Wendy Hanna-Rose Associate Professor of Biochemistry and Molecular Biology 104D Life Sciences Building, University Park, PA 16802 Phone: (814) 865-7904 Fax: (814) 863-7024 E-mail: wxh21@psu.edu B.A. in Biology , Anderson University Ph.D. in Microbiology & Molecular Genetics, Harvard University Postdoctoral, Molecular, Cellular & Developmental Biology, University of Colorado, Boulder Hanna-Rose Lab Web Site

Molecular Genetics of Metabolism and Development in C. elegans

The Caenorhabditis elegans model system

During animal development, cells of various identities must coordinate to organize themselves into functional structures.  The overarching goals of the Hanna-Rose lab are to elucidate fundamental mechanisms of how development is genetically programmed and controlled and how the development of the animal body plan is coordinated among organs and throughout the organism. We study development of the reproductive structures in the nematode Caenorhabditis elegans as models to address questions of how development is controlled. The nematode C. elegans is a simple organism with few cells.  Yet, its development and physiology are sufficiently complex to represent the major mechanisms in animal development and homeostasis. The invariant cell lineage provides a reproducible background for deducing the molecular intricacies of complex processes with cellular resolution.  C. elegans has been a valuable model for probing the impact of metabolism in aging and health and principles deduced in this system are relevant to higher organisms, including humans. By studying how and why development in C. elegans goes awry, we propose that we will gain insight into the causes of developmental disease, such as birth defects, in humans.

Research Projects

1. Biological roles of NAD+ salvage biosynthesis in cell survival and development

Nicotinamide (NAM) and nicotinic acid (NA) are forms of the essential vitamin B3, which has therapeutic effects in diseases such as diabetes, stroke and coronary artery disease.  NAM and NA are precursors for biosynthesis of nicotinamide adenine dinucleotide (NAD+).  NAD+ is a central molecule in cellular metabolism and a co-substrate for NAD+ consuming enzymes that regulate key biological processes, such as longevity and stress responses.   NAD+ and NAM each regulate the enzymatic activity of these NAD+ consumers, eliciting specific biological responses.

Figure 1. NAD+ salvage biosynthesis pathways in vertebrates and invertebrates. This pathway regulates NAD+ consumer enzymes that impact numerous aspects of normal cell physiology and function.

Nicotinamide (NAM) and nicotinic acid (NA) are forms of the essential vitamin B3, which has therapeutic effects in diseases such as diabetes, stroke and coronary artery disease.  NAM and NA are precursors for biosynthesis of nicotinamide adenine dinucleotide (NAD+).  NAD+ is a central molecule in cellular metabolism and a co-substrate for NAD+ consuming enzymes that regulate key biological processes, such as longevity and stress responses.   NAD+ and NAM each regulate the enzymatic activity of these NAD+ consumers, eliciting specific biological responses.

Serious dietary deficiency of vitamin B3 causes pellagra in humans, which results in life-threatening abnormalities in skin, brain and gastro-intestinal tract functions.  While the biochemistry of NAD+ salvage from vitamin B3 precursors is well studied, and the biological impacts of disruption of this biosynthetic pathway can be easily observed, the molecular mechanisms that mediate the dramatic effects on organ function, including whether perturbed NAD+ or metabolite levels are causative, are still mysterious.  We use the C. elegans model to investigate the biology of NAD+ metabolism.

We have made the novel discovery that mutation of the first enzyme in the NAM to NAD+ salvage pathway, PNC-1 nicotinamidase in C. elegans, has specific biological roles during development.  Mutations in PNC-1 cause developmental and functional defects in the reproductive system of hermaphrodites and males; the development of the gonad is delayed in both sexes, four uterine cells die by necrosis, the male spicules are crumpled, the hermaphrodites are egg-laying defective, and the males cannot mate. 

There has been considerable debate over the relative importance of salvage activity modulation of NAM levels versus NAD+ levels in vivo.  We have made an important contribution to this open question by showing that the developmental delay of the gonad and the necrosis of the uv1 cells are separable phenotypes that result in the absence of PNC-1 activity from depletion of the salvage pathway product (NAD+) or accumulation of PNC-1 substrate (nicotinamide), respectively.  Thus, regulation of substrate as well as product level is key to the biological activity of PNC-1.  We have also identified a secreted form of the enzyme and demonstrated its function in vivo.  Because nicotinamide phosphoribosyltransferease (Nampt), the equivalent enzyme involved in nicotinamide recycling to NAD+ in vertebrates, is also secreted, we postulate an evolutionarily conserved extracellular role for NAD+ biosynthetic enzymes and are investigating this idea. 

Ongoing studies are aimed at investigating other enzymes in the salvage pathway and determining the NAD+ consumers that mediate the specific developmental phenotypes

2. Gene Regulation in C. elegans

By identifying and studying genetic suppressors of egl-13, which is a Sox domain transcription factor important for maintenance of uterine seam cell fate, we have revealed a novel function for the HIM-8 zinc finger protein and the related ZIM proteins in gene regulation (Nelms and Hanna-Rose, 2006 and Sun et al., 2007).  Mutations in the zinc fingers of HIM-8 can suppress missense mutations in the DNA binding domain, but not null alleles, of EGL-13 and every other transcription factor that we have tested.  Prior to our work, HIM-8 was believed to act exclusively in chromosome segregation during meiosis; HIM-8 promotes pairing of the X chromosomes, while ZIM-1, ZIM-2 and ZIM-3 control pairing of the autosomes.  We used genetic analyses to prove that HIM-8 acts independently of the germ line to antagonize the activity of EGL-13; neither the germ line nor compromised pairing of the X chromosomes is required to observe EGL-13 suppression upon mutation of HIM-8.  Furthermore, the meiotic and somatic roles are separable; there are mutations in HIM-8 that compromise pairing but not gene regulatory activity.  This gene regulatory activity of HIM-8 is shared among the related ZIM proteins.  Mutations in the zim genes can also suppress missense mutations in transcription factors. We are actively pursuing experiments to determine the unusual mechanism whereby this novel family of genes regulates somatic gene activity.

Representative Publications:

• Kathleen A. Estes and Wendy Hanna-Rose (2009). The anchor cell initiates dorsal lumen formation during C. elegans vulval tubulogenesis. Developmental Biology doi:10.1016/j.ydbio.2009.01.034.
• Ryan W. Johnson, Leah Y. Liu, Wendy Hanna-Rose, and Helen M. Chamberlin (2009) The C. elegans heterochronic gene lin-14 coordinates temporal progression and maturation in the egg-laying system. Developmental Dynamics 238(2):394-404.
• Nicholas N. Lyssenko, Yana Miteva, Simon Gilroy, Wendy Hanna-Rose, and Robert A. Schlegel (2008). An unexpectedly high degree of specialization and a widespread involvement in sterol metabolism among the C. elegans putative aminophospholipid translocases. BMC Developmental Biology 8 (1):96.
• Nicholas N. Lyssenko, Wendy Hanna-Rose, and Robert A. Schlegel. (2007) A cognate putative nuclear localization signal effects strong nuclear localization of a GFP reporter and facilitates gene expression studies in C. elegans. BioTechniques 43(5):596-600.
• Kathleen A. Estes, Rasika Kalamegham, and Wendy Hanna-Rose. (2007) Membrane localization of the NlpC/P60 family protein EGL-26 correlates with regulation of vulval cell morphogenesis in C. elegans". Developmental Biology 308(1):196-205.
• Hongliu Sun, Brian L. Nelms, Sama F. Sleiman, Helen M. Chamberlin and Wendy Hanna-Rose. (2007) Genetic modulation of gene activity in C. elegans by HIM-8 and related C2H2 zinc finger proteins. Genetics 177(2):1221-6.
• Li Huang and Wendy Hanna-Rose. (2006) EGF signaling overcomes a uterine cell death associated with temporal mis-coordination of organogenesis within the C. elegans egg-laying apparatus. Developmental Biology 300(2):599-611.
• Brian Nelms and Wendy Hanna-Rose. (2006) C. elegans HIM-8 has a meiosis-independent function in antagonizing the activity of the EGL-13 Sox protein. Developmental Biology 293(2): 392-402.
• Wendy Hanna-Rose and Min Han. (2002) The Caenorhabditis elegans EGL-26 protein mediates vulval cell morphogenesis. Developmental Biology 241(2):247-258.
• Kelly Grant, Wendy Hanna-Rose and Min Han. (2000) sem-4 Promotes Vulval Cell-Fate Determination in Caenorhabditis elegans through Regulation of lin-39 Hox. Developmental Biology 223: 496-506.
• Wendy Hanna-Rose and Min Han. (1999) COG-2, a Sox domain protein necessary for establishing a functional vulval-uterine connection in Caenorhabditis elegans. Development 126(1): 169-179.

   

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