Stefano Di Talia, Ph.D. - US grants

DESCRIPTION (provided by applicant): The candidate is currently a Life Science Research Fellow in the laboratory of Professor Eric Wieschaus in the Department of Molecular Biology at Princeton University. The candidate was awarded a PhD from The Rockefeller University for research in quantitative cell biology. During the Postdoctoral Fellowship, the candidate is transitioning to the field of developmental biology. The candidate will apply the quantitative and analytical techniques from previous research as well as further training in genetics and developmental biology to the study of the control of timing of cell behaviors during embryonic development. The NIH Pathway to Independence Award would provide necessary support to the candidate during this transition period. The award would allow the candidate to acquire new skills in genetics and developmental biology as well as to establish novel research directions. The candidate will benefit from the opportunity to take the graduate course 'Genetics of Multicellular Organisms' at Princeton University as well as the courses 'Eukaryotic Gene Expression' and 'Gene Regulatory Networks for Development' at Cold Spring Harbor Laboratory and at the Marine Biological Laboratory respectively. The candidate will study the molecular mechanisms ensuring precise temporal regulation of cell division through control of gene expression, signaling and protein degradation during Drosophila embryonic development. During the K99 phase of the award, the candidate will 1) Develop theoretical analysis of the integration time of signaling systems 2) Perform genetic screens and molecular biology experiments to identify regulators of Cdc25 transcription (rate-limiting activator of the cell cycl) 3) Determine the importance of regulation of Cdc25 protein degradation at the maternal-to-zygotic transition, a critical developmental transition. These aims will be accomplished by combining genetics, embryology, molecular biology, quantitative live imaging and mathematical modeling. During the R00 phase of the award, the candidate will extend the research by determining the molecular mechanisms ensuring that Cdc25 is transcribed and degraded with high temporal precision and by analyzing signaling systems beyond cell cycle control. The candidate ultimately desires to pursue an academic career in research and teaching.

During embryonic development each body part is programmed to contain an accurate number and arrangement of cells. This accuracy is achieved through precise regulation of cell proliferation in the face of the molecular noise characteristic of the biochemical processes regulating the cell cycle. The molecular mechanisms by which embryos suppress noise remain poorly understood. Uncovering these mechanisms is a central goal of Developmental Biology and requires the development of novel methodologies to measure quantitatively cellular dynamics in living embryos. The overarching goal of this proposal is to reveal the molecular mechanisms that ensure accurate control of the cell cycle during Drosophila embryonic development. We will study the molecular mechanisms ensuring precise temporal regulation of cell division through control of gene expression, signaling and protein degradation. We have developed live imaging and computational approaches to quantify the dynamics of the major enzymes regulating the cell cycle during embryonic development. In Aim 1, we will use biosensors for the activities of of Cdk1 and Chk1 to identify how chemical waves act to synchronize mitosis in the syncytial embryo. In Aim 2, we will use live imaging to dissect the molecular mechanisms that ensure the cell cycle remodeling at the maternal-to-zygotic transition. In Aim 3, we will elucidate how transcriptional regulation of cdc25string ensures precise regulation of the timing of mitosis during gastrulation. These experiments will define a novel quantitative framework for uncovering how the cell cycle is regulated accurately during embryonic development.

Abstract     Mammalian  bone  has  the  capacity  throughout  life  to  regenerate  in  response  to  fracture  injury.  However,  there  is  a  ceiling  for  this  regenerative  potential,  with  hurdles  to  regeneration  after  a  major  trauma  like  limb  amputation. This has a significant socioeconomic impact, as it is estimated that at least one in two Americans  over  age  50  is  expected  to  have  or  be  at  risk  of  bone  disease,  and  every  year  an  estimated  1.5  million  individuals suffer a fracture due to bone disease. Recently, we have developed imaging methods to study how  osteoblasts  drive  bone  regeneration  in  zebrafish,  which  display  robust  regeneration  after  major  injury  to  bony  structures  like  their  fins,  scales,  and  jaws.  Our  goal  is  to  exploit  this  regenerative  capacity,  new  imaging  platforms we have created, and the molecular genetic approaches available in zebrafish to improve our ability  to understand and manipulate the regenerative capacity of bone. The goal of this proposal is to generate an in  toto map of the cellular and signaling events that regenerate patterned skeletal bone. Our experiments will test  the  hypothesis  that  correct  patterning  of  regenerating  bone  requires  dynamic  signaling  events  that  control  osteoblast  behaviors  at  individual  and  population  levels.    1)  We  will  use  long-­term  live  imaging,  labeling  with  photo-­convertible  proteins,  and  computational  analysis  to  generate  a  detailed  map  of  how  cell  proliferation,  hypertrophy  and  cellular  flows,  and  interactions  with  neighboring  tissues  drive  bone  regeneration.  2)  We  will  use  cutting  edge  biosensors,  live  imaging,  computational  approaches,  and  mathematical  modeling  to  dissect  how  traveling  waves  of  chemical  signals  stimulate  the  growth  of  a  regenerating  osteoblast  population.  3)  We  will use transcriptome profiling approaches to derive further insights on the dynamics of growth factor signaling,  including  single-­cell  sequencing-­based  approaches  to  link  gene  expression  programs  with  osteoblast  behaviors.  These  experiments  will  define  a  novel  quantitative  framework  for  understanding  how  osteoblast  behaviors orchestrate bone regeneration.