A wealth of specialized neuroendocrine command systems intercalated within the hypothalamus control the most fundamental physiological needs 1 , 2 . Nevertheless, a developmental blueprint integrating molecular determinants of neuronal and glial diversity along temporal and spatial scales of hypothalamus development remains unresolved 3 . Here, we combine single-cell RNA-seq on 51,199 cells of ectodermal origin, gene regulatory network (GRN) screens in conjunction with GWAS-based disease phenotyping and genetic lineage reconstruction to show that 9 glial and 33 neuronal subtypes are generated by mid-gestation under the control of distinct GRNs. Combinatorial molecular codes arising from neurotransmitters, neuropeptides and transcription factors are minimally required to decode the taxonomical hierarchy of hypothalamic neurons. Differentiation of GABA and dopamine but not glutamate neurons relies on quasi-stable intermediate states with a pool of GABA progenitors giving rise to dopamine cells 4 . An unexpected abundance of chemotropic proliferation and guidance cues commonly implicated in dorsal (cortical) patterning 5 was found in the hypothalamus. Particularly, Slit / Robo loss-of-function impacted both the production and positioning of periventricular dopamine neurons. Overall, we uncover molecular principles shaping the developmental architecture of the hypothalamus and show how neuronal heterogeneity is transformed into a multimodal neural unit to endow a virtually infinite adaptive potential throughout life.

Highlights d GWAS in the EGCUT biobank identifies ALK as a candidate thinness gene d Knockdown of Alk in Drosophila results in reduced triglyceride levels d Alk mutant mice exhibit resistance to diet-and leptinmutation-induced obesity d ALK controls energy expenditure via sympathetic tone to the adipose organ

Stress‐induced cortical alertness is maintained by a heightened excitability of noradrenergic neurons innervating, notably, the prefrontal cortex. However, neither the signaling axis linking hypothalamic activation to delayed and lasting noradrenergic excitability nor the molecular cascade gating noradrenaline synthesis is defined. Here, we show that hypothalamic corticotropin‐releasing hormone‐releasing neurons innervate ependymal cells of the 3rd ventricle to induce ciliary neurotrophic factor (CNTF) release for transport through the brain's aqueductal system. CNTF binding to its cognate receptors on norepinephrinergic neurons in the locus coeruleus then initiates sequential phosphorylation of extracellular signal‐regulated kinase 1 and tyrosine hydroxylase with the Ca2+‐sensor secretagogin ensuring activity dependence in both rodent and human brains. Both CNTF and secretagogin ablation occlude stress‐induced cortical norepinephrine synthesis, ensuing neuronal excitation and behavioral stereotypes. Cumulatively, we identify a multimodal pathway that is rate‐limited by CNTF volume transmission and poised to directly convert hypothalamic activation into long‐lasting cortical excitability following acute stress.

The mutational spectrum of the mitochondrial DNA (mtDNA) does not resemble any of the known mutational signatures of the nuclear genome and variation in mtDNA mutational spectra between different organisms is still incomprehensible. Since mitochondria are responsible for aerobic respiration, it is expected that mtDNA mutational spectrum is affected by oxidative damage. Assuming that oxidative damage increases with age, we analyse mtDNA mutagenesis of different species in regards to their generation length. Analysing, (i) dozens of thousands of somatic mtDNA mutations in samples of different ages (ii) 70053 polymorphic synonymous mtDNA substitutions reconstructed in 424 mammalian species with different generation lengths and (iii) synonymous nucleotide content of 650 complete mitochondrial genomes of mammalian species we observed that the frequency of AH > GH substitutions (H: heavy strand notation) is twice bigger in species with high versus low generation length making their mtDNA more AH poor and GH rich. Considering that AH > GH substitutions are also sensitive to the time spent single-stranded (TSSS) during asynchronous mtDNA replication we demonstrated that AH > GH substitution rate is a function of both species-specific generation length and position-specific TSSS. We propose that AH > GH is a mitochondria-specific signature of oxidative damage associated with both aging and TSSS.

Maternal drug abuse during pregnancy is a rapidly escalating societal problem. Psychostimulants, including amphetamine, cocaine, and methamphetamine, are amongst the illicit drugs most commonly consumed by pregnant women. Neuropharmacology concepts posit that psychostimulants affect monoamine signaling in the nervous system by their affinities to neurotransmitter reuptake and vesicular transporters to heighten neurotransmitter availability extracellularly. Exacerbated dopamine signaling is particularly considered as a key determinant of psychostimulant action. Much less is known about possible adverse effects of these drugs on peripheral organs, and if in utero exposure induces lifelong pathologies. Here, we addressed this question by combining human RNA‐seq data with cellular and mouse models of neuroendocrine development. We show that episodic maternal exposure to psychostimulants during pregnancy coincident with the intrauterine specification of pancreatic β cells permanently impairs their ability of insulin production, leading to glucose intolerance in adult female but not male offspring. We link psychostimulant action specifically to serotonin signaling and implicate the sex‐specific epigenetic reprogramming of serotonin‐related gene regulatory networks upstream from the transcription factor Pet1/Fev as determinants of reduced insulin production.

Significance The receptor tyrosine kinase Alk was originally discovered as an oncogenic fusion protein generated in anaplastic large cell lymphoma. A variety of oncogenic Alk fusion proteins were subsequently identified as key drivers of subsets of different cancers, including non-small cell lung cancer patients, large B cell lymphomas, and inflammatory myofibroblast tumors. In addition, activating oncogenic somatic mutations were identified in populations of pediatric neuroblastoma patients. Crizotininb, lorlatinib, and other drugs that inhibit the tyrosine kinase activity of Alk were successfully applied for the treatment of patients harboring oncogenic Alk mutants. In this report, we present experiments demonstrating that the physiological ligands of Alk function in the hypothalamus to control body weight, offering new therapeutic treatments for metabolic diseases and cancer.

Mitochondrial mutational signature is very conserved and low deviations between species have been associated with longevity. By reconstructing species-specific mtDNA mutational spectrum for ray-finned fishes (Actinopterygii), we observed that temperature is a strong additional factor shaping the mtDNA mutational spectrum in ectotherms. The analysis of mammalian endotherms, with a special focus on species with temporarily or permanently low metabolic rates (hibernators, daily torpors, naked mole rat, etc.), confirmed the temperature effect, suggesting that two main factors shape between-species variation in mitochondrial mutational spectra: longevity and temperature.

Background Aging in postmitotic tissues is associated with clonal expansion of somatic mitochondrial deletions, the origin of which is not well understood. Such deletions are often flanked by direct nucleotide repeats, but this alone does not fully explain their distribution. Here, we hypothesized that the close proximity of direct repeats on single-stranded mitochondrial DNA (mtDNA) might play a role in the formation of deletions. Results By analyzing human mtDNA deletions in the major arc of mtDNA, which is single-stranded during replication and is characterized by a high number of deletions, we found a non-uniform distribution with a “hot spot” where one deletion breakpoint occurred within the region of 6–9 kb and another within 13–16 kb of the mtDNA. This distribution was not explained by the presence of direct repeats, suggesting that other factors, such as the spatial proximity of these two regions, can be the cause. In silico analyses revealed that the single-stranded major arc may be organized as a large-scale hairpin-like loop with a center close to 11 kb and contacting regions between 6–9 kb and 13–16 kb, which would explain the high deletion activity in this contact zone. The direct repeats located within the contact zone, such as the well-known common repeat with a first arm at 8470–8482 bp (base pair) and a second arm at 13,447–13,459 bp, are three times more likely to cause deletions compared to direct repeats located outside of the contact zone. A comparison of age- and disease-associated deletions demonstrated that the contact zone plays a crucial role in explaining the age-associated deletions, emphasizing its importance in the rate of healthy aging. Conclusions Overall, we provide topological insights into the mechanism of age-associated deletion formation in human mtDNA, which could be used to predict somatic deletion burden and maximum lifespan in different human haplogroups and mammalian species.