#ScienceSaturday posts share exciting scientific developments and educational resources with the KAND community. Each week, Dr. Dominique Lessard and Dr. Dylan Verden of KIF1A.ORG summarize newly published KIF1A-related research and highlight progress in rare disease research and therapeutic development.
Single-Molecule Studies on the Motion and Force Generation of the Kinesin-3 Motor KIF1A
“The only difference between screwing around and science is writing it down.” ~ Alex Jason, crime scene analyst and Mythbusters contributor
Typically in #ScienceSaturday we focus on new ideas and data being generated by researchers, studies that add to our understanding of KIF1A and KAND. But science isn’t just a collection of results, it’s a process; it fundamentally relies on conducting transparent experiments that can be repeated and built upon with common tools. This week we’re highlighting work by Dr. Lu Rao and Dr. Arne Gennerich at Albert Einstein University, who have published standardized instructions (called protocols) to study molecular traits of KIF1A. Below we will describe some of the methods they outlined and how they relate to accelerating KAND research.
- Generating dimerized KIF1A: To understand how mutations change KIF1A movement, researchers perform experiments on simplified systems; KIF1A can be expressed in cells on a dish, or even purified and placed directly on microtubules. But under normal conditions KIF1A might not form active pairs (called dimers) without the proper cargo, which can make studying motor properties in these systems messier. The first protocol of this paper creates a customized version of KIF1A that lacks the cargo-binding domain and automatically forms dimers so researchers can study the traits of active KIF1A motors.
- KIF1A mutagenesis: Mutagenesis refers to the generation of mutations; in this case, specific disease-relevant mutations in KIF1A. This protocol provides a standardized way of creating different KIF1A mutations so they can be studied side-by-side.
- MT-binding and -release assay: When studying KIF1A movement along microtubules, it is important that each motor can bind to the microtubule in the first place, but some KIF1A molecules may not bind due to reasons other than designed mutations. This assay ensures that an experiment includes functional KIF1A proteins for more reliable results.
- TIRF microscopy: Total Internal Reflection Fluorescent (TIRF) Microscopy is a technique that only images molecules directly next to a glass surface. By coating glass with microtubules and then adding KIF1A molecules, researchers can capture videos of KIF1A movement for analysis! Because KIF1A is a motor protein, these videos are incredibly useful for understanding subtle differences between healthy and mutant KIF1A function including speed, distance traveled, and de-attachment and re-attachment rates.
- Optical tweezers: Because KIF1A carries cargo and competes with other motor proteins, it is important to understand how much force healthy and mutant KIF1A can generate, similar to a truck’s horsepower. Optical tweezer techniques attach KIF1A molecules to large beads that are trapped in place by a laser. This laser can change the amount of resistance, allowing researchers to see how KIF1A pulls against light or heavy loads. You can hear more about optical tweezers in our interview with Dr. Will Hancock.
As a hub for an ever-expanding Research Network of scientists investigating KIF1A, KIF1A.ORG values sharing data and methods so our community can make concerted efforts to understand KIF1A and find therapeutic targets for KAND. We are grateful to Drs. Rao and Gennerich for creating these accessible research approaches.
FDA drafts guidance on pediatric clinical pharmacology studies
In medicine and drug development, a crucial imperative is to treat the patient, not the disease. Even drugs that reverse molecular aspects of a disease must be considered in the context of their safety and impact on quality of life. This is especially important for children, whose development opens them up to vulnerabilities when treated with drugs. Their small size, differential metabolism, and continuously changing biology are all reasons children may react differently to a drug than their adult counterparts. For this reason, the FDA is providing guidance for developing clinical trials in pediatric populations. The guidance includes a number of measures intended to protect children in the testing of potential therapies:
- Considerations for participants of multiple pediatric ages including neonates, infants, children, and adolescents.
- Evidence of a treatment’s direct benefit for pediatric study participants.
- Drug metabolism data, including maximal dosage, absorption, and secretion.
- Ethical justification for study endpoints, especially for invasive measurements.
These guidelines demonstrate the prioritization of keeping children safe even as they participate in the search for a cure for their diseases.