wnt16 regulates spine and muscle morphogenesis through parallel signals from notochord and dermomyotome.

Bone and muscle are coupled through developmental, mechanical, paracrine, and autocrine signals. Genetic variants at the CPED1-WNT16 locus are dually associated with bone- and muscle-related traits. While Wnt16 is necessary for bone mass and strength, this fails to explain pleiotropy at this locus. Here, we show wnt16 is required for spine and muscle morphogenesis in zebrafish. In embryos, wnt16 is expressed in dermomyotome and developing notochord, and contributes to larval myotome morphology and notochord elongation. Later, wnt16 is expressed at the ventral midline of the notochord sheath, and contributes to spine mineralization and osteoblast recruitment. Morphological changes in wnt16 mutant larvae are mirrored in adults, indicating that wnt16 impacts bone and muscle morphology throughout the lifespan. Finally, we show that wnt16 is a gene of major effect on lean mass at the CPED1-WNT16 locus. Our findings indicate that Wnt16 is secreted in structures adjacent to developing bone (notochord) and muscle (dermomyotome) where it affects the morphogenesis of each tissue, thereby rendering wnt16 expression into dual effects on bone and muscle morphology. This work expands our understanding of wnt16 in musculoskeletal development and supports the potential for variants to act through WNT16 to influence bone and muscle via parallel morphogenetic processes.

AMPK is required for uterine receptivity and normal responses to steroid hormones.

We previously demonstrated that 5'-AMP-activated protein kinase (AMPK) is essential for normal reproductive functions in female mice. Conditional ablation of Prkaa1 and Prkaa2, genes that encode the α1 and α2 catalytic domains of AMPK, resulted in early reproductive senescence, faulty artificial decidualization, uterine inflammation and fibrotic postparturient endometrial regeneration. We also noted a delay in the timing of embryo implantation in Prkaa1/2d/d female mice, suggesting a role for AMPK in establishing uterine receptivity. As outlined in new studies here, conditional uterine ablation of Prkaa1/2 led to an increase in ESR1 in the uteri of Prkaa1/2d/d mice, resulting in prolonged epithelial cell proliferation and retention of E2-induced gene expression (e.g. Msx1, Muc1, Ltf) through the implantation window. Within the stromal compartment, stromal cell proliferation was reduced by five-fold in Prkaa1/2d/d mice, and this was accompanied by a significant decrease in cell cycle regulatory genes and aberrant expression of decidualization marker genes such as Hand2, Bmp2, Fst and Inhbb. This phenotype is consistent with our prior study, demonstrating a failure of the Prkaa1/2d/d uterus to undergo decidualization. Despite these uterine defects, ovarian function seemed to be normal following ablation of Prkaa1/2 from peri-ovulatory follicles in which ovulation, luteinization and serum progesterone levels were not different on day 5 of pregnancy or pseudopregnancy between Prkaa1/2fl/fl and Prkaa1/2d/d mice. These cumulative findings demonstrate that AMPK activity plays a prominent role in mediating several steroid hormone-dependent events such as epithelial cell proliferation, uterine receptivity and decidualization as pregnancy is established.