Patricia A. DeLeon, Ph.D.

Teaching

• BISC 105 - Human Heredity and Development
• BISC 492 - Human Molecular Cytogenetics
• BISC 693 - Human Molecular Genetics (Syllabus)
• BISC 693 - Human Molecular Genetics (Schedule)

Research Interests

The identification of genes and mechanisms that are involved in sperm dysfunction and male factor infertility/subfertility is the focus of our laboratory. We are interested in candidate or novel genes that play a role in spermatogenesis, epididymal sperm maturation, and fertilization. The latter can be considered as the process by which the genome passes from one generation to the next. Not only is the laboratory interested in the function of the genes and their impact on male germ cell differentiation, but also in their regulation (transcriptional and posttranscriptional). Thus our interest lies in the genetic and molecular mechanisms of spermatogenesis, epididymal function, and the molecular aspects of fertilization.

One class of genes being currently studied is the mammalian hyaluronidases which are abundantly expressed in the testis. There are seven family members of these genes and they are tightly linked in two clusters on different chromosomes. The best studied of these is the Sperm Adhesion Molecule 1 (SPAM1) which is widely conserved, being found in every mammalian species that has been studied to date. SPAM1 encodes a sperm membrane glycosyl phosphatidylinositol- (GPI)-linked protein (SPAM1 or PH-20) which plays multiple essential roles in fertilization. These include cumulus penetration, zona pellucida binding, and hyaluronic acid receptor activity during the signal transduction involved in acrosomal exocytosis. We are interested in determining if all the hyaluronidase genes have unique or overlapping functions, or if they operate as a classical polygenic system.

Current Projects

• Posttranscriptional Regulation of Spam1 - Spam1 is abundantly expressed in round spermatids and transcription levels off in elongated spermatids. Similar to other spermatid-expressed genes, for SPAM1 the condensation of the chromatin during the transformation of the round spermatid into a polarized cell results in premature termination of transcription. Thus there is a heavy reliance on posttranscriptional regulation. We are investigating the posttranscriptional regulation of expression of the murine Spam1 as a model for spermatid-expressed genes. The hypothesis that testicular Spam1 is regulated by cis-acting AU-rich elements (AREs) in the 3'UTR which recognize RNA-binding proteins and which are modulated by antisense transcription is being tested.
• The basis of sperm infertility following Spam1 overexpression and the retention of cytoplasmic droplets - Transgenic overexpression of murine Spam1 leads to abnormal spermiogenesis which results in the retention of cytoplasmic droplets (CDs), organelles which are present on the flagellum and which are generally associated with sperm infertility in mammals. The CDs resulting from Spam1 overexpression are engorged with Spam1 which is absent from the sperm head, the normal location. Our overall hypothesis is that the infertility of these sperm results partly from their reduced motility as well as the absence of hyaluronidases on the heads. Studies to test several hypotheses related to this overall hypothesis are being investigated.
• SPAM1 overexpression and Metastatic cancer - Overexpression of SPAM1 is also associated with a variety of cancers in both reproductive and non-reproductive organs. The transcript, normally present in low abundance in these non-testicular tissues, is upregulated and detectable by Northern analysis during tumor progression. Our discovery of the ARE-mediated stabilization of Spam1 RNA allows us to hypothesize that trans-acting RNA-binding proteins are involved in the upregulation of the RNA and the ensuing cancer progression. Understanding the molecular mechanisms involved in the upregulation is key to developing therapeutic strategies to overcome the disease, and studies are proposed to identify the proteins involved.
• The Mechanism of Cross-talk between Spam1 and related Hyaluronidases - Our findings have suggested that there is cross-talk between members of the hyaluronidase family members. Using double null mice, experiments have been designed to verify whether or not there is cross-talk between Spam1 and Hyal5 as well as other hyase family members; and how the cross-talk may be modulated, specifically with respect to antisense RNA. The latter has been detected for Spam1. The antisense regulation of these genes could serve as a model for spermatid-expressed gene families.
• The Mechanism of Sperm uptake of Epididymal Spam1 - Our lab was the first to discover the expression of Spam1 in the extratesticular pathway (the efferent duct, the epididymis and the vas deferens) as well as the female tract. We have also shown that in these organs Spam1 is secreted in the luminal fluid in a form in which it can be taken up by sperm. Recently, we have shown the in vitro uptake of luminal Spam1 by sperm and are currently determining the mechanism by which the binding occurs on the sperm plasma membrane.
• The Role of JAM-A in Ca²⁺ Clearance in Sperm - Another sperm membrane protein in which our lab is interested is Junctional Adhesion Molecule A (JAM-A) which is known to regulate tight junction integrity, and is present between the Sertoli cells that maintain the blood testis barrier. Our lab discovered its presence in human and mouse sperm and showed that its absence results in elevated Ca²⁺ levels, decreased ATP levels, and reduced sperm motility. Further, we have shown that JAM-A interacts with the Ca²⁺ extrusion pump (PMCA4) and Ca²⁺ serine kinase (CASK). Studies are proposed to document this interaction and determine how deletion of Cask might affect the tripartite protein complex, the function of the pump, and sperm motility.

Research Group

• Amal Aldossary, M.A.
• Rachel Andrews, B.A.
• Kathie Wu - Undergraduate researcher.
• Rebecca Pollak - Undregraduate researcher.
• Ramkrishna Patel - Undergraduate Researcher. Post-testicular Expression of PMCA4.
• Emily Jacobson - Undergraduate Researcher. The regulation of Nitri Oxide in sperm.

Selected Publications

• Mei-Jiao Wang, Jia-Xian Ou, Guo-Wu Chen, Jun-Ping Wu, Hui-Juan Shi5 Wai-Sum O, Martin-DeLeon, P. A.: Hong Chen: Does Prohibitin Expression Regulate Mitochondrial Membrane Potential, Sperm Motility, and Male Fertility?  Antioxid. Redox Signal. doi: 10.1089/ars.2012.4514. (2012)
• Aravindan, G.R, Fomin,V.R,  Naik, U.P., Modelski MJ, Naik MU, Galileo, D. S., Duncan, R.L., Martin-DeLeon, P.A. : CASK interacts with PMCA4b and  JAM-A on the mouse sperm flagellum to regulate motility and Ca2+ homeostasis. J Cell Physiol doi: 10. 1002/jcp.24000 (2011).
• Martin-DeLeon, P.A. : Germ-cell hyaluronidases: Their Roles in Sperm Function. International J. Androl.doi 10 1111 1365-2605 (2010).
• Reese KL, Aravindan RG, Griffiths GS, et al. Acidic hyaluronidase activity is present in mouse sperm and is reduced in the absence of SPAM1: evidence for a role for hyaluronidase 3 in mouse and human sperm. Mol reprod Dev. 2010;77(9):759–72.
• Griffiths GS, Galileo DS, Aravindan RG, Martin-DeLeon PA. Clusterin Facilitates Exchange of Glycosyl-Phosphosphatidylinositol-Linkind SPAM1 Between Reproductive Luminal Fluids and Mouse and Human Sperm Membranes. Biology of Reproduction. 2009;81:562–570.
• Griffiths GS, Galileo DS, Reese K, Martin-Deleon PA. Investigating the role of murine epididymosomes and uterosomes in GPI-linked protein transfer to sperm using SPAM1 as a model. Mol Reprod Dev. 2008;75(11):1627–1636.
• Shao M, Ghosh A, Cooke V.G., Naik U.P., Martin-DeLeon, P.A.: JAM-A is present in Mammalian Spermatozoa where it is Essential for Normal Motility. Dev Biol 313: 246-255 (2007).
• Martin-DeLeon PA. Epididymal SPAM1 and its impact on sperm function. Mol Cell Endocrinol. 2006;250(1-2):114–121.
• Zhang H, Barnoski BL, Sol-Church K, Stabley DL, Martin-Deleon PA. Murine Spam1 mRNA: involvement of AU-rich elements in the 3'UTR and antisense RNA in its tight post-transcriptional regulation in spermatids. Mol Reprod Dev. 2006;73(2):247–255.
• Martin-DeLeon PA, Zhang H, Evans EA, Jones R, Morales CR, Grigorieva A. SPAM1 (PH-20) Expression along the mammalian male reproductive tract, the accessory organs and the kidney: Evidence for multiple roles in the extratesticular pathways. In: Balazs EA, Hascall VC, eds. Hyaluronan: Structure, Metabolism, Biological Activities, Therapeutic Applications. Vol. I. Edgewater, NJ: Matrix Biology Institute; 2005:229–234.
• Martin-DeLeon PA, Zhang H, Morales CR, et al. Spam1-associated transmission ratio distortion in mice: elucidating the mechanism. Reprod Biol Endocrinol. 2005;3:32.
• Zhang H, Shertok S, Miller K, Taylor L, Martin-Deleon PA. Sperm dysfunction in the Rb(6.16)- and Rb(6.15)-bearing mice revisited: involvement of Hyalp1 and Hyal5. Mol Reprod Dev. 2005;72(3):404–410.
• Morales CR, Badran H, El-Alfy M, Men H, Zhang H, Martin-DeLeon PA. Cytoplasmic localization during testicular biogenesis of the murine mRNA for Spam1 (PH-20), a protein involved in acrosomal exocytosis. Mol Reprod Dev. 2004;69(4):475–482.
• Zhang H, Jones R, Martin-DeLeon PA. Expression and secretion of rat SPAM1(2B1 or PH-20) in the epididymis: role of testicular lumicrine factors. Matrix Biol. 2004;22(8):653–661.
• Zhang H, Morales CR, Badran H, El-Alfy M, Martin-DeLeon PA. Spam1 (PH-20) expression in the extratesticular duct and accessory organs of the mouse: a possible role in sperm fluid reabsorption. Biol Reprod. 2004;71(4):1101–1107.
• Evans EA, Zhang H, Martin-DeLeon PA. SPAM1 (PH-20) protein and mRNA expression in the epididymides of humans and macaques: utilizing laser microdissection/RT-PCR. Reprod Biol Endocrinol. 2003;1:54.
• Zhang H, Martin-Deleon PA. Mouse epididymal Spam1 (pH-20) is released in the luminal fluid with its lipid anchor. J Androl. 2003;24(1):51–58.
• Zhang H, Martin-DeLeon PA. Mouse Spam1 (PH-20) is a multifunctional protein: evidence for its expression in the female reproductive tract. Biol Reprod. 2003;69(2):446–454.
• Martin-DeLeon PA, Piumi F, Canaff L, Rogel-Gaillard C, Hendy GN. Assignment of the parathyroid hormone/parathyroid hormone-related peptide receptor (PTHR1) to rabbit chromosome band 9p14-->p13 by fluorescence in situ hybridization. Cytogenet Cell Genet. 2001;94(1-2):90–91.
• Zhang H, Martin-DeLeon PA. Mouse epididymal Spam1 (PH-20) is released in vivo and in vitro, and Spam1 is differentially regulated in testis and epididymis. Biol Reprod. 2001;65(5):1586–1593.
• Zheng Y, Deng X, Martin-DeLeon PA. Lack of sharing of Spam1 (Ph-20) among mouse spermatids and transmission ratio distortion. Biol Reprod. 2001;64(6):1730–1738.
• Zheng Y, Deng X, Zhao Y, Zhang H, Martin-DeLeon PA. Spam1 (PH-20) mutations and sperm dysfunction in mice with the Rb(6.16) or Rb(6.15) translocation. Mamm Genome. 2001;12(11):822–829.
• Deng X, He Y, Martin-Deleon PA. Mouse Spam1 (PH-20): evidence for its expression in the epididymis and for a new category of spermatogenic-expressed genes. J Androl. 2000;21(6):822–832.
• Zheng Y, Martin-Deleon PA. Characterization of the genomic structure of the murine Spam1 gene and its promoter: evidence for transcriptional regulation by a cAMP-responsive element. Mol Reprod Dev. 1999;54(1):8–16.
• Zheng Y, Martin-Deleon PA. The murine Spam1 gene: RNA expression pattern and lower steady-state levels associated with the Rb(6.16) translocation. Mol Reprod Dev. 1997;46(3):252–257.
• Nagle DL, Martin-DeLeon P, Hough RB, Bucan M. Structural analysis of chromosomal rearrangements associated with the developmental mutations Ph, W19H, and Rw on mouse chromosome 5. Proc Natl Acad Sci U S A. 1994;91(15):7237–7241.
• Nigro, J.M., Schweinfest, C.W., Rajkovic, A., Pavlovic, J., Jamal, S., Dottin, R.P., Hart, J.T., Kamarck, M. E., Rae, P.M.M., Carty, M.D. and Martin-DeLeon, P.A.  cDNA cloning and mapping of the human creatine kinase M gene to 19q13.  Am. J. Hum. Gen. 40:115-125 (1987).
• Taylor, E. F. and Martin-DeLeon, P. A. Familial silver staining patterns of human nucleolus organizer regions, Amer. J. Hum. Gen. 33:67-76 (1981).
• Martin, P.A.  Cannabis and Chromosomes. Lancet 1: 370 (1969).