During sexual reproduction of flowering plants, the pollen tube grows fast and over a long distance within the pistil to deliver two sperms for double fertilization. Growing plant cells need to communicate constantly with external stimuli as well as monitor changes in surface tension of the cell wall and plasma membrane to coordinate these signals and internal growth machinery; however, the underlying mechanisms remain largely unknown. Here we show that the rice member of plant-specific receptor-like kinase CrRLK1Ls subfamily, Ruptured Pollen tube (RUPO), is specifically expressed in rice pollen. RUPO localizes to the apical plasma membrane and vesicle of pollen tubes and is required for male gamete transmission. K+ levels were greater in pollen of homozygous CRISPR-knockout lines than wild-type plants, and pollen tubes burst shortly after germination. We reveal the interaction of RUPO with high-affinity potassium transporters. Phosphorylation of RUPO established and dephosphorylation abolished the interaction. These results have revealed the receptor-like kinase as a regulator of high-affinity potassium transporters via phosphorylation-dependent interaction, and demonstrated a novel receptor-like kinase signaling pathway that mediates K+ homeostasis required for pollen tube growth and integrity.

Epithelioid hemangioendothelioma is an extremely rare intracranial tumor and is regarded as a low-proliferation tumor. We present two cases of primary intracranial epithelioid hemangioendothelioma and give an overview of the English literature pertaining to this disease. We described two new cases of primary intracranial epithelioid hemangioendothelioma and performed a search of MEDLINE (PubMed) using the words "epithelioid hemangioendothelioma". Only cases in the English language that were intracranially located and contained clinical information pertinent to the analysis were included. The tumor in case 1 originated from the right temporal bone and invaded the surrounding cranium, dura and temple muscles. The tumor in case 2 was located in the petroclival bone and had also invaded the surrounding cranium. Both tumors were well vascularized. The tumors were totally (case 1) or subtotally (case 2) removed with moderate blood loss. A total of 36 cases of intracranial epithelioid hemangioendothelioma were found in the literature. The tumor was typically diagnosed in young adults and infants. There was no sex predominance in adult patients, while in children, males were more frequently affected (M/F ratio, 3.5:1). Surgical removal was the main therapeutic protocol, and adjuvant therapy included radiotherapy or chemotherapy. Including the 2 patients presented here, a total of 38 patients were analyzed: 32 % showed local invasion, 24 % suffered a recurrence, 15 % had metastases, and the mortality rate was 15 %. Intracranial epithelioid hemangioendothelioma is a rare, low-proliferation tumor, but it exhibits some clinically malignant behaviors, such as local invasion, recurrence and metastasis. Total resection is mandatory where possible, and radiotherapy and/or chemotherapy are otherwise required. Preoperative feeding-artery embolization is recommended.