Biology subjects

Ding, W.-X.

Publications and source records attributed to Ding, W.-X..

6 recordsLinked to original sources

bioRxiv2026

Myofibroblast- specific autophagy drives cyst growth in autosomal dominant polycystic kidney disease

BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst expansion, fibrosis and inflammation, leading to kidney failure. Myofibroblasts (MFs) often accumulate around cysts and promote fibrosis and cyst growth, but the cellular mechanisms enabling their pro-cystogenic activity remain unclear. Here we examined the role of autophagy within MFs, on their paracrine stimulation of cyst expansion in ADPKD. MethodsAutophagy was assessed in human ADPKD nephrectomy tissue, primary human ADPKD renal myofibroblasts (ADPKD-MFs) and male RC/RC mouse model of ADPKD using immunostaining, LC3/p62 analyses, and transmission electron microscopy. Autophagy in MFs was inhibited pharmacologically in ADPKD-MFs, or by conditional Atg5 deletion in PDGFR{beta}-expressing renal stromal cells in RC/RC (RC/RC;Atg5KO) and wild type (WT;Atg5KO) mice. ResultsIn human and mouse ADPKD kidneys, we detected LC3 puncta and autophagic organelles within SMA-expressing MFs. Inhibition of autophagy in ADPKD-MFs blocked their paracrine stimulation of cyst epithelial cell proliferation in vitro. RC/RC;Atg5KO mice showed significantly reduced cystic growth, fibrosis, MF abundance, and improved kidney function. WT;Atg5KO mice showed no abnormalities in kidney structure or function. Targeted metabolomics performed on ADPKD cyst epithelial-cell conditioned media (ADPKD-ECs CM) revealed moderate increase in lactate levels compared to normal human kidney epithelial-cell conditioned media. Furthermore, lactate treatment stabilized hypoxia-inducible factor-1 (HIF1) in myofibroblasts, while pharmacological inhibition of HIF1 reduced the expression of autophagy-related genes and impaired autophagic flux. ConclusionThese findings reveal that autophagy in MFs is a previously unrecognized driver of cyst expansion and fibrosis in ADPKD. Lactate-mediated HIF1 stabilization in MFs promotes autophagy that is required for their paracrine stimulation of cyst epithelial growth. Targeting MF-specific autophagy or its upstream regulators may represent a therapeutic strategy to limit cyst growth and fibrosis in ADPKD.

molecular biology↗

bioRxiv2025

Distinct yet Overlapping Functions of VMP1 and TMEM41B in Modulating Hepatic Lipoprotein Secretion and Autophagy in MASH

BackgroundTransmembrane protein 41B (TMEM41B) and vacuolar membrane protein 1 (VMP1) are endoplasmic reticulum (ER) scramblases that shuttle phospholipids between the inner and outer leaflets of the ER membrane. Both TMEM41B and VMP1 also play critical roles in regulating hepatic lipoprotein secretion and autophagy. Despite these similarities, whether TMEM41B and VMP1 exhibit different roles in very low-density lipoprotein (VLDL) secretion and autophagy in the pathogenesis of metabolic-associated steatotic liver disease (MASLD) remains unclear. MethodsWe created liver- and hepatocyte-specific single knockout (KO) and double knockout (DKO) mice for Tmem41b and Vmp1, as well as overexpression knock-in (KI) mice with hepatic overexpression of TMEM41B, Tmem41b KO/Vmp1 KI, and Vmp1 KO/Tmem41b KI. We conducted lipidomic, metabolomic, biochemical, and functional studies in these mice, fed either a chow diet or a MASLD diet. ResultsTMEM41B protein levels were decreased in the livers of human subjects with MASLD. The loss of hepatic Tmem41b impaired VLDL secretion, resulting in steatosis, inflammation, and fibrosis. Vmp1 KO mice exhibited similar phenotypes to DKO mice, displaying a more severe defect in VLDL secretion and greater liver injury than Tmem41b KO mice. Lipidomic analysis revealed decreased levels of phosphatidylcholine and phosphatidylethanolamine, along with increased neutral lipids in both Tmem41b KO and Vmp1 KO mice; however, these changes were generally more pronounced in Vmp1 KO mice. VMP1 and TMEM41B localized at the mitochondrial-associated membrane (MAM), and a reduction in mitochondria-ER contact was observed in hepatocytes deficient in either VMP1 or TMEM41B. Ultrastructural electron microscopy analysis showed increased accumulation of "lipid droplet" in the ER membrane bilayer and ER lumen in both Vmp1 KO and Tmem41b KO hepatocytes, with greater ER luminal "lipid droplet" accumulation in Tmem41b KO hepatocytes. The loss of hepatic Vmp1 or Tmem41b led to elevated levels of LC3-II and p62, with significantly higher levels of both markers in Vmp1 KO and DKO mouse livers compared to Tmem41b KO mouse livers. Restoring Vmp1 in Tmem41b KO mice partially improved defective VLDL secretion; however, high expression levels of VMP1 did not correct the hepatic autophagy defect. In contrast, restoring Tmem41b in Vmp1 KO mice dose-dependently enhanced both defective VLDL secretion and autophagy. Importantly, overexpression of hepatic TMEM41B mitigated diet-induced MASLD in mice. ConclusionThe loss of hepatic Vmp1 or Tmem41b decreases hepatic MAM and phospholipid content, leading to decreased VLDL secretion and promoting MASLD. While VMP1 and TMEM41B have overlapping functions, VMP1 appears to play a more critical role in regulating VLDL secretion and autophagy in mouse livers than TMEM41B.

cell biology↗

bioRxiv2025

Disruption of Mitochondrial Dynamics and Stasis Leads to Liver Injury and Tumorigenesis

Background & AimsMitochondrial dysfunction has been implicated in aging and various cancer development. As highly dynamic organelles, mitochondria constantly undergo fission, mediated by dynamin-related protein 1 (DRP1, gene name Dnm1l), and fusion, regulated by mitofusin 1 (MFN1), MFN2, and optic atrophy 1 (OPA1). However, whether and how dysregulation of mitochondria dynamics would be involved in liver pathogenesis and tumorigenesis is unknown. MethodsDnm1l Flox/Flox (Dnm1lF/F), Mfn1F/F and Mfn2F/F mice were crossed with albumin-Cre mice to generate liver-specific Dnm1l knockout (L-Dnm1l KO), L-Mfn1 KO, L-Mfn2 KO, L-Mfn1, Mfn2 double KO (DKO), and L-Mfn1, Mfn2, Dnm1l triple KO (TKO) mice. These mice were housed for various periods up to 18 months. Some mice also received hydrodynamic tail vein injections of a Sleeping Beauty transposon-transposase plasmid system with c-MYC and YAP. Blood and liver tissues were harvested for biochemical and histological analysis. ResultsL-Dnm1l KO mice had elevated serum alanine aminotransferase levels and increased hepatic fibrosis as early as two months of age. By 12 to 18 months, male L-Dnm1l KO mice developed spontaneous liver tumors, primarily hepatocellular adenomas. While female L-Dnm1l KO mice also developed liver tumors, their incidence was much lower. In contrast, neither L-Mfn1 KO nor L-Mfn2 KO mice had notable liver injury or tumorigenesis. However, a small portion of DKO mice developed tumors at 15-18 month-old. Increased DNA damage, senescence and compensatory proliferation were observed in L-Dnm1l KO mice but were less evident in L-Mfn1 KO, L-Mfn2 KO or DKO mice, indicating that mitochondrial fission is more important to maintain hepatocyte homeostasis and prevent liver tumorigenesis. Interestingly, further deletion of Mfn1 and Mfn2 in L-Dnm1l KO mice markedly abolished liver injury, fibrosis, and both spontaneous and oncogene-induced tumorigenesis. RNA sequencing and metabolomics analysis revealed significant activation of the cGAS-STING-interferon pathway and alterations in the tumor microenvironment pathways, alongside increased pyrimidine synthesis and metabolism in the livers of L-Dnm1l KO mice. Notably, the changes in gene expression and pyrimidine metabolism were considerably corrected in the TKO mice. ConclusionsMitochondrial dynamics and stability are essential for maintaining hepatic mitochondrial homeostasis and hepatocyte functions. Loss of hepatic DRP1 promotes liver tumorigenesis by increasing pyrimidine metabolism and activating the cGAS-STING-mediated innate immune response.

cell biology↗

bioRxiv2024

Late-Life Alcohol Exposure Does Not Exacerbate Age-Dependent Reductions in Mouse Spatial Memory and Brain TFEB Activity

Alcohol consumption is believed to affect Alzheimers disease (AD) risk, but the contributing mechanisms are not well understood. A potential mediator of the proposed alcohol-AD connection is autophagy, a degradation pathway that maintains organelle and protein homeostasis. Autophagy is in turn regulated through the activity of Transcription factor EB (TFEB), which promotes lysosome and autophagy-related gene expression. To explore the effect of alcohol on brain TFEB and autophagy, we exposed young (3-month old) and aged (23-month old) mice to two alcohol-feeding paradigms and assessed biochemical, transcriptome, histology, and behavioral endpoints. In young mice, alcohol decreased hippocampal nuclear TFEB staining but increased SQSTM1/p62, LC3-II, ubiquitinated proteins, and phosphorylated Tau. Hippocampal TFEB activity was lower in aged mice than it was in young mice, and Gao-binge alcohol feeding did not worsen the age-related reduction in TFEB activity. To better assess the impact of chronic alcohol exposure, we fed young and aged mice alcohol for four weeks before completing Morris Water and Barnes Maze spatial memory testing. The aged mice showed worse spatial memory on both tests. While alcohol feeding slightly impaired spatial memory in the young mice, it had little effect or even slightly improved spatial memory in the aged mice. These findings suggest that aging is a far more important driver of spatial memory impairment and reduced autophagy flux than alcohol consumption.

animal behavior and cognition↗

bioRxiv2023

Modulation of hepatic transcription factor EB activity during cold exposure uncovers direct regulation of bis(monoacylglycerol)phosphate lipids by Pla2g15

Cold exposure is a selective environmental stress that elicits a rapid metabolic shift to maintain energy homeostasis. In response to cold exposure, the liver rewires the metabolic state shifting from glucose to lipid catabolism. By probing the liver lipids in cold exposure, we observed that the lysosomal bis(monoacylglycero)phosphate (BMP) lipids were rapidly increased during cold exposure. BMP lipid changes occurred independently of lysosomal abundance but were dependent on the lysosomal transcriptional regulator transcription factor EB (TFEB). Knockdown of TFEB in hepatocytes decreased BMP lipid levels and led to cold intolerance in mice. We assessed TFEB binding sites of lysosomal genes and determined that the phospholipase Pla2g15 regulates BMP lipid catabolism. Knockdown of Pla2g15 in mice increased BMP lipid levels, ablated the cold-induced rise, and improved cold tolerance. Knockout of Pla2g15 in mice and hepatocytes led to increased BMP lipid levels, that were decreased with re-expression of Pla2g15. Mutation of the catalytic site of Pla2g15 ablated the BMP lipid breakdown. Together, our studies uncover TFEB regulation of BMP lipids through Pla2g15 catabolism.

biochemistry↗

bioRxiv2022

Obesity Disrupts Pituitary UPR Leading to NAFLD

Obesity is the major risk factor for nonalcoholic fatty liver disease (NAFLD), for which effective cures are lacking. Despite the notion that obesity is associated with aberrant levels and action of pituitary hormones that are essential for maintaining hepatic metabolic and inflammatory states, the intrinsic pituitary endocrine abnormalities and their systemic consequences are incompletely defined. By characterizing the impact of diet-induced obesity (DIO) on the pituitary whole tissue and single cell transcriptome, we demonstrated that obesity disrupts pituitary endoplasmic reticulum (ER) homeostasis by suppressing the inositol-requiring enzyme- (IRE1)-mediated adaptive unfolded protein response (UPR). We further showed that defective pituitary UPR by IRE1-deletion in the anterior pituitary strikingly augmented obesity-associated systemic metabolic abnormalities, particularly the NAFLD-associated pathologies. Conversely, enhancing the adaptive UPR in the anterior pituitary, by genetic gain-of-function of spliced X-box binding protein 1 (sXBP1), ameliorated the systemic and hepatic metabolic defects observed in mice with pituitary IRE1 deletion. Intriguingly, disruption of the UPR in the pituitary resulted in impaired hepatic UPR, which was in part due to a defective thyroid hormone receptor (THR)-mediated activation of hepatic Xbp1. In contrast, activation of the hepatic THR signaling improved obesity-associated glucose intolerance and attenuated the impaired hepatic ER homeostasis in anterior pituitary-IRE1 deficient mice. Together, our study provides the first insight into disruption of endocrine signaling-mediated inter-organ UPR communication drives obesity-associated hepatic pathologies. Unraveling these connections might uncover new therapeutic targets for NAFLD and other obesity-associated diseases.

physiology↗