Laboratory of Margarita Vigodner, Ph.D.

Research Projects And Funding


Dr. Margarita Vigodner's Lab:

Our previous research work focused on the studies of spermatogenesis and the development of new methodologies using flow cytometry and confocal microscopy for monitoring germ cell progression and to distinguish between normal and abnormal spermatogenesis.

Current research project in my group focuses on the characterization of the role of novel small proteins known as SUMO (small-ubiquitin-related modifiers) in testicular cells, sperm, stress response in the testis and the development of the testicular cancer.

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Project 1: Understanding the role of sumoylation during spermatogenesis (supported by NIH)  

Post-translational modification by Small Ubiquitin-like Modifiers or SUMO proteins has been identified as an important regulatory event that is implicated in several cellular processes, seemingly based on the cell type. Recent findings from our laboratory suggest diverse and potentially multiple roles of SUMO in testicular function and spermatogenesis however, SUMO targets remain uncharacterized in the testis due to the complex multicellular nature of testicular tissue, the inability to maintain and manipulate spermatogenesis in vitro, and the technical challenges involved in identifying low-abundance endogenous SUMO targets. In this study, we performed cell-specific identification of sumoylated proteins using concentrated cell lysates prepared with de-sumoylation inhibitors from freshly purified spermatocytes and spermatids. Hundred and twenty proteins were uniquely identified in the spermatocyte and/or spermatid fractions. The identified proteins   are involved in the regulation of transcription, stress response, microRNA biogenesis, regulation of major enzymatic pathways, nuclear-cytoplasmic transport, cell cycle control, acrosome biogenesis, and other processes. Several proteins with important roles during spermatogenesis were chosen for further characterization by co-immunoprecipitation, co-localization and in-vitro sumoylation studies. GPS-SUMO software was used to identify consensus and non-consensus sumoylation sites within amino acid sequences of the proteins. The analyses confirmed the sumoylation of several novel, previously uncharacterized, SUMO targets, such as CDK1, RNAP II, CDC5, MILI, DDX4, and Stk31. Furthermore, several proteins that were previously identified as SUMO targets in somatic cells (e.g., KAP1, MDC1) were identified as SUMO targets in germ cells. Many of these proteins have a unique role in spermatogenesis, particularly during meiotic progression. Notably, the inhibition of sumoylation blocked the G2/M transition in spermatocytes in vitro. Co-localization studies suggest a role of sumoylation in modifying proteins within heterochromatic and intra-chromasomal sub-domains of germ cells. This research opens a novel avenue for numerous further studies of SUMO at the level of individual targets.  



Project 2: Understanding the effect of tobacco smoke on cell signaling (FAMRI supported)  

2.1) Sperm project 

Sperm are highly dependent on posttranslational modifications of proteins. Massive phosphorylation on tyrosine residue is required for sperm capacitation. Sumoylation has also been recently implicated in spermatogenesis and sperm functions. Cigarette smoke is known to cause oxidative stress in different tissues, and several studies suggest that it causes oxidative stress in sperm. Whether tobacco affects posttranslational modifications in human sperm is currently unknown. We have showed  that a short exposure of human sperm to physiological concentrations of cigarette smoke extract (CSE) causes the partial de-sumoylation of many sperm proteins. Furthermore, the presence of a low concentration of CSE in the human tubal fluid during an induction of in vitro capacitation inhibits the capacitation-associated increase in protein phosphorylation. Collectively, changes in posttranslational modifications may be one of the mechanisms through which exposure to tobacco can negatively affect sperm functions and cause fertility problems. 


2.2) CDK14 project: 

DNA arrays have been employed to monitor gene expression patterns in testis of mice exposed to tobacco smoke for 24 weeks and compared to control animals. The results of the analysis revealed significant changes in expression of several genes that may have a role in spermatogenesis. Cdk14 was chosen for further characterization because of a suggested role in the testis and in regulation of Wnt signaling. RT-PCR analysis confirmed down regulation of Cdk14 in mice exposed to cigarette smoke (CS). Cdk14 is expressed in all testicular cells; spermatogonia- and Sertoli-derived cell lines treated with cigarette smoke extract (CSE) in vitro showed down-regulation of CDK14 mRNA and protein levels as well as down-regulation of β-catenin levels. CS-induced down-regulation of CDK14 mRNA and protein levels was also observed in several lung epithelium-derived cell lines including primary normal human bronchial epithelial cells (NHBE), suggesting that the effect is not restricted to the testis. Similar to testicular cells, CS-induced down-regulation of CDK14 in lung cells correlated with decreased levels of β-catenin, a finding suggesting impaired Wnt signaling. In the lungs, CDK14 was localized to the alveolar and bronchial epithelium.




Funding sources

National Institutes of Health, DHHS          



And The Mitrani foundation.

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