Journal of Physiology-London最新文献

The human placenta acts as a critical barrier within the body, protecting the fetus from the potentially harmful effects of xenobiotics encountered by the mother during pregnancy. Membrane transporter proteins play a central role in this protective function, yet their expression patterns and how this changes across gestation remains poorly understood. A range of in vitro models have been generated to try and understand human placental transport processes; however, uncertainties persist regarding the developmental stage and cellular composition that each model represents. This review summarises the current understanding of membrane transporter expression in the most widely used in vitro systems, including primary placental tissue, choriocarcinoma cell lines and trophoblast stem cells. It also highlights recent advances in culturing techniques. Key gaps in the knowledge are identified, and opportunities for refining experimental approaches to study xenobiotic uptake and transport across the placenta in vitro are discussed.

Intrinsic biological rhythms regulate key physiological and behavioural processes, yet the influence of sex and age on these rhythms is not fully understood. We comprehensively examined 24 h (circadian) and >24 h (infradian; 5 and 10 day) rhythms in wheel-running and ingestive behaviours in single-housed young and middle-aged male and female mice. Circadian analysis revealed that middle-aged mice, particularly females, exhibited more precise daily rhythms and shifted a greater proportion of activity and feeding to the lights-on phase than young female mice. Middle-aged animals also ran for longer durations per day, suggesting age-related changes in activity regulation. Analysis of infradian rhythms further highlighted sex- and age-specific differences. Young female mice displayed robust 5 day rhythms in wheel-running activity, which were absent in middle-aged females. In contrast, few males (young or middle-aged) showed significant 5 day rhythms. Ten-day rhythms were most prominent in male mice, while females rarely expressed this periodicity. Physiologically, middle-aged mice lost more body weight in response to single housing, with middle-aged females being most affected. Interactions among behavioural rhythms in females also showed greater complexity, which increased with age. These findings reveal distinct sex- and age-dependent patterns in circadian and infradian rhythms as well as in physiological responses to isolation. Our work highlights the need to account for sex and age in chronobiological research, with broader implications for understanding vulnerability to age-related metabolic and behavioural disorders. KEY POINTS: Physiological findings: -Middle-aged mice lost more body weight after single housing, with females most affected. Circadian findings: -Older mice show more daytime activity. -Precision in daily rhythm differs by sex and age. -Middle-aged females showed prolonged daily wheel running. Infradian findings: -Young females had robust 5 day rhythms, absent in middle-aged females. -Some males showed 5 day rhythms, but 10 day rhythms were most prominent in males. Complexity of rhythms: -Complexity of interactions among behavioural rhythms increases with age, particularly in females.

Leucine-rich repeat-containing protein 8A (LRRC8A) is an essential subunit of the ubiquitously expressed volume-regulated anion channels (VRACs). Previous work has shown that LRRC8A is overexpressed in several cancers and is associated with poor survival outcomes. However, the underlying mechanisms remain obscure. In the present study, we investigated the role of LRRC8A and VRACs in the progression of glioblastoma (GBM), the most common and aggressive primary brain tumour. We found that, compared with healthy brain tissue, LRRC8A mRNA is significantly upregulated in surgical GBM specimens, patient-derived GBM cell lines and GBM datasets from The Cancer Genome Atlas. GBM patients in the lowest quartile of LRRC8A expression exhibited a trend toward longer survival. In patient-derived GBM cultures, RNA interference-mediated knockdown of LRRC8A or pharmacological blockade of VRAC with 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) reduced cell proliferation, lowered intracellular chloride levels and inhibited activity of mammalian target of rapamycin (mTOR) complex 2 (mTORC2). The anti-proliferative effects of LRRC8A knockdown and DIDS were non-additive, suggesting a shared mechanism. Biochemical and molecular analyses revealed that LRRC8A-containing VRACs promote GBM cell proliferation through a new non-enzymatic function of the chloride-sensitive protein kinase WNK1. Specifically, VRAC activity facilitates WNK1-dependent activation of mTORC2 and its downstream kinases AKT and SGK. In support of this model, either downregulation of WNK1 or pharmacological inhibition of mTOR or SGK/AKT suppressed GBM cell proliferation and mimicked the effect of LRRC8A knockdown. Together, these findings establish a new mTORC2-centric signalling axis for VRAC-dependent control of cellular functions and highlight several potential molecular targets for limiting GBM proliferation. KEY POINTS: Volume-regulated anion channels (VRACs) are considered to contribute to the progression of several human cancers. The essential VRAC subunit LRRC8A is significantly overexpressed in clinical specimens of glioblastoma, the most common and aggressive primary brain malignancy. RNA interference-mediated downregulation of LRRC8A reduces proliferation in patient-derived GBM cell cultures, suggesting that VRACs promote cancer cell growth. LRRC8A/VRAC-mediated effects on cell proliferation are driven by a mechanism involving the chloride-sensitive protein kinase WNK1, mTOR complex 2 and activation of downstream kinases AKT and SGK.