SAN JOSE — WeWork is leasing a new downtown San Jose location, a clear indication of an ongoing expansion by the co-working titan in the core area of the Bay Area’s largest city.

The newest WeWork location is at 152 N. Third St., a downtown San Jose office building owned by a group led by Gary Dillabough, a realty investor who is partnering with WeWork on the Bank of Italy office tower project a few blocks away.

The interest from WeWork in the North Third Street building appears to point to a rising focus on downtown San Jose, spurred by potential major developments in the area by tech titans such as Google and Adobe Systems.

WeWork agreed to lease 75,000 square feet at 152 N. Third St., according to commercial realty experts and information from sources with knowledge about the WeWork plans at that office building. The WeWork operation on North Third Street also shows up on the company’s website as a “just announced” location.

“It’s very encouraging that WeWork is getting more interested in downtown San Jose,” said Mark Ritchie, president of Ritchie Commercial, a realty firm.

In addition, WeWork has taken space in one of the Riverpark Towers office high-rises at 333 W. San Carlos St. and the tower at 75 E. Santa Clara St.

“WeWork is now into four buildings in downtown San Jose,” Ritchie said. “152 N. Third St. should function very well as a co-working building.”

A group headed by Dillabough bought the prominent nine-story office building in June, paying $40 million for the 149,000-square-foot property, which is perched on St. James Park.

“WeWork is proving itself to be a trailblazer in commercial real estate, changing the way that leases happen and doing a co-sharing of work space approach,” said Bob Staedler, principal executive with Silicon Valley Synergy, a land use and planning consultancy.

The activity of some tech titans has added to rising optimism about downtown San Jose.

Google has proposed a transit-oriented community near the Diridon train station where 25,000 people could work, including 15,000 to 20,000 employees of the search giant, in a development of office buildings, homes, restaurants, shops and parks.

Adobe Systems is actively planning an expansion of its existing three-building downtown San Jose headquarters campus by adding a fourth office tower at an adjacent site.

Despite these potentially vast new developments, it’s also important for the downtown to be bolstered by an array of smaller efforts, according to Staedler.

“We shouldn’t just stop everything until Google gets here,” Staedler said. “It’s getting home runs along with singles and doubles. The downtown needs all of these.”