TET2 mutation as prototypic clonal hematopoiesis lesion

Abstract

Loss of function TET2 mutation (TET2^MT) is one of the most frequently observed lesions in clonal hematopoiesis (CH). TET2 a member TET-dioxygenase family of enzymes that along with TET1 and TET3, progressively oxidize 5-methyl cytosine (mC) resulting in regulated demethylation of promoter, enhancer and silencer elements of the genome. This process is critical for efficient transcription that determine cell lineage fate, proliferation and survival and the maintenance of the genomic fidelity with aging of the organism. Partial or complete loss-of-function TET2 mutations create regional and contextual DNA hypermethylation leading to gene silencing or activation that result in skewed myeloid differentiation and clonal expansion. In addition to myeloid skewing, loss of TET2 creates differentiation block and provides proliferative advantage to hematopoietic stem and progenitor cells (HSPCs). TET2^MT is a prototypical lesion in CH, since the mutant clones dominate during stress hematopoiesis and often associates with evolution of myeloid malignancies. TET2^MT clones has unique privilege to create and persist in pro-inflammatory milieu. Despite extensive knowledge regarding biochemical mechanisms underlying distorted myeloid differentiation, and enhanced self-replication of TET2^MT HSPC, the mechanistic link of various pathogenesis associated with TET2 loss in CHIP is less understood. Here we review the recent development in TET2 biology and its probable mechanistic link in CH with aging and inflammation. We also explored the therapeutic strategies of targeting TET2^MT associated CHIP and the utility of targeting TET2 in normal hematopoiesis and somatic cell reprograming. We explore the biochemical mechanisms and candidate therapies that emerged in last decade of research.

Keywords: Aging; CHIP; Epigenetics; Inflammation; TET2; Targeting; Therapeutic development.