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Divergent Functions of Histone Acetyltransferase Paralogs KAT2A and KAT2B in Keratinocyte Stemness and Differentiation

ABSTRACT: The mammalian epidermis undergoes constant renewal replenished by a pool of stem cells and terminal differentiation of their progeny. This is accompanied by changes in gene expression and morphology orchestrated, in part, by epigenetic modifiers. Here, we defined the role of histone acetyltransferase KAT2A in epidermal homeostasis and provided a comparative analysis that revealed key functional divergence with its paralogue, KAT2B. In contrast to KAT2B's reported function in epidermal differentiation, KAT2A supports the undifferentiated state in keratinocytes. RNA-seq analysis of KAT2A- and KAT2B- depleted keratinocytes revealed dysregulated epidermal differentiation. Depletion of KAT2A led to premature expression of epidermal differentiation genes in the absence of inductive signals, whilst loss of KAT2B delayed differentiation. KAT2A acetyltransferase activity was indispensable in regulating epidermal differentiation gene expression. The metazoan-specific N-terminus of KAT2A was also required to support its function in keratinocytes. We further showed that the interplay between KAT2A- and KAT2B- mediated regulation was important for normal cutaneous wound healing in vivo. Overall, these findings reveal a distinct mechanism in which keratinocytes utilize a pair of highly homologous histone acetyltransferases to support divergent functions in self-renewal and differentiation processes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE215244 | GEO | 2023/06/09

REPOSITORIES: GEO

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Project description:During fasting, increases in circulating pancreatic glucagon maintain glucose balance by up-regulating hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates the gluconeogenic program through the phosphorylation of CREB and via the de-phosphorylation of the CREB coactivator CRTC2. Hormonal and nutrient signals are also thought to modulate gluconeogenic genes by promoting epigenetic changes that facilitate assembly of the transcriptional machinery, although the nature of these modifications is unclear. Here we show that histone H3 acetylation at Lys 9 (H3K9Ac) is elevated over gluconeogenic genes during fasting and in diabetes, where it contributes to increases in hepatic glucose production. Following its dephosphorylation, CRTC2 promoted increases in H3K9Ac by mediating the recruitment of the lysine acetyltransferase 2B (KAT2B) and WD repeat-containing protein 5 (WDR5), a core subunit of histone methyltransferase (HMT) complexes. In turn, KAT2B and WDR5 stimulated the gluconeogenic program through a self-reinforcing cycle whereby increases in H3K9Ac further potentiated CRTC2 occupancy at CREB binding sites. Breaking this cycle, by depletion of KAT2B or WDR5, decreased gluconeogenic gene expression. As administration of a small molecule KAT2B antagonist lowered circulating blood glucose concentrations in insulin resistance, our results demonstrate how this enzyme may be a useful target for diabetes treatment. A subset of cAMP responsive genes depend on specific recruitment of KAT2B (pcaf), which in concert with WDR5 acetylates H3K9. By selectively depleting hepatocytes for KAT2B or WDR5 prior to glucagon stimulation we explore, which genes rely on KAT2B and WDR5 activity. mKAT2B or mWDR5 were knocked down in primary mouse hepatocytes using adenoviral transduction with appropriate shRNAs. Control cells were transduced with a non-specific (NS) shRNA. 72 hours post transduction some cells were stimulated for 90 minutes with 100nM glucagon and others with PBS. Total RNA was purified and subjected to micro-RNA analysis. All samples are pools of RNA from three sepearate dishes. One replicate is included for most samples.

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Divergent Functions of Histone Acetyltransferase Paralogs KAT2A and KAT2B in Keratinocyte Stemness and Differentiation

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