Day 17 (1q12-1q21.1): RBM8A – the cell’s memory of the splicing process

 

https://commons.wikimedia.org/wiki/File:X-ray_of_arm_showing_absent_radius_and_radially_deviated_hand,_caused_by_Thrombocytopenia_and_Absent_Radius_syndrome.jpg

https://commons.wikimedia.org/wiki/File:X-ray_of_arm_showing_absent_radius_and_radially_deviated_hand,_caused_by_Thrombocytopenia_and_Absent_Radius_syndrome.jpg

Day 17 starts with the constitutive heterochromatin of Day 16, then continues with 23 protein-coding genes, including RBM8A (RNA-binding protein 8A). RBM8A encodes an RNA-binding protein. RNA-binding proteins can regulate the expression of genes by influencing the rate that messenger RNAs made from genes are degraded and translated into proteins.

RBM8A protein plays a role in the fascinating process of nonsense-mediated decay: cells detect mRNAs with premature stop codons (due to mutatations or mistakes in splicing) and destroy the transcript because making a partial protein could be more toxic than no protein at all.

The cell detects premature stop codons by seeing if there was an intron after the stop codon. In order to know this, it has to have a memory of splicing events while the ribosome is translating the mRNA. That memory is provided by the exon junction complex, which is stuck to the mRNA like a Post-It Note where splicing happened. RBM8A is part of that complex.

Deletion of the RBM8A causes TAR syndrome which leads to the absence of the radius bone in the forearm.

The nonsense-mediated decay system is ancient – conserved across all domains of life, so it is billions of years old.

Click here to see Day 17, jumping to RBM8A.

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