D'Angelo Donato, Al Saidi Aya, Ghirardo Giorgia, Vecellio Reane Denis, Gasparini Nicola, Rizzuto Rosario, Raffaello Anna
Department of Biomedical Sciences, University of Padua, Padua, Italy.
Department of Biomedical Sciences, University of Padua, Padua, Italy; National Center on Gene Therapy and RNA-Based Drugs, 35131 Padua, Italy.
Biochim Biophys Acta Mol Cell Res. 2025 Oct;1872(7):119998. doi: 10.1016/j.bbamcr.2025.119998. Epub 2025 Jun 6.
The presenilin-associated rhomboid-like protein (PARL) is a mitochondrial inner membrane serine protease that is a key regulator of several cellular processes, including apoptosis, metabolism, inflammation and stress responses. While recent studies suggest that PARL may play a role in mitochondrial calcium homeostasis, the underlying mechanisms remain poorly understood. In this study, we investigated the effects of PARL modulation on mitochondrial and cytosolic calcium dynamics, as well as mitochondrial membrane potential. Our results show that altering PARL protein levels, through both overexpression and silencing, significantly affects mitochondrial calcium uptake, without influencing cytosolic calcium transients or mitochondrial membrane potential. Despite the observed changes in mitochondrial calcium dynamics, PARL does not interact with the mitochondrial calcium uniporter complex (mtCU) regulators MICU1 and MICU2, which are critical for regulating mitochondrial calcium influx. However, we observed alterations in the protein levels of MICU1 and MICU2, either in their monomeric or dimeric forms, suggesting that PARL may influence these mtCU components indirectly. Interestingly, the pore-forming subunit MCU, and the structural subunit EMRE, essential for the assembly of the mtCU, were unaffected by PARL modulation. These findings suggest that the role of PARL in modulating mitochondrial calcium homeostasis may involve indirect mechanisms, potentially involving other regulatory pathways. Overall, our study provides novel insights into the functional role of PARL in mitochondrial calcium regulation, offering potential avenues for further investigation into its broader cellular functions.
早老素相关类菱形蛋白酶（PARL）是一种线粒体内膜丝氨酸蛋白酶，是包括细胞凋亡、代谢、炎症和应激反应在内的多种细胞过程的关键调节因子。虽然最近的研究表明PARL可能在线粒体钙稳态中发挥作用，但其潜在机制仍知之甚少。在本研究中，我们研究了PARL调节对线粒体和细胞质钙动力学以及线粒体膜电位的影响。我们的结果表明，通过过表达和沉默改变PARL蛋白水平，会显著影响线粒体钙摄取，而不影响细胞质钙瞬变或线粒体膜电位。尽管观察到线粒体钙动力学发生了变化，但PARL并不与线粒体钙单向转运体复合物（mtCU）的调节因子MICU1和MICU2相互作用，而MICU1和MICU2对调节线粒体钙内流至关重要。然而，我们观察到MICU1和MICU2的单体或二聚体形式的蛋白水平发生了变化，这表明PARL可能间接影响这些mtCU成分。有趣的是，mtCU组装所必需的成孔亚基MCU和结构亚基EMRE不受PARL调节的影响。这些发现表明，PARL在调节线粒体钙稳态中的作用可能涉及间接机制，可能涉及其他调节途径。总体而言，我们的研究为PARL在线粒体钙调节中的功能作用提供了新的见解，为进一步研究其更广泛的细胞功能提供了潜在途径。
