Pseudogene

About: Pseudogene is a research topic. Over the lifetime, 5528 publications have been published within this topic receiving 336634 citations. The topic is also known as: Ψ & pseudogenes.

The nature and mechanisms of human gene mutation

Abstract: There are a variety of different types of mutations in the human genome and many diverse mechanisms for their generation. Single-base-pair substitutions account for the majority of gene defects. Among them, the hypermutability of CpG dinucleotides represents the most important and frequent cause of mutation in humans. Point mutations may affect transcription and translation, as well as mRNA splicing and processing. Mutations in regulatory elements are of particular significance, since they often reveal the existence of DNA domains that are bound by regulatory proteins. Similarly, mutations that affect mRNA splicing can contribute to our understanding of the splicing mechanism. We describe mechanisms of gene deletion and the DNA sequences that may predispose to such lesions, as well as potential mechanisms underlying insertions, duplications, or inversions, with representative examples. Retrotransposition is a rare but biologically fascinating phenomenon that can lead to abnormal phenotypes if the double-stranded DNA is inserted in functionally important regions of a gene. Long interspersed repeat elements (LINEs) and Alu repetitive elements and pseudogenes have been shown to function as retrotransposons, and their de novo insertion in the genome can produce disease. The expansion of trinucleotide repeats represents a relatively novel category of mutations in humans. There is a growing list of disorders that result from an abnormal copy number of trinucleotides within the 5′ or 3′ untranslated regions, coding sequences, and introns of genes. The pathophysiologic effects of the expansion of the trinucleotide repeat are unknown. Additionally, at least one disorder is caused by expansion of a 12mer repeat (progressive myoclonus epilepsy). The study of mutations in human genes is of paramount importance in understanding the pathophysiology of hereditary disorders, in providing improved diagnostic tests, and in designing appropriate therapeutic approaches.

hsp70 genes in the human genome: Conservation and differentiation patterns predict a wide array of overlapping and specialized functions

Abstract: Hsp70 chaperones are required for key cellular processes and response to environmental changes and survival but they have not been fully characterized yet. The human hsp70-gene family has an unknown number of members (eleven counted over ten years ago); some have been described but the information is incomplete and inconsistent. A coherent body of knowledge encompassing all family components that would facilitate their study individually and as a group is lacking. Nowadays, the study of chaperone genes benefits from the availability of genome sequences and a new protocol, chaperonomics, which we applied to elucidate the human hsp70 family. We identified 47 hsp70 sequences, 17 genes and 30 pseudogenes. The genes distributed into seven evolutionarily distinct groups with distinguishable subgroups according to phylogenetic and other data, such as exon-intron and protein features. The N-terminal ATP-binding domain (ABD) was conserved at least partially in the majority of the proteins but the C-terminal substrate-binding domain (SBD) was not. Nine proteins were typical Hsp70s (65–80 kDa) with ABD and SBD, two were lighter lacking partly or totally the SBD, and six were heavier (>80 kDa) with divergent C-terminal domains. We also analyzed exon-intron features, transcriptional variants and protein structure and isoforms, and modality and patterns of expression in various tissues and developmental stages. Evolutionary analyses, including human hsp70 genes and pseudogenes, and other eukaryotic hsp70 genes, showed that six human genes encoding cytosolic Hsp70s and 27 pseudogenes originated from retro-transposition of HSPA8, a gene highly expressed in most tissues and developmental stages. The human hsp70-gene family is characterized by a remarkable evolutionary diversity that mainly resulted from multiple duplications and retrotranspositions of a highly expressed gene, HSPA8. Human Hsp70 proteins are clustered into seven evolutionary Groups, with divergent C-terminal domains likely defining their distinctive functions. These functions may also be further defined by the observed differences in the N-terminal domain.