Transient Neuroprotection by SRY Upregulation in Dopamine Cells Following Injury in Males

Abstract

Emerging evidence suggest sex-specific regulation of dopamine neurons may underlie susceptibility of males to disorders such as Parkinson's disease (PD). In healthy male dopamine neurons, the Y-chromosome gene product, the sex-determining region on the Y chromosome (SRY) modulates dopamine biosynthesis and motor function. We investigated the regulation and function of SRY in a model of dopamine cell injury. Treatment with the dopaminergic toxin, 6-hydroxydopamine (6-OHDA), significantly elevated SRY mRNA expression (9-fold) in human male dopamine M17 cells. SRY up-regulation occurred via the p-quinone pathway, associated with a 3.5-fold increase in expression of GADD45γ, a DNA damage inducible factor gene and known SRY regulator. In turn, a signaling cascade involving GADD45γ/p38-MAPK/GATA activated the SRY promoter. Knockdown of SRY mRNA in 6-OHDA-treated M17 cells was deleterious, increasing levels of reactive oxygen species (ROS), pro-apoptotic marker PUMA mRNA, and cell injury (+25%, +32% and +34%, respectively). Conversely, ectopic over-expression of SRY in 6-OHDA-treated female SH-SY5Y cells was protective, decreasing ROS, PUMA, and cell injury (-40%, -46%, and -30%, respectively). However, the 6-OHDA-induced increase in SRY expression was diminished with higher concentrations of toxins or with chronic exposure to 6-OHDA. We conclude that SRY upregulation after dopamine cell injury is initially a protective response in males, but diminishes with gradual loss in dopamine cells. We speculate that dysregulation of SRY may contribute the susceptibility of males to PD.

Effect of early embryonic deletion of huntingtin from pyramidal neurons on the development and long-term survival of neurons in cerebral cortex and striatum

“…The membranes were blocked in 5% non-fat milk in PBS for 1 h at room temperature and incubated overnight at 4 °C with mouse monoclonal antibody against huntingtin (Millipore MAB 2166, 1:3000), rabbit polyclonal against BDNF (Alomone labs ANT-010, 1:1000), rabbit monoclonal against Erk1/2 (Cell Signaling mAb 4695, 1:1000), rabbit monoclonal against phospho-Erk1/2 (Cell Signaling mAb 4370, 1:2000), rabbit polyclonal against phospho-Akt (Cell Signaling Ab 9271, 1:1000), or mouse monoclonal against beta-tubulin (Chemicon, MAB 3408, 1:5000). The specificity of these antibodies for their target antigens has been demonstrated by the manufacturer by Western blot and in published studies by others (Harrington et al, 2012; Milman and Woulfe, 2013; Czech et al, 2014; Duarte-Neves et al, 2015; Gu et al, 2017; Patel et al, 2017). The membranes were then washed in PBS containing 0.2% Tween, and incubated with anti-mouse or anti-rabbit secondary antibodies at room temperature for 1 h. The membranes were subsequently washed in PBS containing 0.2% Tween, and protein bands were visualized by chemiluminescence (Pierce, Rockford, IL) and autoradiography.…”

Sex: A Significant Risk Factor for Neurodevelopmental and Neurodegenerative Disorders

“…Considering the expression of SRY in the human male SNc [280], a brain region that degenerates in PD, dysregulation of SRY in male dopamine neurons may underlie the male preponderance to PD. Indeed, SRY expression is aberrantly elevated in a human cell culture model of PD [320]. Whilst other Y-linked genes, such as neuroligin 4, will also need to be examined for their role in male-biased neurodevelopmental disorders [321], these results highlight the need to better understand the molecular regulation, function, and targets of SRY in the healthy and diseased male brain.…”

A general theory of sexual differentiation

“…Examples are as follows: Sry acts directly within the brain to make it function differently (Czech et al, 2014; Dewing et al, 2006). Other Y genes have an inherently male function because they act on germ cells in a cell-autonomous fashion and are required for spermatogenesis, a male-specific function (Burgoyne and Mitchell, 2007).…”