3 minute lightning oral presentation (and poster) ESA-SRB-APEG-NZSE 2022

Chronic excess of activin A perturbs lipid profile and steroid production in the mouse gonads and adrenal gland (#98)

Jennifer C Hutchison 1 2 , Paul J Trim 3 , Penny AF Whiley 1 2 , David J Handelsman 4 , Marten F Snel 3 , Kate L Loveland 1 2
  1. Hudson Institute of Medical Research, Clayton, VIC, Australia
  2. Department of Molecular and Translational Science, Monash University, Clayton, VIC, Australia
  3. Proteomics, Metabolomics and MS-Imaging Core Facility, South Australian Health and Medical Research Institute, Adelaide, SA
  4. ANZAC Institute, Concord Hospital, University of Sydney, Sydney, NSW, Australia

The versatile TGF-B superfamily member Activin A (AA) is important in organogenesis and maintenance of the reproductive system; transient elevation occurs in fetal testes during masculinisation, and its signalling inhibition is characteristic of ovarian development. AA absence results in abnormal testicular lipid droplet composition and steroid production in fetal mouse testes, while chronic elevation promotes tumour formation in adult mouse gonads. Inappropriate AA elevation in humans is associated with preeclampsia, medications, and postnatal pathologies including infection. We hypothesize altered steroid synthesis is a key mechanism underpinning effects of chronic AA excess.

Aim: define the effects of chronic AA elevation on gonadal and adrenal lipid and steroid profiles.

In adult mice with excess AA (Inhibin-alpha knockout, InhaKO), Oil-Red-O staining identified gonadal and adrenal lipid droplets, and mass spectrometry imaging (MSI) profiled testicular lipids. Transcript analyses and liquid chromatography mass spectrometry (LC-MS) defined alterations in steroid production, and tumour-microenvironment effects (tumour, associated seminiferous tubules, and morphologically normal regions) investigated by RNA-sequencing and immunohistochemistry.

InhaKO mice exhibit increased lipid droplet size and number in proximity to testis and ovarian tumours, with no effect apparent in the adrenal cortex. MSI identified a cohort of lipids differentially present in the InhaKO testis, including cholesterol ([m-H2O+H]+ ion m/z 369.3489 elevated). Statistically significant changes in steroidogenic enzyme transcript levels support abnormal metabolism of cholesterol to steroids (testes: reduced Star, Cyp17a1, Hsd17b3, elevated Hsd3b1, Cyp19a1; ovary: reduced Cyp11a1, Srd5a1, elevated Hsd17b1; adrenal: Cyp11a1 elevated) with local effects of tumour microenvironment detected at the transcript and protein level (HSD3B1 and CYP11A1). LC-MS confirmed abnormal steroid production in InhaKO gonads, including reduced testicular testosterone and DHT.

This study identified abnormal gonadal lipid and steroid profiles, with localised effects of the tumour-microenvironment, highlighting aspects of steroidogenesis from foundation to fruition that are vulnerable to excess AA bioactivity.