Identifying a possible mechanism for Sudden Infant Death with Dysgenesis of Testes Syndrome (SIDDT)

Abstract

<p><strong>Background and aims</strong>:</p><p>SIDDT is caused by loss-of-function mutations of TSPYL1 gene which was firstly reported in 2004. It is characterized by sudden cardiac or respiratory arrest, disordered testicular development, neurologic dysfunction and patients die in the first year of life. However, so far how mutations of TSPYL1 cause SIDDT is unknown. Previously, we found that the level of TSPYL2 increased upon TSPYL1 knockdown (KD) through Transforming growth factor β (TGFβ) signalling. Therefore, we aimed to decipher TSPYL1 function <em>in vivo</em> and contribute to the understanding of pathology of SIDDT.</p><p><br></p><p><strong>Methods</strong>:</p><p>We used lentivirus system to generate TSPYL1 KD in mouse embryonic fibroblasts (MEF). We verified TGFβ target genes by qPCR and Western Blot. We also generated <em>Tspyl1 </em>knockout (KO) mice and compared the disease phenotype with SIDDT patients. Then we collected lung tissue at different days of embryonic and postnatal stage. Histological analysis was also done at postnatal day 14. To identify the function of TSPYL2 upon TSPYL1 deficiency, we generated double KO mice.</p><p><br></p><p><strong>Results</strong>:</p><p>We found TSPYL1 KD in MEF increased the transcript of TGFβ target genes and also increased the expression of TSPYL2. Although the <em>Tspyl1</em> KO mouse model cannot represent SIDDT, it was still helpful for identifying TSPYL1 function. We found that <em>Tspyl1</em> KO mice had pre-weaning lethality and had disease phenotype such as small size and hypothermia. However, the lethal phenotype of <em>Tspyl1</em> KO can be completely rescued by loss of TSPYL2. We also detected increased TSPYL2 proteins in <em>Tspyl1</em>^-/- lung samples collected from 0-, 7- and 14-day old KO mice. Abnormal alveolarization was found in <em>Tspyl1</em> KO mice.</p><p><br></p><p><strong>Conclusions</strong>:</p><p>TSPYL1 acted as a vital regulator to suppress TSPYL2 expression through TGFβ signalling <em>in vivo</em>.</p>