsically disordered proteins (IDPs). Although such discovery is coherent and promising in light of their involvement in proteinopathies, their amyloidogenic pathway remains largely unexplored. As environmental variations in pH and ionic strength are relevant to DPF3 pathophysiological landscape, we therefore enquired the effect of these physicochemical parameters on the protein structural and prone-to-aggregation properties, by focusing on the more disordered DPF3a isoform. In the present study, we exploited in vitro and in silico strategies by combining spectroscopy, microscopy, and all-atom molecular dynamics methods. Very good consistency and complementary information were found between the experiments and the simulations. Acidification unequivocally abrogated DPF3a fibrillation upon maintaining the protein in highly hydrated and expanded conformers due to extensive repulsion between positively charged regions. In contrast, alkaline pH delayed the aggregation process due to loss in intramolecular contacts and chain decompaction, the extent of which was partly reduced thanks to the compensation of negative charge by arginine side chains. Through screening attractive electrostatic interactions, high ionic strength conditions (300 and 500 mM NaCl) shifted the conformational ensemble towards more swollen, heterogeneous, and less H-bonded structures, which were responsible for slowing down the conversion into β-sheeted species and restricting the fibril elongation. For defining the self-assembly pathway of DPF3a, we unveiled that the protein amyloidogenicity intimately communicates with its conformational landscape, which is particularly sensitive to modification of its physicochemical environment. As such, understanding how to modulate DPF3a conformational ensemble will help designing novel protein-specific strategies for targeting neurodegeneration.

TET2 suppresses vascular calcification by forming an inhibitory complex with HDAC1/2 and SNIP1 independent of demethylation

Osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) has been recognized as the principal mechanism underlying vascular calcification (VC). Runt-related transcription factor 2 (RUNX2) in VSMCs plays a pivotal role because it constitutes an osteogenic transcription factor essential for bone formation. As a key DNA demethylation enzyme, ten-eleven translocation 2 (TET2) is crucial in maintaining the VSMC phenotype. However, whether TET2 involves in VC progression remains elusive. Here we identified a substantial downregulation of TET2 in calcified human and mouse arteries, as well as human primary VSMCs. In vitro gain- and loss-of-function experiments demonstrated that TET2 regulated VC. Subsequently, in vivo knockdown of TET2 significantly exacerbated VC in both vitamin D3- and adenine diet-induced chronic kidney disease (CKD) mouse models. Mechanistically, TET2 bound to and suppressed activity of the P2 promoter within the RUNX2 gene; however, an enzymatic loss-of-function mutation of TET2 did not change its binding and suppressive effects. Furthermore, TET2 formed a complex with histone deacetylases 1/2 (HDAC1/2) to deacetylate H3K27ac on the P2 promoter, thereby inhibiting its transcription. Moreover, SNIP1 was indispensable for TET2 to interact with HDAC1/2 to exert an inhibitory effect on VC, and knockdown of SNIP1 accelerated VC in mice. Collectively, our findings imply that TET2 might serve as a potential therapeutic target for VC.

Identifying potential risk genes for clear cell renal cell carcinoma with deep reinforcement learning

Clear cell renal cell carcinoma (ccRCC) is the most prevalent type of renal cell carcinoma. However, our understanding of ccRCC risk genes remains limited. This gap in knowledge poses challenges to the effective diagnosis and treatment of ccRCC. To address this problem, we propose a deep reinforcement learning-based computational approach named RL-GenRisk to identify ccRCC risk genes. Distinct from traditional supervised models, RL-GenRisk frames the identification of ccRCC risk genes as a Markov Decision Process, combining the graph convolutional network and Deep Q-Network for risk gene identification. Moreover, a well-designed data-driven reward is proposed for mitigating the limitation of scant known risk genes. The evaluation demonstrates that RL-GenRisk outperforms existing methods in ccRCC risk gene identification. Additionally, RL-GenRisk identifies eight potential ccRCC risk genes. We successfully validated epidermal growth factor receptor (EGFR) and piccolo presynaptic cytomatrix protein (PCLO), corroborated through independent datasets and biological experimentation. This approach may also be used for other diseases in the future.

Kidney cancer: From tumor biology to innovative therapeutics

Renal cell carcinoma (RCC) constitutes the most frequent kidney cancer of the adult population and one of the most lethal malignant tumors worldwide. RCC often presents without early symptoms, leading to late diagnosis. Prognosis varies widely based on the stage of cancer at diagnosis. In the early-stage, localized RCC has a relatively good prognosis, while advanced or metastatic RCC has a poor outcome. Obesity, smoking, genetic mutations and family history are all considered risk factors for RCC, while inherited disorders, such as Tuberous Sclerosis and von Hippel-Lindau syndrome, are causally associated with RCC development. Genetic screening, deep sequencing analysis, quantitative proteomics and immunostaining analysis on RCC tissues, biological fluids and blood samples have been employed to identify novel biomarkers, predisposing factors and therapeutic targets for RCC with important clinical implications for patient treatment. Combined approaches of gene-targeting strategies coupled to a deep functional analysis of cancer cell biology, both in vitro and in appropriate animal models of RCC, significantly contributed to identify and characterize relevant pathogenic mechanisms underlying development and progression of RCC. These studies provided also important cues for the generation of novel target-specific therapeutics that selectively restore deranged cancer cell signalling and dysfunctional immune checkpoints, positively impacting on the survival rate of treated RCC patients. In this review, we will describe the recent discoveries concerning the most relevant pathogenic mechanisms of RCC and will highlight novel therapeutic strategies that interrupt oncogenic pathways and restore immune defences in RCC patients.

The important role of the histone acetyltransferases p300/CBP in cancer and the promising anticancer effects of p300/CBP inhibitors

Histone acetyltransferases p300 (E1A-associated protein p300) and CBP (CREB binding protein), collectively known as p300/CBP due to shared sequence and functional synergy, catalyze histone H3K27 acetylation and consequently induce gene transcription. p300/CBP over-expression or over-activity activates the transcription of oncogenes, leading to cancer cell growth, resistance to apoptosis, tumor initiation and development. The discovery of small molecule inhibitors targeting p300/CBP histone acetyltransferase activity, bromodomains, dual inhibitors of p300/CBP and BRD4 bromodomains, as well as proteolysis-targeted-chimaera p300/CBP protein degraders, marks significant progress in cancer therapeutics. These inhibitors and degraders induce histone H3K27 deacetylation, reduce oncogene expression and cancer cell proliferation, promote cancer cell death, and decrease tumor progression in mice. Furthermore, p300/CBP inhibitors and protein degraders have been demonstrated to exert synergy when in combination with conventional radiotherapy, chemotherapy and BRD4 inhibitors in vitro as well as in mice. Importantly, two p300/CBP bromodomain inhibitors, CCS1477 and FT-7051, as well as the dual p300/CBP and BRD4 bromodomain inhibitor NEO2734 have entered Phase I and IIa clinical trials in patients with advanced and refractory hematological malignancies or solid tumors. Taken together, the identification of p300/CBP as critical drivers of tumorigenesis and the development of p300/CBP inhibitors and proteolysis-targeted-chimaera protein degraders represent promising avenues for clinical translation of novel cancer therapeutics.

Crosstalk between metabolic and epigenetic modifications during cell carcinogenesis

Genetic mutations arising from various internal and external factors drive cells to become cancerous. Cancerous cells undergo numerous changes, including metabolic reprogramming and epigenetic modifications, to support their abnormal proliferation. This metabolic reprogramming leads to the altered expression of many metabolic enzymes and the accumulation of metabolites. Recent studies have shown that these enzymes and metabolites can serve as substrates or cofactors for chromatin-modifying enzymes, thereby participating in epigenetic modifications and promoting carcinogenesis. Additionally, epigenetic modifications play a role in the metabolic reprogramming and immune evasion of cancer cells, influencing cancer progression. This review focuses on the origins of cancer, particularly the metabolic reprogramming of cancer cells and changes in epigenetic modifications. We discuss how metabolites in cancer cells contribute to epigenetic remodeling, including lactylation, acetylation, succinylation, and crotonylation. Finally, we review the impact of epigenetic modifications on tumor immunity and the latest advancements in cancer therapies targeting these modifications.

The Drosophila toothrin Gene Related to the d4 Family Genes: An Evolutionary View on Origin and Function

D. melanogaster has two paralogs, tth and dd4, related to the evolutionarily conserved d4 family genes. In mammals, the family consists of Dpf1-3, encoding transcription co-factors involved in the regulation of development and cell fate determination. The function of tth and dd4 in Drosophila remains unclear. The typical domain structure of the proteins encoded by the d4 family consists of an N-terminal 2/3 domain (Requiem_N), a central Kruppel-type zinc finger, and a C-terminal D4 domain of paired PHD zinc fingers (DPFs). In Drosophila, both paralogs lack the Kruppel-type ZF, and tth encodes a protein that contains only Requiem_N. In contrast, vertebrate Dpf1-3 paralogs encode all the domains, but some paralogs have specific splice isoforms. For example, the DPF3a isoform lacks the D4 domain necessary for histone reading. The occurrence of proteins without the D4 domain in mammals and flies implies functional significance and analogous roles across animal taxa. In this study, we reconstructed the evolutionary events that led to the emergence of Drosophila tth by analyzing the divergence of d4 paralogs across different evolutionary lineages. Our genomic and transcriptomic data analysis revealed duplications and gene copy loss events. Among insects, gene duplication was only observed in Diptera. In other lineages, we found the specialization of paralogs for producing isoforms and further specialization for coding proteins with specific domain organizations. We hypothesize that this pathway is a common mechanism for the emergence of paralogues lacking the D4 domain across different evolutionary lineages. We, thus, postulate that TTH may function as a splice isoform of the ancestral single-copy gene, possibly a DPF3a-like isoform characteristic of related insect species. Our analysis provides insights into the possible impact of paralogue divergence, emphasizing the functional significance of the 2/3 domain and the potential roles of isoforms lacking the D4 domain.

Identification of gasdermin B function in the progression of renal clear cell carcinoma by a pan-cancer analysis

The Gasdermin (GSDM) protein family is critically involved in pyroptosis, which participates in the onset and progression of human malignancies. The exact role and impact of the GSDM family genes in various malignancies, particularly renal clear cell carcinoma (KIRC), is still uncertain. The present results indicated GSDMB gene expression significantly upregulated in individuals with KIRC, whose diagnostic effectiveness was confirmed through ROC analysis. Kaplan-Meier analysis also revealed KIRC patients had poor survival prognosis. The high expression of GSDMB served as an independent risk factor for overall survival (OS) in KIRC, based on multivariate cox analysis for confirmation. A nomogram based on GSDMB expression and clinical characteristics displayed remarkable diagnostic effectiveness for KIRC. Collectively, these findings may shed light on functions of GSDM family genes in tumor progression and offer new directions for future research into their potential as therapeutic targets in various types of tumors. Furthermore, the outcomes of this research highlighted that the prediction of treatment responses in KIRC patients may get improved through in-depth exploration into the impact of GSDMB expression on individuals with KIRC patients.

Epigenetic regulation of TGF-β and vice versa in cancers - A review on recent developments

This review explores the complex relationship between epigenetic mechanisms and Transforming Growth Factor-beta (TGF-β) signalling pathways in the field of cancer research. The study provides an overview of the latest advancements in understanding the crucial functions of epigenetic alterations, such as DNA methylation, histone modifications, and chromatin remodeling, in significantly impacting the TGF-β signalling pathway. The dynamic epigenetic modifications are essential in determining the behaviour of cancer cells, impacting the interactions with the tumor microenvironment, and affecting the overall process of carcinogenesis. Significant attention is given to Breast cancer, Lung cancer, Liver cancer, Prostate cancer, and Pancreatic cancer. Research has revealed intricate regulatory networks in these cancers, involving long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and histone post-translational modifications. These networks are closely connected to TGF-β signalling. Both findings highlight the significant interaction between epigenetic regulation and TGF-β signalling in cancer. They provide valuable insights that can guide the development of new treatment approaches to target both pathways and prevent cancer growth and metastasis.

Novel insights into regulators and functional modulators of adipogenesis

Adipogenesis is a process that differentiates new adipocytes from precursor cells and is tightly regulated by several factors, including many transcription factors and various post-translational modifications. Recently, new roles of adipogenesis have been suggested in various diseases. However, the molecular mechanisms and functional modulation of these adipogenic genes remain poorly understood. This review summarizes the regulatory factors and modulators of adipogenesis and discusses future research directions to identify novel mechanisms regulating adipogenesis and the effects of adipogenic regulators in pathological conditions. The master adipogenic transcriptional factors PPARγ and C/EBPα were identified along with other crucial regulatory factors such as SREBP, Kroxs, STAT5, Wnt, FOXO1, SWI/SNF, KLFs, and PARPs. These transcriptional factors regulate adipogenesis through specific mechanisms, depending on the adipogenic stage. However, further studies related to the in vivo role of newly discovered adipogenic regulators and their function in various diseases are needed to develop new potent therapeutic strategies for metabolic diseases and cancer.

Epigenetic regulation of TGF-β pathway and its role in radiation response

PURPOSE

Transforming growth factor (TGF-β) plays a dual role in tumor progression as well as a pivotal role in radiation response. TGF-β-related epigenetic regulations, including DNA methylation, histone modifications (including methylation, acetylation, phosphorylation, ubiquitination), chromatin remodeling and non-coding RNA regulation, have been found to affect the occurrence and development of tumors as well as their radiation response in multiple dimensions. Due to the significance of radiotherapy in tumor treatment and the essential roles of TGF-β signaling in radiation response, it is important to better understand the role of epigenetic regulation mechanisms mediated by TGF-β signaling pathways in radiation-induced targeted and non-targeted effects.

CONCLUSIONS

By revealing the epigenetic mechanism related to TGF-β-mediated radiation response, summarizing the existing relevant adjuvant strategies for radiotherapy based on TGF-β signaling, and discovering potential therapeutic targets, we hope to provide a new perspective for improving clinical treatment.

The clinical utilization of SNIP1 and its pathophysiological mechanisms in disease

Smad intranuclear binding protein 1 (SNIP1), a highly conserved nuclear protein, functions as a transcriptional regulator and exerts a significant influence on disease progression. In addition, the N-terminal domain of SNIP1 facilitates its interaction with Smad4, a signaling protein associated with the TGF-β family, and RelA/p65, a transcription factor connected to NF-κB. This interaction further enhances the transcriptional activation of c-Myc-dependent genes. Presently, the primary emphasis in research is directed towards targeting the catalytic domain of SNIP1, as it holds promise as a potential therapeutic target for various diseases. While the significance of SNIP1 in pathological mechanisms remains uncertain, this review aims to comprehensively examine the existing literature on the association between SNIP1 and proteins implicated in the regulation of diverse clinical conditions, including cancer, inflammation, and related diseases.

Functioning and mechanisms of PTMs in renal diseases

Post-translational modifications (PTMs) are crucial epigenetic mechanisms that regulate various cellular biological processes. The use of mass spectrometry (MS)-proteomics has led to the discovery of numerous novel types of protein PTMs, such as acetylation, crotonylation, 2-hydroxyisobutyrylation, β-hydroxybutyrylation, protein propionylation and butyrylation, succinylation, malonylation, lactylation, and histone methylation. In this review, we specifically highlight the molecular mechanisms and roles of various histone and some non-histone PTMs in renal diseases, including diabetic kidney disease. PTMs exhibit diverse effects on renal diseases, which can be either protective or detrimental, depending on the specific type of protein PTMs and their respective targets. Different PTMs activate various signaling pathways in diverse renal pathological conditions, which could provide novel insights for studying epigenetic mechanisms and developing potential therapeutic strategies for renal diseases.

Oncogenic signaling-mediated regulation of chromatin during tumorigenesis

Signaling pathways play critical roles in executing and controlling important biological processes within cells. Cells/organisms trigger appropriate signal transduction pathways in order to turn on or off intracellular gene expression in response to environmental stimuli. An orchestrated regulation of different signaling pathways across different organs and tissues is the basis of many important biological functions. Presumably, any malfunctions or dysregulation of these signaling pathways contribute to the pathogenesis of disease, particularly cancer. In this review, we discuss how the dysregulation of signaling pathways (TGF-β signaling, Hippo signaling, Wnt signaling, Notch signaling, and PI3K-AKT signaling) modulates chromatin modifications to regulate the epigenome, thereby contributing to tumorigenesis and metastasis.

Establishing a prognostic model of chromatin modulators and identifying potential drug candidates in renal clear cell patients

BACKGROUND

Renal carcinoma is a common malignant tumor of the urinary system. Advanced renal carcinoma has a low 5-year survival rate and a poor prognosis. More and more studies have confirmed that chromatin regulators (CRs) can regulate the occurrence and development of cancer. This article investigates the functional and prognostic value of CRs in renal carcinoma patients.

METHODS

mRNA expression and clinical information were obtained from The Cancer Genome Atlas database. Univariate Cox regression analysis and LASSO regression analysis were used to select prognostic chromatin-regulated genes and use them to construct a risk model for predicting the prognosis of renal cancer. Differences in prognosis between high-risk and low-risk groups were compared using Kaplan-Meier analysis. In addition, we analyzed the relationship between chromatin regulators and tumor immune infiltration, and explored differences in drug sensitivity between risk groups.

RESULTS

We constructed a model consisting of 11 CRs to predict the prognosis of renal cancer patients. We not only successfully validated its feasibility, but also found that the 11 CR-based model was an independent prognostic factor. Functional analysis showed that CRs were mainly enriched in cancer development-related signalling pathways. We also found through the TIMER database that CR-based models were also associated with immune cell infiltration and immune checkpoints. At the same time, the genomics of drug sensitivity in cancer database was used to analyze the commonly used drugs of renal clear cell carcinoma patients. It was found that patients in the low-risk group were sensitive to medicines such as axitinib, pazopanib, sorafenib, and gemcitabine. In contrast, those in the high-risk group may be sensitive to sunitinib.

CONCLUSION

The chromatin regulator-related prognostic model we constructed can be used to assess the prognostic risk of patients with clear cell renal cell carcinoma. The results of this study can bring new ideas for targeted therapy of clear cell renal carcinoma, helping doctors to take corresponding measures in advance for patients with different risks.

Development of a TGF-β signaling-related genes signature to predict clinical prognosis and immunotherapy responses in clear cell renal cell carcinoma

Background

Transforming growth factor (TGF)-β signaling is strongly related to the development and progression of tumor. We aimed to construct a prognostic gene signature based on TGF-β signaling-related genes for predicting clinical prognosis and immunotherapy responses of patients with clear cell renal cell carcinoma (ccRCC).

Methods

The gene expression profiles and corresponding clinical information of ccRCC were collected from the TCGA and the ArrayExpress (E-MTAB-1980) databases. LASSO, univariate and multivariate Cox regression analyses were conducted to construct a prognostic signature in the TCGA cohort. The E-MTAB-1980 cohort were used for validation. Kaplan-Meier (K-M) survival and time-dependent receiver operating characteristic (ROC) were conducted to assess effectiveness and reliability of the signature. The differences in gene enrichments, immune cell infiltration, and expression of immune checkpoints in ccRCC patients showing different risks were investigated.

Results

We constructed a seven gene (PML, CDKN2B, COL1A2, CHRDL1, HPGD, CGN and TGFBR3) signature, which divided the ccRCC patients into high risk group and low risk group. The K-M analysis indicated that patients in the high risk group had a significantly shorter overall survival (OS) time than that in the low risk group in the TCGA (p < 0.001) and E-MTAB-1980 (p = 0.012). The AUC of the signature reached 0.77 at 1 year, 0.7 at 3 years, and 0.71 at 5 years in the TCGA, respectively, and reached 0.69 at 1 year, 0.72 at 3 years, and 0.75 at 5 years in the E-MTAB-1980, respectively. Further analyses confirmed the risk score as an independent prognostic factor for ccRCC (p < 0.001). The results of ssGSEA that immune cell infiltration degree and the scores of immune-related functions were significantly increased in the high risk group. The CIBERSORT analysis indicated that the abundance of immune cell were significantly different between two risk groups. Furthermore, The risk score was positively related to the expression of PD-1, CTLA4 and LAG3.These results indicated that patients in the high risk group benefit more from immunotherapy.

Conclusion

We constructed a novel TGF-β signaling-related genes signature that could serve as an promising independent factor for predicting clinical prognosis and immunotherapy responses in ccRCC patients.

Unveiling the Metal-Dependent Aggregation Properties of the C-terminal Region of Amyloidogenic Intrinsically Disordered Protein Isoforms DPF3b and DPF3a

Double-PHD fingers 3 (DPF3) is a BAF-associated human epigenetic regulator, which is increasingly recognised as a major contributor to various pathological contexts, such as cardiac defects, cancer, and neurodegenerative diseases. Recently, we unveiled that its two isoforms (DPF3b and DPF3a) are amyloidogenic intrinsically disordered proteins. DPF3 isoforms differ from their C-terminal region (C-TERb and C-TERa), containing zinc fingers and disordered domains. Herein, we investigated the disorder aggregation properties of C-TER isoforms. In agreement with the predictions, spectroscopy highlighted a lack of a highly ordered structure, especially for C-TERa. Over a few days, both C-TERs were shown to spontaneously assemble into similar antiparallel and parallel β-sheet-rich fibrils. Altered metal homeostasis being a neurodegeneration hallmark, we also assessed the influence of divalent metal cations, namely Cu²⁺, Mg²⁺, Ni²⁺, and Zn²⁺, on the C-TER aggregation pathway. Circular dichroism revealed that metal binding does not impair the formation of β-sheets, though metal-specific tertiary structure modifications were observed. Through intrinsic and extrinsic fluorescence, we found that metal cations differently affect C-TERb and C-TERa. Cu²⁺ and Ni²⁺ have a strong inhibitory effect on the aggregation of both isoforms, whereas Mg²⁺ impedes C-TERb fibrillation and, on the contrary, enhances that of C-TERa. Upon Zn²⁺ binding, C-TERb aggregation is also hindered, and the amyloid autofluorescence of C-TERa is remarkably red-shifted. Using electron microscopy, we confirmed that the metal-induced spectral changes are related to the morphological diversity of the aggregates. While metal-treated C-TERb formed breakable and fragmented filaments, C-TERa fibrils retained their flexibility and packing properties in the presence of Mg²⁺ and Zn²⁺ cations.