bims-raghud 2024-08-18 papers

bims-raghud

Biomed News

on RagGTPases in human diseases

Issue of 2024‒08‒18
six papers selected by
Irene Sambri, TIGEM

Inhibition of TFEB deacetylation in proximal tubular epithelial cells (TECs) promotes TFEB activation and alleviates TEC damage in diabetic kidney disease.
Emerging Role of Hippo-YAP (Yes-Associated Protein)/TAZ (Transcriptional Coactivator with PDZ-Binding Motif) Pathway Dysregulation in Renal Cell Carcinoma Progression.
TFEB activation hallmarks antigenic experience of B lymphocytes and directs germinal center fate decisions.
Mitochondrial complex I promotes kidney cancer metastasis.
mTORC1 phosphorylates and stabilizes LST2 to negatively regulate EGFR.
TFE3 fusions direct an oncogenic transcriptional program that drives OXPHOS and unveils vulnerabilities in translocation renal cell carcinoma.

FASEB J. 2024 Aug 31. 38(16): e23884

Inhibition of TFEB deacetylation in proximal tubular epithelial cells (TECs) promotes TFEB activation and alleviates TEC damage in diabetic kidney disease.

Xiaoyu Li, Yaozhi Zhang, Huixia Chen, Yang Wu, Yongming Chen, Siqiao Gong, Yonghan Liu, Huafeng Liu.

  The inhibition of the autophagolysosomal pathway mediated by transcription factor EB (TFEB) inactivation in proximal tubular epithelial cells (TECs) is a key mechanism of TEC injury in diabetic kidney disease (DKD). Acetylation is a novel mechanism that regulates TFEB activity. However, there are currently no studies on whether the adjustment of the acetylation level of TFEB can reduce the damage of diabetic TECs. In this study, we investigated the effect of Trichostatin A (TSA), a typical deacetylase inhibitor, on TFEB activity and damage to TECs in both in vivo and in vitro models of DKD. Here, we show that TSA treatment can alleviate the pathological damage of glomeruli and renal tubules and delay the DKD progression in db/db mice, which is associated with the increased expression of TFEB and its downstream genes. In vitro studies further confirmed that TSA treatment can upregulate the acetylation level of TFEB, promote its nuclear translocation, and activate the expression of its downstream genes, thereby reducing the apoptosis level of TECs. TFEB deletion or HDAC6 knockdown in TECs can counteract the activation effect of TSA on autophagolysosomal pathway. We also found that TFEB enhances the transcription of Tfeb through binding to its promoter and promotes its own expression. Our results, thus, provide a novel therapeutic mechanism for DKD that the alleviation of TEC damage by activating the autophagic lysosomal pathway through upregulating TFEB acetylation can, thus, delay DKD progression.

Keywords:  Trichostatin A; acetylation; diabetic kidney disease; transcription factor EB; tubular epithelial cells

DOI:  https://doi.org/10.1096/fj.202302634R
Cancers (Basel). 2024 Aug 03. pii: 2758. [Epub ahead of print]16(15):

Emerging Role of Hippo-YAP (Yes-Associated Protein)/TAZ (Transcriptional Coactivator with PDZ-Binding Motif) Pathway Dysregulation in Renal Cell Carcinoma Progression.

Varsha Mondal, Paul J Higgins, Rohan Samarakoon.

  Although Hippo-YAP/TAZ pathway involvement has been extensively studied in the development of certain cancers, the involvement of this cascade in kidney cancer progression is not well-established and, therefore, will be the focus of this review. Renal cell carcinoma (RCC), the most prevalent kidney tumor subtype, has a poor prognosis and a high mortality rate. Core Hippo signaling inactivation (e.g., LATS kinases) leads to the nuclear translocation of YAP/TAZ where they bind to co-transcriptional factors such as TEAD promoting transcription of genes which initiates various fibrotic and neoplastic diseases. Loss of expression of LATS1/2 kinase and activation of YAP/TAZ correlates with poor survival in RCC patients. Renal-specific ablation of LATS1 in mice leads to the spontaneous development of several subtypes of RCC in a YAP/TAZ-dependent manner. Genetic and pharmacological inactivation of YAP/TAZ reverses the oncogenic potential in LATS1-deficient mice, highlighting the therapeutic benefit of network targeting in RCC. Here, we explore the unique upstream controls and downstream consequences of the Hippo-YAP/TAZ pathway deregulation in renal cancer. This review critically evaluates the current literature on the role of the Hippo pathway in RCC progression and highlights the recent scientific evidence designating YAP/TAZ as novel therapeutic targets against kidney cancer.

Keywords:  LATS1/2; MST; TEAD; YAP/TAZ; clear cell RCC; core hippo pathway; growth factors; kidney cancer; tumorigenesis

DOI:  https://doi.org/10.3390/cancers16152758
Nat Commun. 2024 Aug 14. 15(1): 6971

TFEB activation hallmarks antigenic experience of B lymphocytes and directs germinal center fate decisions.

Matthias Münchhalfen, Richard Görg, Michael Haberl, Jens Löber, Jakob Willenbrink, Laura Schwarzt, Charlotte Höltermann, Christian Ickes, Leonard Hammermann, Jan Kus, Björn Chapuy, Andrea Ballabio, Sybille D Reichardt, Alexander Flügel, Niklas Engels, Jürgen Wienands.

Ligation of the B cell antigen receptor (BCR) initiates humoral immunity. However, BCR signaling without appropriate co-stimulation commits B cells to death rather than to differentiation into immune effector cells. How BCR activation depletes potentially autoreactive B cells while simultaneously primes for receiving rescue and differentiation signals from cognate T lymphocytes remains unknown. Here, we use a mass spectrometry-based proteomic approach to identify cytosolic/nuclear shuttling elements and uncover transcription factor EB (TFEB) as a central BCR-controlled rheostat that drives activation-induced apoptosis, and concurrently promotes the reception of co-stimulatory rescue signals by supporting B cell migration and antigen presentation. CD40 co-stimulation prevents TFEB-driven cell death, while enhancing and prolonging TFEB's nuclear residency, which hallmarks antigenic experience also of memory B cells. In mice, TFEB shapes the transcriptional landscape of germinal center B cells. Within the germinal center, TFEB facilitates the dark zone entry of light-zone-residing centrocytes through regulation of chemokine receptors and, by balancing the expression of Bcl-2/BH3-only family members, integrates antigen-induced apoptosis with T cell-provided CD40 survival signals. Thus, TFEB reprograms antigen-primed germinal center B cells for cell fate decisions.

DOI: https://doi.org/10.1038/s41467-024-51166-3
Nature. 2024 Aug 14.

Mitochondrial complex I promotes kidney cancer metastasis.

Divya Bezwada, Luigi Perelli, Nicholas P Lesner, Ling Cai, Bailey Brooks, Zheng Wu, Hieu S Vu, Varun Sondhi, Daniel L Cassidy, Stacy Kasitinon, Sherwin Kelekar, Feng Cai, Arin B Aurora, McKenzie Patrick, Ashley Leach, Rashed Ghandour, Yuanyuan Zhang, Duyen Do, Phyllis McDaniel, Jessica Sudderth, Dennis Dumesnil, Sara House, Tracy Rosales, Alan M Poole, Yair Lotan, Solomon Woldu, Aditya Bagrodia, Xiaosong Meng, Jeffrey A Cadeddu, Prashant Mishra, Javier Garcia-Bermudez, Ivan Pedrosa, Payal Kapur, Kevin D Courtney, Craig R Malloy, Giannicola Genovese, Vitaly Margulis, Ralph J DeBerardinis.

Most kidney cancers are metabolically dysfunctional1-4, but how this dysfunction affects cancer progression in humans is unknown. We infused 13C-labelled nutrients in over 80 patients with kidney cancer during surgical tumour resection. Labelling from [U-13C]glucose varies across subtypes, indicating that the kidney environment alone cannot account for all tumour metabolic reprogramming. Compared with the adjacent kidney, clear cell renal cell carcinomas (ccRCCs) display suppressed labelling of tricarboxylic acid (TCA) cycle intermediates in vivo and in ex vivo organotypic cultures, indicating that suppressed labelling is tissue intrinsic. [1,2-13C]acetate and [U-13C]glutamine infusions in patients, coupled with measurements of respiration in isolated human kidney and tumour mitochondria, reveal lower electron transport chain activity in ccRCCs that contributes to decreased oxidative and enhanced reductive TCA cycle labelling. However, ccRCC metastases unexpectedly have enhanced TCA cycle labelling compared with that of primary ccRCCs, indicating a divergent metabolic program during metastasis in patients. In mice, stimulating respiration or NADH recycling in kidney cancer cells is sufficient to promote metastasis, whereas inhibiting electron transport chain complex I decreases metastasis. These findings in humans and mice indicate that metabolic properties and liabilities evolve during kidney cancer progression, and that mitochondrial function is limiting for metastasis but not growth at the original site.

DOI: https://doi.org/10.1038/s41586-024-07812-3
Proc Natl Acad Sci U S A. 2024 Aug 20. 121(34): e2405959121

mTORC1 phosphorylates and stabilizes LST2 to negatively regulate EGFR.

Stefania Battaglioni, Louise-Marie Craigie, Sofia Filippini, Timm Maier, Michael N Hall.

  TORC1 (target of rapamycin complex 1) is a highly conserved protein kinase that plays a central role in regulating cell growth. Given the role of mammalian TORC1 (mTORC1) in metabolism and disease, understanding mTORC1 downstream signaling and feedback loops is important. mTORC1 recognizes some of its substrates via a five amino acid binding sequence called the TOR signaling (TOS) motif. mTORC1 binding to a TOS motif facilitates phosphorylation of a distinct, distal site. Here, we show that LST2, also known as ZFYVE28, contains a TOS motif (amino acids 401 to 405) and is directly phosphorylated by mTORC1 at serine 670 (S670). mTORC1-mediated S670 phosphorylation promotes LST2 monoubiquitination on lysine 87 (K87). Monoubiquitinated LST2 is stable and displays a broad reticular distribution. When mTORC1 is inactive, unphosphorylated LST2 is degraded by the proteasome. The absence of LST2 enhances EGFR (epidermal growth factor receptor) signaling. We propose that mTORC1 negatively feeds back on its upstream receptor EGFR via LST2.

Keywords:  LST2; TOS motif; mTOR signaling; negative feedback; phosphorylation substrate

DOI:  https://doi.org/10.1073/pnas.2405959121
bioRxiv. 2024 Aug 10. pii: 2024.08.09.607311. [Epub ahead of print]

TFE3 fusions direct an oncogenic transcriptional program that drives OXPHOS and unveils vulnerabilities in translocation renal cell carcinoma.

Jiao Li, Kaimeng Huang, Fiona McBride, Ananthan Sadagopan, Daniel S Gallant, Meha Thakur, Prateek Khanna, Bingchen Li, Maolin Ge, Cary N Weiss, Mingkee Achom, Qingru Xu, Kun Huang, Birgitta A Ryback, Miao Gui, Liron Bar-Peled, Srinivas R Viswanathan.

Translocation renal cell carcinoma (tRCC) is an aggressive subtype of kidney cancer driven by TFE3 gene fusions, which act via poorly characterized downstream mechanisms. Here we report that TFE3 fusions transcriptionally rewire tRCCs toward oxidative phosphorylation (OXPHOS), contrasting with the highly glycolytic metabolism of most other renal cancers. This TFE3 fusion-driven OXPHOS program, together with heightened glutathione levels found in renal cancers, renders tRCCs sensitive to reductive stress - a metabolic stress state induced by an imbalance of reducing equivalents. Genome-scale CRISPR screening identifies tRCC-selective vulnerabilities linked to this metabolic state, including EGLN1 , which hydroxylates HIF-1α and targets it for proteolysis. Inhibition of EGLN1 compromises tRCC cell growth by stabilizing HIF-1a and promoting metabolic reprogramming away from OXPHOS, thus representing a vulnerability to OXPHOS-dependent tRCC cells. Our study defines a distinctive tRCC-essential metabolic program driven by TFE3 fusions and nominates EGLN1 inhibition as a therapeutic strategy to counteract fusion-induced metabolic rewiring.

DOI: https://doi.org/10.1101/2024.08.09.607311