bims-lypmec 2024-12-22 papers

Autophagy. 2024 Dec 15. 1-21

AMPK protects proximal tubular epithelial cells from lysosomal dysfunction and dedifferentiation induced by lipotoxicity.

Louise Pierre, Florian Juszczak, Valentine Delmotte, Morgane Decarnoncle, Benjamin Ledoux, Laurent Bultot, Luc Bertrand, Marielle Boonen, Patricia Renard, Thierry Arnould, Anne-Emilie Declèves.

Renal proximal tubules are a primary site of injury in metabolic diseases. In obese patients and animal models, proximal tubular epithelial cells (PTECs) display dysregulated lipid metabolism, organelle dysfunctions, and oxidative stress that contribute to interstitial inflammation, fibrosis and ultimately end-stage renal failure. Our research group previously pointed out AMP-activated protein kinase (AMPK) decline as a driver of obesity-induced renal disease. Because PTECs display high macroautophagic/autophagic activity and rely heavily on their endo-lysosomal system, we investigated the effect of lipid stress on autophagic flux and lysosomes in these cells. Using a model of highly differentiated primary PTECs challenged with palmitate, our data placed lysosomes at the cornerstone of the lipotoxic phenotype. As soon as 6 h after palmitate exposure, cells displayed impaired lysosomal acidification subsequently leading to autophagosome accumulation and activation of lysosomal biogenesis. We also showed the inability of lysosomal quality control to restore acidic pH which finally drove PTECs dedifferentiation. When palmitate-induced AMPK activity decline was prevented by AMPK activators, lysosomal acidification and the differentiation profile of PTECs were preserved. Our work provided key insights on the importance of lysosomes in PTECs homeostasis and lipotoxicity and demonstrated the potential of AMPK in protecting the organelle from lipid stress.Abbreviation: ACAC: acetyl-CoA carboxylase; ACTB: actin beta; AICAR: 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside; AMPK: AMP-activated protein kinase; APQ1: aquaporin 1 (Colton blood group); BSA: bovine serum albumin; CDH16: cadherin 16; CKD: chronic kidney disease; CTSB: cathepsin B; CTSD: cathepsin D; EPB41L5: erythrocyte membrane protein band 4.1 like 5; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; EMT: epithelial-to-mesenchymal transition; FA: fatty acid; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; GFP: green fluorescent protein; GUSB: glucuronidase beta; HEXB: hexosaminidase subunit beta; LAMP: lysosomal associated membrane protein; LD: lipid droplet; LGALS3: galectin 3; LLOMe: L-leucyl-L-leucine methyl ester hydrobromide; LMP: lysosomal membrane permeabilization; LRP2: LDL receptor related protein 2; LSD: lysosomal storage disorder; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MCOLN1: mucolipin TRP cation channel 1; MG132: N-benzyloxycarbonyl-L-leucyl-L-leucyl-L-leucinal; MmPTECs: Mus musculus (mouse) proximal tubular epithelial cells; MTORC1: mechanistic target of rapamycin kinase complex 1; OA: oleate; PA: palmitate; PIKFYVE: phosphoinositide kinase, FYVE-type zinc finger containing; PTs: proximal tubules; PTECs: proximal tubular epithelial cells; PRKAA: protein kinase AMP-activated catalytic subunit alpha; RFP: red fluorescent protein; RPS6KB: ribosomal protein S6 kinase B; SLC5A2: solute carrier family 5 member 2; SOX9: SRY-box transcription factor 9; SQSTM1: sequestosome 1; TFEB: transcription factor EB; Ub: ubiquitin; ULK1: unc-51 like autophagy activating kinase 1; VIM: vimentin.

Keywords: AMPK; Autophagy; chronic kidney disease; lipid accumulation; obesity; proximal tubules

DOI: https://doi.org/10.1080/15548627.2024.2435238

J Cell Biol. 2025 Jan 06. pii: e202412011. [Epub ahead of print]224(1):

Painting lysosomes to study organelle heterogeneity.

Di Chen, Maximiliano G Gutierrez.

Like other organelles, the heterogeneity of lysosomes within a single cell has been challenging to capture and study in detail. In this issue, Chen and Gutierrez discuss new work that tackles this question using DNA-PAINT imaging, from Lakadamyali and colleagues (https://doi.org/10.1083/jcb.202403116).

DOI: https://doi.org/10.1083/jcb.202412011

J Inorg Biochem. 2024 Dec 10. pii: S0162-0134(24)00336-2. [Epub ahead of print]264 112811

Quantification of lysosomal labile Zn2+ and monitoring of Zn2+ efflux using a small-molecule-protein hybrid fluorescent probe.

Yuyin Du, Toshiyuki Kowada, EunHye Sung, Rong Liu, Andrei Soloviev, Toshitaka Matsui, Shin Mizukami.

Lysosomal labile Zn2+ levels have been unclear. By targeting a small-molecule fluorescent Zn2+ probe, ZnDA-3H, to lysosomes via VAMP7-Halo, the lysosomal labile Zn2+ concentration was determined to be 1.9 nM in HeLa cells. Furthermore, ZnDA-3H enabled direct visualization of the Zn2+ efflux from the lysosomes to cytosol upon TRPMLs activation.

Keywords: Fluorescence imaging; HaloTag; Lysosome; Protein labeling; TRPMLs; Zinc

DOI: https://doi.org/10.1016/j.jinorgbio.2024.112811

Nature. 2024 Dec 18.

Lithocholic acid binds TULP3 to activate sirtuins and AMPK to slow down ageing.

Lithocholic acid (LCA) is accumulated in mammals during calorie restriction and it can activate AMP-activated protein kinase (AMPK) to slow down ageing1. However, the molecular details of how LCA activates AMPK and induces these biological effects are unclear. Here we show that LCA enhances the activity of sirtuins to deacetylate and subsequently inhibit vacuolar H+-ATPase (v-ATPase), which leads to AMPK activation through the lysosomal glucose-sensing pathway. Proteomics analyses of proteins that co-immunoprecipitated with sirtuin 1 (SIRT1) identified TUB-like protein 3 (TULP3), a sirtuin-interacting protein2, as a LCA receptor. In detail, LCA-bound TULP3 allosterically activates sirtuins, which then deacetylate the V1E1 subunit of v-ATPase on residues K52, K99 and K191. Muscle-specific expression of a V1E1 mutant (3KR), which mimics the deacetylated state, strongly activates AMPK and rejuvenates muscles in aged mice. In nematodes and flies, LCA depends on the TULP3 homologues tub-1 and ktub, respectively, to activate AMPK and extend lifespan and healthspan. Our study demonstrates that activation of the TULP3-sirtuin-v-ATPase-AMPK pathway by LCA reproduces the benefits of calorie restriction.

DOI: https://doi.org/10.1038/s41586-024-08348-2

Nutrients. 2024 Nov 30. pii: 4171. [Epub ahead of print]16(23):

4-Hydroxynonenal from Mitochondrial and Dietary Sources Causes Lysosomal Cell Death for Lifestyle-Related Diseases.

Tetsumori Yamashima.

Excessive consumption of vegetable oils such as soybean and canolla oils containing ω-6 polyunsaturated fatty acids is considered one of the most important epidemiological factors leading to the progression of lifestyle-related diseases. However, the underlying mechanism of vegetable-oil-induced organ damage is incompletely elucidated. Since proopiomelanocortin (POMC) neurons in the hypothalamus are related to the control of appetite and energy expenditure, their cell degeneration/death is crucial for the occurrence of obesity. In patients with metabolic syndrome, saturated fatty acids, especially palmitate, are used as an energy source. Since abundant reactive oxygen species are produced during β-oxidation of the palmitate in mitochondria, an increased amount of 4-hydroxy-2-nonenal (4-HNE) is endogenously generated from linoleic acids constituting cardiolipin of the inner membranes. Further, due to the daily intake of deep-fried foods and/or high-fat diets cooked using vegetable oils, exogenous 4-HNE being generated via lipid peroxidation during heating is incorporated into the blood. By binding with atheromatous and/or senile plaques, 4-HNE inactivates proteins via forming hybrid covalent chemical addition compounds and causes cellular dysfunction and tissue damage by the specific oxidation carbonylation. 4-HNE overstimulates G-protein-coupled receptors to induce abnormal Ca2+ mobilization and µ-calpain activation. This endogenous and exogenous 4-HNE synergically causes POMC neuronal degeneration/death and obesity. Then, the resultant metabolic disorder facilitates degeneration/death of hippocampal neurons, pancreatic β-cells, and hepatocytes. Hsp70.1 is a molecular chaperone which is crucial for both protein quality control and the stabilization of lysosomal limiting membranes. Focusing on the monkey hippocampus after ischemia, previously we formulated the 'calpain-cathepsin hypothesis', i.e., that calpain-mediated cleavage of carbonylated Hsp70.1 is a trigger of programmed neuronal death. This review aims to report that in diverse organs, lysosomal cell degeneration/death occurs via the calpain-cathepsin cascade after the consecutive injections of synthetic 4-HNE in monkeys. Presumably, 4-HNE is a root substance of lysosomal cell death for lifestyle-related diseases.

Keywords: GPR40; Hsp70.1; POMC neuron; ROS; calpain–cathepsin hypothesis; cardiolipin; lysosomal rupture

DOI: https://doi.org/10.3390/nu16234171

Can J Physiol Pharmacol. 2024 Dec 18.

Right ventricular dysfunction in preclinical models of type I and type II diabetes.

Sydney M Polson, Joshua P Thornburg, Benjamin D McNair, Christian Z Cook, Elizabeth A Straight, Kevin C Fontana, Caleb R Hoopes, Sreejayan Nair, Danielle R Bruns.

Diabetic cardiomyopathy (DCM) is a growing clinical entity and major health burden characterized by comorbid diabetes mellitus and heart failure. DCM has been commonly associated with impaired function of the left ventricle (LV); however, DCM likely also occurs in the right ventricle (RV) which has distinct physiology and pathophysiology from the LV. RV dysfunction is the strongest determinant of mortality in several clinical contexts yet remains poorly studied in diabetes. We investigated RV-specific pathophysiology using two models of diabetes- a well-characterized type 2 diabetes (T2DM) model of high-fat diet (HFD) and low-dose streptozotocin (STZ) in the mouse and a large animal model of type I diabetes in domestic pigs rendered diabetic with STZ. RV global and systolic function deteriorated with diabetes, alongside hypertrophic and fibrotic remodeling. We report evidence of impaired RV insulin sensitivity, dysregulated RV metabolic gene expression, and impaired mitochondrial dynamics. Importantly, while some of these outcomes were similar to those widely reported in the LV, others were not, such as unchanged antioxidant gene expression and regulators of fatty acid uptake. These RV-specific outcomes emphasize the importance of distinguishing the RV from the LV when studying DCM and beg the consideration of RV-specific therapies.

DOI: https://doi.org/10.1139/cjpp-2024-0195

J Clin Endocrinol Metab. 2024 Dec 06. pii: dgae844. [Epub ahead of print]

A Research Roadmap to Address the Heterogeneity of Diabetes and Advance Precision Medicine.

Paul W Franks, Stephen S Rich, Barbara Linder, Norann A Zaghloul, William T Cefalu.

The current classification of diabetes had its genesis over 85 years ago, when individuals with diabetes were first subclassified into insulin sensitive and insulin insensitive states based on the response to an oral glucose tolerance test. About 35 years later, the contemporary classifications of type 1 and type 2 diabetes were coined. Today's evidence, however, suggests that multiple etiologic and pathogenic processes lead to both type 1 and type 2 diabetes, reflecting significant heterogeneity in factors associated with initiation, progression, and clinical presentation of each disorder of glucose homeostasis. Further, the current classification fails to recognize what is currently defined as "atypical" diabetes. Heterogeneity of diabetes continues through the life-course of an individual, with modification of prognosis risk (e.g., diabetic complications) altered by genetics, life experience, comorbidities, and therapy. Understanding the sources of heterogeneity in diabetes will likely improve diagnosis, prevention, treatment, and prediction of complications in both the medical and public health settings. Such knowledge will help inform progress in the emerging era of precision diabetes medicine. This article presents NIDDK's Heterogeneity of Diabetes Initiative and a corresponding roadmap for future research in type 2 diabetes heterogeneity.

Keywords: diabetes; heterogeneity

DOI: https://doi.org/10.1210/clinem/dgae844