Growth arrest-specific 5 is a non-protein coding RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 that in humans is encoded by the GAS5 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

GAS5 noncoding RNA, which accumulates in growth arrested cells, acts as a decoy hormone response element

Hormone response element

A hormone response element is a response element for hormones, a short sequence of DNA within the promoter of a gene that is able to bind a specific hormone receptor complex and therefore regulate transcription...

 for the glucocorticoid receptor

Glucocorticoid receptor

The glucocorticoid receptor also known as NR3C1 is the receptor to which cortisol and other glucocorticoids bind....

 (GR) and hence blocks the upregulation of gene expression by activated GR.

A number of studies have linked GAS5 to apoptosis

Apoptosis

Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...

 and it may play a role in the progression of some types of cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

.

The GAS5 introns host several snoRNA

SnoRNA

Small nucleolar RNAs are a class of small RNA molecules that primarily guide chemical modifications of other RNAs, mainly ribosomal RNAs, transfer RNAs and small nuclear RNAs...

 sequences, including SNORD81

Small nucleolar RNA SNORD81

U81 is a member of the C/D class of snoRNA which contain the C and D box motifs. U81 acts as a guanine methylation guide and is found in intron 11 of the gas5 gene in mammals....

, SNORD47

Small nucleolar RNA SNORD47

SNORD47 is a non-coding RNA molecule which functions in the modification of other small nuclear RNAs . This type of modifiying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

, SNORD80

Small nucleolar RNA snR60/Z15/Z230/Z193/J17

snoRNA snR60 is a non-coding RNA molecule which functions in the modification of other small nuclear RNAs . This type of modifiying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

, SNORD79

Small nucleolar RNA SNORD79

snoRNA U79 is a non-coding RNA molecule which functions in the modification of other small nuclear RNAs . This type of modifiying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

, SNORD78

Small nucleolar RNA SNORD78

U78 belongs to the CD family of snoRNAs. It is predicted to guide 2'O-ribose methylation of the large 28S rRNA subunit at position G4593. The snoRNAs U44, U47, U74, U75, U76, U77, U79, U80 and U81, also of the C/D family, share the same host gene with U78 ....

, SNORD44

Small nucleolar RNA SNORD44

snoRNA U44 is a non-coding RNA molecule which functions in the modification of other small nuclear RNAs . This type of modifiying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

, SNORD77

Small nucleolar RNA SNORD77

U77 belongs to the C/D family of snoRNAs. It is predicted to guide 2'O-ribose methylation of large 28S rRNA subunit at position A1521. The C/D snoRNAs U44, U47, U74, U75, U76, U78, U79, U80 and U81 share the same host gene as U77 ....

, SNORD76

Small nucleolar RNA SNORD24

U24 is a member of the C/D class of snoRNA which contain the C and D box motifs. C/D box snoRNAs have been shown to act as methylation guides for a number of RNA targets. U24 is encoded within an intron of the gene for ribosomal protein L7a in mammals, chicken and Fugu...

, SNORD75

Small nucleolar RNA SNORD75

Small Nucleolar RNA SNORD75 is a non-coding RNA molecule which functions in the biogenesis of other small nuclear RNAs . This type of modifiying RNA is located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

 and SNORD74

Z18 small nucleolar RNA

Z18 small nucleolar RNA is a non-coding RNA molecule which functions in the modification of other small nuclear RNAs . This type of modifiying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis...

. These intronic sequences are more conserved than the exons of the host gene, these sorts of genes are often called "inside-out genes".