Skip to content

Menu
  • USC Stem Cell
  • About
    • Stem Cell FAQs
    • Mission and History
    • California’s Leadership in Stem Cell Research
    • Founding Supporters and Ambassadors
    • Well-being
    • Jobs
  • News & Events
    • News
    • Events
    • Videos
    • Impact Reports and Newsletters
  • Research
    • Department Faculty
    • Eli and Edythe Broad Center Faculty
    • Research Facilities
    • USC+CHLA Alpha Clinic
    • Translational Research Committee
    • USC Stem Cell Research Oversight Committee (SCRO)
    • Apply to Become Center Faculty
  • Education & Training
    • Undergraduate
    • Master’s Program
    • PhD Program
    • Medical Education
    • Postdoctoral Opportunities
    • Our Trainees
  • Funding
  • Inclusive Excellence
  • Support Us
  • Contact
    • Directory
    • Subscribe
  • Search

USC study reveals a protein that keeps people—and their skeletons—organized

By  Cristy Lytal

Posted November 12, 2013
Reading Time 2 minutes

in this section

  • News
  • Events
  • Videos
  • Impact Reports and Newsletters

read this next

Rendition of developing vertebrate bones. In their study, Hojo and colleagues address the transcriptional action and evolution of Sp7/Osx, a key determinant of vertebrate-restricted bone forming osteoblasts. (Painting by Kristen Chen; courtesy of Developmental Cell 2016)

USC Stem Cell study illuminates bone formation and vertebrate evolution

  • Follow us on
  • Like us on
  • Follow us on
  • Follow us on
Mouse femur with enchondroma-like structure (Image by Lick Lai)
Mouse femur with enchondroma-like structure (Image by Lick Lai)

Most people think that their planners or their iPhones keep them organized, when proteins such as liver kinase b1 (Lkb1) actually have a lot more to do with it. New research from postdoctoral fellow Lick Lai in the lab of USC scientist Andy McMahon published in Proceedings of the National Academy of Sciences (PNAS) sheds light on how this important protein keeps people organized on a basic level by promoting orderly skeletal growth and preventing skeletal tumors.

In a developing embryo, many bones form based on cartilage templates. The study found that to form these templates, Lkb1 protein controls the progression of immature, dividing cartilage cells into larger, mature and fully differentiated cartilage cells. Without Lkb1, the population of immature cartilage cells disproportionately increases, leading to skeletal tumors.

The way that Lkb1 controls the differentiation of cartilage cells is by suppressing what’s known as the “mammalian target of rapamycin (mTOR) pathway” — a very important complex of molecules that coordinates growth in response to available nutrients and other factors. Problems with the mTOR pathway have been implicated in a host of human diseases, including diabetes, obesity, depression and many cancers.

The influence of abnormal Lkb1 isn’t restricted to the skeleton, however. Mutant forms of Lkb1 are frequently present in patients with lung, cervical, breast, intestinal, testicular, pancreatic and skin cancers, and in patients with the Peutz–Jeghers syndrome, characterized by benign polyps in the gastrointestinal tract.

“By understanding Lkb1 and the mechanisms that control normal skeletal development, we also learn how we might prevent this development from going awry in cancers and other disorders,” said McMahon, who directs the USC Stem Cell initiative and the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC.

Co-authors Brendan N. Lilley and Joshua R. Sanes from Harvard University also contributed to the paper.

National Institutes of Health/ National Institute of Diabetes and Digestive and Kidney Diseases Grant P01 DK056246 provided funding for the work in the McMahon lab, and Dr. Lai is a recipient of an Arthritis Foundation Postdoctoral fellowship.

Read more about: Muscles and Skeleton
Mentioned in this article: Andrew P. McMahon, PhD, FRS

Post navigation

← Requests for Applications (RFAs) for the CIRM Alpha Stem Cell Clinics (CASC) Network
Winner of the October 2013 USC Stem Cell Image of the Month Contest →
Keck School of Medicine of USC
1975 Zonal Ave.
Los Angeles, CA 90033
Google Map
Phone: (323) 442-1900
Hours:
Monday–Friday
7:30am–5:00pm PST
Resources For
  • Current Students
  • Faculty & Staff
  • Patients
  • Community
  • Press
  • Visitors
Areas of Focus
  • Education & Training
  • Research
  • Patient Care
  • Community
Departments and Offices
  • Departments
  • Institutes and Centers
  • Research Programs
  • Administrative Offices
About Keck
  • History
  • Leadership
  • Annual Report
  • Digital Accessibility
Intranet
  • Privacy Notice
  • Notice of Non-Discrimination
  • Smoke-Free Policy

Copyright © 2025 University of Southern California

  • Research
    • Research HomeCutting-edge research drives innovation in healthcare at the Keck School of Medicine
    • Where Research Happens
    • Research Funding
    • Training and Education
    • Researcher Resources
    • Collaborate and Partner
  • Education
    • Education HomeNurturing future healthcare leaders through excellence in education
    • MD Program
    • Residencies and Clinical Fellowships
    • PhD Programs
    • Master’s Programs
    • Professional Programs
    • Post-Doctoral Researchers
    • CME, Certificate & Undergraduate Programs
  • Departments, Institutes & Centers
    • Basic Science and Clinical DepartmentsExploring foundational science and specialized clinical fields
    • Institutes and Centers
    • Research Programs
  • About
    • About the Keck SchoolDiscover the mission, history, and vision of the Keck School of Medicine
    • History
    • Leadership
    • Dean’s Corner
    • Life in Southern California
    • Visit
  • Our Faculty
  • Current Students
  • Newsroom
  • Events Calendar
  • Support the Keck School
  • USC.edu
  • Are you a Patient?