Biology subjects

Smaldino, P. J.

Publications and source records attributed to Smaldino, P. J..

4 recordsLinked to original sources

bioRxiv2025

Loss of DHX36/G4R1, a G4 resolvase, drives genome instability and regulates innate immune gene expression in cancer cells

G-quadruplexes (G4s) are four-stranded alternative secondary structures formed by guanine-rich nucleic acids and are prevalent across the human genome. G4s are enzymatically resolved using specialized helicases. Previous in vitro studies showed that DEAH-box Helicase 36 (DHX36/G4R1/RHAU), has the highest specificity and affinity for G4 structures. Here, by mapping genome-wide DNA double-strand breaks (DSBs), we demonstrate that knockout (KO) of DHX36 helicase increases DSB enrichment at G4 sites and that the presence of the G4 motif is a significant mediator of genome instability at regulatory regions. The loss of DHX36 corresponds with the significant upregulation of NF-{kappa}B transcriptional programs, culminating in the production and secretion of proinflammatory cytokines. Loss of DHX36 expression results in an increase in the innate immune signaling stimulator of interferon response cGAMP interactor 1 (STING1) expression and activation of genes involved in immune response pathways. Importantly, higher levels of DHX36 mRNA expression in human B-cell acute lymphoblastic leukemia correlate with improved overall survival relative to lower expression of DHX36, highlighting its critical role in preserving genome integrity at a cellular level and in the context of cancer.

molecular biology↗

bioRxiv2023

"Important enough to show the world": Using Authentic Research Opportunities and Micropublications to Build Students' Science Identities

Primarily undergraduate institutions (PUIs) often struggle to provide authentic research opportunities that culminate in peer-reviewed publications due to "recipe-driven" lab courses and the comprehensive body of work necessary for traditional scientific publication. However, the advent of short-form, single-figure "micropublications" has created novel opportunities for early-career scientists to make and publish authentic scientific contributions on a scale and in a timespan compatible with their training periods. The purpose of this qualitative case study is to explore the benefits accrued by eight undergraduate and masters students who participated in authentic, small-scale research projects and disseminated their work as coauthors of peer-reviewed micropublications at a PUI. In these interviews, students reported that through the process of conducting and publishing their research, they developed specific competencies: reading scientific literature, proposing experiments, and collecting/interpreting publication-worthy data. Further, they reported this process enabled them to identify as contributing members of the greater scientific community.

scientific communication and education↗

bioRxiv2022

Lipid Biosynthesis Perturbation Impairs Endoplasmic Reticulum-Associated Degradation

The relationship between lipid homeostasis and protein homeostasis (proteostasis) is complex and remains incompletely understood. We conducted a screen for genes required for efficient degradation of Deg1-Sec62, a model aberrant translocon-associated substrate of the endoplasmic reticulum (ER) ubiquitin ligase Hrd1, in Saccharomyces cerevisiae. This screen revealed that INO4 is required for efficient Deg1-Sec62 degradation. INO4 encodes one subunit of the Ino2/Ino4 heterodimeric transcription factor, which regulates expression of genes required for lipid biosynthesis. Deg1-Sec62 degradation was also impaired by mutation of genes encoding several enzymes mediating phospholipid and sterol biosynthesis. The degradation defect in ino4{Delta} yeast was rescued by supplementation with metabolites whose synthesis and uptake are mediated by Ino2/Ino4 targets. Stabilization of a panel of substrates of the Hrd1 and Doa10 ER ubiquitin ligases by INO4 deletion indicates ER protein quality control is generally sensitive to perturbed lipid homeostasis. Further, loss of INO4 sensitized yeast to proteotoxic stress, suggesting a broad requirement for lipid homeostasis in maintaining proteostasis. Abundance of the ER ubiquitin-conjugating enzyme Ubc7 was reduced in the absence of INO4, consistent with a model whereby perturbed lipid biosynthesis alters the abundance of critical protein quality control mediators, with broad consequences for ER proteostasis. A better understanding of the dynamic relationship between lipid homeostasis and proteostasis may lead to improved understanding and treatment of several human diseases associated with altered lipid biosynthesis.

cell biology↗

bioRxiv2021

The RNA helicase DHX36/G4R1 modulates C9orf72 GGGGCC repeat-associated translation

GGGGCC (G4C2) hexanucleotide repeat expansions (HRE) in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat-associated non-AUG (RAN) translation of this expansion generates toxic proteins that accumulate in patient brains and contribute to disease pathogenesis. The DEAH-Box Helicase 36 (DHX36/G4R1) plays active roles in RNA and DNA G-quadruplex (G4) resolution in cells. As G4C2 repeats form G4 structures in vitro, we sought to determine the impact of manipulating DHX36 expression on repeat transcription and RAN translation. We found that DHX36 depletion suppresses RAN translation from reporter constructs in a repeat length dependent manner while overexpression of DHX36 enhances RAN translation from G4C2 reporter RNAs. Taken together, these results suggest that DHX36 is active in regulating G4C2 repeat translation, providing potential implications for therapeutic development in nucleotide repeats expansion disorders.

molecular biology↗