TPX2 prompts mitotic survival via the induction of BCL2L1 through YAP1 protein stabilization in human embryonic stem cells

Abstract

Genetic alterations have been reported for decades in most human embryonic stem cells (hESCs). Survival advantage, a typical trait acquired during long-term in vitro culture, results from the induction of BCL2L1 upon frequent copy number variation (CNV) at locus 20q11.21 and is one of the strongest candidates associated with genetic alterations that occur via escape from mitotic stress. However, the underlying mechanisms for BCL2L1 induction remain unknown. Furthermore, abnormal mitosis and the survival advantage that frequently occur in late passage are associated with the expression of BCL2L1, which is in locus 20q11.21. In this study, we demonstrated that the expression of TPX2, a gene located in 20q11.21, led to BCL2L1 induction and consequent survival traits under mitotic stress in isogenic pairs of hESCs and human induced pluripotent stem cells (iPSCs) with normal and 20q11.21 CNVs. High Aurora A kinase activity by TPX2 stabilized the YAP1 protein to induce YAP1-dependent BCL2L1 expression. A chemical inhibitor of Aurora A kinase and knockdown of YAP/TAZ significantly abrogated the high tolerance to mitotic stress through BCL2L1 suppression. These results suggest that the collective expression of TPX2 and BCL2L1 from CNV at loci 20q11.21 and a consequent increase in YAP1 signaling promote genome instability during long-term in vitro hESC culture.

TPX2 expression promotes sensitivity to dasatinib in breast cancer by activating the YAP transcriptional signaling

“…Since we also observed that the stress kinase JNK is activated upon TPX2 expression and dasatinib addition leads to a significant reduction of JNK activation (Figure 2), we deeply analyzed the impact of TPX2 expression on YAP signaling, demonstrating that TPX2 high levels promote YAP activation and this is probably the reason for dasatinib-increased sensitivity (Figure 3). Our data is concomitant with previous works showing that TPX2 expression increases YAP signaling in breast cancer cells, and this is dependent on Aurora A kinase activity [81,82,97]. Moreover, Aurora A is also known for modulating SRC through the cofactor NEDD9, affecting dasatinib response [108].…”

“…TPX2 expression leads to a reduction in the YAP inhibitory phosphorylation at Ser127, elevated levels of TAZ, and increased pSer909-LATS1 (Figure 3B), which is in accordance with the described YAP-LATS1 feedback loop [80], and with previous data showing that TPX2 also leads to YAP/TAZ stabilization and activation [81,82]. This YAP activation is reversed when dasatinib is added to TPX2-expressing cells, restoring YAP-Ser127 phosphorylation and recovering basal levels of TAZ protein (Figure 3B).…”

Sequential genetic and epigenetic alterations in human pluripotent stem cells for recurrent abnormality

“…S5F). These findings suggest that the TEAD family of TFs, consistent with YAP activation (or the loss of Hippo signaling) in culture-adapted variants (Kim et al, 2023;Price et al, 2021;Weissbein et al, 2019), may be pivotal in achieving culture-adapted phenotypes.…”

“…However, the 20q11.21 gain alone is insufficient to drive precise phenotypic changes such as 'acquired survival advantage (Jo et al, 2020).' Thus, additional cue would be necessary to induce BCL2L1 and TPX2 gene transcription, which yields clear 'acquired survival traits' through BCL-xL protein and YAP/TEAD4-dependent gene expressions, respectively (Avery et al, 2013;Cho et al, 2018;Kim et al, 2023;Nguyen et al, 2014).…”

“…However, the 20q11.21 gain alone is insufficient to drive precise phenotypic changes such as ‘acquired survival advantage (Jo et al , 2020). ’ Thus, additional cue would be necessary to induce BCL2L1 and TPX2 gene transcription, which yields clear ‘acquired survival traits’ through BCL-xL protein and YAP/TEAD4-dependent gene expressions, respectively (Avery et al ., 2013; Cho et al ., 2018; Kim et al , 2023; Nguyen et al ., 2014). Recurrent epigenetic changes, such as hyper-/hypo-methylation, parental imprinting loss, and variable X chromosome inactivation, transpire during prolonged hPSC cultures (Bar & Benvenisty, 2019).…”