Polarized NHE1 and SWELL1 regulate migration direction, efficiency and metastasis.

Cell migration regulates diverse (patho)physiological processes, including cancer metastasis. According to the Osmotic Engine Model, polarization of NHE1 at the leading edge of confined cells facilitates water uptake, cell protrusion and motility. The physiological relevance of the Osmotic Engine Model and the identity of molecules mediating cell rear shrinkage remain elusive. Here, we demonstrate that NHE1 and SWELL1 preferentially polarize at the cell leading and trailing edges, respectively, mediate cell volume regulation, cell dissemination from spheroids and confined migration. SWELL1 polarization confers migration direction and efficiency, as predicted mathematically and determined experimentally via optogenetic spatiotemporal regulation. Optogenetic RhoA activation at the cell front triggers SWELL1 re-distribution and migration direction reversal in SWELL1-expressing, but not SWELL1-knockdown, cells. Efficient cell reversal also requires Cdc42, which controls NHE1 repolarization. Dual NHE1/SWELL1 knockdown inhibits breast cancer cell extravasation and metastasis in vivo, thereby illustrating the physiological significance of the Osmotic Engine Model.

Sequence specific integration by the family 1 casposase from Candidatus Nitrosopumilus koreensis AR1.

Casposase, a homolog of Cas1 integrase, is encoded by a superfamily of mobile genetic elements known as casposons. While family 2 casposase has been well documented in both function and structure, little is known about the other three casposase families. Here, we studied the family 1 casposase lacking the helix-turn-helix (HTH) domain from Candidatus Nitrosopumilus koreensis AR1 (Ca. N. koreensis). The determinants for integration by Ca. N. koreensis casposase were extensively investigated, and it was found that a 13-bp target site duplication (TSD) sequence, a minimal 3-bp leader and three different nucleotides of the TSD sequences are indispensable for target specific integration. Significantly, the casposase can site-specifically integrate a broad range of terminal inverted repeat (TIR)-derived oligonucleotides ranging from 7-nt to ∼4000-bp, and various oligonucleotides lacking the 5'-TTCTA-3' motif at the 3' end of TIR sequence can be integrated efficiently. Furthermore, similar to some Cas1 homologs, the casposase utilizes a 5'-ATAA-3' motif in the TSD as a molecular ruler to dictate nucleophilic attack at 9-bp downstream of the end of the ruler during the spacer-side integration. By characterizing the family 1 Ca. N. koreensis casposase, we have extended our understanding on mechanistic similarities and evolutionary connections between casposons and the adaptation elements of CRISPR-Cas immunity.

Enhanced Ferroptosis by Oxygen-Boosted Phototherapy Based on a 2-in-1 Nanoplatform of Ferrous Hemoglobin for Tumor Synergistic Therapy.

Photodynamic therapy (PDT) combined with oxygenating strategies is widely employed in cancer treatment; however, oxygen-boosted PDT has failed to achieve an ideal effect due to the complexity, heterogeneity, and irreversible hypoxic environment generated by tumor tissues. With the emergence of Fe-dependent ferroptosis boasting reactive oxygen species (ROS) cytotoxicity as well, such a chemodynamic approach to cancer therapy has drawn extensive attention. In this study, hemoglobin (Hb) is connected with the photosensitizer chlorin e6 (Ce6) to construct a 2-in-1 nanoplatform (SRF@Hb-Ce6) with Sorafenib (SRF, ferroptosis promotor) loaded, combining oxygen-boosted PDT and potent ferroptosis. Benefiting from the intrinsic presence of Fe capable of binding oxygen, hemoglobin concurrently furnishes oxygen for oxygen-dependent PDT and Fe for Fe-dependent ferroptosis. Furthermore, amphiphilic MMP2-responsive peptide is incorporated into the skeleton of the nanoplatform to ensure drug-release specificity for safety improvement. Correlative measurements demonstrate the potentiation of PDT and ferroptosis with SRF@Hb-Ce6. More importantly, PDT strengthens ferroptosis by recruiting immune cells to secrete IFN-γ, which can sensitize the tumor to ferroptosis in our findings. The therapeutic effect of synergistic treatment with SRF@Hb-Ce6 in vitro and in vivo was proven significant, revealing the promising prospects of combined PDT and ferroptosis therapy with the 2-in-1 nanoplatform.