scholarly journals Germ cell-specific localization of immunoreactive riboflavin carrier protein in the male golden hamster: appearance during spermatogenesis and role in sperm function

Reproduction ◽  
2005 ◽  
Vol 129 (5) ◽  
pp. 577-587
Author(s):  
A Sreekumar ◽  
K K Acharya ◽  
H S Lalitha ◽  
S S Indi ◽  
P Bali ◽  
...  
Keyword(s):  
Germ Cell ◽  
Golden Hamster ◽  
Acrosome Reaction ◽  
Physiological Mechanism ◽  
Active Immunization ◽  
Male Rats ◽  
Sperm Function ◽  
Carrier Protein ◽  
Specific Localization ◽  
Riboflavin Carrier Protein

Riboflavin carrier protein (RCP) is a phosphoglycoprotein (37 kDa) that is well studied in chicken. An immunologically cross-reacting protein was identified in mammals and active immunization of male rats and bonnet monkeys with chicken RCP lead to an ∼80% reduction in fertility. However, the physiological mechanism responsible for inhibition of male fertility has not been investigated. Moreover, information on the cell type-specific localization and the origin of immunoreactive RCP during spermatogenesis is extremely limited. Hence, studies were carried out to determine the pattern of expression of immunoreactive RCP during spermatogenesis and its role in sperm function in the golden hamster. Immunoreactive RCP was germ cell-specific, found to be associated with the acrosome-organizing region of early spermatids and showed interesting patterns of immunolocalization during late stages of spermiogenesis. Mature spermatozoa exhibited acrosome-specific localization, mainly in the peri-acrosomal membrane. The immunoreactive protein was undetectable in (non)gonadal somatic cells tested. The protein had a molecular mass of 45–55 kDa and was biosynthesized by round spermatids. The acrosome-specific localization of immunoreactive RCP was unchanged during capacitation, but it was substantially lost during acrosome reaction. Functional studies indicated that treatment of spermatozoa with anti-RCP antibodies did not have any effect on either capacitation or acrosome reaction, but markedly reduced the rate of sperm penetration into zona-free hamster oocytes. These results show the existence of male germ cell-specific immunoreactive RCP, having a potential role in sperm–egg interaction in hamsters. Also the pattern of immunoreactive-RCP localization makes it an ideal marker to monitor development of acrosome in mammalian spermatozoa.

scholarly journals Effects of Hexachlorocyclohexane (HCH-γ-Isomer, Lindane) Intoxication on the Proliferation and Apoptosis in Rat Testes

2009 ◽  
Vol 78 (4) ◽  
pp. 615-620 ◽  
Author(s):  
Hayati Yuksel ◽  
Erkan Karadas ◽  
Hikmet Keles ◽  
Hasan Huseyin Demirel
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Male Rats ◽  
Control Group ◽  
High Dose ◽  
Histopathological Changes ◽  
Proliferation And Apoptosis ◽  
Group A ◽  
Higher Doses ◽  
Group 1

In this study, experimentally lindane-induced histopathological changes and proliferation and/or apoptosis in germ cells in the rat testes were investigated. A total of 40 healthy fertile 3-month-old male rats were used. Animals were divided into 4 groups, each containing 10 rats. Group 1 (control) was given only pure olive oil, Groups 2, 3 and 4 were administered lindane at 10, 20 and 40 mg/kg/bw, respectively, by gastric gavage for 30 days. Microscopically, degenerative changes were observed in the lindane-treated groups. For proliferative activity PCNA immunolabelling and for germ cells apoptosis TUNEL methods were performed. Although a strong PCNA positivity in the control group was observed, a gradual decrease was noted in the lindane-treated groups especially at higher doses. Significant increases of apoptosis were seen in the lindane-treated groups compared to the control group. A decrease in testosterone concentrations was observed in lindane-treated groups compared to the control group. The study indicates that high-dose lindane intoxication contributes to the suppression of spermatogenesis through a reduction of germ cell proliferation and an increase of germ cell death in rat testes.

scholarly journals Riboflavin-Targeted Drug Delivery

Cancers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 295 ◽  
Author(s):  
Milita Darguzyte ◽  
Natascha Drude ◽  
Twan Lammers ◽  
Fabian Kiessling
Keyword(s):  
Drug Delivery ◽  
Targeted Drug Delivery ◽  
Review Article ◽  
Carrier Protein ◽  
Tumor Stem Cells ◽  
Vitamin B9 ◽  
Riboflavin Carrier Protein ◽  
Targeted Drug ◽  
The 1960S ◽  
Tumor Types

Active targeting can improve the retention of drugs and drug delivery systems in tumors, thereby enhancing their therapeutic efficacy. In this context, vitamin receptors that are overexpressed in many cancers are promising targets. In the last decade, attention and research were mainly centered on vitamin B9 (folate) targeting; however, the focus is slowly shifting towards vitamin B2 (riboflavin). Interestingly, while the riboflavin carrier protein was discovered in the 1960s, the three riboflavin transporters (RFVT 1-3) were only identified recently. It has been shown that riboflavin transporters and the riboflavin carrier protein are overexpressed in many tumor types, tumor stem cells, and the tumor neovasculature. Furthermore, a clinical study has demonstrated that tumor cells exhibit increased riboflavin metabolism as compared to normal cells. Moreover, riboflavin and its derivatives have been conjugated to ultrasmall iron oxide nanoparticles, polyethylene glycol polymers, dendrimers, and liposomes. These conjugates have shown a high affinity towards tumors in preclinical studies. This review article summarizes knowledge on RFVT expression in healthy and pathological tissues, discusses riboflavin internalization pathways, and provides an overview of RF-targeted diagnostics and therapeutics.

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