Insight into the Regulatory Relationships between the Insulin-Like Androgenic Gland Hormone Gene and the Insulin-Like Androgenic Gland Hormone-binding Protein Gene in Giant Freshwater Prawns (Macrobrachium rosenbergii)

Abstract

Giant freshwater prawns (Macrobrachium rosenbergii) are commonly found throughout the world. The size of the male giant freshwater prawn is much larger than that of the female. Therefore, understanding the molecular mechanism that underlies the sexual differentiation of M. rosenbergii is of both commercial and scientific importance. Insulin-like androgenic gland hormone (IAG) plays a key role in the differentiation of sex in M. rosenbergii. Although IAG has been investigated, the regulatory relationship between IAG and its binding protein partner, the insulin-like androgenic gland hormone-binding protein (IAGBP), has not been studied in M. rosenbergii. Here, we cloned and characterized the IAGBP from M. rosenbergii (Mr-IAGBP) for the very first time. Transcriptomic analysis showed that Mr-IAGBP mRNA was detected in a wide array of tissues with the highest expression found in the androgenic gland. The importance of IAG in male development was further demonstrated by an increase in IAG transcripts during the development of the androgenic gland and Mr-IAG was only highly transcribed in the androgenic gland of M. rosenbergii. Interestingly, we found that the Mr-IAG gene expression started during the 20th-day larva after hatching stage (LH20), followed (20th-day post-larval stage, PL20) by a gradual elevation of Mr-IAGBP levels. The levels of both genes peaked at the adult stage. The relationship between Mr-IAGBP and Mr-IAG was further analyzed using RNA interference. The injection of Mr-IAGBP double-stranded RNA (dsRNA) significantly reduced the transcription of Mr-IAG, while the amount of Mr-IAGBP mRNA and the translation of IAGBP protein was significantly reduced by the injection of Mr-IAG dsRNA. These results revealed that IAGBP is involved in IAG signaling. Furthermore, our data supports the hypothesis that (IAG and IAGBP)-IAG receptor signaling schemes exist in M. rosenbergii. Our results will provide important information for the further study of determining the sex of M. rosenbergii.

The Regulatory Relationships Between the Gonad-Inhibiting Hormone and Insulin-Like Androgenic Gland Hormone-Binding Protein Genes in the Eyestalk-Androgenic Gland-Testis Axis of Macrobrachium rosenbergii

“…The IAG signaling pathway is directly activated by the binding of insulin-like peptides to their receptors, including IAGR and IAGBP. For example, the knockdown of IAGBP in M. rosenbergii (Yang et al, 2020) and the knockdown of IAGR in M. nipponense (Li et al, 2015a) lead to the downregulation of IAG expression. The XO-SG, located at the base of the eyestalk, is the centralhub of the neuroendocrine system in crustaceans (Dircksen et al, 2001).…”

“…HIScript R Q Select RT SuperMix and ChamQ SYBR qPCR Master Mix were both obtained from Vazyme (Nanjing, China). Rabbit polyclonal antibodies against MrGIH and MrIAGBP ( Yang et al, 2020) were produced and purified by Frdbio Bioscience and Technology Company (Wuhan, China) and stored at −80 • C prior to use.…”

“…In brief, the expression profile of MrGIH was tested in each of the tissue types by quantitative polymerase chain reaction (qPCR). The β−actin gene (Yang et al, 2020) was used as an internal reference and the 2 − CT method was used to calculate the relative expression levels of MrGIH.…”

“…Surprisingly, GIH acts directly on the AG rather than the testis in male crustaceans. The GIH gene interacts with other AG genes containing insulin-like androgenic gland hormone (IAG) (Ventura et al, 2011), insulin-like androgenic gland hormone receptor (IAGR) (Sharabi et al, 2016), and insulin-like androgenic gland hormone-binding protein (IAGBP) (Yang et al, 2020) to regulate sexual reproduction and the maturation of gonads (Fingerman, 1997a,b). The GIH gene, which encodes a specific eyestalk-derived hormone, exerts action on the eyestalk-androgenic gland (AG)-testis axis to mediate the activity of the AG (Khalaila et al, 2002).…”

A sex‐reversing factor: insulin‐like androgenic gland hormone in decapods

“…4). The relationship between IAG and insulin-like androgenic gland hormone-binding protein (IAGBP) was revealed by RNAi in M. nipponense (Li et al 2015a) and M. rosenbergii (Yang et al 2020). These two studies showed that silencing IAG in AG caused the reduction of IAGBP expression level, and vice versa.…”