BREAKING NEWS: The discovery of a new organelle named the ‘hemifusome’ has broken headlines which makes one wonder whether in the next few decades, this will be on the GCSE specification. You never know…
In a groundbreaking study published in Nature Communications, researchers from the University of Virginia School of Medicine and the National Institutes of Health (NIH) have discovered a previously unknown cellular structure—the hemifusome—that could fundamentally reshape our understanding of how cells recycle their contents and sort and direct intracellular cargo which they do by helping our cells sort, recycle and discard important cargo within themselves. The new discovery could help scientists better understand what goes wrong in genetic conditions that disrupt these essential ‘housekeeping’ functions.
“This is the first time anyone has visualized this structure inside cells,” said researcher Seham Ebrahim, PhD, of UVA’s Department of Molecular Physiology. “The hemifusome is a brand-new organelle, and we believe it plays a central role in a newly discovered pathway for building multivesicular bodies—key recycling centres within our cells.”
Multivesicular bodies (MVBs) help cells sort and remove unwanted proteins. They’re critical for processes like immune function, communication between cells, and protection against neurological diseases. Until now, researchers believed that nearly all MVBs formed using a protein-based system called ESCRT. The hemifusome, however, appears to follow a completely different path—one that relies on lipid-based remodelling rather than protein scaffolding.
Hey, what is ESCRT I hear you asking (I asked this myself). ESCRT stands for endosomal sorting complex required for transport are proteins that are part of a pathway inside cells that helps sort and move other proteins. So instead of the hemifusome following this usual pathway, it has decided it has found a better path that relies on remodelling rather than scaffolding.
These vesicle-like structures appeared in a unique, partially fused membrane state and were consistently associated with tiny lipid-rich droplets known as proteolipid nanodroplets (PNDs). Surprisingly, nearly 1 in 10 vesicles observed near the cell membrane were hemifusomes—underscoring their likely biological significance.
So how exactly did they discover this organelle?
The use of cryo-electron tomography, a cutting-edge imaging technique that flash-freezes cells and captures nanometre-resolution with 3D snapshots of their internal architecture, was essential to this discovery,” said Kachar. “It allowed us to see cellular structures that were completely invisible with conventional microscopy.”
The implications of this discovery are far-reaching. By revealing a new way that cells sort and move materials internally, this work could help scientists better understand diseases where these processes go wrong, including Alzheimer’s, viral infections, and certain cancers.
The discovery of the hemifusome reminds us that even after centuries of poking, prodding, and peering into cells, biology still has a few surprises tucked away under the microscope. It’s both humbling and thrilling to think that our textbooks are still being rewritten – “the rest is still unwritten” reference – one organelle at a time. For all the aspiring medics out there (me being one of course), it is a timely reminder that science isn’t static; it’s a living, breathing pursuit of curiosity. Who knows – perhaps the next ‘new organelle’ is just waiting for a keen student to stumble upon it.
See you next week for a new question and a new answer.
