PICK1 deficiency causes male infertility in mice by disrupting acrosome formation

Abstract

Protein interacting with C kinase 1 (PICK1) is a peripheral membrane protein involved in protein trafficking, a function that has been well characterized in neurons. Here, we report that male mice deficient in PICK1 are infertile and have a phenotype resembling the human disease globozoospermia. The primary defect in the testes of Pick1-knockout mice was fragmentation of acrosomes in the early stages of spermiogenesis. This fragmentation was followed by defects in nuclear elongation and mitochondrial sheath formation, leading to round-headed sperm, reduced sperm count, and severely impaired sperm motility. We found that PICK1 interacted with Golgi-associated PDZ-and coiled-coil motif-containing protein (GOPC) and the primary catalytic subunit of protein kinase 2 (CK2α′), proteins whose deficiencies lead to globozoospermia in mice. PICK1 was highly expressed in round spermatids and localized to Golgi-derived proacrosomal granules. GOPC colocalized with PICK1 in the Golgi region and facilitated formation of PICK1-positive clusters. Furthermore, there was an increase in apoptosis in the seminiferous tubules of Pick1 -/-mice, a phenotype also seen in CK2α′-deficient mice. Our results suggest that PICK1 is involved in vesicle trafficking from the Golgi apparatus to the acrosome and cooperates with other proteins such as GOPC and CK2α′ in acrosome biogenesis. IntroductionProtein interacting with C kinase 1 (PICK1) is a peripheral membrane protein involved in protein trafficking. PICK1 was initially identified as a protein kinase C-interacting protein from a yeast two-hybrid screen (1). Subsequently, many proteins have been found to interact with PICK1 (2). The majority of these proteins are membrane proteins, such as glutamate receptors, dopamine transporter, Eph receptors, and acid-sensing ion channels (3-8). These interactions usually occur between the C termini of the membrane proteins and PICK1's postsynaptic density 95, discs large, and zonula occludens-1 (PDZ) domain, a well-characterized protein-protein interaction module. In most cases, PICK1 regulates the subcellular localization or cell-surface expression of its PDZ domain-binding partners.Studies of PICK1's role in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor trafficking have provided much information that helps us to understand PICK1's function. The AMPA receptor is a subtype of glutamate receptor that mediates the majority of excitatory synaptic transmission in the brain (9). The role of PICK1 has been extensively studied in AMPA receptor trafficking because of its implication in synaptic plasticity, a cellular model of learning and memory (10). PICK1 was found to interact specifically with the C termini of AMPA receptor subunits

Atg7 is required for acrosome biogenesis during spermatogenesis in mice

“…A significant number of apoptotic cells were found in TNAPAtg7 −/− mouse testes compared with those in the Atg7 Flox/ Flox mice (Supplementary information, Figure S1A). These results are consistent with a previous report [11] and suggest that those vacuoles might come from dead germ cells. However, even in the testis of the TNAPAtg7 −/− mice, no more than 0.5% of the germ cells died by apoptosis (Supplementary information, Figure S1B).…”

“…The results of histology study showed that although the diameters of round seminiferous tubules in TNAP-Atg7 −/− mice were comparable to those in Atg7 Flox/ Flox mice ( Figure 1E), a substantial portion of the tubule structure was disorganized with large vacuoles in TNAPAtg7 −/− compared with the normal seminiferous tubules in the Atg7 Flox/Flox male siblings ( Figure 1F and 1G). Those vacuoles in the tubule lumens usually come from dead germ cells [11]. We next used terminal deoxynucleotidyl transferase dUTP nick end labeling assay to investigate whether there was apoptosis in those germ cells.…”

PICK1 promotes caveolin-dependent degradation of TGF-β type I receptor

“…PICK1 is a scaffold protein to control trafficking of several membrane receptors, including AMPA receptor and ASIC, and has been implicated to function in nervous system and male fertility [17,19,20,42]. Here, we identify PICK1 as a novel negative regulator of TGF-β signaling by modulating subcellular localization and trafficking of TβRI.…”

“…Pick1 -/-mice have been reported [42]. MEFs were isolated and cultured as previously described [51].…”

Genetic aspects of monomorphic teratozoospermia: a review

“…Indeed, the SPATA16 protein localizes to the Golgi apparatus and the proacrosomal granules that are transported in the acrosome in round and elongated spermatids [41]. Pick1 localizes to Golgi-derived proacrosomal granules and is involved in vesicle trafficking from the Golgi to the acrosome and participates in acrosome biogenesis [42].…”