Purpose of review: Hematopoiesis is regulated by cellular factors including transcription factors, microRNAs, and epigenetic modifiers. Understanding how these factors regulate hematopoiesis is pivotal for manipulating them to achieve their desired potential. In this review, we will focus on HIV-1 Tat-interacting protein of 110 kDa (Tip110) and its regulation of hematopoiesis.
Recent findings: There are several pathways in hematopoiesis that involve Tip110 regulation. Tip110 is expressed in human cord blood CD34 cells; its expression decreases when CD34 cells begin to differentiate. Tip110 is also expressed in mouse marrow hematopoietic stem cells (HSC) and hematopoietic progenitor cells (HPC). Tip110 expression increases the number, survival, and cell cycling of HPC. Tip110-mediated regulation of hematopoiesis has been linked to its reciprocal control of proto-oncogene expression. Small noncoding microRNAs (miRs) have been shown to play important roles in regulation of hematopoiesis. miR-124 specifically targets 3'-untranslated region of Tip110 and subsequently regulates Tip110 expression in HSC.
Summary: Our recent findings for manipulating expression levels of Tip110 in HSC and HPC could be useful for expanding HSC and HPC and for improving engraftment of cord blood HSC/HPC.