Pacific White Shrimp (Litopenaeus vannamei) Vitellogenesis-Inhibiting Hormone (VIH) Is Predominantly Expressed in the Brain and Negatively Regulates Hepatopancreatic Vitellogenin (VTG) Gene Expression1

Abstract

Ovarian maturation in crustaceans is temporally orchestrated by two processes: oogenesis and vitellogenesis. The peptide hormone vitellogenesis-inhibiting hormone (VIH), by far the most potent negative regulator of crustacean reproduction known, critically modulates crustacean ovarian maturation by suppressing vitellogenin (VTG) synthesis. In this study, cDNA encoding VIH was cloned from the eyestalk of Pacific white shrimp, Litopenaeus vannamei, a highly significant commercial culture species. Phylogenetic analysis suggests that L. vannamei VIH (lvVIH) can be classified as a member of the type II crustacean hyperglycemic hormone family. Northern blot and RT-PCR results reveal that both the brain and eyestalk were the major sources for lvVIH mRNA expression. In in vitro experiments on primary culture of shrimp hepatopancreatic cells, it was confirmed that some endogenous inhibitory factors existed in L. vannamei hemolymph, brain, and eyestalk that suppressed hepatopancreatic VTG gene expression. Purified recombinant lvVIH protein was effective in inhibiting VTG mRNA expression in both in vitro primary hepatopancreatic cell culture and in vivo injection experiments. Injection of recombinant VIH could also reverse ovarian growth induced by eyestalk ablation. Furthermore, unilateral eyestalk ablation reduced the mRNA level of lvVIH in the brain but not in the remaining contralateral eyestalk. Our study, as a whole, provides new insights on VIH regulation of shrimp reproduction: 1) the brain and eyestalk are both important sites of VIH expression and therefore possible coregulators of hepatopancreatic VTG mRNA expression and 2) eyestalk ablation could increase hepatopancreatic VTG expression by transcriptionally abolishing eyestalk-derived VIH and diminishing brain-derived VIH.

In vivo and in vitro inhibitory action of 17β-estradiol and environmental estrogen 4-nonylphenol on gonad-inhibiting hormone (GIH) expression in the eyestalks of Litopenaeus vannamei

“…Furthermore, the injection of anti-GIH antibodies can produce ovarian maturation and spawning effects similar to those resulting from unilateral eyestalk ablation in Penaeus monodon (Treerattrakool et al, 2014). In Metanephrops japonicus and Litopenaeus vannamei, recombinant GIH administration can significantly reduce Vtg mRNA levels (Ohira et al, 2005;Chen et al, 2014). These results strongly suggest that GIH is a major factor involved in female crustacean reproduction.…”

“…Therefore, it is possible that estrogens might be involved in the regulation of oocytes at early stages in mysid shrimp (Neomysis japonica) (Yang et al, 2012). The brain and eyestalks are well-known major synthesis sites for GIH that is involved in crustacean reproductive endocrine functions (Treerattrakool, 2008;Chen et al, 2014). However, whether estrogens are also involved in the feedback regulation of GIH synthesis and secretion is still unknown.…”

Isolation of crustacean hyperglycemic hormone-family peptides with vitellogenesis-inhibiting activity from the shiba shrimp Metapenaeus joyneri

“…These results suggest that Mej-SGP-II might have a C-terminal amide. On the other hand, a cDNA encoding a new CHH-family peptide (lvVIH) was cloned from L. vannamei recently and its recombinant peptide inhibited hepatopancreas vg expression in vitro primary cell culture [19]. Both lvVIH and the aforementioned Pem-GIH are classified as type II and possess a free C-terminus.…”

“…On the other hand, a type II peptide, Pem-GIH, has been reported to regulate ovarian vg expression in Penaeus monodon [18]. Regarding the regulation in the extraovarian site, it has recently been reported that another type II peptide, lvVIH, derived from the eyestalk and brain possesses vitellogenesis-inhibiting activity on the hepatopancreas of L. vannamei [19]. Thus, it has been shown that various CHH-family peptides are involved in the regulation of vitellogenesis using vg expression as a molecular index in commercially important penaeid species.…”

cDNA cloning, expression, and immunolocalization of gonad-inhibiting hormone (GIH) in Litopenaeus vannamei

“…Members of the CHH family contain six conserved cysteine residues and can be divided into two subfamilies, Type I (CHH/ITP) and Type II (MIH, MOIH, GIH/VIH), according to their amino acid sequences and precursor structures (Chan et al 2003). GIH (also known as vitellogenesis inhibiting hormone, VIH) is a member of the CHH family (Edomi et al 2002;Lacombe et al 1999) and since the first report of the primary structure of two VIH isoforms from the lobster, Homarus americanus (Soyez et al 1991), many putative GIH or VIH sequences have been reported from a variety of species including P. monodon (Treerattrakool et al 2008), Nephrops norvegicus (Edomi et al 2002), L. vannamei (Tsutsui et al 2013;Chen et al 2014), Procambarus bouvieri (Aguilar et al 1992), and H. americanus (De Kleijn et al 1994). The majority of the GIH peptides comprise 77-83 amino acids with a molecular mass between 7 and 11 kDa, and they share a high degree of amino acid sequence similarity.…”