bims-mimbat 2024-06-23 papers

Cell Metab. 2024 Jun 12. pii: S1550-4131(24)00187-6. [Epub ahead of print]

Short-term cold exposure induces persistent epigenomic memory in brown fat.

Shin-Ichi Inoue, Matthew J Emmett, Hee-Woong Lim, Mohit Midha, Hannah J Richter, Isaac J Celwyn, Rashid Mehmood, Maria Chondronikola, Samuel Klein, Amy K Hauck, Mitchell A Lazar.

Deficiency of the epigenome modulator histone deacetylase 3 (HDAC3) in brown adipose tissue (BAT) impairs the ability of mice to survive in near-freezing temperatures. Here, we report that short-term exposure to mild cold temperature (STEMCT: 15°C for 24 h) averted lethal hypothermia of mice lacking HDAC3 in BAT (HDAC3 BAT KO) exposed to 4°C. STEMCT restored the induction of the thermogenic coactivator PGC-1α along with UCP1 at 22°C, which is greatly impaired in HDAC3-deficient BAT, and deletion of either UCP1 or PGC-1α prevented the protective effect of STEMCT. Remarkably, this protection lasted for up to 7 days. Transcriptional activator C/EBPβ was induced by short-term cold exposure in mouse and human BAT and, uniquely, remained high for 7 days following STEMCT. Adeno-associated virus-mediated knockdown of BAT C/EBPβ in HDAC3 BAT KO mice erased the persistent memory of STEMCT, revealing the existence of a C/EBPβ-dependent and HDAC3-independent cold-adaptive epigenomic memory.

Keywords: C/EBPβ; ERRα; HDAC3; PGC-1α; UCP1; brown adipose tissue; cold memory; mitochondria; oxidative phosphorylation; thermogenesis

DOI: https://doi.org/10.1016/j.cmet.2024.05.011

J Clin Invest. 2024 Jun 18. pii: e178303. [Epub ahead of print]

Myostatin regulates energy homeostasis through autocrine- and paracrine-mediated microenvironment communications.

Hui Wang, Shanshan Guo, Huanqing Gao, Jiyang Ding, Hongyun Li, Xingyu Kong, Shuang Zhang, Muyang He, Yonghao Feng, Wei Wu, Kexin Xu, Yuxuan Chen, Hanyin Zhang, Tiemin Liu, Xingxing Kong.

Myostatin (MSTN) has long been recognized as a critical regulator of muscle mass. Recently, there has been an increasing interest in its role in metabolism. In our study, we specifically knocked out MSTN in brown adipose tissue (BAT) from mice (MSTNΔUCP1) and found that the mice gained more weight than controls when fed a high-fat diet, with progressive hepatosteatosis and impaired skeletal muscle activity. RNA-seq analysis indicated signatures of mitochondrial dysfunction and inflammation in the MSTN-ablation BAT. Further studies demonstrated that the the Kruppel-like factor 4 (KLF4) was responsible for the metabolic phenotypes observed, while FGF21 contributed to the microenvironment communication between adipocytes and macrophages induced by the loss of MSTN. Moreover, the MSTN-SMAD2/3-p38 signaling pathway mediated the expression of KLF4 and FGF21 in adipocytes. In summary, our findings suggest that brown adipocytes-derived MSTN regulates BAT thermogenesis via autocrine and paracrine effects on adipocytes or macrophages, ultimately regulating systemic energy homeostasis.

Keywords: Adipose tissue; Endocrinology

DOI: https://doi.org/10.1172/JCI178303

Cell Rep. 2024 Jun 19. pii: S2211-1247(24)00718-6. [Epub ahead of print]43(7): 114390

Insulin and leptin oscillations license food-entrained browning and metabolic flexibility.

Pamela Mattar, Andressa Reginato, Christian Lavados, Debajyoti Das, Manu Kalyani, Nuria Martinez-Lopez, Mridul Sharma, Grethe Skovbjerg, Jacob Lercke Skytte, Urmas Roostalu, Rajasekaran Subbarayan, Elodie Picarda, Xingxing Zang, Jinghang Zhang, Chandan Guha, Gary Schwartz, Prashant Rajbhandari, Rajat Singh.

Timed feeding drives adipose browning, although the integrative mechanisms for the same remain unclear. Here, we show that twice-a-night (TAN) feeding generates biphasic oscillations of circulating insulin and leptin, representing their entrainment by timed feeding. Insulin and leptin surges lead to marked cellular, functional, and metabolic remodeling of subcutaneous white adipose tissue (sWAT), resulting in increased energy expenditure. Single-cell RNA-sequencing (scRNA-seq) analyses and flow cytometry demonstrate a role for insulin and leptin surges in innate lymphoid type 2 (ILC2) cell recruitment and sWAT browning, since sWAT depot denervation or loss of leptin or insulin receptor signaling or ILC2 recruitment each dampens TAN feeding-induced sWAT remodeling and energy expenditure. Consistently, recreating insulin and leptin oscillations via once-a-day timed co-injections is sufficient to favorably remodel innervated sWAT. Innervation is necessary for sWAT remodeling, since denervation of sWAT, but not brown adipose tissue (BAT), blocks TAN-induced sWAT remodeling and resolution of inflammation. In sum, reorganization of nutrient-sensitive pathways remodels sWAT and drives the metabolic benefits of timed feeding.

Keywords: CP: Metabolism; ILC2; browning; circadian; insulin; intermittent fasting; leptin; oscillations; time-restricted feeding

DOI: https://doi.org/10.1016/j.celrep.2024.114390

Nat Commun. 2024 Jun 20. 15(1): 5265

DYRK1A signalling synchronizes the mitochondrial import pathways for metabolic rewiring.

Adinarayana Marada, Corvin Walter, Tamara Suhm, Sahana Shankar, Arpita Nandy, Tilman Brummer, Ines Dhaouadi, F-Nora Vögtle, Chris Meisinger.

Mitochondria require an extensive proteome to maintain a variety of metabolic reactions, and changes in cellular demand depend on rapid adaptation of the mitochondrial protein composition. The TOM complex, the organellar entry gate for mitochondrial precursors in the outer membrane, is a target for cytosolic kinases to modulate protein influx. DYRK1A phosphorylation of the carrier import receptor TOM70 at Ser91 enables its efficient docking and thus transfer of precursor proteins to the TOM complex. Here, we probe TOM70 phosphorylation in molecular detail and find that TOM70 is not a CK2 target nor import receptor for MIC19 as previously suggested. Instead, we identify TOM20 as a MIC19 import receptor and show off-target inhibition of the DYRK1A-TOM70 axis with the clinically used CK2 inhibitor CX4945 which activates TOM20-dependent import pathways. Taken together, modulation of DYRK1A signalling adapts the central mitochondrial protein entry gate via synchronization of TOM70- and TOM20-dependent import pathways for metabolic rewiring. Thus, DYRK1A emerges as a cytosolic surveillance kinase to regulate and fine-tune mitochondrial protein biogenesis.

DOI: https://doi.org/10.1038/s41467-024-49611-4

Biosystems. 2024 Jun 19. pii: S0303-2647(24)00140-0. [Epub ahead of print]242 105255

Size matters in metabolic scaling: Critical role of the thermodynamic efficiency of ATP synthesis and its dependence on mitochondrial H+ leak across mammalian species.

Sunil Nath.

In this last article of the trilogy, the unified biothermokinetic theory of ATP synthesis developed in the previous two papers is applied to a major problem in comparative physiology, biochemistry, and ecology-that of metabolic scaling as a function of body mass across species. A clear distinction is made between intraspecific and interspecific relationships in energy metabolism, clearing up confusion that had existed from the very beginning since Kleiber first proposed his mouse-to-elephant rule almost a century ago. It is shown that the overall mass exponent of basal/standard metabolic rate in the allometric relationship [Formula: see text] is composed of two parts, one emerging from the relative intraspecific constancy of the slope (b), and the other (b') arising from the interspecific variation of the mass coefficient, a(M) with body size. Quantitative analysis is shown to reveal the hidden underlying relationship followed by the interspecific mass coefficient, a(M)=P0M0.10, and a universal value of P0=3.23 watts, W is derived from empirical data on mammals from mouse to cattle. The above relationship is shown to be understood only within an evolutionary biological context, and provides a physiological explanation for Cope's rule. The analysis also helps in fundamentally understanding how variability and a diversity of scaling exponents arises in allometric relations in biology and ecology. Next, a molecular-level understanding of the scaling of metabolism across mammalian species is shown to be obtained by consideration of the thermodynamic efficiency of ATP synthesis η, taking mitochondrial proton leak as a major determinant of basal metabolic rate in biosystems. An iterative solution is obtained by solving the mathematical equations of the biothermokinetic ATP theory, and the key thermodynamic parameters, e.g. the degree of coupling q, the operative P/O ratio, and the metabolic efficiency of ATP synthesis η are quantitatively evaluated for mammals from rat to cattle. Increases in η (by ∼15%) over a 2000-fold body size range from rat to cattle, primarily arising from an ∼3-fold decrease in the mitochondrial H+ leak rate are quantified by the unified ATP theory. Biochemical and mechanistic consequences for the interpretation of basal metabolism, and the various molecular implications arising are discussed in detail. The results are extended to maximum metabolic rate, and interpreted mathematically as a limiting case of the general ATP theory. The limitations of the analysis are pointed out. In sum, a comprehensive quantitative analysis based on the unified biothermokinetic theory of ATP synthesis is shown to solve a central problem in biology, physiology, and ecology on the scaling of energy metabolism with body size.

Keywords: Basal metabolic rate; Biological energy transduction; Cope's rule; Coupling; Darwinian natural selecion; Efficiency of ATP synthesis; Evolutionary implications; F(O)F(1)-ATP synthase; Interspecific allometry; Intraspecific and interspecific variation in metabolism; Mass coefficient; Mass exponent; Metabolic scaling as a function of body mass; Molecular mechanism; Nath's torsional mechanism of energy transduction and ATP synthesis; Nath's two-ion theory of energy coupling; Nath's unified biothermokinetic theory of ATP synthesis; Nath‒Kleiber number, NaKl; Nonequilibrium/irreversible thermodynamics; Phylogeny; Selective advantage

DOI: https://doi.org/10.1016/j.biosystems.2024.105255

Nat Commun. 2024 Jun 15. 15(1): 5119

A tripartite organelle platform links growth factor receptor signaling to mitochondrial metabolism.

One open question in the biology of growth factor receptors is how a quantitative input (i.e., ligand concentration) is decoded by the cell to produce specific response(s). Here, we show that an EGFR endocytic mechanism, non-clathrin endocytosis (NCE), which is activated only at high ligand concentrations and targets receptor to degradation, requires a tripartite organelle platform involving the plasma membrane (PM), endoplasmic reticulum (ER) and mitochondria. At these contact sites, EGFR-dependent, ER-generated Ca2+ oscillations are sensed by mitochondria, leading to increased metabolism and ATP production. Locally released ATP is required for cortical actin remodeling and EGFR-NCE vesicle fission. The same biochemical circuitry is also needed for an effector function of EGFR, i.e., collective motility. The multiorganelle signaling platform herein described mediates direct communication between EGFR signaling and mitochondrial metabolism, and is predicted to have a broad impact on cell physiology as it is activated by another growth factor receptor, HGFR/MET.

DOI: https://doi.org/10.1038/s41467-024-49543-z