Investigating the human teashirt genes TSHZ2 and TSHZ3 in pancreatic and endocrine lineage commitment using genome modified human embryonic stem cells (hESC)

• Main Author: Eng, Shermaine Zi Hui
• Other Authors: Norris Ray Dunn
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Biological sciences
• Online Access: http://hdl.handle.net/10356/63169
• Institution: Nanyang Technological University

Pancreatic and Duodenal Homeobox 1 (PDX1) encodes a homeobox transcription factor expressed early in human embryonic pancreatic development. Loss of PDX1 results in complete pancreatic agenesis in both mice and man, indicating that it is a master regulator that coordinates the morphogenesis of this indispensable organ. PDX1 null cells fail to activate the pancreatic transcriptional program and divert to alternate fates in vitro. Corresponding microarray studies of PDX1 null mutant hESC with PDX1 Chromatin Immunoprecipitation-Sequencing data revealed a novel list of candidate PDX1 transcriptional targets including TSHZ2 and TSHZ3, the human homologs of the Drosophila homeotic gene teashirt, which is involved in gut and limb development. To better understand the role of these genes in human pancreatic development, the expression of TSHZ2 Variant 1 and TSHZ3 was characterized, revealing a novel spliced variant of TSHZ2 Variant 1. The CRISPR RNA-guided FokI-dCas9 nuclease (RFN) genome editing system was employed to create loss-of-function hESC lines. Two guide RNAs revealed successful editing in the 3’ end of TSHZ2 coding sequence while gRNAs tested for the 5’ end of TSHZ2 and for TSHZ3 were ineffective. Future knockout studies of TSHZ2 and TSHZ3 following ongoing redesign of gRNAs for genome editing will allow functionalization of these genes.