Henning Walczak | Search PubMed

PubMed2025

Linear ubiquitination prevents lipodystrophy and obesity-associated metabolic syndrome.

Adipocyte hypertrophy during obesity triggers chronic inflammation, leading to metabolic disorders. However, the role of adipocyte-specific inflammatory signaling in metabolic syndrome remains unclear. The linear ubiquitin chain assembly complex, LUBAC, is an E3-ligase that generates nondegradative linear ubiquitination (Lin-Ub). LUBAC regulates NF-κB/MAPK-driven inflammation and prevents cell death triggered by immune receptors like TNF receptor-1. Here, we show that mice lacking HOIP, the Lin-E3 ligase catalytic subunit of LUBAC, in adipocytes (HoipA-KO) display lipodystrophy and heightened susceptibility to obesity-induced metabolic syndrome, particularly metabolic dysfunction-associated steatotic liver disease (MASLD). Mechanistically, loss of HOIP attenuates TNF-induced NF-κB activation and promotes cell death in human adipocytes. Inhibiting caspase-8-mediated cell death is sufficient to prevent lipodystrophy and MASLD in HoipA-KO obese mice. HOIP expression in adipose tissue positively correlates with metabolic fitness in obese individuals. Overall, our findings reveal a fundamental developmental role for Lin-Ub in adipocytes by mitigating cell death-driven adipose tissue inflammation and protecting against obesity-related metabolic syndrome.

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PubMed2025

Functional synapses between neurons and small cell lung cancer.

Small cell lung cancer (SCLC) is a highly aggressive type of lung cancer, characterized by rapid proliferation, early metastatic spread, frequent early relapse and a high mortality rate1-3. Recent evidence has suggested that innervation has an important role in the development and progression of several types of cancer4,5. Cancer-to-neuron synapses have been reported in gliomas6,7, but whether peripheral tumours can form such structures is unknown. Here we show that SCLC cells can form functional synapses and receive synaptic transmission. Using in vivo insertional mutagenesis screening in conjunction with cross-species genomic and transcriptomic validation, we identified neuronal, synaptic and glutamatergic signalling gene sets in mouse and human SCLC. Further experiments revealed the ability of SCLC cells to form synaptic structures with neurons in vitro and in vivo. Electrophysiology and optogenetic experiments confirmed that cancer cells can receive NMDA receptor- and GABAA receptor-mediated synaptic inputs. Fitting with a potential oncogenic role of neuron-SCLC interactions, we showed that SCLC cells derive a proliferation advantage when co-cultured with vagal sensory or cortical neurons. Moreover, inhibition of glutamate signalling had therapeutic efficacy in an autochthonous mouse model of SCLC. Therefore, following malignant transformation, SCLC cells seem to hijack synaptic signalling to promote tumour growth, thereby exposing a new route for therapeutic intervention.

Animals↗