Fig. 6: Schematic representation of the mechanistic role of PtHSF2 in P. tricornutum. | Nature Communications

Fig. 6: Schematic representation of the mechanistic role of PtHSF2 in P. tricornutum.

From: Heat shock transcription factor-mediated thermal tolerance and cell size plasticity in marine diatoms

Fig. 6

Characteristically, overexpression of PtHSF2 enhanced tolerance to high temperatures and increased cell size. RNA-seq analysis and qPCR validation revealed significant differential expression of key genes, including PtCdc45-like, Lhcx2, ABC, FAD, ATM, and ATR. CUT&Tag and CUT&Tag-qPCR analyses confirmed that PtCdc45-like, Lhcx2, and ABC are directly targeted and regulated by PtHSF2. Functional validation of PtCdc45-like demonstrated that its overexpression resulted in increased cell size and enhanced thermal tolerance. Mechanistically, PtCdc45-like likely exerts these effects by upregulating ATM and ATR expression, thereby activating DNA replication and cell cycle checkpoints to promote the repair of DNA damage caused by high temperatures. Additionally, the activation of these checkpoints induced cell cycle arrest, contributing to the observed enlargement of cells. Solid red and green arrows denote the direct targets of PtHSF2, while dashed red and green arrows indicate its indirect targets. Up- and down-regulated genes are indicated in red and green, respectively. Gray arrows indicated biological processes involved.

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