bims-lypmec Biomed News
on Lysosomal positioning and metabolism in cardiomyocytes
Issue of 2025–11–02
five papers selected by
Satoru Kobayashi, New York Institute of Technology



  1. Cell Mol Life Sci. 2025 Oct 30. 82(1): 380
      Lysosomes respond to cellular nutrient availability and diverse oncoming vesicle traffic such as endocytosis and autophagy by switching between anabolic signaling or catabolic hydrolase activity, which coincides with a drastic shift in their cellular distribution, organelle contacts, ion homeostasis, membrane proteome and lipidome. Emerging evidence now reveals a dynamic remodeling of lysosomal membrane to counter membrane damage, acting via extensive lipid transfer from the endoplasmic reticulum or by localized membrane repair. Functionally, lysosomes play a key role in lipid metabolism and intracellular calcium signaling. Unsurprisingly, disease-associated lysosomes are either often hyperactive- thus promoting abnormal tissue growth, or hypoactive, promoting storage. Taken together, this presents an incredible functional diversity among the cellular population of lysosomes. Here, we discuss this intracellular heterogeneity and intercellular diversity in context of lysosomal function in health and disease.
    Keywords:  Lipid storage disorders; Lysosome plasticity; Lysosome quality control; Lysosome subpopulations; Phosphoinositides
    DOI:  https://doi.org/10.1007/s00018-025-05883-7
  2. Pharmaceutics. 2025 Sep 24. pii: 1255. [Epub ahead of print]17(10):
      Background: Drug resistance (DR) mediated by ABC transporters in the cytoplasmic membrane has been one of the best studied mechanisms of DR in vitro. More recently, it has also been suggested that ABC transporters expressed on lysosomal membranes could increase the sequestration of anticancer drugs in lysosomes, thereby reducing their concentration at target sites, and causing DR. Unfortunately, convincing evidence that such a DR mechanism actually exists is lacking, even in the case of in vitro experiments. Methods: This hypothetical study using simplified models evaluates the effect of ABC transporter-mediated accumulation of anticancer drugs in lysosomes on their concentration at target sites under standard in vitro conditions. Results: Calculations show that an ABC transporter resident on the plasma membrane must create and maintain a relatively small concentration gradient between extracellular space and the target site to reduce the drug concentration at the target site by, for example, half. In contrast, if a lysosomal ABC transporter is to also halve the concentration of the drug at the target site, then it must create and maintain a huge concentration gradient between lysosomes and target sites. It is very likely that massive accumulation of drugs in lysosomes would have a negative effect on the function of the lysosomes themselves. Conclusions: The results of this hypothetical study strongly suggest that the mechanism of DR mediated by lysosomal ABC transporters is questionable, as it requires enormous accumulation of the drug in lysosomes, which would likely also impair their function. Therefore, it is highly unlikely that this hypothetical DR mechanism could actually be utilized by tumor cells to defend against the cytotoxic effects of chemotherapy in vitro.
    Keywords:  lysosomal ABC transporters; lysosomal mediated drug resistance; mechanisms of drug resistance
    DOI:  https://doi.org/10.3390/pharmaceutics17101255
  3. Elife. 2025 Oct 28. pii: RP102663. [Epub ahead of print]13
      Macroautophagy, a major self-degradation pathway in eukaryotic cells, utilizes autophagosomes to transport self-material to lysosomes for degradation. While microtubular transport is crucial for the proper function of autophagy, the exact roles of factors responsible for positioning autophagosomes remain incompletely understood. In this study, we performed a loss-of-function genetic screen targeting genes potentially involved in microtubular motility. A genetic background that blocks autophagosome-lysosome fusions was used to accurately analyze autophagosome positioning. We discovered that pre-fusion autophagosomes move towards the non-centrosomal microtubule organizing center (ncMTOC) in Drosophila fat cells, which requires a dynein-dynactin complex. This process is regulated by the small GTPases Rab7 and Rab39 together with their adaptors: Epg5 and ema, respectively. The dynein-dependent movement of vesicles toward the nucleus/ncMTOC is essential for efficient autophagosomal fusions with lysosomes and subsequent degradation. Remarkably, altering the balance of kinesin and dynein motors changes the direction of autophagosome movement, indicating a competitive relationship where normally dynein-mediated transport prevails. Since pre-fusion lysosomes were positioned similarly to autophagosomes, it indicates that pre-fusion autophagosomes and lysosomes converge at the ncMTOC, which increases the efficiency of vesicle fusions.
    Keywords:  D. melanogaster; autophagosome; cell biology; dynein; fusion; lysosome; microtubular transport; ncMTOC
    DOI:  https://doi.org/10.7554/eLife.102663
  4. Cardiovasc Res. 2025 Oct 27. pii: cvaf203. [Epub ahead of print]
      Autophagy is a lysosomal-dependent mechanism of cellular degradation characterized by the presence of double membraned vesicles called autophagosomes. Increasing lines of evidence suggest that both non-selective autophagy and cargo-specific forms of autophagy, such as the mitochondria-specific form of autophagy, termed mitophagy, are activated in the heart in response to stress. However, their activation is often transient and insufficient during the chronic phase of cardiac conditions, including both pressure and volume overload, heart failure with preserved ejection fraction, obesity and diabetic cardiomyopathy and aging cardiomyopathy. Indeed, interventions to restore the levels of autophagy and mitophagy often alleviate cardiac dysfunction in animal models of heart failure. It is, therefore, important to understand the molecular mechanisms that inhibit or activate autophagy and mitophagy during the chronic phase of heart failure. Under some conditions, autophagy can become dysregulated in the heart and induce cellular dysfunction and death. For example, lysosomal function is attenuated through multiple mechanisms. Autosis, a specific form of cell death caused by autophagy dysregulation, is characterized by unique morphologies, including perinuclear space, and sensitivity to cardiac glycoside, and contributes to the late phase of myocardial ischemia/reperfusion injury. Over the past decade, previously unrecognized functions of autophagy have been discovered, including organelle- and protein-specific degradation, and even inter-cellular communication through secretion of extracellular vesicles, which may also contribute to the pathogenesis of heart disease. The purpose of this review is to highlight recent progress in autophagy research in the heart, with a particular focus on underlying signaling mechanisms, cargo-specific autophagy and pharmacological interventions.
    DOI:  https://doi.org/10.1093/cvr/cvaf203
  5. JCI Insight. 2025 Oct 30. pii: e183334. [Epub ahead of print]
      Impaired cardiac lipid metabolism has been reported to cause heart failure. Lipin1, a multifunctional protein, is a phosphatidate phosphatase that generates diacylglycerol from phosphatidic acid and a transcriptional cofactor that regulates lipid metabolism-related gene expression. Here, we investigated the roles of lipin1 in cardiac remodeling after myocardial infarction (MI). The expression levels of lipin1 significantly decreased in cardiomyocytes of the human failing heart and murine ischemic myocardium. Cardiomyocyte-specific Lpin1 knockout (cKO) mice showed left ventricle enlargement and reduced fractional shortening after MI, compared to control mice. This was accompanied by elevated cardiac fibrosis, accumulation of reactive oxygen species, and increased expression of inflammatory cytokines. In contrast, cardiomyocyte-specific Lpin1 overexpression (cOE) mice showed reduced fibrosis and inflammation and improved cardiac function compared to control mice. Cardiac lipid droplets (LDs) were reduced after MI in wild-type (WT) mice hearts and were further downregulated in the hearts of cKO mice with a decrease in triglyceride and free fatty acid content, while cOE mice hearts exhibited increased LDs and lipid content. Expression levels of genes involved in fatty acid oxidation, such as Ppargc1a (PGC1A) and Acaa2, were decreased and increased in the MI hearts of cKO mice and cOE mice, respectively. These results suggest the protective role of lipin1 against ischemic injury by maintaining lipid metabolism in ischemic cardiomyocytes.
    Keywords:  Cardiology; Cardiovascular disease; Metabolism
    DOI:  https://doi.org/10.1172/jci.insight.183334