Kugoh, H. | bioRxiv Science

bioRxiv2021

Endothelial metastasis-associated protein 1 (MTA1) is an essential molecule for angiogenesis

Our previous study revealed that metastasis-associated protein 1 (MTA1), expressed in endothelial cells acts as a factor promoting tube formation. In this study, we aimed to clarify the importance of MTA1 in tube formation using MTA1-knockout endothelial cells (MTA1-KO MSS31 cells). Tube formation was strongly suppressed in MTA1-KO MSS31 cells, whereas MTA1-overexpressed MTA1-KO MSS31 cells regained the ability to form tube-like structures. Furthermore, MTA1-KO MSS31 cells showed higher phosphorylation of non-muscle myosin heavy chain IIa (NMIIa), which resulted in suppression of tube formation; this was attributed to a decrease of MTA1- S100 calcium-binding protein A4 (S100A4) complex formation. Moreover, inhibition of tube formation in MTA1-KO MSS31 cells could not be rescued by stimulation with vascular endothelial growth factor (VEGF). These results demonstrated that MTA1 is an essential molecule for angiogenesis, and that it may be involved in different steps of the angiogenic process compared to the VEGF-VEGF receptor 2 (VEGFR2) pathway. Our findings showed that endothelial MTA1 and its pathway are promising targets for inhibiting tumor angiogenesis, supporting the development of MTA1-based anti-angiogenic therapies.

cell biology↗

bioRxiv2019

PITX1 protein interacts with ZCCHC10 to regulate hTERT mRNA transcription

Telomerase is a ribonucleoprotein ribonucleic enzyme that is essential for cellular immortalization via elongation of telomere repeat sequences at the end of chromosomes. Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase holoenzyme, is a key regulator of telomerase activity. Telomerase activity, which has been detected in the majority of cancer cells, is accompanied by hTERT expression, resulting in continuous cell division that is a crucial factor for malignant transformation. Thus, hTERT is an attractive target for cancer-specific treatments. We previously reported that pared-like homeodomain 1 (PITX1) is a negative regulator of hTERT through direct binding to the hTERT promoter. However, the mechanism by which the function of PITX1 contributes to transcriptional silencing of the hTERT gene remains to be clarified. Here, we show that PITX1 and zinc finger CCHC-type containing 10 (ZCCHC10) proteins cooperate to facilitate the transcriptional regulation of the hTERT gene by functional studies via FLAG pull-down assay. Co-expression of PITX1 and ZCCHC10 resulted in inhibition of hTERT transcription, in melanoma cell lines, whereas mutate-deletion of homeodomain in PITX1 that interact with ZCCHC10 did not induce similar phenotypes. In addition, ZCCHC10 expression levels showed marked decrease in the majority of melanoma cell lines and tissues. Taken together, these results suggest that ZCCHC10-PITX1 complex is a new functional unit that suppresses hTERT transcription, and plays a crucial role in cancer development through regulation of telomerase activity.

cancer biology↗