John H. Richburg, Ph.D.

Dr. John Richburg

Associate Dean for Research and Graduate Studies
Professor of Pharmacology & Toxicology
Gustavus & Louise Pfeiffer Professor in Toxicology

Dr. Richburg’s responsibilities as Associate Dean include the oversight of the College’s research and graduate programs, including enhancement of outside research funding and recruitment of the most qualified graduate students into our graduate training programs.

Dr. Richburg, the Gustavus and Louise Pfeiffer Professor in Toxicology, has had near continuous NIH grant funding to support his research program over the last 18 years.

The longstanding focus the Richburg research program is to decipher the molecular and cellular mechanisms by which exposure to certain environmental (e.g., phthalate acid ester-based plasticizers) or clinical chemotherapeutic agents (e.g., cisplatin) can result in disruption of male reproduction.

The goal of this research is to provide molecular and cellular insights on toxicant action that will be useful for predicting and preventing human reproductive health risks to both chemotherapeutic agents as well as chemicals found in the environment.

Collage of images from Richburg research lab

The longstanding focus of the Richburg Laboratory is to decipher the molecular and cellular mechanisms by which exposure to environmental toxicants (e.g., phthalates) or clinical chemotherapeutic agents (e.g., cisplatin) can result in the disruption in spermatogenesis. Specifically, the unifying theme of my research program is to reveal the paracrine cellular signaling mechanisms between cells in the testis that regulate the balance between survival and death of germ cells. It is anticipated that mechanistic insights garnered from research in the laboratory will provide foundational cellular and mechanistic insights underlying the sensitivity of the testis to environmental toxicants that can be exploited in developing strategies to prevent the long-term disruption of male fertility from exposure to these agents.

Recent Laboratory News: A 5 -year NIH/NIEHS R01 grant has been received to delineate the functional contribution of cells of the innate immune system (macrophages & monocytes) in the sequence of events that occur in the pubertal rodent testis after exposure to the environmental toxicant, mono-(2-ethylhexyl) phthalate (MEHP). The work of this research proposal is relevant to human health as it is anticipated to provide mechanistic insights that will be valuable for predicting and preventing human reproductive health risks to environmental toxicants. Assessing the individual susceptibility to interactions of environmental toxicants with the immune system is consistent with goals of the NIEHS 2018-2023 strategic plan.

Recent Peer-Reviewed Publications:

See Google Scholar for full Listing

  • Gillette, R, Tiwary, R, Voss, JJLP and Richburg, JH (2019). Peritubular macrophages and spermatogonia are sequentially increased in the testis of rats after mono-(2-ethylhexyl) phthalate exposure. BioRXiv. Posted online Sep. 12, 2019; doi: 10.1101/767707
  • Ghaffari, R, and Richburg, JH (2019). Mice with a Sertoli cell-specific knockout of the Ctr1 gene exhibit a reduced sensitivity to cisplatin-induced testicular germ cell apoptosis. Toxicology Research. 8, 972-978. PMC7344760
  • Ghaffari, R, Di Bona, KR, Riley, CL and Richburg, JH (2019). Copper transporter 1 (CTR1) expression by mouse testicular germ cells, but not Sertoli cells, is essential for functional spermatogenesis. PlosOne. 14 (4) PMC6474593
  • Voss, JJLP, Stermer, AR, Ghaffari, R, Tiwary, R, and Richburg, JH (2018). MEHP-induced rat testicular inflammation does not exacerbate germ cell apoptosis. Reproduction. 156 (1): 35-46. PMCID: PMC6021206
  • Bao, J, Perez, CJ, Kim, J, Zhang, H, Murphy, CJ, Hamidi, T, Jaubert, J, Platt, C, Deng, M, Gaitán-Peñas, H, Guénet, J-L, Chen, T, Bedford, MT, Dent, SYR, Richburg, JH, Estévez, R, Pan, H-L, Geha, RS, Shi, Q, and Benavides, F (2018). Deficient LRRC8A-dependent volume-regulated anion channel activity is associated with male infertility in mice. Journal of Clinical Investigation Insight. 3(16) e99767. PMCID: PMC6141173


Project 1: MEHP-induced testicular inflammation &  germ cell apoptosis
The role of cells of the innate immune system in mediating testicular toxicity

The newest line of investigation in my laboratory is centered on evaluating the participation of cells of the innate immune system in the pathogenic sequence of events that occur in the testis after exposure to the Sertoli cell toxicant mono-(2-ethylyhexyl) phthalate (MEHP). Phthalates are a class of compounds that are incorporated into cosmetics, food packaging, biomedical devices, and PVC products to impart flexibility. Since these agents are not covalently bound to the final product they readily leach out of these products and, as a result, are found widely distributed in the environment and human tissues. The most abundantly produced and studied phthalate is di-(2-ethylhexyl) phthalate (DEHP) that is rapidly hydrolyzed in the gastrointestinal tract, liver and blood, by nonspecific esterases to produce its corresponding toxic monoester, MEHP. Although the collective human median phthalate exposure level is estimated to be ~30 µg/kg/bw/day, certain individual populations, such as young children receiving parenteral fluids via polyvinyl-chloride based tubing, show levels of 10-20 mg/kg/day. It is widely recognized that peripubertal rodents (~postnatal day, PND, 14-28) are more sensitive than adults to testicular injury by phthalates. The work of this research project is anticipated to  provide  key  insights into the mechanisms that account for the age-dependent susceptibility to phthalate-induced testicular injury.

Image of macrophages from Richburg research lab
Representative micrographs of MHCII+ (green) peritubular macrophages are shown on the surface of seminiferous tubules in close proximity to PLZF+ (red) spermatogonia in both VEH and MEHP treated rats.

The testis is referred to as an “immune privileged” organ as it protects auto-antigenic haploid GCs that appear at puberty, long after the establishment of immune tolerance mechanisms. The immune privilege mechanism is maintained by a specialized physical barrier that exists between adjacent SCs, the blood-testis barrier, and the secretion of immunosuppressive molecules from cells of the seminiferous epithelium, predominantly by Sertoli cells. Therefore, exposure to MEHP may create a disruption in the testis’ immunosuppressive environment and allows for the infiltration of these cells into the testis in numbers not normally observed. In agreement with this idea, we have reported a MEHP dose dependent infiltration of macrophages and neutrophils into the testis that occurs in a time-, age- (postnatal day vs adult age), and species- (Fischer rats vsC57BL/6J mice) dependent manner. Nevertheless, experimental approaches that significantly reduced the levels of macrophage infiltration into the testis failed to prevent MEHP-induced increases GC apoptosis. Interestingly, our recent detailed evaluation of the cells that lie adjacent to the basement membrane of the seminiferous tubules revealed a specific sub-population of macrophages, the peritubular macrophages (ptMφs), that are increased in numbers as well as in specific regional clusters for a sustained period (>2 weeks) after MEHP exposure. The ptMφs in the testis are thought to play a critical role in the maintenance of the microenvironment supporting the spermatogonial niche. In this research project we challenge the hypothesis that the ptMφs cells arise from a phenotypic switch from the infiltrating macrophages that occur in response to MEHP exposure and that their function is to facilitate the efficient recovery of spermatogenesis. 

Relevant Manuscripts:

Murphy, CJ, Stermer, AR and Richburg, JH (2014). Age- and species-dependent infiltration of macrophages into the testis of rats and mice exposed to mono-(2-ethylyhexyl) phthalate (MEHP). Biology of Reproduction. 91(1):18, 1-11. PMCID: PMC4434960

Stermer, AR, Myers, JL, Murphy, CJ, Di Bona, KR and Richburg, JH (2016). Female mice with a loss-of-function ITCH display an altered reproductive phenotype. Experimental Biology and Medicine. 241 (4):367-374. Epub 2015 Oct 28. PMCID: PMC4935413 **This was the featured article for the February 2016 Issue**.

Stermer, AR, Murphy, CJ, Ghaffari, R., Di Bona, KR, Voss, J.J. and Richburg, JH (2017). Mono (2-ethylhexyl) phthalate-induced Sertoli cell injury stimulates the production of pro-inflammatory cytokines in Fisher 344 rats. Reproductive Toxicology. 69: 150-158. PMCID: PMC5406244.

Voss, JJLP, Stermer, AR, Ghaffari, R, Tiwary, R, and Richburg, JH (2018). MEHP-induced rat testicular inflammation does not exacerbate germ cell apoptosis. Reproduction. 156 (1): 35-46.  PMCID: PMC6021206

Gillette, R, Tiwary, R, Voss, JJLP and Richburg, JH (2019). Peritubular macrophages and spermatogonia are sequentially increased in the testis of rats after mono-(2-ethylhexyl) phthalate exposure. BioRXiv. Posted online Sep. 12, 2019; doi: 10.1101/767707


Project 2: Deciphering mechanisms of cisplatin-induced male infertility

Project Overview:

In 1972, the introduction of cis-diamminedichloroplatinum (II) (cDDP, cisplatin) for the treatment of testicular germ cell tumors dramatically increased the overall cure rate and patient survivorship. Unfortunately, since testicular cancers occur most commonly in young men ~15-34 years of age, the prolonged, sometimes permanent, infertility that often results from cDDP treatment is a devastating side effect for these young men. We (Seaman et al., 2003 Apoptosis 8 (1):101-108), and others have shown that testicular germ cells are extremely sensitive to undergo apoptosis after cDDP exposure. The germ cell subtypes reported to undergo cDDP-induced cell death in rodent models include undifferentiated and differentiated spermatogonia as well as spermatocytes; with subtype sensitivity closely dependent on both the dose and developmental age of the animal. We developed a cDDP multi-cycle dosing paradigm in mice that closely mimics that used in the clinic and showed that this treatment results in the prolonged disruption in spermatogenesis in these mice (Sawhney et al., 2005 Journal of Andrology 26:136-145) and that the undifferentiated spermatogonia were increasingly affected by multiple cycles of cDDP treatment (Harman et al., 2014 Toxicology Letters 227:99-112). Although spermatogonial stem cells (SSCs) are regarded to be mostly insensitive to DNA-damaging agents like cDDP due to their quiescent nature, it has recently been shown in the lab of Shosei Yoshida (2014, Cell Stem Cell14:658-672) that the progeny of SSCs, the undifferentiated spermatogonia, can dedifferentiate into SSCs and serve as a mechanism for maintaining the functional stem cell pool throughout the life of the animal. Therefore, the prolonged loss of spermatogonia that we have observed in mice using the cDDP multi-cycle dosing paradigm in mice may negatively affect the size of the testicular SSC pool, reducing male fertility. This  research project is specifically targeted to test if cDDP is preferentially taken up in specific germ cell subtypes viatheir enhanced expression of the high affinity membrane copper transporter 1 (CTR1; SLC31A1) and accounts for their distinctive sensitivity to elimination after cDDP exposure. This hypothesis is based upon the growing body of evidence in the literature indicating that CTR1 is the major influx transporter for cDDP. As well as our preliminary observations showing a robust expression of this protein in the testis and that the testis of Ctr1+/- mice show a limited loss of germ cells after 2 treatment cycles of cDDP. Although our hypothesis predicts that germ cell CTR1 underlies the sensitivity of these cells to cDDP-induced apoptosis, the evaluation of CTR1 in other cells of the seminiferous epithelium (e.g., Sertoli cells) is also closely considered as CTR1-mediated cDDP influx in other testicular cells could also contribute to the pathogenic mechanism responsible for the sustained loss of germ cells after a repeated multi-cycle treatment of cDDP by disrupting the maintenance of the microenvironment necessary for germ cell development.

It is anticipated that this research will impact the field by offering a mechanistic foundation to explain the distinct sensitivity of testicular germ cells to cDDP-induced elimination thus providing insights for the development of translational research into innovative clinical strategies that will continue to allow for the efficient elimination of tumor cells by cDDP while sparing the long-term fertility of men.

Relevant Publications:

Ghaffari, R, Di Bona, KR, Riley, CL and Richburg, JH (2019). Copper transporter 1 (CTR1) expression by mouse testicular germ cells, but not Sertoli cells, is essential for functional spermatogenesis. PlosOne. 14 (4) e0215522

Ghaffari, R, and Richburg, JH (2019). Mice with a Sertoli cell-specific knockout of the Ctr1 gene exhibit a reduced sensitivity to cisplatin-induced testicular germ cell apoptosis. Toxicology Research. DOI: 10.1039/C9TX00142E

Harman, J and Richburg, JH (2014). Cisplatin-induced alterations in the functional stem cell pool and niche in C57BL/6J mice following a clinically relevant multi-cycle exposure. Toxicology Letters Apr 2;227(2):99-112.

Sawhney, P, Giammona, CJ, Meistrich, ML and Richburg, JH (2005). Cisplatin-induced long-term failure of spermatogenesis in adult C57/Bl/6J mice. Journal of Andrology 26:136-145.

Seaman FC, Sawhney, P, Giammona, CJ and Richburg, JH (2003). Cisplatin-induced pulse of germ cell apoptosis precedes long-term elevated apoptotic rates in C57/B6 mouse testis. Apoptosis 8 (1):101-108.

John Richburg, Ph.D., Principal Investigator
For more detailed information, view CV

Richa Tiwary, Ph.D., Research Scientist
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Narayan Acharya, Ph.D., Postdoctoral Fellow
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Christy Lite, Ph.D., Postdoctoral Fellow
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Xin Fang, Graduate Student

Abril Calderon, Undergraduate Student

Siddhant Bhat, Undergraduate Student

Nirvana Maleki, Undergraduate Student

Vivian Nguyen, Undergraduate Student

Peter Zhang, Undergraduate Student

Postdoctoral Fellows

Collage of postdoctoral fellows from Richburg lab

Doctoral Students

Collage of Ph.D. alumni from Richburg lab
  • C. John Giammona, Ph.D., Toxicology Program, Defense Date 12/2002, Current Position - VP, Commercial Operations (Medical Education) Veru Pharma, Missoula, MT
  • Yu “Matt” Liu, Ph.D. (Co-advisor with Dr. Walker), Toxicology Program, Defense Date 05/2004, Current Position - Toxicologist, Regeneron Pharmaceuticals, Tarrytown, NY
  • Yamini Chandrasekaran, Ph.D., Toxicology Program, Defense Date 07/2005, Current Position - Independent Marketing Content /Science Writer, Bengaluru, India
  • Minhao Wu, Ph.D. (Co-advisor with Dr. Aldaz), Toxicology Program, Defense Date 05/2007, Current Position - Physician Anesthesiologist, Medical College of Georgia at Augusta University
  • Chad McKee, Ph.D., Molecular Biology Program, Defense Date 09/2007, Current Position - Associate Director of Medical Affairs, Lexicon Pharmaceuticals, Raleigh, NC
  • Raju Pusapati, Ph.D. (Co-advisor with Dr. Johnson), Toxicology Program, Defense Date 11/2008, Current Position - Scientist, Ribon Therapeutics., Lexington, MA
  • Pei-Li Yao, Ph.D., Molecular Biology Program, Defense Date 12/2008, Current Position - Research Scholar, Dept. of Biological Sciences, NC State University, Raleigh, NC
  • Jelena Todorovic, Ph.D. (Co-advisor with Dr. Mihic), Toxicology Program, Defense Date 10/2010, Current Position - Postdoctoral Fellow, The University of Texas at Austin
  • Yichen Lin, Ph.D., Toxicology Program, Defense Date 04/2012, Current Position - Senior Toxicologist, Safety and Health Technology Center, Tainan City, Taiwan
  • Jessica (Dwyer) Myers, Ph.D., Molecular Biology Program, Defense Date 10/2012, Current Position - Toxicologist, Texas Commission on Environmental Quality, Austin, TX
  • James Harman, Ph.D., Toxicology Program, Defense Date 12/2013, Current Position - Toxicologist, Conestoga-Rovers & Associates, Dallas, TX
  • Angela Stermer, Ph.D., Toxicology Program, Defense Date 08/2016, Current Position - Study Director, Developmental and Reproductive Toxicology, Merck, PA
  • Rashin Ghaffari, Ph.D., Molecular Biology Program, Defense Date 04/2018, Current Position - Postdoctoral Fellow at Corteva Agriscience, Newark, DE

Masters Degree Students

Dr. Yang Ye, MD
  • Kathleen Wurm, M.S., Toxicology Program, Defense Date 11/1999, Current Position - Occupational Health & Safety Specialist II, Division of Public Safety, University of Connecticut, Storrs, CT
  • Karen Romelfanger, M.S. (Co-advisor with Dr. Miller), Neuroscience Program, Defense Date 05/2002, Current Position - Assistant Professor, Emory University School of Medicine
  • Yang Ye, M.S., Toxicology Program, Defense Date 08/2005, Current Position - Family Physician, Kaiser Permanente, Midland, Texas

Undergraduate Students

Special Topics:

Dr. Adrian Nanez
  • Adrian Nañez, Summer 1997-Spring 2002
  • Steven Pavlas, Fall 1998-Spring 1999
  • Cathy Lau, Summer-Fall 2000
  • Bianca Gonzales, Summer 2001-Spring 2002
  • Mohammed Akbani, Fall 2000-Spring 2002
  • Azuka Onwudiegwu, Fall 2002
  • Marissa Meyers, Spring 2003
  • Junaid Akbani, Fall 2002-Spring 2003
  • Ruth Starvolt, Fall 2003-Spring 2004, Fall 2004-Spring 2005
  • Tiffany Robinson, Fall 2004-Spring 2005, Fall 2005-Spring 2006
  • Borna Karamzadeh, Spring 2007 - Summer 2007
  • Brittany Robison, Fall 2007-Spring 2008, Fall 2008
  • Linda Do, Spring 2007-Summer 2008, Fall 2008 -Spring 2009
  • Vitali Azouz, Summer 2009
  • Emily Lao, Fall 2011-Fall 2012
  • Susan De La Torre, Fall 2013-Spring 2014
  • Puneet Patel, Fall 2013-Spring 2014
  • Jevon Chu, Fall 2015-Summer 2016
  • Alan Hao, Spring 2017
  • Shavi Hewage, Fall 2017 – Spring 2020
  • Kim B Ly, Spring 2018 – 2019

Pharmacy Honors Program:

  • Ashkya Patel, Fall 1998
  • Greg Russell, Summer 1998, Fall 1998, Spring 1999
  • Samantha Alexander, Fall 2007, Spring 2008
  • Scott Mosley, Fall 2010-Spring 2011

Pharmacy Council, Disease Awareness Project on Sun Safety:
(Students listed are the Pharmacy Council Chairs of the Disease Awareness Committee)

  • Grace Wang, Spring 2006
  • Clara Ngo, Fall 2006-Summer 2007
  • Lynn Stamps, Fall 2007-Summer 2008

Summer Minority Undergraduate Research Program:

Azuka Onwudiegwu
  • Claribel Luciano Montalvo, Summer 2000
  • Bianca Gonzales, Summer 2001
  • Azuka Onwudiegwu, Summer 2002
  • Patrice Miller, Summer 2002
  • Baru-Ta Foma, Summer 2003
  • Cynthia Roland, Summer 2003
  • Christopher Piña, Summer 2004
  • Joshua Hubbard, Summer 2005
  • Keith Rodriguez, Summer & Fall 2005
  • Tiffany Robison, Summer 2006
  • Chelsea Perfect, Summer 2011
  • Jacob Donchez, Summer 2012
  • Vineet Ravoori, Summer 2013

 

Publications

Testis cross section from Richburg lab

Please visit Google Scholar for an updated list of publications from the Richburg Laboratory.

For a curated site of Richburg publication PDFs, please visit Research Gate.

News

Best Paper Award for 2021!

Exciting news! The Society of Toxicology (SOT)'s Reproductive and Developmental Specialty Section has just announced that a recent paper published by UT Pharmacy lab group Ross Gilette, Richa Tiwary, Jorine Voss, Shavini Hewage and John Richburg in the Society's journal "Toxicological Sciences" (Oxford Academic Press) has won the "Best Paper" award for 2021!

New publication for 2021!

Gillette, R, Tiwary, R, Voss, JJLP, Hewage, S and Richburg, JH (2021). Peritubular macrophages are recruited to the testis of peri-pubertal rats after mono-(2-ethylhexyl) phthalate exposure and is associated with increases in the numbers of spermatogonia. <published on-line 5/19/2021, https://doi.org/10.1093/toxsci/kfab059>

Dr. Richburg on the news!

In 2010, Dr. Richburg spoke with KXAN News about his research in how male fertility can be affected by environmental toxins found in everyday plastic products and by chemotherapy in the treatment of testicular cancer.  The video is viewable at this link.

Contact Information
Phone:
Campus location:
PHR 4.220

US Mail Address:
The University of Texas at Austin
PHR 4.220
2409 University Ave., A1915
Austin, TX 78712

FEDEX Address:
107 W. Dean Keeton St.
PHR 4.220
The University of Texas at Austin
Austin, TX 78712