Cell biology
Abstract
Nuclear size is crucial for cellular functions and often increases with malignancy. Irregular nuclei are linked to aggressive tumors, driven by genetic and epigenetic changes. However, the precise mechanisms controlling nuclear size are still not fully understood. In this study, we demonstrated that cancer-associated speckle-type POZ protein (SPOP) mutations enlarged nuclear size by reducing the protein level of lamin B2 (LMNB2), a key nuclear integrity protein. Mechanistically, SPOP bound to LMNB2 and promoted its mono-ubiquitination at lysine-484, which protected it from degradation by the E3 ubiquitin ligase WD repeat domain 26. SPOP mutations disrupted this process, leading to reduced LMNB2 levels and impaired nuclear envelope (NE) integrity. This compromised NE was more vulnerable to damage from farnesyltransferase inhibitors (FTIs), causing nuclear rupture in SPOP-mutant tumor cells. This study identified SPOP as a positive regulator of nuclear size; the findings suggest tumors with SPOP mutations may be vulnerable to FTI-based therapies.
Authors
Zixi Wang, Lei Li, Qi Ye, Yuzeshi Lei, Mingming Lu, Leihong Ye, Jialu Kang, Wenyue Huang, Shan Xu, Ke Wang, Jing Liu, Yang Gao, Chenji Wang, Jian Ma, Lei Li
Abstract
The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is intimately associated with anti-tumoral immunity; however, the direct involvement of this pathway in tumor cell demise remains elusive. Here, we identified a compound dodecyl 6-hydroxy-2-naphthoate (DHN) that induces pyroptosis in melanoma cells through activating the non-canonical cGAS-STING signaling. DHN targets mitochondrial protein cyclophilin D (CypD) to induce the release of mitochondrial DNA, leading to cGAS activation and cyclic GMP-AMP (cGAMP) generation. Meanwhile, DHN-caused intracellular acidification induces PRKR-like endoplasmic reticulum kinase (PERK) activation, which promotes STING phosphorylation and polymerization in the presence of cGAMP, thereby facilitating the aggregation of STING in the endoplasmic reticulum, which serves as a platform to recruit Fas associated via death domain (FADD) and caspase-8, leading to caspase-8 activation and subsequent gasdermin E (GSDME) cleavage, which ultimately results in pyroptosis of tumor cells and tumor regression in mouse models. The occurrence of this non-canonical cGAS-STING pathway-associated pyroptosis is also observed when both cGAS is activated and intracellular pH declines. Collectively, our findings reveal a pathway that links non-canonical cGAS-STING signaling to GSDME-mediated pyroptosis, thereby offering valuable insights for tumor therapy.
Authors
Li Xiao, Yuan-li Ai, Xiang-yu Mi, Han Liang, Xiang Zhi, Liu-zheng Wu, Qi-tao Chen, Tong Gou, Chao Chen, Bo Zhou, Wen-bin Hong, Lu-ming Yao, Jun-jie Chen, Xianming Deng, Fu-nan Li, Qiao Wu, Hang-zi Chen
Abstract
Somatic mutations that increase clone fitness or resist disease are positively selected, but the impact of these mutations on organismal health remains unclear. We previously showed that Tbx3 deletion increases hepatocyte fitness within fatty livers. Here, we detected TBX3 somatic mutations in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). In mice, Tbx3 deletion protected against, whereas Tbx3 overexpression exacerbated MASLD. Tbx3 deletion reduced lipid overload by accelerating VLDL secretion. Choline deficient diets, which block VLDL secretion, abrogated this protective effect. TBX3 transcriptionally suppressed the conventional secretory pathway and cholesterol biosynthesis. Hdlbp is a direct target of TBX3 that is responsible for the altered VLDL secretion. In contrast to wild-type TBX3, the TBX3 I155S and A280S mutations found in patients failed to suppress VLDL secretion. In conclusion, TBX3 mutant clones expand during MASLD through increased lipid disposal, demonstrating that clonal fitness can benefit the liver at the cost of hyperlipidemia.
Authors
Gregory Mannino, Gabriella Quinn, Min Zhu, Zixi Wang, Xun Wang, Boyuan Li, Meng-Hsiung Hsieh, Thomas Mathews, Lauren Zacharias, Wen Gu, Purva Gopal, Natalia Brzozowska, Peter Campbell, Matt Hoare, Glen Liszczak, Hao Zhu
Abstract
Downregulation of antigen presentation and lack of immune infiltration are defining features of small cell lung cancer (SCLC) limiting response to immune checkpoint blockade (ICB). While a high MHC Class I, immune-inflamed subset benefits from ICB, underlying mechanisms of immune response in SCLC have yet to be elucidated. Here we show that in the landmark IMpower133 clinical trial high, but not low, NOTCH1 expression is significantly associated with longer survival with the addition of ICB to chemotherapy among ~80% of SCLC patients with neuroendocrine-enriched tumors (ASCL1-enriched, HR 0.39, P = 0.0012; NEUROD1-enriched, HR 0.44, P = 0.024). Overexpression or pharmacologic activation of NOTCH1 in ASCL1 and NEUROD1 SCLC cell lines dramatically upregulates MHC Class I through epigenetic reactivation of STING. In syngeneic mouse models, Notch1 activation reprograms SCLC tumors from immune-excluded to immune-inflamed, facilitating durable, complete responses with ICB combined with a STING agonist. STING1 expression is significantly enriched in high compared to low NOTCH1 expressing tumors in IMpower133 thereby validating our proposed mechanism. Our data reveal a previously undiscovered role for NOTCH1 as a critical driver of SCLC immunogenicity and a potential predictive biomarker for ICB in SCLC. NOTCH1 activation may be a therapeutic strategy to unleash anti-tumor immune responses in SCLC and other neuroendocrine cancers in which NOTCH1 is typically suppressed.
Authors
Yoo Sun Kim, Barzin Y. Nabet, Briana N. Cortez, Nai-Yun Sun, Robin Sebastian, Christophe E. Redon, Anagh Ray, Liang Liu, Afeez A. Ishola, Sarah Loew, Anjali Dhall, Sivasish Sindiri, Velimir Gayevskiy, Min-Jung Lee, Shraddha Rastogi, Nahoko Sato, Noemi Kedei, Thorkell Andresson, Sudipto Das, Suresh Kumar, Alan E. Bers, Hongliang Zhang, Alberto Chiappori, Priyanka Gopal, Mohamed E. Abazeed, Haobin Chen, Mirit I. Aladjem, Yves Pommier, Moises J. Velez, David S. Shames, Nitin Roper
Abstract
SPNS1 is a lysosomal transporter mediating the salvage of lysoglycerophospholipids, the degradative products of lysosomal phospholipid catabolism. However, a role of lysolipid transport and salvage in regulating cellular lipid homeostasis and in disease is lacking. Here, we identified two families with biallelic SPNS1 loss-of-function variants that presented primarily with progressive liver and striated muscle injury. Patient fibroblasts accumulated lysophospholipids including lysoplasmalogens and cholesterol in lysosomes with reduced cellular plasmalogens. Notably, SPNS1 deficiency resulted in reduced biogenesis of cytosolic lipid droplets containing triglycerides and cholesteryl esters. Mechanistically, we found that lysophospholipids transported by SPNS1 into the cytosol quantitatively contributed to triglyceride synthesis while lysosomal buildup of lyso-ether-phospholipid inhibited lysosomal cholesterol egress, effects that were enhanced with inhibition of mTOR. These findings support a gene-disease association and reveal connectivity between lysosomal transport of lysophospholipids and storage of reserve cellular energy as triglyceride and in the regulation of cholesterol homeostasis, processes that become important under nutrient limitation.
Authors
Menglan He, Mei Ding, Michaela Chocholouskova, Cheen Fei Chin, Martin Engvall, Helena Malmgren, Matias Wagner, Marlen C. Lauffer, Jacob Heisinger, May Christine V. Malicdan, Valérie Allamand, Madeleine Durbeej, Angelica M. Delgado-Vega, Thomas Sejersen, Ann Nordgren, Federico Torta, David L. Silver
Abstract
Oncogene expression can cause replication stress (RS), leading to DNA double-strand breaks (DSB) that require repair through pathways such as homologous recombination, non-homologous end-joining, and microhomology-mediated end-joining (MMEJ). Cyclin D1 (encoded by CCND1) is a well-known oncoprotein overexpressed in cancer; however, its role in RS is unknown. Using mantle cell lymphoma (MCL) as a naturally occurring model of cyclin D1 overexpression, we examined its impact on RS and DSB-repair mechanisms. Cyclin D1 overexpression elevated RS, increased DNA damage, especially during mitosis, and caused specific upregulation of MMEJ. Furthermore, cyclin D1 activates the polymerase theta (POLQ) transcription by binding its promoter loci, driving POLΘ-mediated MMEJ that is essential to withstand cyclin D1-induced RS. Moreover, concurrent ATM deficiency further intensifies RS, enhances POLQ expression and heightens reliance on MMEJ mediated DNA damage repair. Consequently, inhibition of POLΘ in cyclin D1-overexpressed settings further exacerbates RS, causing single-strand DNA gap accumulations and chromosomal instability, ultimately leading to apoptosis, an effect amplified in ATM-deficient cells. Targeting MMEJ via POLΘ inhibition is, therefore, an effective strategy in the context of cyclin D1 overexpression and ATM deficiency and may provide a unique therapeutic approach for treating MCL and other malignancies characterized by similar alterations.
Authors
Jithma Abeykoon, Shuhei Asada, Guangli Zhu, Yuna Hirohashi, Lisa Moreau, Divya R. Iyer, Sirisha Mukkavalli, Kalindi Parmar, Gabriella Zambrano, Lige Jiang, Dongni Yi, Michelle Manske, Kimberly Gwin, Rebecca L. King, James R. Cerhan, Xiaosheng Wu, Zhenkun Lou, Geoffrey I. Shapiro, Thomas Witzig, Alan D'Andrea
Abstract
Sustaining the strong rhythmic interactions between cellular adaptations and environmental cues has been posited as essential for preserving the physiological and behavioral alignment of an organism to the proper phase of the daily light/dark (LD) cycle. Here, we demonstrate that mitochondria and synaptic input organization of suprachiasmatic (SCN) vasoactive intestinal peptide–expressing (VIP-expressing) neurons showed circadian rhythmicity. Perturbed mitochondrial dynamics achieved by conditional ablation of the fusogenic protein mitofusin 2 (Mfn2) in VIP neurons caused disrupted circadian oscillation in mitochondria and synapses in SCN VIP neurons, leading to desynchronization of entrainment to the LD cycle in Mfn2-deficient mice that resulted in an advanced phase angle of their locomotor activity onset, alterations in core body temperature, and sleep-wake amount and architecture. Our data provide direct evidence of circadian SCN clock machinery dependence on high-performance, Mfn2-regulated mitochondrial dynamics in VIP neurons for maintaining the coherence in daily biological rhythms of the mammalian organism.
Authors
Milan Stoiljkovic, Jae Eun Song, Hee-kyung Hong, Heiko Endle, Luis Varela, Jonatas Catarino, Xiao-Bing Gao, Zong-Wu Liu, Peter Sotonyi, Sabrina Diano, Jonathan Cedernaes, Joseph T. Bass, Tamas L. Horvath
Abstract
Neuropathic pain is often comorbid with affective disorders. Synaptic plasticity in anterior cingulate cortex (ACC) is assumed to be a crucial interface for pain perception and emotion. Laminin β1 (LAMB1), a key element of extracellular matrix (ECM) in ACC was recently revealed to convey extracellular alterations to intracellular synaptic plasticity and underlie neuropathic pain and aversive emotion. However, it remains elusive what triggers activity-dependent changes of LAMB1 and ECM remodeling after nerve injury. Here, we uncovered a key role of retinoic acid (RA)/RARB signaling in neuropathic pain and associated anxiodepression via regulation of ECM homeostasis. We showed that nerve injury reduced RA level in the serum and ACC in mice and human, which brought about downregulation of its corresponding receptor, RARB. Overexpressing RARB relieved pain hypersensitivity and comorbid anxiodepression, while silencing RARB exacerbated pain sensitivity and induced anxiodepression. Further mechanistic analysis revealed that RARB maintained ECM homeostasis via transcriptional regulation of LAMB1, reversing abnormal synaptic plasticity and eventually improved neuropathic pain and aversive emotion. Taken together with our previous study, we revealed an intracellular-extracellular-intracellular feedforward regulatory network in modulating pain plasticity. Moreover, we identified cingulate RA/RARB signaling as a promising therapeutic target for treatment of neuropathic pain and associated anxiodepression.
Authors
Zhen-Zhen Li, Wan-Neng Liu, Ke-Xin Liu, Zhi-Wei Dou, Rui Zhao, Yun Chen, Meng-Meng Wang, Tao-Zhi Wang, Fei Wang, Wen-Juan Han, Wen-Guang Chu, Xing-Xing Zheng, Rou-Gang Xie, Hua Yuan, Xiao-Fan Jiang, Xiao-Long Sun, Ceng Luo, Shengxi Wu
Abstract
Cytoplasmic TDP43 mislocalization and aggregation are pathological hallmarks of amyotrophic lateral sclerosis (ALS). However, the initial cellular insults that lead to TDP43 mislocalization remain unclear. In this study, we demonstrate that Nemo-like kinase (NLK) — a proline-directed serine/threonine kinase — promotes the mislocalization of TDP43 and other RNA-binding proteins by disrupting nuclear import. NLK levels are selectively elevated in neurons exhibiting TDP43 mislocalization in ALS patient tissues, while genetic reduction of NLK reduces toxicity in human neuron models of ALS. Our findings suggest that NLK is a promising therapeutic target for neurodegenerative diseases.
Authors
Michael E. Bekier II, Emile S. Pinarbasi, Gopinath Krishnan, Jack J. Mesojedec, Madelaine Hurley, Harisankar Harikumar Sheela, Catherine A. Collins, Layla T. Ghaffari, Martina de Majo, Erik M. Ullian, Mark Koontz, Sarah Coleman, Xingli Li, Elizabeth M.H. Tank, Jacob Waksmacki, Fen-Biao Gao, Sami J. Barmada
Abstract
A subgroup (~20-30%) of castration-resistant prostate cancer (CRPC) aberrantly expresses a gastrointestinal (GI) transcriptome governed by two GI-lineage-restricted transcription factors, HNF1A and HNF4G. In this study, we found that expression of GI transcriptome in CRPC correlates with adverse clinical outcomes to androgen receptor signaling inhibitor treatment and shorter overall survival. Bromo- and extra-terminal domain inhibitors (BETi) downregulated HNF1A, HNF4G, and the GI transcriptome in multiple CRPC models, including cell lines, patient-derived organoids, and patient-derived xenografts, while AR and the androgen-dependent transcriptome were largely spared. Accordingly, BETi selectively inhibited growth of GI transcriptome-positive preclinical models of prostate cancer. Mechanistically, BETi inhibited BRD4 binding at enhancers globally, including both AR and HNF4G bound enhancers while gene expression was selectively perturbed. Restoration of HNF4G expression in the presence of BETi rescued target gene expression without rescuing BRD4 binding. This suggests that inhibition of master transcription factors expression underlies the selective transcriptional effects of BETi.
Authors
Shipra Shukla, Dan Li, Woo Hyun Cho, Dana M. Schoeps, Holly M. Nguyen, Jennifer L. Conner, Marjorie L. Roskes, Anisha Tehim, Gabriella Bayshtok, Mohini R. Pachai, Juan Yan, Nicholas A. Teri, Eric Campeau, Sarah Attwell, Patrick Trojer, Irina Ostrovnaya, Anuradha Gopalan, Ekta Khurana, Eva Corey, Ping Chi, Yu Chen
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ISSN: 0021-9738 (print), 1558-8238 (online)