scholarly journals The association between CDC42 and caveolin-1 is involved in the regulation of capacitation and acrosome reaction of guinea pig and mouse sperm

Reproduction ◽  
2012 ◽  
Vol 144 (1) ◽  
pp. 123-134 ◽  
Author(s):  
R Baltiérrez-Hoyos ◽  
A L Roa-Espitia ◽  
E O Hernández-González
Keyword(s):  
Actin Polymerization ◽  
Acrosome Reaction ◽  
Snare Proteins ◽  
Inhibitor Protein ◽  
Rho Proteins ◽  
Essential Requirement ◽  
Regulated Exocytosis ◽  
Caveolin 1 ◽  
Mammalian Sperm ◽  
Guanine Nucleotide Dissociation Inhibitor

In the mammalian sperm, the acrosome reaction (AR) is considered to be a regulated secretion that is an essential requirement for physiological fertilization. The AR is the all-or-nothing secretion system that allows for multiple membrane fusion events. It is a Ca2+-regulated exocytosis reaction that has also been shown to be regulated by several signaling pathways. CDC42 has a central role in the regulated exocytosis through the activation of SNARE proteins and actin polymerization. Furthermore, the lipid raft protein caveolin-1 (CAV1) functions as a scaffold and guanine nucleotide dissociation inhibitor protein for CDC42, which is inactivated when associated with CAV1. CDC42 and other RHO proteins have been shown to localize in the acrosome region of mammalian sperm; however, their relationship with the AR is unknown. Here, we present the first evidence that CDC42 and CAV1 could be involved in the regulation of capacitation and the AR. Our findings show that CDC42 is activated early during capacitation, reaching an activation maximum after 20 min of capacitation. Spontaneous and progesterone-induced ARs were inhibited when sperm were capacitated in presence of secramine A, a specific CDC42 inhibitor. CAV1 and CDC42 were co-immunoprecipitated from the membranes of noncapacitated sperm; this association was reduced in capacitated sperm, and our data suggest that the phosphorylation (Tyr14) of CAV1 by c-Src is involved in such reductions. We suggest that CDC42 activation is favored by the disruption of the CAV1–CDC42 interaction, allowing for its participation in the regulation of capacitation and the AR.

scholarly journals CDC42 drives RHOA activity and actin polymerization during capacitation

Reproduction ◽  
2020 ◽  
Vol 160 (3) ◽  
pp. 393-404
Author(s):  
Tania Reyes-Miguel ◽  
Ana L Roa-Espitia ◽  
Rafael Baltiérrez-Hoyos ◽  
Enrique O Hernández-González
Keyword(s):  
Actin Polymerization ◽  
Acrosome Reaction ◽  
Maximum Activity ◽  
Main Function ◽  
Rho Proteins ◽  
Rhoa Activity ◽  
Mammalian Sperm ◽  
Acrosomal Reaction ◽  
Reaction Processes ◽  
Kinetics Of

Mammalian sperm cells acquire fertilizing capacity as a result of a process termed capacitation. Actin polymerization is important for capacitation; inhibiting actin polymerization prevents the adhesion and fusion of the sperm with the ovule. The main function of RHO proteins CDC42 and RHOA is to direct actin polymerization. Although these two RHO proteins are present in mammalian sperm, little is known about their role in capacitation, the acrosome reaction, and the way in which they direct actin polymerization. The purpose of this study was to determine the participation of CDC42 and RHOA in capacitation and the acrosome reaction and their relationship with actin polymerization using guinea pig sperm. Our results show that the inhibition of CDC42 and RHOA alters the kinetics of actin polymerization, capacitation, and the acrosome reaction in different ways. Our results also show that the initiation of actin polymerization and RHOA activation depend on the activation of CDC42 and that RHOA starts its activity and effect on actin polymerization when CDC42 reaches its maximum activity. Given that the inhibition of ROCK1 failed to prevent the acrosomal reaction, the participation of RHOA in capacitation and the acrosomal reaction is independent of its kinase 1 (ROCK1). In general, our results indicate that CDC42 and RHOA have different roles in capacitation and acrosomal reaction processes and that CDC42 plays a preeminent role.

scholarly journals The Crossroads between RAS and RHO Signaling Pathways in Cellular Transformation, Motility and Contraction

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 819
Author(s):  
Olga Soriano ◽  
Marta Alcón-Pérez ◽  
Miguel Vicente-Manzanares ◽  
Esther Castellano
Keyword(s):  
Signaling Pathways ◽  
Actin Polymerization ◽  
Mapk Pathway ◽  
Human Cancer ◽  
Cellular Transformation ◽  
Dependent Manner ◽  
Rho Proteins ◽  
Filament Assembly ◽  
Multiple Signaling ◽  
Mechanical Feedback

Ras and Rho proteins are GTP-regulated molecular switches that control multiple signaling pathways in eukaryotic cells. Ras was among the first identified oncogenes, and it appears mutated in many forms of human cancer. It mainly promotes proliferation and survival through the MAPK pathway and the PI3K/AKT pathways, respectively. However, the myriad proteins close to the plasma membrane that activate or inhibit Ras make it a major regulator of many apparently unrelated pathways. On the other hand, Rho is weakly oncogenic by itself, but it critically regulates microfilament dynamics; that is, actin polymerization, disassembly and contraction. Polymerization is driven mainly by the Arp2/3 complex and formins, whereas contraction depends on myosin mini-filament assembly and activity. These two pathways intersect at numerous points: from Ras-dependent triggering of Rho activators, some of which act through PI3K, to mechanical feedback driven by actomyosin action. Here, we describe the main points of connection between the Ras and Rho pathways as they coordinately drive oncogenic transformation. We emphasize the biochemical crosstalk that drives actomyosin contraction driven by Ras in a Rho-dependent manner. We also describe possible routes of mechanical feedback through which myosin II activation may control Ras/Rho activation.

scholarly journals Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1844
Author(s):  
Maria Luísa da Silveira Hahmeyer ◽  
José Eduardo da Silva-Santos
Keyword(s):  
Septic Shock ◽  
Actin Polymerization ◽  
Current Knowledge ◽  
Cecal Ligation ◽  
Experimental Models ◽  
Rho Proteins ◽  
Growing Cell ◽  
Sepsis And Septic Shock

Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.

scholarly journals Discrete Dynamic Model of the Mammalian Sperm Acrosome Reaction: The Influence of Acrosomal pH and Physiological Heterogeneity

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrés Aldana ◽  
Jorge Carneiro ◽  
Gustavo Martínez-Mekler ◽  
Alberto Darszon
Keyword(s):  
Acrosome Reaction ◽  
Human Sperm ◽  
Extracellular Medium ◽  
Mammalian Sperm ◽  
Discrete Dynamic Model ◽  
Acrosomal Exocytosis ◽  
Mammalian Fertilization ◽  
Main Components ◽  
Discrete Mathematical Model ◽  
Physiological Heterogeneity

The acrosome reaction (AR) is an exocytotic process essential for mammalian fertilization. It involves diverse physiological changes (biochemical, biophysical, and morphological) that culminate in the release of the acrosomal content to the extracellular medium as well as a reorganization of the plasma membrane (PM) that allows sperm to interact and fuse with the egg. In spite of many efforts, there are still important pending questions regarding the molecular mechanism regulating the AR. Particularly, the contribution of acrosomal alkalinization to AR triggering physiological conditions is not well understood. Also, the dependence of the proportion of sperm capable of undergoing AR on the physiological heterogeneity within a sperm population has not been studied. Here, we present a discrete mathematical model for the human sperm AR based on the physiological interactions among some of the main components of this complex exocytotic process. We show that this model can qualitatively reproduce diverse experimental results, and that it can be used to analyze how acrosomal pH (pHa) and cell heterogeneity regulate AR. Our results confirm that a pHa increase can on its own trigger AR in a subpopulation of sperm, and furthermore, it indicates that this is a necessary step to trigger acrosomal exocytosis through progesterone, a known natural inducer of AR. Most importantly, we show that the proportion of sperm undergoing AR is directly related to the detailed structure of the population physiological heterogeneity.

scholarly journals Regulated exocytosis in immune function: are SNARE-proteins involved?

2000 ◽  
Vol 94 (1) ◽  
pp. 10-17 ◽  
Author(s):  
A. SHUKLA ◽  
L. BERGLUND ◽  
L.P. NIELSEN ◽  
S. NIELSEN ◽  
H.J. HOFFMANN ◽  
...  
Keyword(s):  
Immune Function ◽  
Snare Proteins ◽  
Regulated Exocytosis

scholarly journals Differential Localization of Rho Gtpases in Live Cells

2001 ◽  
Vol 152 (1) ◽  
pp. 111-126 ◽  
Author(s):  
David Michaelson ◽  
Joseph Silletti ◽  
Gretchen Murphy ◽  
Peter D'Eustachio ◽  
Mark Rush ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Fluorescent Protein ◽  
Essential Feature ◽  
Hypervariable Region ◽  
Dominant Negative ◽  
Live Cells ◽  
Rho Proteins ◽  
Guanine Nucleotide Dissociation Inhibitor ◽  
Membrane Compartment ◽  
Green Fluorescent

Determinants of membrane targeting of Rho proteins were investigated in live cells with green fluorescent fusion proteins expressed with or without Rho-guanine nucleotide dissociation inhibitor (GDI)α. The hypervariable region determined to which membrane compartment each protein was targeted. Targeting was regulated by binding to RhoGDIα in the case of RhoA, Rac1, Rac2, and Cdc42hs but not RhoB or TC10. Although RhoB localized to the plasma membrane (PM), Golgi, and motile peri-Golgi vesicles, TC10 localized to PMs and endosomes. Inhibition of palmitoylation mislocalized H-Ras, RhoB, and TC10 to the endoplasmic reticulum. Although overexpressed Cdc42hs and Rac2 were observed predominantly on endomembrane, Rac1 was predominantly at the PM. RhoA was cytosolic even when expressed at levels in vast excess of RhoGDIα. Oncogenic Dbl stimulated translocation of green fluorescent protein (GFP)-Rac1, GFP-Cdc42hs, and GFP-RhoA to lamellipodia. RhoGDI binding to GFP-Cdc42hs was not affected by substituting farnesylation for geranylgeranylation. A palmitoylation site inserted into RhoA blocked RhoGDIα binding. Mutations that render RhoA, Cdc42hs, or Rac1, either constitutively active or dominant negative abrogated binding to RhoGDIα and redirected expression to both PMs and internal membranes. Thus, despite the common essential feature of the CAAX (prenylation, AAX tripeptide proteolysis, and carboxyl methylation) motif, the subcellular localizations of Rho GTPases, like their functions, are diverse and dynamic.

scholarly journals Calpain modulates capacitation and acrosome reaction through cleavage of the spectrin cytoskeleton

Reproduction ◽  
2010 ◽  
Vol 140 (5) ◽  
pp. 673-684 ◽  
Author(s):  
Yadira Bastián ◽  
Ana L Roa-Espitia ◽  
Adela Mújica ◽  
Enrique O Hernández-González
Keyword(s):  
Plasma Membrane ◽  
Guinea Pig ◽  
Acrosome Reaction ◽  
Mammalian Species ◽  
Physiological Changes ◽  
Signal Transducer ◽  
Mammalian Sperm ◽  
Important Player ◽  
Calpain 2 ◽  
Spectrin Cytoskeleton

Research on fertilization in mammalian species has revealed that Ca2+is an important player in biochemical and physiological events enabling the sperm to penetrate the oocyte. Ca2+is a signal transducer that particularly mediates capacitation and acrosome reaction (AR). Before becoming fertilization competent, sperm must experience several molecular, biochemical, and physiological changes where Ca2+plays a pivotal role. Calpain-1 and calpain-2 are Ca2+-dependent proteases widely studied in mammalian sperm; they have been involved in capacitation and AR but little is known about their mechanism. In this work, we establish the association of calpastatin with calpain-1 and the changes undergone by this complex during capacitation in guinea pig sperm. We found that calpain-1 is relocated and translocated from cytoplasm to plasma membrane (PM) during capacitation, where it could cleave spectrin, one of the proteins of the PM-associated cytoskeleton, and facilitates AR. The aforementioned results were dependent on the calpastatin phosphorylation and the presence of extracellular Ca2+. Our findings underline the contribution of the sperm cytoskeleton in the regulation of both capacitation and AR. In addition, our findings also reveal one of the mechanisms by which calpain and calcium exert its function in sperm.

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