Homeobox containing 1, also known as homeobox telomere-binding protein 1 (HOT1), is a protein that in humans is encoded by the HMBOX1 gene.[5] HMBOX1 directly binds to the double-stranded repeat sequence of telomeres.[6][7]
HMBOX1 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | HMBOX1, HNF1LA, HOT1, PBHNF, homeobox containing 1, TAH1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | MGI: 2445066 HomoloGene: 11589 GeneCards: HMBOX1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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HMBOX1 has originally been identified to associate with telomeric chromatin in telomerase-positive cancer cells and cancer cells that maintain their telomeres based on the Alternative Lengthening of Telomeres (ALT) mechanism by the 'reverse ChIP' technique PICh (Proteomics of Isolated Chromatin segments).[6] Subsequently, direct binding to telomeric DNA was demonstrated through a co-crystal structure of the DNA-binding domain of HMBOX1 with telomeric DNA.[7] Loss-of-function and gain-of-function experiments classify HMBOX1 as a positive regulator of telomere length.[7][8] HMBOX1 had originally been described as a transcriptional repressor based on reporter gene assays,[9] but genome-wide approaches using RNA-seq and ChIP-seq see little to no such effect at least in several cancer cell lines.[10]