MsSOCS expression indicates a potential role for JAK/STAT signalling in the early stages of Manduca sexta spermatogenesis

Our understanding of the Drosophila melanogaster testis stem cell niche has identified the signalling pathways required to maintain stem cells and promote self-renewal. Here we present the first detailed examination of the testes stem cell niche in the lepidopteran Manduca sexta . We show that larval testes contain hub-like structures surrounded by mitotically active cells likely to represent a self-renewing stem cell population. In addition, we have cloned DNA fragments encoding parts of M. sexta Signal Transducer and Activators of Transcription (STAT) and Suppressor of Cytokine Signalling (SOCS) homologues and show that expression of MsSOCS is upregulated in hub-adjacent cells. Given the conservation of socs-like genes and their regulation as Janus Kinases/Signal Transducer and Activators Transcription (JAK/STAT) pathway targets, we suggest that increased expression within the testis stem cells indicates increased levels of JAK/STAT signalling and a conserved role for pathway signalling in testis stem cell maintenance.