mRNA translation biology

The Selectivity of mRNA Translation Biology

Tissue
Tissue specific regulation
Cells
Normal vs. cancer cells
Pathway
Up or down regulated in pathological pathway
mRNA
Sequence and structure

The biology of mRNA translation is an emerging science of the last decade. At Anima Biotech, we are experts in this science.

Our target space encompasses proteins that have specific biological roles in coordinating and regulating translation of individual mRNAs and pathways, allowing for the discovery of small molecules that selectively modulate the translation of almost any protein of interest.

Anima's translation modulators can be tissue or disease-specific

Tissue selective mRNA localization

Specific mRNA regulated in a tissue selective manner



Cells from Tissue A or Tissue B were treated with induction cocktail for 72 hours and imaged at different timepoints and a probe specific to a single mRNA was visualized (orange). Cells from Tissue A exhibited low but evident amounts of protein X mRNA in the cytoplasm and two transcription sites in the nucleus at steady state, before induction. Following induction, the protein X mRNA levels increased over the tested time period as demonstrated by increased spot sizes in the nucleus, indicating higher transcription rate, and increase in accumulation of mRNA in the cytoplasm. In cells from Tissue B on the other hand, protein X mRNA was undetectable in cytoplasm at steady state. However, many spots were detected in the nucleus, indicating a unique mode of regulation, storing the mRNA in the nucleus. Twenty-four hours following induction, protein X mRNA levels in the cytoplasm remained, but an increase in the intensity of spots in the nucleus was detected, suggesting mRNA was accumulating there. Forty-eight to seventy-two hours after induction, the mRNA was transported from the nucleus to the cytoplasm, until protein X mRNA was completely exported from the nucleus to cytoplasm. These findings reveal a unique regulation process on mRNA translation for the same mRNA in different cells.

Mutated mRNA selective localization

Mutated mRNA is regulated in a selective manner



Cells expressing a wildtype (W.T) or Mut (Mutated) mRNA variants of a protein of interest exhibit different mRNA localization phenotypes. This phenomenon implies different regulatory processes that operate selectively on the two forms of mRNA. W.T. mRNA expressing cells exhibit one high intensity spot in the nucleus (transcription site) and a pool of mRNAs in the cytoplasm. Mutant mRNA expressing cells show accumulation of mRNA in many nuclear spots, a phenotype observed in patients.

Specific mRNA localization to RNA granules upon compound treatment

Compound from series X induces mRNA localization to RNA granules resulting in the decrease of mRNA translation



Cells were treated with translation modulators of a specific mRNA, identified at Anima. Compounds belong to three different compound families. Series X compound re-localizes the specific mRNA from being distributed all over the cells to specific spots in the cell (marked by white arrows). The mRNA sequestration in the cytoplasmic granules inhibits ribosomes binding to this mRNA, resulting in the decrease of its translation. This mRNA-relocalization was series specific, indicating a unique mechanism of action for series X.

Our small molecules are targeting novel proteins involved in the regulation of mRNA translation

Protein synthesis is a high energy consuming process. The translation machinery, therefore, must pose the ability to respond rapidly to various environmental cues, to conserve energy. Subsequently, distinct mechanisms enabling cells to respond quickly and efficiently to extracellular signals have evolved. These mechanisms include:

  1. Coordinated changes in translation initiation such as changing the components of the initiation complex
  2. Shuttling of mRNA, in a protected manner, to different cellular compartments where their translation is needed
  3. The use of non-protein vehicles to regulate mRNA stability, such as short lived small noncoding RNAs (termed microRNA)

In different tissues, cells need to respond to distinct sets of cues. For example, mRNA translation in neurons is localized to different cellular compartments. Ribosomes are located around the nucleus, along exons and at nerve endings to enable supply on demand of specific proteins required at these different cellular locations. Thus, to enable these diverse requirements and responses, mRNA translation has developed elaborate, tissue specific and mRNA selective regulatory systems.

mRNA
Biology
Ribosome accessory proteins
Epitranscriptomics (mRNA modifying proteins)
Splicing factors
Modifiers of ribosomal proteins (Kinases, methylases etc...)
tRNA abundance and control
RNA binding proteins

mRNA translation is a highly regulated process: once mRNA is transcribed, it is bound by RNA binding proteins (RBPs) in a highly specific and selective manner. An additional layer of regulation is mediated by modifications of ribonucleotides in mRNA (epitranscriptomics), that modulate RBP-mRNA interactions. Together, these mechanisms regulate mRNA processing, nuclear export and mRNA steady state levels. RBPs regulate the localization of mRNAs in the nucleus and cytoplasm, thereby determining mRNA translation in a temporal and spatial manner. Moreover, ribosomes, much like RNA polymerases and proteasomes, have accessory proteins associated with them in a tissue and signal-specific manner. This lends mRNA translation an additional layer of selectivity.


Bi-directional mRNA translation regulation

Targeting the regulatory mechanisms of mRNA translation enables the discovery of compounds that not only decrease but can also increase protein translation in a selective manner.

The images below are taken from Anima’s Collagen I program. During the screening campaign, both COL1A1 mRNA translation inhibitors and activators were identified.



A compound which reduces the rate of translation of Collagen I, decreases the light. Subsequently, this compound reduces Collagen I protein accumulation (middle panel).

A compound which enhances the rate of translation of Collagen I, increases the light. The compound also enhances production of Collagen I protein (right panel).