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New Research Uncovers Mechanisms of Gene Transcription Regulation and Termination in Disease

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WEHI Research Uncovers Novel Mechanisms in Gene Expression, Advancing Disease Understanding

New research from the Vervoort Laboratory at WEHI has advanced the understanding of RNA Polymerase II (RNAPII)-driven transcription, a fundamental process in gene expression. Separate presentations by Laura Corso and Oliver Ozaydin detailed novel functions of the Integrator complex in transcriptional regulation and identified a key termination axis influencing the response to transcription elongation stress in cancer. These findings contribute to the understanding of mechanisms underlying various human diseases, including cancer, neurological disorders, and autoimmunity.

Understanding RNAPII Transcription and Its Disease Links

RNA Polymerase II (RNAPII)-driven transcription is a highly regulated process essential for normal cellular development and homeostasis. Dysregulation of this process has been observed in various human diseases, including neurological disorders, autoimmunity, and cancer. The progression of RNAPII transcription is also regulated by cyclin-dependent kinases (CDKs), which are frequently implicated in human diseases.

Insights into the Integrator Complex

Laura Corso's PhD research focused on the Integrator complex, which comprises 15 subunits and plays a role in regulating the initiation, pausing, and termination of transcription.

The complex's endonuclease and phosphatase activities are involved in the premature termination of paused RNAPII by counteracting CDK9 pause-release activity.

Corso's findings, derived from genomics, proteomics, and CRISPR knock-out screening, include:

  • The discovery of a non-canonical Integrator complex.
  • Identification of a mechanism for Integrator complex recruitment.
  • The paralogue of Integrator subunit INTS6, INTS6-Like (INTS6L), can integrate into the complex and exhibits functions redundant to INTS6.
  • INTS6 and INTS6L do not share the CDK9 antagonism activity observed in other Integrator components.
  • The Integrator subunit INTS12 links the NELF complex to Integrator, a process that prevents the release of defective RNAPII molecules into elongation.

This research aims to deepen the understanding of RNAPII transcription, potentially contributing to the identification of new therapeutic targets in diseases where this regulatory process is impaired.

Identifying a Termination Axis in Cancer

Oliver Ozaydin's research explored the termination dynamics influencing the response to transcription elongation stress, particularly in the context of cancer. The loss of CDK12, a cyclin-dependent kinase, is known to induce widespread elongation stress, leading to premature transcript termination and reduced RNAPII processivity. Recurrent CDK12 mutations primarily affect DNA damage response genes and are found in up to 12% of breast, bladder, colorectal, and endometrial cancers. The specific factors responsible for premature transcript termination under elongation stress, which may contribute to cancer progression, had previously not been fully understood.

Ozaydin's study identified a SCAF4/UBE3D/CPSF3 termination axis through genome-wide CRISPR screening, genomics, and proteomics techniques.

Key findings include:

  • Disrupting this identified axis leads to widespread resistance to elongation stress.
  • The disruption restores full-length transcription in over 60% of disproportionately long and AT-rich genes.
  • The loss of members of this axis increases RNAPII elongation rates, suggesting a connection between termination factors and RNAPII elongation rate dynamics.

This research identifies factors underlying the premature termination of RNAPII under elongation stress. It also highlights potential mechanisms that could contribute to therapeutic resistance to small molecule inhibitors currently in preclinical development for CDK12-driven cancers.

Broader Implications

Both research efforts from the Vervoort Laboratory contribute to a more detailed understanding of the complex regulatory processes governing RNAPII transcription.

The findings may aid in identifying new therapeutic strategies for diseases linked to transcriptional dysregulation, including various cancers and other conditions.