Alternative splicing and its role in pathologies of the endocrine system.

Alternative splicing of pre-mRNA is a process in which noncoding regions of primary transcript are removed and coding regions are joined in different manners to produce mRNA molecules of different sequences. Alternative splicing affects nearly all human genes and is a key source of diversity of proteins coded by a relatively small number of genes. Since alternative splicing is of crucial importance for the proper functioning of cells, including those involved in hormonal signalling, aberrations of alternative splicing can lead to disruption of cellular mechanisms and in consequence result in serious endocrine pathologies. Disturbances of alternative splicing include mutations of consensus splice regulatory sites and improprieties in the action of splicing factors, the proteins involved in regulating the process. In consequence of disturbed alternative splicing, improperly spliced mRNA and protein isoforms can be produced which can lead to disruption of function of their wild type counterparts. This review aims to discuss the role of alternative splicing in pathologies of the endocrine system and gives examples that highlight the importance of this process in the proper functioning of hormones, hormone receptors and other factors involved in hormonal regulation. The examples given include endocrine-related tumours (pituitary tumours, cancers of the thyroid, prostate, ovary and breast, and insulinoma), isolated growth hormone deficiency, and Frasier syndrome. Non-endocrine pathologies in which aberrant alternative splicing of transcripts of genes involved in hormonal signalling have been detected are also described. Finally, we discuss future perspectives on the possible usage of alternative splicing in diagnostics and therapy.