Cadmium-induced Sertoli Cell Injury Through p38-MAPK and Related Signaling Proteins-A Study by RNA Sequencing

Environmental toxicants, such as cadmium, found in foods, water, and consumer products are known to induce male reproductive dysfunction. However, the underlying molecular mechanism(s) by which cadmium-induced Sertoli cell injury as manifested by a disruption of the blood-testis barrier (BTB) remains unknown. Interestingly, one of the primary targets of cadmium toxicity in the testis is the cytoskeletons of the Sertoli cells, which, in turn, impedes cell junctions in the seminiferous epithelium. In order to expand these earlier observations and to provide a roadmap for future studies, we embarked a study using RNA sequencing to identify the pertinent genes involved in cadmium-induced Sertoli cell injury. Using bioinformatics analyses, multiple gene sets that regulated actin and microtubule (MT) cytoskeletons were identified along with components of the mitogen-activated protein kinase (MAPK) signaling protein and several signaling pathways. More important, we have also discovered that while the gene expression of p38-MAPK (also JNK or c-Jun) was considerably up- or downregulated during cadmium-induced Sertoli cell injury, the activated (phosphorylated) form was upregulated. Importantly, doramapimod (also known as BIRB 796), a specific p38-MARK inhibitor, that was shown to selectively block cadmium-induced p-p38 MAPK activation via phosphorylation in Sertoli cells, was indeed capable of blocking cadmium-induced Sertoli cell injury including disruption of the Sertoli cell-permeability barrier function, disruptive distribution of BTB-associated proteins, and disruptive organization of the actin and MT cytoskeletons. These data provide a helpful source of information for investigators to probe the role of signaling proteins and/or their signaling cascades, besides MAPKs, that likely utilized by cadmium to induce reproductive dysfunction.