Research Techniques Made Simple: Forward Genetic Screening to Uncover Genes Involved in Skin Biology

Characterization of a spontaneous osteopetrosis model using RANKL-dysfunctional mice

Tumor necrosis factor superfamily member 11 (TNFSF11), or receptor activator of nuclear factor-κB ligand (RANKL), is a crucial osteoclast-stimulating factor binding to RANK on osteoclast membranes. Mouse models are powerful tools for understanding the genetic mechanisms of related diseases. Here, we examined the utility of Tnfsf11 mutation in mice for understanding the mechanisms of bone remodeling and dysmorphology. The Tnfsf11gum mouse, discovered in 2011 at Jackson Laboratory, was used to study the genetic landscape associated with TNFSF11 inactivation in bone marrow tissues. Tnfsf11gum/+ and Tnfsf11+/+ mice were subjected to Micro-CT observation, ELISA analysis, histological evaluation, and massively-parallel mRNA sequencing (RNA-Seq) analysis. Tnfsf11gum/+ mice exhibited severe osteopetrotic changes in the bone marrow cavity, along with significantly lower serum RANKL levels and a reduced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the bone marrow compared to those in Tnfsf11+/+ mice. However, tooth eruption between Tnfsf11gum/+ and Tnfsf11+/+ mice did not differ. Furthermore, genes involved in osteoblast proliferation and differentiation, including Gli1, Slc35b2, Lrrc17, and Junb were differentially expressed. Heterozygous mutation of TNFSF11 was also associated with a slightly increased expression of genes involved in osteoclast proliferation and differentiation, including Tcirg1, Junb, Anxa2, and Atp6ap1. Overall, we demonstrate that single gene mutations in Tnfsf11 cause bone resorption instability without significantly altering the genes related to osteoblast and osteoclast activity in the bone marrow cavity, thus establishing an optimal resource as an experimental animal model for bone resorption in bone biology research.

Tandem mass tag-based thermal proteome profiling for the discovery of drug-protein interactions in cancer cells

Identification of effector targets is imperative to the characterization of the mechanisms of action of novel small molecules. Here, we describe steps to identify effector drug-protein interactions in lysates derived from cancer cell lines using a thermal proteome profiling (TPP) protocol. Building on existing TTP approaches, we detail the use of an in-solution trypsin digestion technique to streamline sample preparation, a nonparametric analysis to rank proteins for prioritization, and a follow-up strategy for identifying effector interactors. For complete details on the use and execution of this protocol, please refer to Johnson et al. (2022).1.