major sperm protein
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2022 ◽  
Vol 221 (3) ◽  
Author(s):  
Suzan Kors ◽  
Christian Hacker ◽  
Chloe Bolton ◽  
Renate Maier ◽  
Lena Reimann ◽  
...  

Peroxisomes and the endoplasmic reticulum (ER) cooperate in cellular lipid metabolism. They form membrane contacts through interaction of the peroxisomal membrane protein ACBD5 (acyl-coenzyme A–binding domain protein 5) and the ER-resident protein VAPB (vesicle-associated membrane protein–associated protein B). ACBD5 binds to the major sperm protein domain of VAPB via its FFAT-like (two phenylalanines [FF] in an acidic tract) motif. However, molecular mechanisms, which regulate formation of these membrane contact sites, are unknown. Here, we reveal that peroxisome–ER associations via the ACBD5-VAPB tether are regulated by phosphorylation. We show that ACBD5-VAPB binding is phosphatase-sensitive and identify phosphorylation sites in the flanking regions and core of the FFAT-like motif, which alter interaction with VAPB—and thus peroxisome–ER contact sites—differently. Moreover, we demonstrate that GSK3β (glycogen synthase kinase-3 β) regulates this interaction. Our findings reveal for the first time a molecular mechanism for the regulation of peroxisome–ER contacts in mammalian cells and expand the current model of FFAT motifs and VAP interaction.


Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 55
Author(s):  
Andrea Springer ◽  
Christian von Holtum ◽  
Georg von Samson-Himmelstjerna ◽  
Christina Strube

The lungworm Dictyocaulus viviparus is one of the most economically important bovine parasites in temperate climate regions. Following infection, D. viviparus induces a temporary protective immunity, and a vaccine based on attenuated, infective larvae is commercially available. However, due to several disadvantages of the live vaccine, the development of a recombinant subunit vaccine is highly desirable. Therefore, the major sperm protein (MSP), which is essential for the parasite’s reproduction, was tested as a recombinantly Escherichia coli-expressed glutathione-S-transferase (GST)-fused vaccine antigen in immunization trials with two different adjuvants, Quil A and Al(OH)3. Calves (N = 4 per group) were immunized on study day (SD) 0, 21 and 42 and given a challenge infection on SD 63–65. The two control groups received only the respective adjuvant. Based on geometric means (GM), a 53.64% reduction in larvae per female worm was observed in the rMSP Quil A group vs. its control group (arithmetic means (AM): 54.43%), but this difference was not statistically significant. In the rMSP Al(OH)3 group, the mean number of larvae per female worm was even higher than in the respective control group (GM: 9.24%, AM: 14.14%). Furthermore, male and female worm burdens and the absolute number of larvae did not differ significantly, while the Al(OH)3 control group harbored significantly longer worms than the vaccinated group. Vaccinated animals showed a rise in rMSP-specific antibodies, particularly IgG and its subclass IgG1, and the native protein was detected by immunoblots. Although rMSP alone did not lead to significantly reduced worm fecundity, it might still prove useful as part of a multi-component vaccine.


2021 ◽  
Author(s):  
Xia Wang ◽  
Qiushi Wang ◽  
Ruijun He ◽  
Qi Zhang ◽  
Jin Shan ◽  
...  

Sperm motility acquisition during maturation is essential for successful fertilization.Extracellular adenosine-5'-triphosphate (ATP) level mediation by MIG-23, which is a homolog of human ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), was required for major sperm protein filament dynamics and sperm motility in the nematode Ascaris suum. MIG-23 was localized on the sperm plasma membrane. During sperm activation, mitochondrial activity was increased dramatically, and a large amount of ATP was produced and stored in refringent granules (RGs). In addition, a portion of the produced ATP was released to the extracellular space through ATP channels, which were composed of innexins and localized on the sperm plasma membrane. Spermatozoa, instead of spermatids, hydrolyzed exogenous ATP and processed ecto-ATPase activity. MIG-23 contributed to the ecto-ATPase activity of spermatozoa. MIG-23 activity was interrupted, spermatozoa also decreased their ATP hydrolysis activity. Blocking MIG-23 activity resulted in an increase in the depolymerization rate of MSP filaments in pseudopodia, which eventually affected nematode sperm migration. Overall, our data imply that MIG-23, which contributes to the ecto-ATPase activity of spermatozoa, regulates sperm migration by modulating extracellular ATP levels.


2021 ◽  
Author(s):  
Suzan Kors ◽  
Christian Hacker ◽  
Chloe Bolton ◽  
Renate Maier ◽  
Lena Reimann ◽  
...  

Peroxisomes and the endoplasmic reticulum (ER) cooperate in cellular lipid metabolism. They form membrane contacts through interaction of the peroxisomal membrane protein ACBD5 [acyl-coenzyme A-binding domain protein 5] and the ER-resident protein VAPB [vesicle-associated membrane protein-associated protein B]. ACBD5 binds to the major sperm protein domain of VAPB via its FFAT-like [two phenylalanines (FF) in an acidic tract] motif. However, molecular mechanisms, which regulate formation of these membrane contact sites, are unknown. Here, we reveal that peroxisome-ER associations via the ACBD5-VAPB tether are regulated by phosphorylation. We show that ACBD5-VAPB binding is phosphatase-sensitive and identify phosphorylation sites in the flanking regions and core of the FFAT-like motif, which alter interaction with VAPB and thus, peroxisome-ER contact sites differently. Moreover, we demonstrate that GSK3β [glycogen synthase kinase-3 beta] regulates this interaction. Our findings reveal for the first time a molecular mechanism for the regulation of peroxisome-ER contacts in mammalian cells and expand the current model of FFAT motifs and VAP interaction.


2021 ◽  
Author(s):  
Mikaela Murph ◽  
Shaneen Singh ◽  
Mara Schvarzstein

AbstractCentrosomes are organelles that function as hubs of microtubule nucleation and organization, with key roles in organelle positioning, asymmetric cell division, and ciliogenesis. Aberrant centrosome structure or function is linked to neurodegenerative diseases, developmental abnormalities, ciliopathies, and tumor development. A major regulator of centrosome biogenesis and function in C. elegans is the highly conserved protein Spindle-defective protein 2 (SPD-2), a homolog of the human CEP-192 protein. CeSPD-2 is required for centrosome maturation, centriole duplication, spindle assembly and cell polarity establishment. Despite its importance, the specific molecular mechanism of CeSPD-2 function is poorly understood. To address this gap in knowledge, we combined computational analysis with cell biology approaches to uncover structure-function relationships of CeSPD-2 that may shed mechanistic light on its function. Domain prediction analysis corroborated and refined previously identified coiled-coils and ASH (Aspm-SPD-2 Hydin) domains and identified new domains and motifs: an additional coiled-coil, a GEF domain, an Ig-like domain, and a PDZ-like domain. Our findings suggest that ASH domain belongs to the same superfold as PapD chaperone domains and Major Sperm Protein (MSP) domains within the larger Immunoglobulin superfamily. We have identified a large novel basic region in the CeSPD-2 ASH domain that harbors most of the predicted protein and nucleic acid contact residues in the ASH domain. In vivo, ASH::GFP localized to centrosomes and centrosome associated microtubules, and forms aggregates in the cytosol when overexpressed. This study lays the groundwork for designing rational hypothesis-based experiments for future analyses to further elaborate the mechanisms of CeSPD-2 function in vivo.


2021 ◽  
Author(s):  
Zengcui Zhang ◽  
Katherine L.D. Running ◽  
Sudeshi Seneviratne ◽  
Amanda R. Peters Haugrud ◽  
Agnes Szabo‐Hever ◽  
...  

Development ◽  
2021 ◽  
Vol 148 (5) ◽  
pp. dev195875
Author(s):  
Kari L. Price ◽  
Marc Presler ◽  
Christopher M. Uyehara ◽  
Diane C. Shakes

ABSTRACTMany specialized cells use unconventional strategies of cytoskeletal control. Nematode spermatocytes discard their actin and tubulin following meiosis, and instead employ the regulated assembly/disassembly of the Major Sperm Protein (MSP) to drive sperm motility. However, prior to the meiotic divisions, MSP is sequestered through its assembly into paracrystalline structures called fibrous bodies (FBs). The accessory proteins that direct this sequestration process have remained mysterious. This study reveals SPE-18 as an intrinsically disordered protein that is essential for MSP assembly within FBs. In spe-18 mutant spermatocytes, MSP forms disorganized cortical fibers, and the cells arrest in meiosis without forming haploid sperm. In wild-type spermatocytes, SPE-18 localizes to pre-FB complexes and functions with the kinase SPE-6 to localize MSP assembly. Changing patterns of SPE-18 localization uncover previously unappreciated complexities in FB maturation. Later, within newly individualized spermatids, SPE-18 is rapidly lost, yet SPE-18 loss alone is insufficient for MSP disassembly. Our findings reveal an alternative strategy for sequestering cytoskeletal elements, not as monomers but in localized, bundled polymers. Additionally, these studies provide an important example of disordered proteins promoting ordered cellular structures.


2021 ◽  
Author(s):  
Hala Zein-Sabatto ◽  
Jim Collawn ◽  
Chenbei Chang ◽  
Michael A. Miller

AbstractVAPB (VPR-1 in C. elegans) is a type-II ER transmembrane protein whose N-terminal Major Sperm Protein domain (MSPd) is cleaved and secreted. Mutations in the MSPd of human VAPB cause impaired secretion and are associated with Amyotrophic Lateral Sclerosis (ALS). In C. elegans, the secreted MSPd signals non-cell-autonomously to regulate striated muscle mitochondrial morphology and gonad development. As VAPB/VPR-1 does not have a signal peptide and its MSPd extends into the cytosol, it is unclear how the protein is proteolytically cleaved and secreted. To identify genes that are involved in VPR-1 cleavage and unconventional secretion, we performed an RNA interference (RNAi) screen in C. elegans. Worms null for vpr-1 are sterile and have striated muscle mitochondrial abnormalities. These defects can be rescued by vpr-1 expression in the neurons, germline, or intestine, implying that these three tissues share a common machinery to cleave and secrete the MSPd. Examination of shared gene expression in these tissues revealed a list of 422 genes, which we targeted with RNAi. vpr-1 null worms expressing vpr-1 from intestine were used in the screen, and the brood size of these worms after RNAi knockdown was scored. Disruption of factors involved in VPR-1 MSPd processing and/or secretion should revert fertility phenotypes in these worms. We identified many genes that induce compromised fertility when knocked down in these but not wild type worms, including a V-SNARE, several proteasome components, stress response molecules, and mitochondrial genes. Our screen thus identified many potential players involved in MSPd processing and/or secretion.SummaryThe MSP domain (MSPd) of a type-II ER transmembrane protein called VAPB is cleaved and secreted to function as a non-cell-autonomous signal. The topology of VAPB positions MSPd in the cytosol. It is thus unclear how MSPd is cleaved from VAPB and released extracellularly. Using C. elegans, we screened 422 genes by RNAi to identify potential candidates regulating MSPd cleaving and secretion. We identified the Golgi v-SNARE YKT-6 and several components of the 20S and 19S proteasome that may mediate MSPd trafficking and cleaving, respectively. These results have promising implications in advancing our understanding of MSPd signaling.


Author(s):  
Katsuya Shimabukuro ◽  
Thomas M. Roberts ◽  
Vikash Verma

Development ◽  
2020 ◽  
Vol 147 (22) ◽  
pp. dev193862
Author(s):  
James Matthew Ragle ◽  
Abigail L. Aita ◽  
Kayleigh N. Morrison ◽  
Raquel Martinez-Mendez ◽  
Hannah N. Saeger ◽  
...  

ABSTRACTIn sexually reproducing metazoans, spermatogenesis is the process by which uncommitted germ cells give rise to haploid sperm. Work in model systems has revealed mechanisms controlling commitment to the sperm fate, but how this fate is subsequently executed remains less clear. While studying the well-established role of the conserved nuclear hormone receptor transcription factor, NHR-23/NR1F1, in regulating C. elegans molting, we discovered that NHR-23/NR1F1 is also constitutively expressed in developing primary spermatocytes and is a critical regulator of spermatogenesis. In this novel role, NHR-23/NR1F1 functions downstream of the canonical sex-determination pathway. Degron-mediated depletion of NHR-23/NR1F1 within hermaphrodite or male germlines causes sterility due to an absence of functional sperm, as depleted animals produce arrested primary spermatocytes rather than haploid sperm. These spermatocytes arrest in prometaphase I and fail to either progress to anaphase or attempt spermatid-residual body partitioning. They make sperm-specific membranous organelles but fail to assemble their major sperm protein into fibrous bodies. NHR-23/NR1F1 appears to function independently of the known SPE-44 gene regulatory network, revealing the existence of an NHR-23/NR1F1-mediated module that regulates the spermatogenesis program.


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