Biology subjects

Polak, K.

Publications and source records attributed to Polak, K..

4 recordsLinked to original sources

bioRxiv2026

miR-378a Controls Cardiomyocyte Metabolism and Angiogenic Signaling

AimsWhile the muscle-enriched microRNA-378a (miR-378a) has been implicated in cardiac hypertrophy and stress responses, its role in maintaining cardiomyocyte metabolic homeostasis, mitochondrial function, and angiogenic paracrine signaling under physiological and post-injury conditions remains unclear. This study addresses these gaps by examining the molecular and functional consequences of miR-378a deficiency in murine heart and human cardiomyocytes. Methods and ResultsCardiac structure and function were analyzed in miR-378a-deficient (miR-378a-/-) and wild-type (miR-378a+/+) mice at 12 weeks and 17 months of age, revealing that miR-378a loss promoted myocardial fibrosis, altered IGF1R-AKT signaling, and impaired cardiac performance, with age-dependent effects. Integrated transcriptomic and proteomic analyses in miR-378a-/- and control mice, as well as in human iPSC-derived cardiomyocytes (hiPSC-CM) of both genotypes, revealed deregulated pathways related to translation, metabolism, and cardiomyopathy-associated signaling. In hiPSC-CM, miR-378a knockout (KO) impaired mitochondrial respiration, disrupted mitochondrial morphology, and reduced mitochondrial DNA content, accompanied by altered mitophagy and biogenesis. KO cells also showed increased glucose uptake but reduced glycogen storage, accompanied by changes in key metabolic regulators, and displayed diminished angiogenic potential. Finally, hiPSC-CM overexpressing miR-378a were delivered in a mouse model of acute myocardial infarction, but overexpression did not further enhance their therapeutic effect. ConclusionsThis study broadens our understanding of miR-378as physiological role in murine hearts and human cardiomyocytes, demonstrating its impact on contractility, mitochondrial integrity, glucose metabolism, and angiogenic paracrine signaling. However, overexpression of miR-378a in hiPSC-CM offers limited additional benefit in cell therapy for acute myocardial infarction.

cell biology↗

bioRxiv2025

Extracellular vesicles carrying surface-anchored adiponectin prevent obesity-related metabolic complications by enhancing insulin sensitivity

Adiponectin (Adpn) is a potent insulin-sensitizing adipokine with therapeutic promise for type 2 diabetes (T2D) and metabolic dysfunction-associated steatohepatitis (MASH). Its clinical use is limited by challenges in producing stable, bioactive high-molecular weight forms. Adipocyte-derived extracellular vesicles (EVs) naturally carry oligomeric Adpn on their surface, enhancing hormone stability and activity. Here, we engineered EVs displaying membrane-anchored Adpn (EVPP-Adpn) and control EVs lacking Adpn (EVCTL), and evaluated their metabolic effects in high fat diet (HFD)-induced obesity mice. EVPP-Adpn were purified from HEK293T cells stably transfected with a chimeric Adpn fused to a transmembrane domain and a pilot peptide (PP) directing it to EVs; EVCTL were produced from non-transfected cells. HFD-fed male and female mice received intraperitoneal EV injections for six weeks. EVPP-Adpn improved glucose tolerance and insulin sensitivity, promoted adipocyte lipid storage through insulin-regulated lipogenesis and alleviated MASH features (liver steatosis, inflammation and fibrosis). EVPP-Adpn lowered circulating ceramides and reduced FGF21, indicating improved hepatic metabolism, and activated AKT and AMPK pathways in liver and skeletal muscle, consistent with increased adiponectin signaling. These results demonstrate that surface-anchored Adpn EVs restore tissue-specific insulin signaling and improve obesity-related metabolic dysfunctions, highlighting their potential as a novel biotherapeutic strategy for T2D and MASH.

bioengineering↗

bioRxiv2022

The crosstalk between DNA-PK and cGAS drives tumor immunogenicity

Cytosolic DNAs promote inflammatory responses upon detection by the cyclic GMP-AMP (cGAMP) synthase (cGAS). It has been thus suggested that cGAS downregulation is an immune escape strategy harnessed by tumor cells. Here, we used glioblastoma cells that lack cGAS to question whether alternative DNA detection pathways can promote pro-inflammatory signaling. We show that the DNA-PK DNA repair complex drives cGAS independent inflammatory responses but that its catalytic activity is required for cGAS-dependent cGAMP production and optimal downstream signaling. We further show that the cooperation between DNA-PK and cGAS favors the expression of chemokines that promote macrophage recruitment in the tumor microenvironment, a process that impaired early tumorigenesis but correlated with poor outcome. Thus, our study supports that cGAS-dependent signaling is acquired during tumorigenesis and that cGAS and DNA-PK activities should be analyzed concertedly to predict the impact of strategies aiming to boost tumor immunogenicity.

cancer biology↗

bioRxiv2020

Extracellular vesicle-based vaccine platform displaying native viral envelope proteins elicits a robust anti-SARS-CoV-2 response in mice.

Extracellular vesicles (EVs) emerge as essential mediators of intercellular communication. DNA vaccines encoding antigens presented on EVs efficiently induce T-cell responses and EV-based vaccines containing the Spike (S) proteins of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) are highly immunogenic in mice. Thus, EVs may serve as vaccine platforms against emerging diseases, going beyond traditional strategies, with the antigen displayed identically to the original protein embedded in the viral membrane and presented as such to the immune system. Compared to their viral and pseudotyped counterparts, EV-based vaccines overcome many safety issues including pre-existing immunity against these vectors. Here, we applied our technology in natural EVs engineering, to express the S proteins of SARS-CoV-2 embedded in the EVs, which mimic the virus with its fully native spikes. Immunizations with a two component CoVEVax vaccine, comprising DNA vector (DNAS-EV) primes, allowing in situ production of Spike harbouring EVs, and a boost using S-EVs produced in mammalian cells, trigger potent neutralizing and cellular responses in mice, in the absence of any adjuvants. CoVEVax would be the prototype of vaccines, where the sole exchange of the envelope proteins on EVs leads to the generation of new vaccine candidates against emerging viruses.

immunology↗