Tissue clearing has been widely used for fluorescence imaging of fixed tissues, but its application to live tissues has been limited by toxicity. Here we develop minimally invasive optical clearing media for fluorescence imaging of live mammalian tissues. Light scattering is minimized by adding spherical polymers with low osmolarity to the extracellular medium. A clearing medium containing bovine serum albumin (SeeDB-Live) is compatible with live cells, enabling structural and functional imaging of live tissues, such as spheroids, organoids, acute brain slices and the mouse brains in vivo. SeeDB-Live minimally affects neuronal electrophysiological properties and sensory responses in vivo, and facilitates fluorescence imaging of deep cortical layers in live animals without detectable toxicity to neurons or behavior. We further demonstrate its utility to epifluorescence voltage imaging in acute brain slices and in vivo preparations. Thus, SeeDB-Live expands both the depth and modality range of fluorescence imaging in live mammalian tissues.

Local dendritic computations are thought to critically influence neuronal signaling and plasticity yet remain largely unexplored in vivo due to challenges in stably imaging small structures at ultrafast timescales. We developed a 3D real-time motion correction platform for movement-stabilized, ultrafast two-photon voltage imaging. By co-labeling CA1 pyramidal neurons with voltage and calcium indicators, we simultaneously measured somato-dendritic and electro-calcium coupling at multiple dendritic sites. We characterized isolated dendritic spikes and distance-dependent backpropagation of naturally occurring and photostimulation-evoked bursts and single spikes. We found that bursts backpropagated more reliably than single spikes, validated that somato-dendritic coupling decreases with distance from soma, and showed that electro-calcium coupling decreases with increasing branch order. These findings provide in vivo evidence for distance-dependent invasion of somatic signals into dendrites, highlight the prevalence of isolated dendritic events, and show that dendritic structure isolates voltage from calcium signaling, potentially enabling unique intracellular pathways in distal dendrites.

Understanding how behavior modulates neuronal integration is a fundamental goal in neuroscience. We combined voltage imaging with optogenetics to reveal how excitatory (E) and inhibitory (I) inputs modulate spiking output, subthreshold dynamics, and gain in genetically defined CA1 neurons. We imaged pyramidal cells (PCs), vasoactive intestinal peptide (VIP), somatostatin (SST), and parvalbumin (PV) interneurons (INs) and found that locomotion reduced firing in PCs and VIP INs while increasing activity in SST and PV INs. Prolonged optical depolarization revealed that inhibitory inputs substantially contribute to intracellular theta oscillations in PCs and VIP cells. Firing rate-laser intensity (F-I) curves revealed distinct gain modulation across cell types, with a divisive gain reduction in PC bursting during locomotion, while simple spikes are unaffected. A two-compartment model suggested that this effect results from a balanced increase in E/I input to the soma and dendrite. These findings reveal how behavior coordinates E/I signaling to modulate hippocampal computations.

Recent advances in the field of Voltage Imaging, with a special focus on new constructs and novel implementations.

Work related to place tuning, spatial navigation, orientation and direction. Mainly includes articles on connectivity in the hippocampus, retrosplenial cortex, and related areas.

Basal Ganglia Advances is a collection highlighting research on the structure, function, and disorders of the basal ganglia. It features studies spanning neuroscience, clinical insights, and computational models, serving as a hub for advances in movement, cognition, and behavior.

Advances in optical techniques and two-photon (2P) sensitive genetic voltage indicators (GEVIs) enabled in-depth voltage imaging at single-spike and single-cell resolution. These results were achieved using ASAP-type sensors, while rhodopsin-based GEVIs were mainly used with one-photon (1P) illumination. Here, we demonstrate compatibility of rhodopsin-based GEVIs with 2P illumination. We rationally engineer a fully genetically encoded, rhodopsin-based GEVI, just another voltage indicating sensor (Jarvis), and demonstrate its utility under 1P and 2P illumination. We further show 2P usability of the fluorescence resonance energy transfer (FRET)-opsin GEVIs pAce and Voltron2. Comparing 2P scanless with fast 2P scanning illumination revealed that responses are resolved with both approaches, but FRET-opsin GEVIs show improved signal-to-noise ratio (SNR) with low irradiance, inherent to scanless illumination. Utilizing Jarvis and pAce, we establish high-SNR action potential detection at kilohertz imaging rates in mouse hippocampal slices, zebrafish larvae, and the cortex of awake mice, demonstrating high-contrast action potential detection under 2P illumination with rhodopsin-based GEVIs in vitro and in vivo.

Resistance to HIF-2α inhibitors such as Belzutifan underscores the need to better understand how HIF-2α is transcriptionally regulated in clear cell renal cell carcinoma (ccRCC). Here, we uncover a cytokine-driven enhancer mechanism that sustains HIF-2α expression through the JAK1-STAT3 signaling pathway. Using a genome-wide CRISPR screen in VHL-deficient ccRCC cells, we identified SOCS3 as a key negative regulator of HIF-2α. Mechanistically, loss of SOCS3 activates JAK1-STAT3 signaling, leading to the recruitment of STAT3 to distal enhancers upstream of EPAS1 that physically loop to its promoter to drive HIF-2α transcription. This cytokine-enhancer circuit was recapitulated in ccRCC patient samples and functionally validated using CRISPR interference, which disrupted enhancer-promoter looping and reduced tumor growth in HIF-2α-dependent models. SOCS3 overexpression or pharmacologic inhibition of JAK1/STAT3 markedly suppressed HIF-2α expression and tumor progression both in vitro and in vivo. Unlike prior studies focusing on VHL/HIF occupancy-driven enhancer activation, this work defines a trans-acting cytokine-JAK1-STAT3 pathway that transcriptionally controls EPAS1. Together, these findings reveal a targetable enhancer mechanism that sustains HIF-2α expression and suggest that combined inhibition of JAK1/STAT3 and HIF-2α may overcome therapeutic resistance in kidney cancer.

Obesity is a well-established risk factor for several cancers, yet the underlying mechanisms remain incompletely understood. We hypothesized that as body size increases with obesity, organ size increases to meet metabolic demands, which in turn raises the number of cells at risk of malignant transformation. Measurement of the liver, pancreas, and kidney volumes in 747 adults across a wide BMI range (17.8 to 70.9 kg/m²) showed a strong positive correlation between BMI and organ size: a 5-unit increase in BMI was significantly associated with volume increases of 12% in the liver, 9% in both kidneys combined, and 7% in the pancreas. To determine the cellular basis of organ enlargement, kidney cell numbers were quantified using both autopsy samples (34,337 proximal tubular epithelial cells) and biopsy data from 25 individuals. The total number of cells increased substantially, indicating that approximately 61% of kidney enlargement was due to hyperplasia, with the remaining 39% increase attributable to hypertrophy. Moreover, organ volume ratios, relative to volume for normal-weight adults, strongly correlated with cancer risk across the three organs, indicating that a doubling in organ volume corresponded approximately to a doubling in cancer risk. These findings suggest a mechanism linking obesity to cancer: as body size and metabolic demands increase, organs expand primarily through hyperplasia that increases the number of cells susceptible to malignant transformation, complementing known pathways involving inflammation, hormones, and metabolic dysregulation.