Maio, G. | bioRxiv Science

bioRxiv2026

DHHC7 palmitoylates KRAS4A and promotes mutant KRAS-driven pancreatic cancers

KRAS mutations underlie many human cancers. While inhibitors such as Sotorasib and Adagrasib targeting KRAS mutants have shown promise, additional strategies are required to address the broader spectrum of KRAS-driven cancers, particularly those displaying drug resistance. Thus, there is a need to better understand KRAS signaling and develop new therapeutic strategies. Here we show that KRAS4A is palmitoylated on Cys180 by a palmitoyl transferase, DHHC7 (gene name ZDHHC7). Palmitoylation promotes KRAS4A plasma membrane localization, and more importantly, nanoclustering. This in turn promotes the activation of ARAF and RAF1, but not BRAF. DHHC7 and KRAS4A Cys180 palmitoylation are important for the normal and anchorage independent growth of pancreatic cancer cell lines. Depletion of ZDHHC7 dramatically inhibits pancreatic tumor growth in mouse xenograft models. These studies provide new understandings about how palmitoylation regulates KRAS4A activity and suggest DHHC7 as a promising new target for KRAS mutant cancers.

cancer biology↗

bioRxiv2025

Improved long transcript representation in Oxford Nanopore direct RNA sequencing with UltraMarathonRT

While most RNA-seq methods sequence amplified cDNA molecules, the advent of direct RNA sequencing (DRS) empowered the scientific community to read native RNA. This technology unlocked characterization of natural RNA modifications and long RNA isoforms without the inherent biases of PCR amplification. In the library preparation prior to Oxford Nanopore (ONT) sequencing, polyadenylated RNAs are copied by a reverse transcriptase (RT) to generate an RNA-cDNA hybrid. The step aims to eliminate the secondary and tertiary structure inherent to most RNA sequences prior to presentation of the RNA strand to the pore for sequencing. The current recommended protocol for DRS utilizes Induro(R) RT and requires reverse transcription at 60{degrees}C. We demonstrate that these RT conditions promote hydrolysis of the RNA strand. We further show that UltraMarathonRT(R) (uMRT), an ultraprocessive reverse transcriptase with intrinsic helicase activity that works optimally at 30{degrees}C, can be incorporated into a new uMRT-based DRS method that results in longer RNA reads in ONT DRS and longer final isoform predictions. We optimize this reaction along with other molecular biology steps and demonstrate the performance improvements of this new workflow on the benchmark sample, Universal Human Reference RNA, along with human brain RNA. This improved DRS protocol should empower new discoveries by the scientific community.

genomics↗