Evolution of a novel adrenal cell type that promotes parental care.

Cell types with specialized functions fundamentally regulate animal behaviour, and yet the genetic mechanisms that underlie the emergence of novel cell types and their consequences for behaviour are not well understood1. Here we show that the monogamous oldfield mouse (Peromyscus polionotus) has recently evolved a novel cell type in the adrenal gland that expresses the enzyme AKR1C18, which converts progesterone into 20α-hydroxyprogesterone. We then demonstrate that 20α-hydroxyprogesterone is more abundant in oldfield mice, where it induces monogamous-typical parental behaviours, than in the closely related promiscuous deer mice (Peromyscus maniculatus). Using quantitative trait locus mapping in a cross between these species, we ultimately find interspecific genetic variation that drives expression of the nuclear protein GADD45A and the glycoprotein tenascin N, which contribute to the emergence and function of this cell type in oldfield mice. Our results provide an example by which the recent evolution of a new cell type in a gland outside the brain contributes to the evolution of social behaviour.

Tbx2 is required for the suppression of mesendoderm during early Xenopus development.

BACKGROUND: T-box family proteins are DNA-binding transcriptional regulators that play crucial roles during germ layer formation in the early vertebrate embryo. Well-characterized members of this family, including the transcriptional activators Brachyury and VegT, are essential for the proper formation of mesoderm and endoderm, respectively. To date, T-box proteins have not been shown to play a role in the promotion of the third primary germ layer, ectoderm. RESULTS: Here, we report that the T-box factor Tbx2 is both sufficient and necessary for ectodermal differentiation in the frog Xenopus laevis. Tbx2 is expressed zygotically in the presumptive ectoderm, during blastula and gastrula stages. Ectopic expression of Tbx2 represses mesoderm and endoderm, while loss of Tbx2 leads to inappropriate expression of mesoderm- and endoderm-specific genes in the region fated to give rise to ectoderm. Misexpression of Tbx2 also promotes neural tissue in animal cap explants, suggesting that Tbx2 plays a role in both the establishment of ectodermal fate and its dorsoventral patterning. CONCLUSIONS: Our studies demonstrate that Tbx2 functions as a transcriptional repressor during germ layer formation, and suggest that this activity is mediated in part through repression of target genes that are stimulated, in the mesendoderm, by transactivating T-box proteins. Taken together, our results point to a critical role for Tbx2 in limiting the potency of blastula-stage progenitor cells during vertebrate germ layer differentiation. Developmental Dynamics 247:903-913, 2018. © 2018 Wiley Periodicals, Inc.

Young non-smokers with oral cancer: What are we missing and why?

OBJECTIVES: There has been an increase in young non-smokers (YNS) who develop oral cavity squamous cell carcinomas (OSCC). Oncological outcomes in YNS are controversial and etiology has not been well-defined. We hypothesize that the etiology of cancer development in YNS and their poor outcome is related to an impaired immune system. MATERIALS AND METHODS: From a database of 2073 OSCC patients treated with primary surgery between 1985 and 2015, 9% were young patients. We categorized patients as: ≤40 years-old/non-smokers (n = 100), ≤40 years-old/smokers (n = 80), >40 years-old/non-smokers (n = 595) and >40 years-old/smokers (n = 1298). Patient and tumor variables were used to calculate propensity scores and stabilized inverse probability of treatment weights were calculated. Weighted proportional hazard models were performed. Survival and recurrence outcomes of YNS were compared to the other 3 groups. Host immune status of YNS measured by peripheral blood neutrophil-to-lymphocyte ratio (NLR) was compared to 2 control groups (YNS with thyroid cancer and YNS with benign pathologies). RESULTS: After adjusting for tumor and host factors, YNS had a higher probability of death compared to young smokers. This was driven by a higher incidence of regional and distant recurrences. Host factors showed a strong association with outcomes suggesting YNS may have an impaired immune system. Compared to the control cohorts YNS with OSCC had a higher NLR (p = .006). CONCLUSION: When adjusted by relevant covariates, YNS with OSCC have poorer survival than their young smoker counterparts. Our results suggest that an impaired immune system may be partly responsible for OSCC development and poorer outcomes in YNS.