Biology subjects

Kondadi, A. K.

Publications and source records attributed to Kondadi, A. K..

6 recordsLinked to original sources

bioRxiv2025

MINDNet: Proximity interactome of the MICOS complex revealing a multifaceted network orchestrating mitochondrial biogenesis

The Mitochondrial contact site and cristae organizing system (MICOS) complex is a multisubunit complex regulating mitochondrial inner membrane (IM) architecture, which is enriched at crista junctions (CJs) and required for cristae membrane dynamics. It modulates various mitochondrial processes including protein and lipid transport and is causally linked to a variety of human diseases. To gain a broad overview of the various pathways modulated by the MICOS complex, we examined its molecular neighbourhood. For this, we employed proximity biotinylation assays using APEX2 fused to four MICOS subunits (MIC10, MIC13, MIC26 and MIC27) in the respective mammalian knockout cells. These four MICOS-APEX2 fusion proteins integrated into the native MICOS complex and properly localised as revealed by electron microscopy combined with DAB staining and STED super-resolution nanoscopy. Here, we identify 119 common and 50 unique proteins, termed MICOS NanoDomain Network (MINDNet) encompassing the versatile proximity proteome of the MIC10/MIC13/MIC26/MIC27 subcomplex playing multifaceted mitochondrial functions. The MINDNet revealed a large number of OXPHOS proteins, protein translocases of the IM and OM, mitochondrial ribosomal proteins and solute carrier family transporters. Using the cues obtained from the proximity interaction studies, we investigated the role of all the MICOS proteins in modulating the function of the OXPHOS complexes. Among all the MICOS proteins, MIC10 and MIC60 consistently regulated the assembly and activity of the OXPHOS complexes. Overall, we propose that the MICOS complex integrates numerous spatial and temporal cues to regulate the dynamic microenvironment, along with IM architecture, which are involved in multiple pathways controlling mitochondrial biogenesis.

cell biology↗

bioRxiv2025

Preconditioning of human iPSCs with doxorubicin causes genome-wide transcriptional reprogramming in iPSC-derived cardiomyocytes linked to mitochondrial dysfunction and impaired cardiac regeneration

BackgroundThe anthracycline doxorubicin (Dox) is a widely used genotoxic chemotherapeutic drug with known dose-limiting cardiotoxic effects. How Dox-induced damage either to cardiomyocytes or to cardiac stem cells, which may compromise cardiac regeneration, contributes to cardiotoxicity remains poorly understood. MethodsHere we used a human induced pluripotent stem cell (iPSC)-based model system to determine the sensitivity of stem cells (iPSCs) and iPSC-derived derived cardiomyocytes (iCMs) applying different treatment regimens of Dox. Next to a broad range of methods to determine cellular and mitochondrial functions we performed an in-depth whole genome transcriptome profiling in iPSCs as well as iCMs. ResultsAs compared to their differentiated counterparts, iPSCs are highly sensitive against even short pulse-treatments with low Dox concentrations. Using such rather mild treatment conditions, we observed major mitochondrial impairments as demonstrated by increased mitochondrial fragmentation, persistent loss of mitochondrial membrane potential, and reduced ATP levels, while neither a markedly increased nuclear DNA damage response nor apoptosis were detected. Albeit mitochondrial dysfunction was not accompanied by changes in mitochondrial ultrastructure or altered OXPHOS complex assembly, mitochondrial genome (mtDNA) organization was altered. This points to a possible role of mtDNA remodelling for contributing to the high susceptibility of iPSCs to Dox. Whole genome transcriptome profiling revealed major differences in the transcriptional response to Dox treatment between iPSCs and iCMs. We could show that a moderate and transient exposure of iPSCs to Dox is sufficient to cause major transcriptional changes as for example reflected by the downregulation of numerous pivotal genes regulating cellular homeostasis and energy metabolism in iPSCs. Furthermore, pulse-treatment with Dox at the iPSC stage, termed preconditioning here, shifts the global transcriptional landscape of iCMs towards the expression of genes associated with impaired cardiac muscle regeneration, disrupted energy metabolism, altered muscle contraction, and increased fibrosis. ConclusionsOur findings support the hypothesis that Dox-induced mitochondrial dysfunction and transcriptional preconditioning in stem cells results in an impaired regenerative capacity after differentiation. This highlights a potential critical role of stem cells in mediating Dox-induced cardiotoxicity.

cell biology↗

bioRxiv2023

Mitochondrial Apolipoprotein MIC26 is a metabolic rheostat regulating central cellular fuel pathways

Mitochondria play central roles in metabolism and metabolic disorders such as type 2 diabetes. MIC26, a MICOS complex subunit, was linked to diabetes and modulation of lipid metabolism. Yet, the functional role of MIC26 in regulating metabolism under hyperglycemia is not understood. We employed a multi-omics approach combined with functional assays using WT and MIC26 KO cells cultured in normoglycemia or hyperglycemia, mimicking altered nutrient availability. We show that MIC26 has an inhibitory role in glycolysis and cholesterol/lipid metabolism under normoglycemic conditions. Under hyperglycemia, this inhibitory role is reversed demonstrating that MIC26 is critical for metabolic adaptations. This is partially mediated by alterations of mitochondrial metabolite transporters. Furthermore, MIC26 deletion led to a major metabolic rewiring of glutamine utilization as well as oxidative phosphorylation. We propose that MIC26 acts as a metabolic rheostat, that modulates mitochondrial metabolite exchange via regulating mitochondrial cristae, allowing cells to cope with nutrient overload.

cell biology↗

bioRxiv2023

SLP2 coordinates MICOS assembly and cristae morphogenesis via MIC13 and YME1L

The MICOS complex subunit MIC13 is essential for mitochondrial cristae organization. Mutations in MIC13 cause severe mitochondrial hepato-encephalopathy displaying defective cristae morphology and loss of the MIC10-subcomplex. Here we identified stomatin-like protein 2 (SLP2) as an interacting partner of MIC13 and decipher a critical role of SLP2 as an auxiliary MICOS subunit, modulating cristae morphology. SLP2 provides a large interaction hub for MICOS subunits and loss of SLP2 leads to drastic alterations in cristae morphology. Double deletion of SLP2 and MIC13 showed reduced assembly of core MICOS subunit, MIC60 into MICOS and dispersion of MIC60-specific puncta, demonstrating a critical role of SLP2-MIC13 in MICOS assembly and crista junction (CJ) formation. We further identified that the mitochondrial i-AAA protease YME1L in coordination either with MIC13 or SLP2 differentially regulates MICOS assembly pathways thereby interlinking MIC13-specific or scaffolding-specific role of SLP2 with quality control and assembly of the MICOS complex. YME1L- depletion in MIC13 KO could restore MIC10-subcomplex and reform the nascent CJ. Taken together, we propose seeder model for MICOS assembly and CJ formation, where SLP2- MIC13 seed the assembly of MIC60 into MICOS complex and promote the formation of CJ by regulating the quality and stability of MIC10-subcomplex.

biochemistry↗

bioRxiv2023

Live-cell super-resolution nanoscopy reveals modulation of cristae dynamics in bioenergetically compromised mitochondria

Cristae membranes have been recently shown to undergo intramitochondrial merging and splitting events. Yet, the metabolic and bioenergetic factors regulating them are unclear. Here we investigated whether and how cristae membrane remodelling is dependent on oxidative phosphorylation (OXPHOS) complexes, the mitochondrial membrane potential ({Delta}{Psi}m), and the ADP/ATP nucleotide translocator. Advanced live-cell STED nanoscopy combined with in-depth quantification were employed to analyse cristae morphology and dynamics after treatment of mammalian cells with rotenone, antimycin A, oligomycin A and CCCP. This led to formation of enlarged mitochondria along with reduced cristae density but did not change the number of cristae remodelling events. CCCP treatment leading to {Delta}{Psi}m abrogation even enhanced the cristae dynamics showing their {Delta}{Psi}m-independent nature. Inhibition of OXPHOS complexes was accompanied by reduced ATP levels but did not affect cristae dynamics. However, inhibition of ADP/ATP exchange led to aberrant cristae morphology and impaired cristae dynamics in a mitochondrial subset. In sum, we provide quantitative data of cristae membrane remodelling under different conditions supporting an important interplay between OXPHOS, metabolite exchange and cristae membrane dynamics. Summary BlurbCristae morphology and dynamics are intricately connected

cell biology↗

bioRxiv2019

Cristae undergo continuous cycles of fusion and fission in a MICOS-dependent manner

The mitochondrial inner membrane can reshape under different physiological conditions. How and at which frequency this occurs in vivo and what are the molecular players involved is unknown. Here we show using state-of-the-art live-cell stimulated emission depletion (STED) super-resolution nanoscopy that crista junctions (CJs) are dynamically fusing and dividing in a reversible and balanced manner at a timescale of seconds. CJ dynamics is strongly reduced in the absence of the MICOS subunit MIC13. Staining of the cristae membrane using different protein markers or two inner mitochondrial membrane-specific dyes revealed that cristae also undergo continuous cycles of fusion and fission. These processes are dependent on MIC13 and occur at a timescale of seconds, resembling CJ dynamics. Our data further suggest that MIC60 acts as a docking platform pioneering CJ formation. Overall, by employing a variety of advanced imaging techniques including FRAP (Fluorescence-Recovery-After Photobleaching), SPT (Single-Particle-Tracking), live-cell STED and confocal Airyscan microscopy we demonstrate that cristae undergo continuous cycles of fusion and fission in a manner that is mechanistically linked to CJ formation and dynamics.

cell biology↗