Collagen IV is an essential substance in our bodies; it helps to form the ‘glue’ between the skin and tissue underneath. Made inside fat cells, or adipocytes, collagen IV is usually pumped out into the surrounding space between cells. But in these adipocytes from a fruit fly (pictured with their nuclei stained blue), the process has gone horribly wrong. Healthy adipocytes bring chemicals in through their cell membranes (shown in purple) by a process called endocytosis. When researchers blocked endocytosis in these adipocytes there was a surprising knock-on effect – collagen IV was trapped inside the cells, forming lumpy aggregates (green). It appears that some cells use the same machinery to control both incoming and outgoing chemical traffic. Investigating this may help to understand how collagen IV sometimes builds up in human tissues leading to fibrosis, a major cause of chronic diseases.
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