bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.11.18.623867

Cold-inducible GOT1 activates the malate-aspartate shuttle in brown adipose tissue to support fuel preference for fatty acids

Park, C.-H.·Park, M.·Kelly, M. E.·Cheng, H.·Lee, S. R.·Jang, C.·Chang, J. S.
View original source ↗Export metadata ↓

Abstract

Brown adipose tissue (BAT) simultaneously metabolizes fatty acids (FA) and glucose under cold stress but favors FA as the primary fuel for heat production. It remains unclear how BAT steer fuel preference toward FA over glucose. Here we show that the malate-aspartate shuttle (MAS) is activated by cold in BAT and plays a crucial role in promoting mitochondrial FA utilization. Mechanistically, cold stress selectively induces glutamic-oxaloacetic transaminase (GOT1), a key MAS enzyme, via the {beta}-adrenergic receptor-PKA-PGC-1 axis. The increase in GOT1 activates MAS, transferring reducing equivalents from the cytosol to mitochondria. This process enhances FA oxidation in mitochondria while limiting glucose oxidation. In contrast, loss of MAS activity by GOT1 deficiency reduces FA oxidation, leading to increased glucose oxidation. Together, our work uncovers a unique regulatory mechanism and role for MAS in mitochondrial fuel selection and advances our understanding of how BAT maintains fuel preference for FA under cold conditions. HighlightsO_LIGot1 is markedly induced by cold in BAT via a {beta}-adrenergic receptor-PKA-PGC-1 axis C_LIO_LIThe increase in cytosolic GOT1 activates the malate-aspartate shuttle (MAS) C_LIO_LIMAS activation promotes fatty acid oxidation while reducing glucose oxidation C_LIO_LILoss of MAS activity in BAT by Got1 deletion shifts the fuel preference to glucose C_LI

Source connections

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Park, C.-H., Park, M., Kelly, M. E., Cheng, H., Lee, S. R., Jang, C., Chang, J. S.. 2024-11-20. Cold-inducible GOT1 activates the malate-aspartate shuttle in brown adipose tissue to support fuel preference for fatty acids. https://doi.org/10.1101/2024.11.18.623867

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

The nuclear membrane protein Samp1 links peripheral genome organization to the myogenic transcriptional program

Samp1 is an inner nuclear membrane protein required for myogenic differentiation and involved in chromatin organization at the nuclear periphery. Here, we investigated whether these functions are connected by studying the effects of Samp1 depletion during C2C12 myogenic differentiation using immunofluorescence microscopy, RNA sequencing, FRIC, and chromosome-positioning analysis. Samp1-depleted cells showed strongly reduced MyHC expression and virtually abrogated multinucleated fiber formation. Although cell-cycle withdrawal was not prevented, the transcriptional program driving differentiation was drastically perturbed, with reduced muscle-associated transcripts and incomplete repression of genes normally downregulated during myogenesis. Samp1 depletion also disrupted peripheral chromatin organization and prevented the accumulation of peripheral heterochromatin typically seen during differentiation. In addition, radial chromosome distribution was disrupted, evidenced by the failure of chromosome 8 to reposition to the nuclear periphery during differentiation. Together, these findings link the requirement for Samp1 in myogenic differentiation to its role in genome organization at the nuclear periphery.

cell biology↗
bioRxiv2026

Unraveling the metabolic landscape of alkaptonuria through a human-relevant in vitro liver disease model

Alkaptonuria (AKU) is a rare inherited metabolic disorder of tyrosine catabolism caused by a deficient homogentisate 1,2-dioxygenase (HGD) enzyme. This results in the accumulation of homogentisic acid (HGA), driving a progressive multisystem pathology characterized by debilitating early-onset osteoarthritis due to connective tissue degeneration. While previous in vitro studies have primarily relied on exogenous HGA exposure in osteoarticular cell models, the direct metabolic consequences of endogenous HGD deficiency within its native hepatic context remain poorly understood. Here, we established the first human-relevant HGD knockout hepatic in vitro model using a universal in-house-developed homology-directed repair approach. Integrative multi-omic analysis revealed that HGD deficiency induces widespread metabolic rewiring extending beyond disrupted tyrosine catabolism. HGD-deficient hepatocytes exhibited elevated oxidative stress accompanied by impaired mitochondrial respiration and a pseudohypoxic metabolic adaptation toward increased glycolytic dependency. Despite this glycolytic shift, the cells displayed reduced anabolic and translational activity alongside attenuated proliferation, consistent with a chronic stress-adaptive survival state rather than a proliferative metabolic phenotype. This study provides systems-level insights into the pathophysiology of AKU and establishes a versatile platform for mechanistic and therapeutic investigation.

cell biology↗
bioRxiv2026

The circadian clock regulates KCNH2 (hERG) promoter activity through daily temperature rhythms.

Background: KCNH2 encodes Kv11.1 channel proteins that conduct the rapidly activating delayed-rectifier K+ current (IKr), which is critical for cardiac repolarization. KCNH2 encodes two functional isoforms, Kv11.1a and Kv11.1b, via alternative transcription start sites. Kv11.1a is the principal determinant of cardiac IKr and ventricular repolarization. The circadian clock, a transcriptional-translational feedback loop that cycles with a period of ~24 hours and drives the circadian expression of many genes, including Kcnh2 in the mouse heart. Because daily body temperature rhythms provide a systemic signal that synchronizes cardiac circadian clocks, we tested whether physiological temperature cycles drive the circadian promoter activity of the cloned human KCNH2 (hKCNH2) promoter. Hypothesis: hKCNH2 is a direct transcriptional target of the circadian clock, with temperature driving its promoter activity through BMAL1:CLOCK acting at a conserved tandem E-box. Methods: We cloned the conserved proximal promoter of KCNH2 (-1631 bp upstream of Kv11.1a exon 1) to generate hKCNH2 promoter luciferase reporter constructs. Constructs were transfected into C2C12 myotubes and synchronized by serum shock (static 37{degrees}C) or temperature cycling (36.5-38.5{degrees}C). Bioluminescence was recorded and assessed for period, phase, and amplitude. BMAL1:CLOCK dependence was tested via dominant-negative CLOCK{Delta}19 co-expression. Results: Temperature cycling did not exhibit the rapid damping characteristic of serum-shock-synchronized oscillations, consistent with continuous entrainment by an external zeitgeber rather than a free-running oscillator. Deletion analysis identified a conserved tandem E-box required for oscillation under both serum shock and temperature cycling, and for BMAL1:CLOCK-dependent transactivation (1.75 {+/-} 0.21 vs. 0.86 {+/-} 0.06 RLU, p = 0.0038). CLOCK{Delta}19 reduced hKCNH2 promoter amplitude under temperature cycling without altering period. Conclusion: The circadian clock regulates KCNH2 promoter activity through daily temperature rhythms.

cell biology↗