BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most common cardiac genetic disorder caused by sarcomeric gene variants and associated with left ventricular hypertrophy and diastolic dysfunction. The role of the microtubule network has recently gained interest with the findings that microtubule detyrosination (dTyr-MT) is markedly elevated in heart failure. Acute reduction of dTyr-MT by inhibition of the detyrosinase (VASH [vasohibin]/SVBP [small VASH-binding protein] complex) or activation of the tyrosinase (TTL [tubulin tyrosine ligase]) markedly improved contractility and reduced stiffness in human failing cardiomyocytes and thus posed a new perspective for HCM treatment. In this study, we tested the impact of chronic tubulin tyrosination in an HCM mouse model ( Mybpc3 knock-in), in human HCM cardiomyocytes, and in SVBP-deficient human engineered heart tissues (EHTs). METHODS: Adeno-associated virus serotype 9–mediated TTL transfer was applied in neonatal wild-type rodents, in 3-week-old knock-in mice, and in HCM human induced pluripotent stem cell–derived cardiomyocytes. RESULTS: We show (1) TTL for 6 weeks dose dependently reduced dTyr-MT and improved contractility without affecting cytosolic calcium transients in wild-type cardiomyocytes; (2) TTL for 12 weeks reduced the abundance of dTyr-MT in the myocardium, improved diastolic filling, compliance, cardiac output, and stroke volume in knock-in mice; (3) TTL for 10 days normalized cell area in HCM human induced pluripotent stem cell–derived cardiomyocytes; (4) TTL overexpression activated transcription of tubulins and other cytoskeleton components but did not significantly impact the proteome in knock-in mice; (5) SVBP-deficient EHTs exhibited reduced dTyr-MT levels, higher force, and faster relaxation than TTL-deficient and wild-type EHTs. RNA sequencing and mass spectrometry analysis revealed distinct enrichment of cardiomyocyte components and pathways in SVBP-deficient versus TTL-deficient EHTs. CONCLUSIONS: This study provides the first proof of concept that chronic activation of tubulin tyrosination in HCM mice and in human EHTs improves heart function and holds promise for targeting the nonsarcomeric cytoskeleton in heart disease.

Extracellular vesicles (EVs) have gained significant attention as pathology mediators and potential diagnostic tools for neurodegenerative diseases. However, isolation of brain‐derived EVs (BDEVs) from tissue remains challenging, often involving enzymatic digestion steps that may compromise the integrity of EV proteins and overall functionality. Here, we describe that collagenase digestion, commonly used for BDEV isolation, produces undesired protein cleavage of EV‐associated proteins in brain tissue homogenates and cell‐derived EVs. In order to avoid this effect, we studied the possibility of isolating BDEVs with a reduced amount of collagenase or without any protease. Characterization of the isolated BDEVs from mouse and human samples (both female and male) revealed their characteristic morphology and size distribution with both approaches. However, we show that even minor enzymatic digestion induces ‘artificial’ proteolytic processing in key BDEV markers, such as Flotillin‐1, CD81, and the cellular prion protein (PrP ^C ), whereas avoiding enzymatic treatment completely preserves their integrity. We found no major differences in mRNA and protein content between non‐enzymatically and enzymatically isolated BDEVs, suggesting that the same BDEV populations are purified with both approaches. Intriguingly, the lack of Golgi marker GM130 signal, often referred to as contamination indicator (or negative marker) in EV preparations, seems to result from enzymatic digestion rather than from its actual absence in BDEV samples. Overall, we show that non‐enzymatic isolation of EVs from brain tissue is possible and avoids artificial pruning of proteins while achieving an overall high BDEV yield and purity. This protocol will help to understand the functions of BDEV and their associated proteins in a near‐physiological setting, thus opening new research approaches.

Truffles of the Tuber species are known as expensive foods, mainly for their distinct aroma and taste. This high price makes them a profitable target of food fraud, e.g., the misdeclaration of cheaper truffle species as expensive ones. While many studies investigated truffles on the metabolomic level or the volatile organic compounds extruded by them, research at the proteome level as a phenotype determining basis is limited. In this study, a bottom-up proteomic approach based on LC-MS/MS measurements in data-independent acquisition mode was performed to analyze the truffle species Tuber aestivum, Tuber albidum pico, Tuber indicum, Tuber magnatum, and Tuber melanosporum, and a protein atlas of the investigated species was obtained. The yielded proteomic fingerprints are unique for each of the of the five truffle species and can now be used in case of suspected food fraud. First, a comprehensive spectral library containing 9000 proteins and 50,000 peptides was generated by two-dimensional liquid chromatography coupled to tandem mass spectrometry (2D-LC-MS/MS). Then, samples of the truffle species were analyzed in data-independent acquisition (DIA) proteomics mode yielding 2715 quantified proteins present in all truffle samples. Individual species were clearly distinguishable by principal component analysis (PCA). Quantitative proteome fingerprints were generated from 2066 ANOVA significant proteins, and side-by-side comparisons of truffles were done by T-tests. A further aim of this study was the annotation of functions for the identified proteins. For Tuber magnatum and Tuber melanosporum conclusive links to their superior aroma were found by enrichment of proteins responsible for sulfur-metabolic processes in comparison with other truffles. The obtained data in this study may serve as a reference library for food analysis laboratories in the future to tackle food fraud by misdeclaration of truffles. Further identified proteins with their corresponding abundance values in the different truffle species may serve as potential protein markers in the establishment of targeted analysis methods. Lastly, the obtained data may serve in the future as a basis for deciphering the biochemistry of truffles more deeply as well, when protein databases of the different truffle species will be more complete.

The hypoxic tumor microenvironment significantly impacts cellular behavior and intercellular communication, with extracellular vesicles (EVs) playing a crucial role in promoting angiogenesis, metastasis, and host immunosuppression, and presumed cancer progression and metastasis are closely associated with the aberrant surface N-glycan expression in EVs. We hypothesize that hypoxic tumors synthesize specific hypoxia-induced N-glycans in response to or as a consequence of hypoxia. This study utilized nano-LC–MS/MS to integrate quantitative proteomic and N-glycomic analyses of both cells and EVs derived from the MDA-MB-231 breast cancer cell line cultured under normoxic and hypoxic conditions. Whole N-glycome and proteome profiling revealed that hypoxia has an impact on the asparagine N-linked glycosylation patterns and on the glycolysis/gluconeogenesis proteins in cells in terms of altered N-glycosylation for their adaptation to low-oxygen conditions. Distinct N-glycan types, high-mannose glycans like Man3 and Man9, were highly abundant in the hypoxic cells. On the other hand, alterations in the sialylation and fucosylation patterns were observed in the hypoxic cells. Furthermore, hypoxia-induced EVs exhibit a signature consisting of mono-antennary structures and specific N-glycans (H4N3F1S2, H3N3F1S0, and H7N4F3S2; H8N4F1S0 and H8N6F1S2), which are significantly associated with poor prognoses for breast tumors, presumably altering the interactions within the tumor microenvironment to promote tumorigenesis and metastasis. Our findings provide an overview of the N-glycan profiles, particularly under hypoxic conditions, and offer insights into the potential biomarkers for tracking tumor microenvironment dynamics and for developing precision medicine approaches in oncology.

BACKGROUND: BMP10 (bone morphogenetic protein 10) is a ligand of the TGF (transforming growth factor) β superfamily secreted mainly by atrial cardiomyocytes. Elevated BMP10 blood concentrations predict atrial fibrillation (AF), AF recurrence after ablation, and AF-related cardiovascular complications like stroke. The conditions increasing BMP10 secretion and the downstream effects of BMP10 in cardiomyocytes are poorly understood. We assessed BMP10 secretion dynamics and BMP10 effects in a human 3-dimensional model of atrial and ventricular engineered heart tissue (EHT). METHODS: Cardiomyocytes (atrial and ventricular) differentiated from human induced pluripotent stem cells were cast into a fibrin-matrix to generate EHT. Atrial EHTs were optogenetically paced (3–5 Hz) or maintained at intrinsic beating rate for 24 hours up to 15 days. Release of BMP10 and other cardiac biomarkers from EHT was quantified. BMP10 plasma concentrations were compared between 1370 patients with different atrial rhythms at blood draw. Additionally, ventricular EHTs were exposed to BMP10 for 10 days. RESULTS: Atrial but not ventricular EHT released BMP10 within 48 hours of culture. High-rate optogenetic pacing increased atrial EHT BMP10 release by ≈3-fold after a latency of at least 24 hours post initiation of pacing. BMP10 plasma concentrations were elevated in patients with documented AF compared with sinus rhythm and even higher in patients with current AF. BMP10 induced upregulation of TGFβ pathway transcripts, increased expression of genes related to AF and heart failure, including PITX2 and NPPB , and increased relative contraction times in ventricular EHTs. CONCLUSIONS: High atrial rates elevate BMP10 expression and release, and higher plasma concentrations of BMP10 are observed in patients with active AF. BMP10 exposure induces transcriptomic changes linked to AF and heart failure in ventricular EHT. These findings support BMP10 as a biomarker and potential mediator of AF-related remodeling and tachycardiomyopathy.

Radiotherapy (RT) is a central treatment for prostate cancer (PCa), relying on the induction of DNA double-strand breaks (DSBs). Tumor ability to repair these breaks limits RT efficacy, making DSB repair inhibitors potential radiosensitizers. However, many of these inhibitors lack tumor specificity and harm normal cells. Therefore, tumor-specific radiosensitization strategies are critically needed for PCa. Approximately 50% of PCa cases harbor the TMPRSS2-ERG gene fusion, leading to overexpression of the ERG transcription factor (ERG ⁺ ). In this study, we demonstrate that ERG ⁺ tumors shift DSB repair toward the poly(ADP-ribose) polymerase 1–dependent end-joining (PARP1-EJ) pathway. Proteomic and Western blot analyses revealed elevated PARP1, XRCC1, and LIG3 levels in ERG ⁺ cells. Notably, PARP inhibition with olaparib increased residual γH2AX/53BP1 foci postirradiation in ERG ⁺ cells, indicating enhanced radiosensitization. In tissue slice cultures (TSCs) from 53 tumors of patients with high-risk PCa, olaparib selectively increased γH2AX/53BP1 foci selectively in ERG ⁺ samples. ERG ⁺ patient–derived organoids also showed significantly delayed growth when treated with olaparib plus RT, compared with either treatment alone. Interestingly, ERG-negative cells within ERG ⁺ TSCs were similarly radiosensitized by olaparib, likely through bystander effect, with residual 53BP1 foci levels comparable to those in ERG ⁺ cells. This was confirmed by medium exchange experiments. These findings suggest that ERG expression promotes dependency on the PARP1-EJ pathway, rendering ERG ⁺ PCa more susceptible to PARP inhibition. This supports combining PARP inhibitors with RT for tumor-selective radiosensitization in ERG ⁺ patients.