Dingxun Wang

Mechanosensing and mechanotransduction are essential for all living cells. In mammals, Piezo1 and Piezo2 are two mechanically activated cation channels that serve as mechanosensors for a variety of physiological and pathological processes, ranging from touch sensing to sickle cell disease. These two channels are well evolutionarily conserved, and orthologous genes can be traced back to the origin of vertebrates, which underwent whole-genome duplications (WGDs). The number of paralogous genes originating from the vertebrate WGD varies across gene families. Thus, whether there are more PIEZO paralogous genes in vertebrates remains understudied. Here, we identified piezo3, a new paralog of the piezo gene family, and analyzed its evolutionary history using phylogenetic and synteny analyses. The piezo3 gene is present in most vertebrate lineages but absent in birds and most mammals, likely due to nonfunctionalization after WGDs. In addition, we demonstrated that this channel could mediate calcium flux in response to mechanical stimuli in HEK293T cells, suggesting that Piezo3 exhibits PIEZO1/2-like activation and conduction channel functions. Our CRISPR mutation analysis revealed that the zebrafish piezo3 gene is not developmentally essential, possibly because its expression overlaps with other PIEZO channels. Mutant zebrafish showed elevated sensitivity to mechanical force and increased locomotor activity under (photopic) light illumination. Our results suggest that this new mechanical-sensing Piezo channel is widespread in vertebrates and may be critical for vertebrate adaptation by modulating mechanical sensing and light responses during evolution.

Voltage-gated potassium channels (Kv) are a large family of potassium channels composed of 40 members across 12 subtypes. The KCNH genes encode three subfamilies of voltage-gated potassium channels: Kv10 (EAG, ether à go go), Kv11 (ERG, EAG-related gene), and Kv12 (ELK, EAG-like K). Kv channels play prominent roles in neuronal and cardiovascular systems. Mutations in Kv channels have been linked to many human diseases, such as epilepsy, heart arrhythmias, and cancers. Significant progress has been made in understanding protein structures, physiological functions, and pharmacological modifiers. However, the evolutionary history and gene expression of vertebrate KCNH genes during embryonic development remain largely unknown. We systematically identified and cloned 14 kcnh genes in zebrafish. Then, we examined the vertebrate KCNH channel evolution by phylogenetic and syntenic analyses. Our data reveal that the three subtypes of the KCNH gene family had already evolved in invertebrates, long before the emergence of vertebrates. The number of vertebrate KCNH genes increased, most likely due to whole-genome duplications (WGDs). In addition, we examined zebrafish kcnh gene expression during early embryogenesis by in situ hybridization. Each subgroup’s genes showed similar but distinct gene expression domains with some exceptions. Most of them were expressed in neural tissues. Notably, kcnh6a showed robust expression in the developing heart, consistent with its conserved role in cardiac repolarization. Additionally, a few kcnh genes were transiently expressed in non-neural tissues, such as somites and the notochord, suggesting they may have a unique role in embryonic development. Our phylogenetic and developmental analyses of KCNH channels shed light on their evolutionary history and potential roles during embryogenesis, in line with their physiological functions and human channelopathies.

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive sarcomas with poor prognosis and a strong tendency for metastasis and relapse. Surgical removal remains the mainstay of treatment but is frequently ineffective or impractical. Currently, no effective targeted therapy exists for this type of malignancy. PRMT5 has recently emerged as a promising therapeutic target in various human cancers with MTAP loss, which results in cancer cell dependency on PRMT5 activity. The frequent loss of MTAP in MPNSTs suggests that PRMT5 inhibition is a promising therapeutic option and enables the stratification of cancer patients with few treatment options. We first examined human nerve sheath tumor samples and found that increased PRMT5 expression and activity correlated with MTAP loss in 86.8% (33/38) of MPNSTs and in atypical neurofibromatous neoplasm with uncertain biologic potential (ANNUBP) (5/5). When PRMT5 activity was inhibited genetically and chemically, the cell growth of MTAP-deficient MPNST cell lines was suppressed, but not that of MTAP-proficient MPNST cell lines. Moreover, in the PRMT5-inhibited MTAP-deficient MPNST cell lines, spontaneous DNA damage accumulation was observed following G2/M cell cycle arrest. The DNA replication stress marker RPA32 decreased, and CHK1 was activated early after PRMT5 knockdown, likely contributing to the accumulation of DNA damage. Additionally, we combined PRMT5 inhibition with the DNA-damaging agents doxorubicin and gemcitabine, resulting in synergistic effects and increased cancer cell death in MTAP-deficient MPNST cell lines. Together, these findings identify PRMT5 as a compelling therapeutic target in MTAP-deficient MPNSTs. This PRMT5 inhibition strategy has strong translational potential for MPNSTs.

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive sarcomas with poor prognosis and a strong tendency for metastasis and relapse. Surgical removal remains the mainstay of treatment but is frequently ineffective or impractical. Currently, no effective targeted therapy exists for this type of malignancy. PRMT5 has recently emerged as a promising therapeutic target in various human cancers with MTAP loss, which results in cancer cell dependency on PRMT5 activity. The frequent loss of MTAP in MPNSTs suggests that PRMT5 inhibition is a promising therapeutic option and enables the stratification of cancer patients with few treatment options. We first examined human nerve sheath tumor samples and found that increased PRMT5 expression and activity correlated with MTAP loss in 86.8% (33/38) of MPNSTs and in atypical neurofibromatous neoplasm with uncertain biologic potential (ANNUBP) (5/5). When PRMT5 activity was inhibited genetically and chemically, the cell growth of MTAP-deficient MPNST cell lines was suppressed, but not that of MTAP-proficient MPNST cell lines. Moreover, in the PRMT5-inhibited MTAP-deficient MPNST cell lines, spontaneous DNA damage accumulation was observed following G2/M cell cycle arrest. The DNA replication stress marker RPA32 decreased, and CHK1 was activated early after PRMT5 knockdown, likely contributing to the accumulation of DNA damage. In addition, we combined PRMT5 inhibition with the DNA-damaging agents doxorubicin and gemcitabine, resulting in synergistic effects and increased cancer cell death in MTAP-deficient MPNST cell lines. Together, these findings identify PRMT5 as a compelling therapeutic target in MTAP-deficient MPNSTs. This PRMT5 inhibition strategy has strong translational potential for MPNSTs. GRAPHICAL

Potassium channels control membrane potential and various physiological processes, including cell migration. However, the specific role of inwardly rectifying potassium channels in immune cell chemotaxis remains unknown. Here, we demonstrate that inwardly rectifying potassium channels, particularly Kir7.1 (Kcnj13), maintain the resting membrane potential and are crucial for directional sensing during neutrophil chemotaxis. Blocking or knocking out Kir in neutrophils disrupted their ability to sense direction toward different chemoattractants in multiple models. Using genetically encoded voltage indicators, we observed oscillating hyperpolarization during tail retraction in zebrafish neutrophils, with Kir7.1 required for depolarization toward the chemokine source. Focal depolarization via optogenetics biased pseudopod selection and triggered new protrusions, which depended on Gα signaling. Global hyperpolarization caused neutrophils to stall migration. Additionally, Kir influences GPCR signaling activation in dHL-60 cells. This research introduces membrane potential as a key component of the complex feedforward mechanism that links the adaptive and excitable networks necessary to guide immune cells in challenging tissue environments.