Transcriptomic analysis links diverse hypothalamic cell types to fibroblast growth factor 1-induced sustained diabetes remission

Marie A Bentsen,José-Manuel García-Verdugo,Thomas H Meek,Vicente Herranz-Pérez,Kristoffer L Egerod,Kenjiro Muta,Arian F Baquero,Karl J Kaiyala,Zaman Mirzadeh,Birgitte Holst,Michael W Schwartz,Jenny Brown ,Jonatan J Thompson ,Yu Zhang,Camdin M Bennett ,Jarrad Scarlett ,Kevin L Grove,Thomas Sparsø ,Gregory J Morton,Rasmus Jørgensen ,Birgitte Rahbek Kornum ,Charles Pyke,Burak Kutlu,Dylan M Rausch,Chelsea L Faber,Kimberly M Alonge,Cecilia Ratner,Anna Secher,Tune H Pers

doi:10.1038/s41467-020-17720-5

Abstract

In rodent models of type 2 diabetes (T2D), sustained remission of hyperglycemia can be induced by a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1), and the mediobasal hypothalamus (MBH) was recently implicated as the brain area responsible for this effect. To better understand the cellular response to FGF1 in the MBH, we sequenced >79,000 single-cell transcriptomes from the hypothalamus of diabetic Lepob/ob mice obtained on Days 1 and 5 after icv injection of either FGF1 or vehicle. A wide range of transcriptional responses to FGF1 was observed across diverse hypothalamic cell types, with glial cell types responding much more robustly than neurons at both time points. Tanycytes and ependymal cells were the most FGF1-responsive cell type at Day 1, but astrocytes and oligodendrocyte lineage cells subsequently became more responsive. Based on histochemical and ultrastructural evidence of enhanced cell-cell interactions between astrocytes and Agrp neurons (key components of the melanocortin system), we performed a series of studies showing that intact melanocortin signaling is required for the sustained antidiabetic action of FGF1. These data collectively suggest that hypothalamic glial cells are leading targets for the effects of FGF1 and that sustained diabetes remission is dependent on intact melanocortin signaling.

Highlights

In rodent models of type 2 diabetes (T2D), sustained remission of hyperglycemia can be induced by a single intracerebroventricular injection of fibroblast growth factor 1 (FGF1), and the mediobasal hypothalamus (MBH) was recently implicated as the brain area responsible for this effect
In Lepob/ob mice and other rodent models of T2D, sustained diabetes remission can be achieved by a single intracerebroventricular injection of fibroblast growth factor 1 (FGF1)[4], and the hypothalamus has been identified as the brain area responsible for this FGF1 effect[5]
We identified Agouti-related peptide (Agrp) neurons, key components of the melanocortin signaling pathway, as the most FGF1responsive neuronal cell type at the transcriptional level, and in a series of in vivo studies, we show that sustained diabetes remission induced by icv FGF1 is dependent on intact melanocortin receptor signaling

Summary

Introduction

In rodent models of type 2 diabetes (T2D), sustained remission of hyperglycemia can be induced by a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1), and the mediobasal hypothalamus (MBH) was recently implicated as the brain area responsible for this effect. In Lepob/ob mice and other rodent models of T2D, sustained diabetes remission can be achieved by a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1)[4], and the hypothalamus has been identified as the brain area responsible for this FGF1 effect[5] While this finding is in line with accumulating evidence supporting a key role for the hypothalamus in glucose homeostasis, our current understanding of glucoregulatory neurocircuitry is limited[6,7]. As an unbiased approach to measuring gene expression within single cells in the hypothalamus[16,17,18], single-cell RNA sequencing (scRNA-seq) provides a useful strategy both for identifying FGF1responsive cell types in this brain area and for characterizing their response to icv FGF1 administration at the transcriptional level With this goal in mind, we performed this analysis across several time points following a single icv injection of FGF1 or vehicle in diabetic Lepob/ob mice. We identified Agrp neurons, key components of the melanocortin signaling pathway, as the most FGF1responsive neuronal cell type at the transcriptional level, and in a series of in vivo studies, we show that sustained diabetes remission induced by icv FGF1 is dependent on intact melanocortin receptor signaling

Methods

Results

Conclusion