Transcriptomic sex differences in sensory neuronal populations of mice

Abstract

Many chronic pain conditions show sex differences in their epidemiology. This could be attributed to sex-dependent differential expression of genes (DEGs) involved in nociceptive pathways, including sensory neurons. This study aimed to identify sex-dependent DEGs in estrous female versus male sensory neurons, which were prepared by using different approaches and ganglion types. RNA-seq on non-purified sensory neuronal preparations, such as whole dorsal root ganglion (DRG) and hindpaw tissues, revealed only a few sex-dependent DEGs. Sensory neuron purification increased numbers of sex-dependent DEGs. These DEG sets were substantially influenced by preparation approaches and ganglion types [DRG vs trigeminal ganglia (TG)]. Percoll-gradient enriched DRG and TG neuronal fractions produced distinct sex-dependent DEG groups. We next isolated a subset of sensory neurons by sorting DRG neurons back-labeled from paw and thigh muscle. These neurons have a unique sex-dependent DEG set, yet there is similarity in biological processes linked to these different groups of sex-dependent DEGs. Female-predominant DEGs in sensory neurons relate to inflammatory, synaptic transmission and extracellular matrix reorganization processes that could exacerbate neuro-inflammation severity, especially in TG. Male-selective DEGs were linked to oxidative phosphorylation and protein/molecule metabolism and production. Our findings catalog preparation-dependent sex differences in neuronal gene expressions in sensory ganglia.

Caldendrin represses neurite regeneration via a sex-dependent mechanism in sensory neurons

“…The fact that this was only applicable to cultures from female and not male caldendrin KO mice (Fig. 6B) was intriguing considering that sex differences have been noted in the transcriptome of mouse DRGNs (Mecklenburg et al, 2020) and in the responses to peripheral nerve injury in animals and humans (Chernov et al, 2020;Franco-Enzastiga et al, 2021;Juarez et al, 2019). This result was not due to major differences in caldendrin protein levels in WT males and females (Fig.…”

“…The absence of any effect of K 40 on neurite growth in caldendrin KO DRGNs in conventional culture (Fig.6A) and following in vitro axotomy (Fig.7) indicates a critical role for caldendrin in coupling Ca v 1 channels to activity-dependent neurite growth repression (Fig.6A). The fact that this was only applicable to cultures from female and not male caldendrin KO mice (Fig.6B) was intriguing considering that sex differences have been noted in the transcriptome of mouse DRGNs (Mecklenburg et al, 2020) and in the responses to peripheral nerve injury in animals and humans (Chernov et al, 2020; Franco-Enzastiga et al, 2021; Juarez et al, 2019). This result was not due to major differences in caldendrin protein levels in WT males and females (Fig.1B).…”

“…However, the slow rate of regrowth and incomplete re-innervation of target tissues remain significant barriers for therapies to restore sensory function in individuals suffering from peripheral nerve damage (Huebner & Strittmatter, 2009). Despite insights into the molecular mechanisms underlying the functional diversity of DRGNs (Mecklenburg et al, 2020; Wu et al, 2021; Zheng et al, 2019), comparatively little is known about the factors that control the regenerative growth of DRGN neurites.…”

Pituitary hormones are specifically expressed in trigeminal sensory neurons and contribute to pain responses in the trigeminal system

“…Moreover, T10-L1 DRG neurons have a unique subset of sensory neuronal groups compared to L3–L5 DRG neurons 11 , 12 . The DRG neuronal transcriptional profile in turn greatly differs from TG neuronal profiles 13 , 14 . Additionally, DRG and TG neurons differ in their translational potential for mTOR-related genes and AMP-activated protein kinase 15 .…”

“…Here, we expand upon this experimental approach by including comparison between neurons of DRG from different levels (T10-L1), lumbar DRG, NG/JG and TG. We have used the Pirt/TdTomato mouse reporter line along with enhanced sorting using both a larger nozzle and double sorting methods 13 that increases purification of sensory neuronal fraction to > 90% while maintaining the natural proportion of large-diameter sensory neurons. Our work, has revealed several additional genes, including prolactin (PRL), growth hormone (GH), and proopiomelanocortin (POMC) with expression restricted to adult male mouse in TG but no other sensory ganglia.…”