Summary The sexually dimorphic distribution of adipose tissue influences the development of obesity-associated pathologies. The accumulation of visceral white adipose tissue (VWAT) that occurs in males is detrimental to metabolic health, while accumulation of subcutaneous adipose tissue (SWAT) seen in females may be protective. Here, we show that adipocyte hyperplasia contributes directly to the differential fat distribution between the sexes. In male mice, high-fat diet (HFD) induces adipogenesis specifically in VWAT, while in females HFD induces adipogenesis in both VWAT and SWAT in a sex hormone-dependent manner. We also show that the activation of adipocyte precursors (APs), which drives adipocyte hyperplasia in obesity, is regulated by the adipose depot microenvironment and not by cell-intrinsic mechanisms. These findings indicate that APs are plastic cells, which respond to both local and systemic signals that influence their differentiation potential independent of depot origin. Therefore, depot-specific AP microenvironment niches coordinate adipose tissue growth and distribution.

Adipocytes were identified in human bone marrow more than a century ago, yet until recently little has been known about their origin, development, function or interactions with other cells in the bone marrow. Little functional significance has been attributed to these cells, a paradigm that still persists today. However, we now know that marrow adipose tissue increases with age and in response to a variety of physiologic induction signals. Bone marrow adipocytes have recently been shown to influence other cell populations within the marrow and can affect whole body metabolism by the secretion of a defined set of adipokines. Recent research shows that marrow adipocytes are distinct from white, brown and beige adipocytes, indicating that the bone marrow is a distinct adipose depot. This review will highlight recent data regarding these areas and the interactions of marrow adipose tissue (MAT) with cells within and outside of the bone marrow.

The type II CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeats/CRISPR-associated) has recently emerged as an efficient and simple tool for site-specific engineering of eukaryotic genomes. To improve its applications in Drosophila genome engineering, we simplified the standard two-component CRISPR/Cas9 system by generating a stable transgenic fly line expressing the Cas9 endonuclease in the germline (Vasa-Cas9 line). By injecting vectors expressing engineered target-specific guide RNAs into Vasa-Cas9 fly embryos, mutations were generated from site-specific DNA cleavages and efficiently transmitted into progenies. Because Cas9 endonuclease is the universal component of the type II CRISPR/Cas9 system, site-specific genomic engineering based on this improved platform can be achieved with lower complexity and toxicity, greater consistency, and excellent versatility.