Properties, metabolism and roles of sulfogalactosylglycerolipid in male reproduction

Abstract

Sulfogalactosylglycerolipid (SGG, aka seminolipid) is selectively synthesized in high amounts in mammalian testicular germ cells (TGCs). SGG is an ordered lipid and directly involved in cell adhesion. SGG is indispensable for spermatogenesis, a process that greatly depends on interaction between Sertoli cells and TGCs. Spermatogenesis is disrupted in mice null for Cgt and Cst, encoding two enzymes essential for SGG biosynthesis. Sperm surface SGG also plays roles in fertilization. All of these results indicate the significance of SGG in male reproduction. SGG homeostasis is also important in male fertility. Approximately 50% of TGCs become apoptotic and phagocytosed by Sertoli cells. SGG in apoptotic remnants needs to be degraded by Sertoli lysosomal enzymes to the lipid backbone. Failure in this event leads to a lysosomal storage disorder and sub-functionality of Sertoli cells, including their support for TGC development, and consequently subfertility. Significantly, both biosynthesis and degradation pathways of the galactosylsulfate head group of SGG are the same as those of sulfogalactosylceramide (SGC), a structurally related sulfoglycolipid important for brain functions. If subfertility in males with gene mutations in SGG/SGC metabolism pathways manifests prior to neurological disorder, sperm SGG levels might be used as a reporting/predicting index of the neurological status.

Sperm can act as vectors for HIV‐1 transmission into vaginal and cervical epithelial cells

“…Although GG is a precursor of SGG, the synthesis of SGG is already completed in the early phase of spermatogenesis. The presence of GG in mature intact sperm is therefore very unlikely . Our gp120‐lipid binding experiments indicated that gp120 interacted with a respectable affinity for SGG, and the computational modeling studies further supported this finding (Figures C and ).…”

“…Similar to GC, SGC is also a non‐canonical attachment receptor of HIV‐1 and the binding of GC, SGC, and SGG liposomes in solution to gp120 has been previously demonstrated . Since SGG is usually present selectively in male germ cells, its presence in Vk2/E6E7 cells is unusual. Nonetheless, as a structural analogue of SGC, SGG may also be a non‐canonical attachment receptor of HIV‐1 on Vk2/E6E7 cells.…”

“…In addition, glycolipids believed to be present on the sperm surface, including galactosylceramide (GC), galactosylglycerolipid (GG), and sulfogalactosylglycerolipid (SGG), have been demonstrated to have affinity for HIV‐1 gp120 (see chemical structures of these lipids and other lipids in Figure ). However, among these glycolipids, only SGG exists on sperm at a substantial amount (10 mole% of total sperm lipids), thus demanding a better understanding of how it interacts with HIV‐1 gp120.…”

Sperm Lipid Composition in Early Diverged Fish Species: Internal vs. External Mode of Fertilization

“…Female stingrays are also assumed to store sperm for a prolonged period [46], like other cartilaginous fishes which can store sperm for a year and beyond [47,48]. In mammals, the sulfogalactosylglycerolipid, called seminolipid, is indispensable for spermatogenesis, sperm function, and fertilization (reviewed in [49]). Specifically, the involvement of seminolipid in the direct binding to the zona pellucida was suggested [50].…”

Unequivocal mapping of molecular ether lipid species by LC-MS/MS in plasmalogen-deficient mice

“…As is demonstrated in Figure 5C, PE ether lipids occur mostly as plasmalogens except for testis where we find equal amounts of 1-O-alkyl and 1-O-alk-1'-enyl PE species. In testis, seminolipid is formed which is a complex ether lipid without a vinyl ether bond and is required for male fertility and sperm maturation 31 . Remarkably, male PEDS knock-out mice are fertile 32 ,5 underlining the notion that no vinyl ether bond is required for seminolipid function.…”