High content analysis of apical versus basolateral trafficking

蛋白质需要被送到不同的细胞隔间，以便这些不同的隔间有效地发挥作用。被称为小泡的小结构调节蛋白质的分类和运输。目前的研究计划旨在阐明囊泡如何介导极化细胞的分选和细胞内向质膜的运输。水通道蛋白是存在于细胞外膜上的透水膜通道。哺乳动物细胞表达13个水通道蛋白，其中水通道蛋白-0、-1、-2、-4、-5、-6和-8只对水渗透，水通道蛋白-3、-7、-9和-10也对尿素和甘油等小分子渗透。在细胞内，水通道蛋白可以定位于特定的膜域。例如，水通道蛋白-4(AQP4)通过并定位于基底膜(细胞的侧面和底部)，而AQP5则存在于顶端质膜(细胞顶部)。虽然AQP的表达受到限制，但调控这种转运的分子机制尚未完全阐明。我们最近展示了AQP4囊泡在细胞中的活跃运输，但令我们惊讶的是，发现囊泡并不指向它们的目的地。相反，我们发现，非极化(没有特定侧面的细胞，底部或顶部)和极化细胞的囊泡动力学相似。这表明，运输囊泡以膜为靶标并融合到适当的靶膜以定位蛋白质，这与目前的想法有很大不同。

Proteins are required to be sent to various cellular compartments in order for those distinct compartments to function efficiently. Small structures called vesicles mediate the sorting and trafficking of proteins. This current research program aims to elucidate how vesicles mediate the sorting and intracellular trafficking to the plasma membrane of polarized cells. Aquaporins are water permeable membrane channels found on the outer membrane of cells. Mammalian cells express 13 aquaporins, with aquaporins-0, -1, -2, -4, -5, -6 and -8 being permeable only to water, while aquaporins-3, -7, -9 and -10 are also permeable to small molecules such as urea and glycerol. Within cells, aquaporins can localize to specific membrane domains. For example, aquaporin-4 (AQP4) traffics and is localized to the basolateral membrane (the side and bottom of cells), while AQP5 is found on the apical plasma membrane (top of the cell). Although AQP expression is restricted, the molecular mechanisms that regulate this trafficking have not been fully elucidated. We have recently shown AQP4 vesicles are actively transported in cells, but to our surprise, found that vesicles are not directed towards their destination. Instead, we found that, vesicle dynamics in non-polarized (cells that do not have specific sides, bottom or top) and polarized cells was similar. This suggested that trafficking vesicles “sample” membrane targets and fuse to the appropriate target membrane to localize proteins, a significant shift away from current thinking.