The Wnt signalling pathway is an ancient cell communication pathway that has important roles in development and cancer. Wnt signals elicit context-dependent transcriptional responses by stabilising a cytoplasmic effector called beta-catenin. This controls the embryonic development of tissues and organs in all animals, from the most primitive ones all the way to humans.
DNA in the nucleus is arranged into nucleosomes to produce an 11nm fibre which then intricately folds into high order assemblies. This nuclear organisation – the 3D arrangement of the genome within the nucleus – is critically linked to nuclear processes. Previously it has only been possible to analyse genome organisation across populations of cells.
The suprachiasmatic nucleus of the hypothalamus (SCN) is our principal “body clock”, controlling our daily (circadian) rhythms of physiology and behaviour that adapt us to the 24-hour cycle of day and night. It ensures that numerous other local tissue clocks distributed across the body are in tune with each other and with the external light-dark cycle.
In all present-day organisms, information encoded in DNA, the genetic material of the cell, is converted via an RNA intermediate into proteins, the molecular machines of the cell. However, evidence suggests that in a distant evolutionary past our single-celled ancestors used only RNA for both genetic information storage and metabolism. A cornerstone of this “RNA world” would have been an RNA able to replicate itself.
Mitochondria are organelles within eukaryotic cells that likely evolved from an ancient bacterium that was engulfed by a primordial eukaryote. Within mitochondria, mitochondrial ribosomes (mitoribosomes) synthesise a subset of essential proteins encoded by the mitochondrial genome.
Every minute, cells make millions of new proteins which must be transported to the correct location, folded, modified and assembled with other proteins in order to function properly. Failure at any of these maturation steps can reduce protein function and lead to the accumulation of aberrant protein intermediates, resulting in disease.
The state of the immune system has effects on brain function, but despite suggestions that immunoregulators can affect people’s mood and behaviour, we are only beginning to understand how these two major body systems interact. The contributions of a neuron to circuit activity and behaviour depend on its responsiveness to upstream inputs, and its ability to drive downstream outputs.
The spliceosome is a molecular machine, which together with RNA polymerases and ribosomes plays a critical role in basic gene expression. Research by Kiyoshi Nagai’s group in the LMB’s Structural Studies Division, has previously revealed the structure of the spliceosome in a fully active, substrate-bound state, immediately after its first catalytic reaction. The group has now expanded upon this work revealing the near-atomic level structure of the spliceosome just before mRNA formation.
Macropinocytosis, the cellular uptake of fluids from the environment, is employed by a variety of cells and requires the formation of a cup-shaped structure that protrudes from the cell’s surface and captures gulps of medium. Polymerisation of actin under the plasma membrane drives the extension of macropinocytic cups. However, until now it has been unclear how the actin forming the walls of the cup is shaped into a ring.
Ribosomes are cellular molecular machines that link amino acids together in the order specified by messenger RNA (mRNA) to make proteins. Near the end of the mRNA molecule a specific nucleotide sequence, known as a stop codon, signals for protein synthesis to terminate by recruiting release factors that release the newly made protein from the ribosome and recycle the ribosome to start another round of protein synthesis.
However, some mRNA molecules are defective.