Hes1, short for Hairy and enhancer of split homolog-1, is a member of the basic helix-loop-helix (bHLH) protein family. It acts as a transcription factor and is crucial in controlling cell cycle, proliferation, differentiation, survival, and apoptosis in various cell types like neuronal, endocrine, T-lymphocyte progenitors, and cancer cells. It is regulated by signaling pathways such as NOTCH, Hedgehog, and Wnt, which are often aberrant in cancer [1].

In hematopoietic stem cells (HSCs), Hes1 deficiency leads to HSC exhaustion under replicative stress. Loss of Hes1 upregulates genes in PPARγ signaling and fatty acid metabolism, and enhancing fatty acid oxidation (FAO) [2]. In human intestinal mesenchyme, HES1 -/- mutations in human embryonic stem cells (hESCs) differentiated into human intestinal organoids (HIO) showed impaired mesenchymal cell development due to down-regulation of WNT5A signaling [3].

In conclusion, Hes1 plays essential roles in multiple biological processes including stem cell maintenance, organ development, and cell fate decisions. Studies using gene knockout models, like the Hes1-deficient mouse models, have provided insights into its functions in diseases such as hematopoietic disorders and potentially in intestinal-related pathologies. These findings enhance our understanding of the biological functions of Hes1 and its significance in disease mechanisms.