Hematopoietic stem and progenitor cells (HSPCs) rely on precisely orchestrated transcriptional networks to generate multiple blood cell lineages. Although TAF4B, a subunit of the TFIID transcription complex, is known for its roles in germline and B‑cell biology, its contribution to human hematopoiesis has remained unclear. To investigate this, the research team introduced shRNA constructs targeting TAF4B into cord blood-derived Lin⁻ CD34⁺ HSPCs and examined the consequences for colony formation and directed lineage differentiation.

In colony‑forming assays, TAF4B knockdown significantly reduced the formation of mixed‑lineage colonies (CFU‑Mix), but erythroid (BFU‑E), granulocyte-macrophage (CFU‑GM), and macrophage (CFU‑M) colonies remained at levels comparable to controls. These findings indicate that multilineage progenitors are particularly sensitive to partial TAF4B depletion, whereas more committed erythroid and myeloid progenitors preserve colony‑forming capacity despite reduced TAF4B levels.

Directed erythroid differentiation revealed a more pronounced lineage‑specific defect. Although the proportion of CD71⁺ CD235a⁺ erythroid cells was maintained, overall erythroid output decreased following TAF4B knockdown. Gene expression analyses showed a significant reduction in adult β‑globin (HBB), while fetal γ‑globin (HBG) and major erythroid regulators, including GATA1, KLF1, and BCL11A, remained largely unchanged. These results suggest that TAF4B may influence late‑stage erythroid maturation or the fetal‑to‑adult globin transition without directly altering upstream transcriptional programs.

In contrast, monocytic differentiation appeared notably resilient to TAF4B suppression. Both the frequency and total number of CD14⁺ CD11b⁺ monocytes generated in directed cultures were similar to controls, consistent with the unaltered CFU‑GM production observed, thus suggesting that monocytic lineages may be buffered by compensatory regulatory pathways that mitigate the effects of partial TAF4B reduction.

The most striking impact of TAF4B knockdown emerged during natural killer (NK) cell development. Although the total number of CD56⁺ NK cells remained unchanged, the acquisition of CD16, a hallmark of terminal NK cell maturation, was substantially impaired, as both the proportion and absolute number of CD56⁺ CD16⁺ NK cells were reduced. Corresponding gene expression analysis revealed a significant decrease in TBX21, a key transcription factor for late‑stage NK maturation, while EOMES, which regulates earlier NK developmental stages, remained stable. These findings demonstrate that TAF4B influences critical regulatory pathways governing NK terminal maturation, potentially acting upstream of TBX21.

Taken together, the study highlights how partial reduction of TAF4B affects erythroid and NK cell maturation while leaving monocytic differentiation largely intact, providing new insights into how components of the general transcription machinery contribute to human hematopoiesis. Further investigations, including chromatin profiling, single‑cell transcriptomics, and precise gene editing, will be essential to fully elucidate how TAF4B regulates β‑globin switching and the molecular events underlying NK cell terminal maturation.

• doi: 10.1016/j.bbrc.2025.153133