Septins at the annulus of mammalian sperm

2011 ◽  
Vol 392 (8-9) ◽  
pp. 799-803 ◽  
Author(s):  
Aminata Toure ◽  
Baptiste Rode ◽  
Gary R. Hunnicutt ◽  
Denise Escalier ◽  
Gérard Gacon
Keyword(s):  
Transmembrane Protein ◽  
Family Studies ◽  
Ring Structure ◽  
Mature Sperm ◽  
Protein Diffusion ◽  
Dense Ring ◽  
Sperm Flagellum ◽  
Mammalian Sperm ◽  
Anion Transporter ◽  
Principal Piece

Abstract The annulus is an electron-dense ring structure connecting the midpiece and the principal piece of the mammalian sperm flagellum. Proteins from the septin family have been shown to localize to the annulus. A septin complex is assembled early in spermiogenesis with the cochaperone DNAJB13 and, in mature sperm, associates with Testis Anion Transporter 1; SLC26A8 (Tat1), a transmembrane protein of the SLC26 family. Studies in mice have shown that the annulus acts as a barrier to protein diffusion and controls correct organization of the midpiece. Consistent with these findings, absence of the annulus is associated with flagellum differentiation defects and asthenozoospermia in humans.

scholarly journals Olfactory receptors are displayed on dog mature sperm cells.

1993 ◽  
Vol 123 (6) ◽  
pp. 1441-1452 ◽  
Author(s):  
P Vanderhaeghen ◽  
S Schurmans ◽  
G Vassart ◽  
M Parmentier
Keyword(s):  
Olfactory Receptor ◽  
Germ Line ◽  
Receptor Gene ◽  
Olfactory Receptors ◽  
Olfactory Mucosa ◽  
Mature Sperm ◽  
Sperm Cells ◽  
Olfactory Receptor Gene ◽  
Mammalian Sperm ◽  
Expression Site

Olfactory receptors constitute a huge family of structurally related G protein-coupled receptors, with up to a thousand members expected. We have shown previously that genes belonging to this family were expressed in the male germ line from both dog and human. The functional significance of this unexpected site of expression was further investigated in the present study. We demonstrate that a few dog genes representative of various subfamilies of olfactory receptors are expressed essentially in testis, with little or no expression in olfactory mucosa. Other randomly selected members of the family show the expected site of expression, restricted to the olfactory system. Antibodies were generated against the deduced amino acid sequence of the most abundantly expressed olfactory receptor gene in dog testis. The purified serum was able to detect the gene product (DTMT receptor) in late round and elongated spermatids, as well as in the cytoplasmic droplet that characterizes the maturation of dog sperm cells, and on the tail midpiece of mature spermatozoa. Western blotting further confirmed the presence of a 40-kD immunoreactive protein in the membrane of mature sperm cells. Altogether , these results demonstrate that the main expression site of a subset of the large olfactory receptor gene family is not olfactory mucosa but testis. This expression correlates with the presence of the corresponding protein during sperm cell maturation, and on mature sperm cells. The pattern of expression is consistent with a role as sensor for unidentified chemicals possibly involved in the control of mammalian sperm maturation, migration, and/or fertilization.

scholarly journals KSper, a pH-sensitive K+ current that controls sperm membrane potential

2007 ◽  
Vol 104 (18) ◽  
pp. 7688-7692 ◽  
Author(s):  
Betsy Navarro ◽  
Yuriy Kirichok ◽  
David E. Clapham
Keyword(s):  
Membrane Potential ◽  
Acrosome Reaction ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
Male Reproductive Tract ◽  
Sperm Flagellum ◽  
K Current ◽  
Sperm Membrane ◽  
Principal Piece ◽  
Mammalian Spermatozoa

Mature mammalian spermatozoa are quiescent in the male reproductive tract. Upon ejaculation and during their transit through the female reproductive tract, they undergo changes that enable them to fertilize the egg. During this process of capacitation, they acquire progressive motility, develop hyperactivated motility, and are readied for the acrosome reaction. All of these processes are regulated by intracellular pH. In the female reproductive tract, the spermatozoan cytoplasm alkalinizes, which in turn activates a Ca2+-selective current (ICatSper) required for hyperactivated motility. Here, we show that alkalinization also has a dramatic effect on membrane potential, producing a rapid hyperpolarization. This hyperpolarization is primarily mediated by a weakly outwardly rectifying K+ current (IKSper) originating from the principal piece of the sperm flagellum. Alkalinization activates the pHi-sensitive IKSper, setting the membrane potential to negative potentials where Ca2+ entry via ICatSper is maximized. IKSper is one of two dominant ion currents of capacitated sperm cells.

scholarly journals Basal Sliding and the Mechanics of Oscillation in a Mammalian Sperm Flagellum

2004 ◽  
Vol 87 (6) ◽  
pp. 3934-3944 ◽  
Author(s):  
Geraint G. Vernon ◽  
David M. Woolley
Keyword(s):  
Sperm Flagellum ◽  
Mammalian Sperm ◽  
Basal Sliding

scholarly journals 3D structure and in situ arrangements of CatSper channel in the sperm flagellum

2021 ◽  
Author(s):  
Yanhe Zhao ◽  
Huafeng Wang ◽  
Caroline Wiesehoefer ◽  
Naman B Shah ◽  
Evan Reetz ◽  
...  
Keyword(s):  
Electron Tomography ◽  
3D Structure ◽  
Human Sperm ◽  
Structural Basis ◽  
Sperm Flagellum ◽  
Mammalian Sperm ◽  
Zigzag Pattern ◽  
Associated Proteins

The sperm calcium channel CatSper plays a central role in successful fertilization as a primary Ca2+ gateway into the sperm flagellum. However, the complex subunit composition of CatSper has impeded its reconstitution in vitro and structural elucidation. Here, we applied cryo-electron tomography to visualize the macromolecular organization of the native CatSper channel complex in intact mammalian sperm, as well as identified three additional CatSper-associated proteins. The repeating CatSper units form long zigzag-rows in four nanodomains along the flagella. In both mouse and human sperm, each CatSper repeat consists of a tetrameric pore complex. Murine CatSper contains an additional outwardly directed wing-structure connected to the tetrameric channel. The majority of the extracellular domains form a canopy above each pore-forming channel that interconnects to a zigzag-shaped roof. The intracellular domains link two neighboring channel complexes to a diagonal array. The loss of this intracellular link in Efcab9-/- sperm distorts the longitudinally aligned zigzag pattern and compromises flagellar movement. This work offers unique insights into the mechanisms underlying the assembly and transport of the CatSper complex to generate the nanodomains and provides a long-sought structural basis for understanding CatSper function in the regulation of sperm motility.

scholarly journals Cyclic Nucleotide-gated Channels on the Flagellum Control Ca2+ Entry into Sperm

1998 ◽  
Vol 142 (2) ◽  
pp. 473-484 ◽  
Author(s):  
Burkhard Wiesner ◽  
Jocelyn Weiner ◽  
Ralf Middendorff ◽  
Volker Hagen ◽  
U. Benjamin Kaupp ◽  
...  
Keyword(s):  
Cyclic Nucleotide ◽  
Photoreceptor Cells ◽  
Structural Basis ◽  
Α Subunit ◽  
Cyclic Nucleotide Gated Channels ◽  
Bending Waves ◽  
Mammalian Sperm ◽  
Vertebrate Photoreceptor ◽  
Α And Β Subunits ◽  
Principal Piece

Cyclic nucleotide-gated (CNG) channels are key elements of cGMP- and cAMP-signaling pathways in vertebrate photoreceptor cells and in olfactory sensory neurons, respectively. These channels form heterooligomeric complexes composed of at least two distinct subunits (α and β). The α subunit of cone photoreceptors is also present in mammalian sperm. Here we identify one short and several long less abundant transcripts of β subunits in testis. The α and β subunits are expressed in a characteristic temporal and spatial pattern in sperm and precursor cells. In mature sperm, the α subunit is observed along the entire flagellum, whereas the short β subunit is restricted to the principal piece of the flagellum. These findings suggest that different forms of CNG channels coexist in the flagellum. Confocal microscopy in conjunction with the Ca2+ indicator Fluo-3 shows that the CNG channels serve as a Ca2+ entry pathway that responds more sensitively to cGMP than to cAMP. Assuming that CNG channel subtypes differ in their Ca2+ permeability, dissimilar localization of α and β subunits may give rise to a pattern of Ca2+ microdomains along the flagellum, thereby providing the structural basis for control of flagellar bending waves.

Mechanics of a lipid bilayer subjected to thickness distension and membrane budding

2016 ◽  
Vol 23 (1) ◽  
pp. 67-84 ◽  
Author(s):  
Tsegay Belay ◽  
Kim Chun IL ◽  
Peter Schiavone
Keyword(s):  
Lipid Membrane ◽  
Transmembrane Protein ◽  
Membrane Surface ◽  
Parametric Representation ◽  
Smooth Transition ◽  
Protein Diffusion ◽  
Energy Potential ◽  
Bud Formation ◽  
Proposed Model ◽  
Shape Equation

We study the distension-induced gradient capillarity in membrane bud formation. The budding process is assumed to be primarily driven by diffusion of transmembrane proteins and acting line tensions on the protein-concentrated interface. The proposed model, based on the Helfrich-type potential, is designed to accommodate inhomogeneous elastic responses of the membrane, non-uniform protein distributions over the membrane surface and, more importantly, the thickness distensions induced by bud formations in the membrane. The latter are employed via the augmented energy potential of bulk incompressibility in a weakened manner. By computing the variations of the proposed membrane energy potential, we obtained the corresponding equilibrium equation (membrane shape equation) describing the morphological transitions of the lipid membrane undergoing bud formation and the associated thickness distensions. The effects of lipid distension on the shape equation and the necessary adjustments to the accompanying boundary conditions are also derived in detail. The resulting shape equation is solved numerically for the parametric representation of the surface which has one-to-one-correspondence with the membrane surface under consideration. The proposed model successfully predicts the bud formation phenomenon on a flat lipid membrane and the associated thickness distensions of the membrane and demonstrates a smooth transition from one phase to the other (including necking domains). It is also found that the final deformed configuration is energetically favorable and therefore is stable. Finally, we show that the inhomogeneous thickness deformation on the membrane in response to transmembrane protein diffusion makes a significant contribution to the budding and necking processes of the membrane.

scholarly journals Polymer-Supported Membranes for Probing Transmembrane Protein Diffusion and Interaction by Single-Molecule Techniques

2011 ◽  
Vol 100 (3) ◽  
pp. 257a
Author(s):  
Friedrich Roder ◽  
Dirk Paterok ◽  
Sharon Waichman ◽  
Oliver Beutel ◽  
Jacob Piehler
Keyword(s):  
Single Molecule ◽  
Transmembrane Protein ◽  
Protein Diffusion ◽  
Supported Membranes ◽  
Polymer Supported

scholarly journals A caged progesterone analog alters intracellular Ca2+ and flagellar bending in human sperm

Reproduction ◽  
2012 ◽  
Vol 144 (1) ◽  
pp. 101-109 ◽  
Author(s):  
M Rocio Servin-Vences ◽  
Yoshiro Tatsu ◽  
Hisanori Ando ◽  
Adán Guerrero ◽  
Noboru Yumoto ◽  
...  
Keyword(s):  
Time Lag ◽  
Human Sperm ◽  
Human Spermatozoa ◽  
Mammalian Sperm ◽  
Intracellular Ca ◽  
Stroboscopic Illumination ◽  
Initial Action ◽  
Principal Piece ◽  
Short Time ◽  
First Time

Progesterone is a physiological agonist for mammalian sperm, modulating its flagellar movement and facilitating the acrosome reaction. To study the initial action of progesterone, we developed a caged analog with a photosensitive group: nitrophenylethanediol, at position 20. Using this compound combined with stroboscopic illumination, we performed Ca2+imaging of human spermatozoa and analyzed the effects of progesterone on the intracellular Ca2+concentration ([Ca2+]i) of beating flagella for the first time. We observed a transient [Ca2+]iincrease in the head and the flagellum upon photolysis of the caged progesterone and an increase in flagellar curvature. Detailed kinetic analysis revealed that progesterone elicits an increase in the [Ca2+]iimmediately in the flagellum (mid-piece and principal piece), thereafter in the head with a short time lag. This observation is different from the progesterone-induced Ca2+mobilization in mouse spermatozoa, where the Ca2+rise initiates at the base of the sperm head. Our finding is mostly consistent with the recent discovery that progesterone activates CatSper channels in human spermatozoa, but not in mouse spermatozoa.

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