Opsahl, A. | Search bioRxiv

bioRxiv2023

SPAG7 deletion causes intrauterine growth restriction, resulting in adulthood obesity and metabolic dysfunction

From a forward mutagenetic screen to discover mutations associated with obesity, we identified mutations in the spag7 gene linked to metabolic dysfunction in mice. Here we show that SPAG7 KO mice are born smaller and develop obesity and glucose intolerance in adulthood. This obesity does not stem from hyperphagia, but a decrease in energy expenditure. The KO animals also display reduced exercise tolerance and muscle function due to impaired mitochondrial function. Furthermore, SPAG7-deficiency in developing embryos leads to intrauterine growth restriction, brought on by placental insufficiency, likely due to abnormal development of the placental junctional zone. This insufficiency leads to loss of SPAG7-deficient fetuses in utero and reduced birth weights of those that survive. We hypothesize that a "thrifty phenotype" is ingrained in SPAG7 KO animals during development that leads to adult obesity. Collectively, these results indicate that SPAG7 is essential for embryonic development and energy homeostasis later in life.

molecular biology↗

bioRxiv2020

Characterizing intra-tumor and inter-tumor variability of immune cell infiltrates in murine syngeneic tumors

By using serial-sectioning methodology combined with immunohistochemistry (IHC) and whole-slide digital image analysis (DIA), we present a systematic analysis of intra-tumor and inter-tumor variability in the abundance of nine immune cell biomarkers in multiple murine tumor models. Our analysis shows that inter-tumor variability is typically the dominant source of variation in measurements of immune cell densities. Statistical power analysis reveals how group size and variance in immune cell density estimates affect the predictive power for detecting a statistically meaningful fold-change in immune cell density. Inter-tumor variability in the ratio of immune cell densities show distinct patterns in select tumor models and reveal the existence of strong correlations between select biomarker pairs. Further, we show that the relative proportion of immune cells at different depths across tumor samples is preserved in some but not all tumor models thereby revealing the existence of compositional heterogeneity. The results and analyses presented here reveal the complex nature of immunologic heterogeneity that exists in murine tumor models and provide guidelines for designing preclinical studies for immuno-oncology research and drug development.

cancer biology↗