Biology subjects

Balaz, M.

Publications and source records attributed to Balaz, M..

6 recordsLinked to original sources

bioRxiv2026

GPR180 deficiency impairs mitochondrial function and insulin secretion in pancreatic β-cells

ObjectiveG protein-coupled receptor 180 (GPR180) has been implicated in systemic energy metabolism, primarily in adipose tissue and the liver. Given impaired whole-body glucose tolerance following GPR180 dysfunction, we aimed to determine whether GPR180 regulates pancreatic {beta}-cell function. We investigated whether GPR180 contributes to {beta}-cell insulin secretion by modulating metabolic processes that couple glucose sensing to mitochondrial energy production. MethodsPhenotyping of whole-body (Gpr180 -/-) and {beta} cell-specific Gpr180 (bGpr180-KO) knockout mice was combined with gain- and loss-of-function studies in MIN6 cells. Glucose-stimulated insulin secretion, pancreatic endocrine architecture and identity, transcriptomic and metabolic profiles, as well as mitochondrial function were assessed using in vivo and in vitro approaches, including metabolic challenge tests, histology, RNA sequencing, targeted metabolomics, respirometry, and transmission electron microscopy. ResultsLoss of GPR180 impaired first-phase insulin secretion and glucose tolerance without affecting insulin sensitivity. These defects were {beta}-cell-autonomous, as confirmed in the bGpr180-KO mice and in MIN6 cells. Functional studies revealed that GPR180 regulates mitochondrial substrate utilization, anaplerotic support of the TCA cycle, and ATP generation without affecting glucose uptake or mitochondrial biogenesis. In particular, Gpr180-deficient {beta} cells showed mitochondrial membrane depolarization, reduced oxygen consumption, and endoplasmic reticulum remodeling, altering the local mitochondrial microenvironment. In vivo, Gpr180 deletion in {beta} cells led to downregulation of mitochondrial gene programs in islets, along with altered endocrine cell identity. ConclusionsGPR180 is a previously unrecognized regulator of pancreatic {beta}-cell metabolic competence and identity, linking defects in insulin secretion with alterations in mitochondrial function and endocrine cell identity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/720098v1_ufig1.gif" ALT="Figure 1"> View larger version (87K): org.highwire.dtl.DTLVardef@1f24a65org.highwire.dtl.DTLVardef@1f2371eorg.highwire.dtl.DTLVardef@10096a5org.highwire.dtl.DTLVardef@1a242be_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2025

Alpha-synuclein overexpression triggers divergent cellular responses and post-translational modifications in SH-SY5Y and ReNcell VM models

Alpha-synuclein (-syn) overexpression models are widely used to unravel the molecular mechanisms of Parkinsons disease (PD), particularly in light of the dose-dependent transition between its physiological and toxic roles. However, existing systems rely on inducible expression, lack robust dose stratification and comparative cellular contexts. Here, we developed and characterized a panel of stable neuronal cell lines in two human cellular models (SH-SY5Y neuroblastoma cells and ReNcell VM neural progenitors) overexpressing GFP-tagged wild-type (WT) or A53T mutant -syn at low and high overexpression levels. Utilizing this framework, we demonstrated that A53T consistently induces cytotoxicity, oxidative stress and mitochondrial dysfunction in both cell types. In contrast, WT -syn had divergent effects depending on the cellular context. In SH-SY5Y cells, it enhanced mitochondrial function and viability, whereas in ReNcell VM cells, the same protein triggered mitochondrial impairment and elevated oxidative stress. This opposing metabolic response was reflected in increased respiratory activity in SH-SY5Y cells and a marked decline across WT -syn overexpressing ReNcell VM. Importantly, post-translational modification (PTM) landscape of overexpressed WT -syn varied dramatically by cell type. ReNcell VM cells exhibited more robust modifications signatures, even in the absence of overt aggregation, which highlights a cell-type-specific PTM landscape that may contribute to differential vulnerability. Our findings underscore a complex interplay between -syn dosage, mutational status, cellular environment, and PTM profiles highlighting that neuronal vulnerability in PD is context-dependent. This work establishes a modular in vitro platform for dissecting -syn pathology and testing targeted therapeutic strategies grounded in cell-type specificity.

neuroscience↗

bioRxiv2023

CRISPR/Cas9 DNA synthesis disruption as a tool to control cell proliferation in vitro and in vivo

Engineered cells hold great promise for regenerative medicine and gene therapy. However, living cell products entail a fundamental biological risk of unwanted growth. Here, we describe a novel metabolic safety system to control cell proliferation without added genetic elements. We inactivated a key enzyme for nucleotide metabolism, TYMS, in several cell lines, thus obtaining cells that proliferate only when supplemented with exogenous thymidine but fail to replicate in its absence. Under supplementation, TYMS-/- pluripotent stem cells proliferate normally, produce teratomas and differentiate into potentially therapeutic cell types such as pancreatic beta cells. After differentiation, the postmitotic cells do not require thymidine to function, as seen by prolonged in vivo production of human insulin in implanted mice. Hence, this method allows robust cell culture and manufacture while mitigating the risk of uncontrolled growth of transplanted cells. One Sentence Summary: Genetic disruption of DNA synthesis prevents unwanted proliferation in cell therapies without affecting cell function.

bioengineering↗

bioRxiv2022

Asymmetric cell division safeguards memory CD8 T cell development

The strength of T cell receptor (TCR) stimulation and asymmetric distribution of fate determinants are both implied to affect T cell differentiation. Here, we uncovered asymmetric cell division (ACD) as a safeguard mechanism for memory CD8 T cell generation specifically upon strong TCR stimulation. Using live imaging approaches, we found that strong TCR stimulation induced elevated ACD rates and subsequent single cell derived colonies comprised both effector and memory precursor cells. The abundance of memory precursor cells emerging from a single activated T cell positively correlated with first mitosis ACD. Accordingly, preventing ACD by inhibition of PKC{zeta} during the first mitosis upon strong TCR stimulation markedly curtailed the formation of memory precursor cells. Conversely, no effect of ACD on fate commitment was observed upon weak TCR stimulation. Our data provide new mechanistic insights into the role of ACD for CD8 T cell fate regulation upon different activation conditions.

immunology↗

bioRxiv2020

Single-nucleus RNA-Seq reveals a new type of brown adipocyte regulating thermogenesis

Adipose tissue usually is classified as either white, brown or beige/brite, based on whether it functions as an energy storage or thermogenic organ(Cannon and Nedergaard, 2004; Rosen and Spiegelman, 2014). It serves as an important regulator of systemic metabolism, exemplified by the fact that dysfunctional adipose tissue in obesity leads to a host of secondary metabolic complications such as diabetes, cardiovascular diseases and cancer(Hajer et al., 2008; Lauby-Secretan et al., 2016). In addition, adipose tissue is an important endocrine organ, which regulates the function of other metabolic tissues through paracrine and endocrine signals(Scheele and Wolfrum, 2019; Scherer, 2006). Work in recent years has demonstrated that tissue heterogeneity is an important factor regulating the functionality of various organs(Cao et al., 2017; Ginhoux et al., 2016; Park et al., 2018). Here we used single nucleus analysis in mice and men to deconvolute adipocyte heterogeneity. We are able to identify a novel subpopulation of adipocytes whose abundance is low in mice (2-8%) and which is increased under higher ambient temperatures. Interestingly, this population is abundant in humans who live close to thermoneutrality. We demonstrate that this novel adipocyte subtype functions as a paracrine cell regulating the activity of brown adipocytes through acetate-mediated regulation of thermogenesis. These findings could explain, why human brown adipose tissue is substantially less active than mouse tissue and targeting this pathway in humans might be utilized to restore thermogenic activity of this tissue.

cell biology↗

bioRxiv2020

Cold exposure distinctively modulates parathyroid and thyroid hormones in cold-acclimatized and non-acclimatized humans

ContextCold-induced activation of thermogenesis modulates energy metabolism, but the role of humoral mediators is not completely understood. ObjectiveTo investigate the role of parathyroid and thyroid hormones in acute and adaptive response to cold in humans. DesignCross-sectional study examining acute response to ice-water swimming and to experimental non-shivering thermogenesis (NST) induction in individuals acclimatized and non-acclimatized to cold. Seasonal variation in energy metabolism of ice-water swimmers and associations between circulating PTH and molecular components of thermogenic program in brown adipose tissue (BAT) of neck-surgery patients were evaluated. SettingClinical Research Center. Patients, ParticipantsIce-water swimmers (winter swim n=15, NST-induction n=6), non-acclimatized volunteers (NST-induction, n=11, elective neck surgery n = 36). Main Outcomes and ResultsIn ice-water swimmers, PTH and TSH increased in response to 15min winter swim, while activation of NST failed to regulate PTH and lowered TSH. In non-acclimatized men, NST-induction decreased PTH and TSH. Positive correlation between systemic levels of PTH and whole-body metabolic preference for lipids as well as BAT 18F-FDG uptake was found across the two populations. Moreover, NST-cooling protocol-induced changes in metabolic preference for lipids correlated positively with changes in PTH. Finally, variability in circulating PTH correlated positively with UCP1/UCP1, PPARGC1A and DIO2 in BAT from neck surgery patients. ConclusionsRegulation of PTH and thyroid hormones during cold exposure in humans depends on the cold acclimatization level and/or cold stimulus intensity. Role of PTH in NST is substantiated by its positive relationships with whole-body metabolic preference for lipids, BAT volume and UCP1 content.

physiology↗