Dataset Information

Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism

ABSTRACT: Accumulation of excess nutrients hampers proper liver function and is linked to non-alcoholic fatty liver disease (NAFLD) in obesity. However, the signals responsible for an impaired adaptation of hepatocytes to obesogenic dietary cues remain still largely unknown. Post-translational modification by the Small Ubiquitin-like Modifier (SUMO), allows for adynamic regulation of numerous processes including transcriptional reprograming. We demonstrate that specific SUMOylation of transcription factor Prox1 represents a nutrient-sensitive determinant of hepatic fasting metabolism. Prox1 was highly SUMOylated on lysine 556 in the liver of ad libitum and re-fed mice, while this modification was abolished upon fasting. In the context of diet-induced obesity, Prox1 SUMOylation became less sensitive to fasting cues. The hepatocyte-selective knock-in of a SUMOylation-deficient Prox1 mutant into mice fed a high-fat/high-fructose diet led to a reduction of systemic cholesterol levels, associated with the induction of liver bile acid detoxifying pathways during fasting. The generation of tools to maintain the nutrient-sensitive SUMO-switch on Prox1 may thus contribute to the development of “fasting-based” approaches for the preservation of metabolic health.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Liver

SUBMITTER: Ralf Pflanz

LAB HEAD: Stephan Herzig

PROVIDER: PXD041329 | Pride | 2023-10-24

REPOSITORIES: Pride

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Publications

Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism.

Alfaro Ana Jimena AJ Dittner Claudia C Becker Janina J Loft Anne A Mhamane Amit A Maida Adriano A Georgiadi Anastasia A Tsokanos Foivos-Filippos FF Klepac Katarina K Molocea Claudia-Eveline CE El-Merahbi Rabih R Motzler Karsten K Geppert Julia J Karikari Rhoda Anane RA Szendrödi Julia J Feuchtinger Annette A Hofmann Susanna S Karaca Samir S Urlaub Henning H Berriel Diaz Mauricio M Melchior Frauke F Herzig Stephan S

EMBO reports 20230810 10

Accumulation of excess nutrients hampers proper liver function and is linked to nonalcoholic fatty liver disease (NAFLD) in obesity. However, the signals responsible for an impaired adaptation of hepatocytes to obesogenic dietary cues remain still largely unknown. Post-translational modification by the small ubiquitin-like modifier (SUMO) allows for a dynamic regulation of numerous processes including transcriptional reprogramming. We demonstrate that specific SUMOylation of transcription factor ...[more]

PMID: 37560809

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Project description:SUMOylation is a key post-translational modification that regulates crucial cellular functions and pathological processes. It has emerged as a fundamental route that may drive different steps of human diseases. Indeed, alteration in expression or activity of one of the different SUMO pathway components may completely subvert cellular properties through fine-tuning modulation of protein(s) involved in cellular/tissue pathways, leading to alter cell proliferation, tissue regeneration, apoptosis resistance and metastatic potential. What is SUMOylation? SUMO, the Small Ubiquitin-like Modifier is a 97-amino acid protein that can be covalently attached to lysine residues on target proteins via an enzymatic cascade reaction named SUMOylation. SUMOylation requires an E1 (hetero-dimer SUMO-activating, SAE1/2), E2 (SUMO-specific conjugating, Ubc9), and, in most cases, E3 (SUMO ligase, PIASs) enzymes. There are four reported SUMO paralogues, SUMO-1 to SUMO-4, present in mammalian. All SUMO paralogues are transiently and reversibly conjugated to substrate proteins by the same enzymatic machinery but they can modify distinct targets although some proteins can be SUMOylated by either SUMO-1 or SUMO-2/3. The modifiers are expressed as immature peptides that must be cleaved prior to conjugation. This is carried out by isopeptidases, known as SENPs or SUMO specific proteases. The cleavage generates a C-terminal carboxyl group, SUMO-Gly-Gly, that will be attached via an isopeptide bond, formed between the epsilon-amino group of a Lys residue in the consensus sequence in target proteins designated ΨKxD/E, where Ψ is a large hydrophobic residue, K is the target lysine (Lys) and D/E are acidic residues. SUMO-2 and -3 have the ability to form poly-SUMO chains by covalent linkage of the C-terminal Gly-Gly residue to the internal Lys residue of their N-terminal consensus sequence motif. SUMO-1 lacks this consensus site and is unable to form chains but may act as a polySUMO chain terminator. SUMO-4 remains enigmatic since it has a restricted tissue distribution and may be unable to SUMOylate substrate proteins due to a proline residue that appears to prevent its maturation and conjugation. Heterodimeric activating enzyme E1 triggers SUMO proteins in an ATP-dependent way and transfers activated SUMO to a conserved catalytic cysteine in the conjugation enzyme E2. Ubc9, the only E2 identified delivers SUMO protein directly to the substrates. Ubc9 alone is sufficient for conjugation and ligation of the SUMO moiety to the substrates. However, the presence of SUMOylation E3 ligases, including the PIAS family, RanBP2, Polycomb2, TOPORS, TRAF7 and mitochondrial-anchored protein ligase (MPAL), stimulates the conjugation efficiency by promoting poly-SUMO chain formation and/or introducing additional SUMO acceptor sites. Despite being a covalent protein modification, SUMOylation is readily reversible due to the protease activity of SUMO specific deSUMOylation enzymes, SENPs. These enzymes exhibit specifically between the SUMO paralogues and have distinct subnuclear and subcellular localization patterns. Seven isoforms are known, including SENP1, SENP2, SENP3, SENP6 and SENP7. The SENPs contain distinct N-terminal domains that regulate their cellular localization, suggesting that each SENP may have a distinct set of substrates. In the last decade, the PTM with SUMO has emerged as a central regulatory mechanism for the control of cellular functions, including developmental and differentiation processes. However most of the studies have been performed on single eukaryotic cells from yeast to primary and model cells. The involvement of SUMOylation processes in regulating activity, function development and/or disorder in a more complex system like differentiated tissues (i.e: brain and cardiac muscle) is just emerging. At present, there is a completely lack of information regarding the functional significance of SUMOylation in skeletal muscle differentiation, regulation and diseases. Using a unique experimental Intensive Care Unit (ICU) rat model allowing long-term MV, diaphragm muscles were collected in rats control and exposed to controlled MV (CMV) for durations varying between 1 and 10 days. Endogenous SUMOylated diaphragm proteins were identified by mass-spectrometry and validated with in-vitro SUMOylation systems. Contractile, calcium regulator and mitochondrial proteins were of specific interest due to their putative involvement in VIDD. Differences were observed in the abundance of SUMOylated proteins between glycolytic and oxidative muscle fibers in control animals and high levels of SUMOylated proteins were present in all fibers during CMV. Finally, previously reported VIDD biomarkers and therapeutic targets were also identified in our datasets which may play an important role in response to muscle weakness seen in ICU patients.

Dataset Information

Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism

Publications

Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism.

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